Parkinson's Disease

Coding Dimension ID: 
313
Coding Dimension path name: 
Neurological Disorders / Parkinson's Disease

Site-specific integration of Lmx1a, FoxA2, & Otx2 to optimize dopaminergic differentiation

Funding Type: 
Tools and Technologies II
Grant Number: 
RT2-01880
ICOC Funds Committed: 
$1 619 627
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Stem Cell Use: 
iPS Cell
Cell Line Generation: 
iPS Cell
Embryonic Stem Cell
oldStatus: 
Active
Public Abstract: 
The objective of this study is to develop a new, optimized technology to obtain a homogenous population of midbrain dopaminergic (mDA) neurons in a culture dish through neuronal differentiation. Dopaminergic neurons of the midbrain are the main source of dopamine in the mammalian central nervous system. Their loss is associated with one of the most prominent human neurological disorders, Parkinson's disease (PD). There is no cure for PD, or good long-term therapeutics without deleterious side effects. Therefore, there is a great need for novel drugs and therapies to halt or reverse the disease. Recent groundbreaking discoveries allow us to use adult human skin cells, transduce them with specific genes, and generate cells that exhibit virtually all characteristics of embryonic stem cells, termed induced pluripotent stem cells (iPSCs). These cell lines, when derived from PD patient skin cells, can be used as an experimental pre-clinical model to study disease mechanisms unique to PD. These cells will not only serve as an ‘authentic’ model for PD when further differentiated into the specific dopaminergic neurons, but that these cells are actually pathologically affected with PD. All of the current protocols for directed neuronal differentiation from iPSCs are lengthy and suboptimal in terms of efficiency and reproducibility of defined cell populations. This hinders the ability to establish a robust model in-a-dish for the disease of interest, in our case PD-related neurodegeneration. We will use a new, efficient gene integration technology to induce expression of midbrain specific transcription factors in iPSC lines derived from a patient with PD and a sibling control. Forced expression of these midbrain transcription factors will direct iPSCs to differentiate into DA neurons in cell culture. We aim at achieving higher efficiency and reproducibility in generating a homogenous population of midbrain DA neurons, which will lay the foundation for successfully modeling PD and improving hit rates of future drug screening approaches. Our study could also set a milestone towards the establishment of efficient, stable, and reproducible neuronal differentiation using a technology that has proven to be safe and is therefore suitable for cell replacement therapies in human. The absence of cellular models of Parkinson’s disease represents a major bottleneck in the scientific field of Parkinson’s disease, which, if solved, would be instantly translated into a wide range of clinical applications, including drug discovery. This is an essential avenue if we want to offer our patients a new therapeutic approach that can give them a near normal life after being diagnosed with this progressively disabling disease.
Statement of Benefit to California: 
The proposed research could lead to a robust model in-a-dish for Parkinson’s disease (PD)-related neurodegeneration. This outcome would deliver a variety of benefits to the state of California. First, there would be a profound personal impact on patients and their families if the current inevitable decline of PD patients could be halted or reversed. This would bring great happiness and satisfaction to the tens of thousands of Californians affected directly or indirectly by PD. Progress toward a cure for PD is also likely to accelerate the development of treatments for other degenerative disorders. The technology for PD modeling in-a-dish could be applied to other cell types such as cardiomyocytes (for heart diseases) and beta-cells (for diabetes). The impact would likely stimulate medical progress on a variety of conditions in which stem cell based drug screening and therapy could be beneficial. An effective drug and therapy for PD would also bring economic benefits to the state. Currently, there is a huge burden of costs associated with the care of patients with long-term degenerative disorders like PD, which afflict tens of thousands of patients statewide. If the clinical condition of these patients could be improved, the cost of maintenance would be reduced, saving billions in medical costs. Many of these patients would be more able to contribute to the workforce and pay taxes. Another benefit is the effect of novel, cutting-edge technologies developed in California on the business economy of the state. Such technologies can have a profound effect on the competitiveness of California through the formation of new manufacturing and health care delivery facilities that would employ California citizens and bring new sources of revenue to the state. Therefore, this project has the potential to bring health and economic benefits to California that is highly desirable for the state.
Progress Report: 
  • Dopaminergic (DA) neurons of the midbrain are the main source of dopamine in the mammalian central nervous system. Their loss is associated with a prominent human neurological disorder, Parkinson's disease (PD). There is no cure for PD, nor are there any good long-term therapeutics without deleterious side effects. Therefore, there is a great need for novel therapies to halt or reverse the disease. The objective of this study is to develop a new technology to obtain a purer, more abundant population of midbrain DA neurons in a culture dish. Such cells would be useful for disease modeling, drug screening, and development of cell therapies.
  • Recent discoveries allow us to use adult human skin cells, introduce specific genes into them, and generate cells, termed induced pluripotent stem cells (iPSC), that exhibit the characteristics of embryonic stem cells. These iPSC, when derived from PD patient skin cells, can be used as an experimental model to study disease mechanisms that are unique to PD. When differentiated into DA neurons, and these cells are actually pathologically affected with PD.
  • The current methods for directed DA neuronal differentiation from iPSC are inadequate in terms of efficiency and reproducibility. This situation hinders the ability to establish a robust model for PD-related neurodegeneration. In this study, we use a new, efficient gene integration technology to induce expression of midbrain-specific genes in iPSC lines derived from a patient with PD and a normal sibling. Forced expression of these midbrain transcription factor genes directs iPSC to differentiate into DA neurons in cell culture. A purer population of midbrain DA neurons may lay the foundation for successfully modeling PD and improving hit rates in drug screening approaches.
  • The milestones for the first year of the project were to establish PD-specific iPSC lines that contain genomic “docking” sites, termed “attP” sites. In year 2, these iPSC/attP cell lines will be used to insert midbrain-specific transcription factors with high efficiency, mediated by enzymes called integrases. We previously established an improved, high-efficiency, site-specific DNA integration technology in mice. This technology combines the integrase system with newly identified, actively expressed locations in the genome and ensures efficient, uniform gene expression.
  • The PD patient-specific iPSC lines we used were PI-1754, which contains a severe mutation in the SNCA (synuclein alpha) gene, and an unaffected sibling line, PI-1761. The SNCA mutation causes dramatic clinical symptoms of PD, with early-onset progressive disease. We use a homologous recombination-based procedure to place the “docking” site, attP, at well-expressed locations in the SNCA and control iPSC lines (Aim 1.1). We also included a human embryonic stem cell line, H9, to monitor our experimental procedures. The genomic locations we chose for placement of the attP sites included a site on chromosome 22 (Chr22) and a second, backup site on chromosome 19 (Chr19). These two sites were chosen based on mouse studies, in which mouse equivalents of both locations conferred strong gene expression. In order to perform recombination, we constructed targeting vectors, each containing an attP cassette flanked by 5’ and 3’ homologous fragments corresponding to the human genomic location we want to target. For the Chr22 locus, we were able to obtain all 3 targeting constructs for the PI-1754, PI-1761 and H9 cell lines. For technical reasons, we were not able to obtain constructs for the Chr19 location Thus, we decided to focus on the Chr22 locus and move to the next step.
  • We introduced the targeting vectors into the cells and selected for positive clones by both drug selection and green fluorescent protein expression. For the H9 cells, we obtained 110 double positive clones and analyzed 98 of them. We found 8 clones that had targeted the attP site precisely to the Chr22 locus. For the PI-1761 sibling control line, we obtained 44 clones, and 1 of them had the attP site inserted at the Chr22 locus. The PI-1754 SNCA mutant line, on the other hand, grows slowly in cell culture. We are in the process of obtaining enough cells to perform the recombination experiment in that cell line.
  • In summary, we demonstrated that the experimental strategy proposed in the grant indeed worked. We were successful in obtaining iPSC lines with a “docking” site placed in a pre-selected human genomic location. These cell lines are the necessary materials that set the stage for us to fulfill the milestones of year 2.
  • Parkinson's disease (PD) is caused by the loss of dopaminergic (DA) neurons in the midbrain. These DA neurons are the main source of dopamine, an important chemical in the central nervous system. PD is a common neurological disorder, affecting 1% of those at 60 years old and 4% of those over 80. Unfortunately, there is no cure for PD, nor are there any long-term therapeutics without harmful side effects. Therefore, there is a need for new therapies to halt or reverse the disease. The goal of this study is to develop a new technology that helps us obtain a purer, more abundant population of DA neurons in a culture dish and to characterize the resulting cells. These cells will be useful for studying the disease, screening potential drugs, and developing cell therapies.
  • Due to recent discoveries, we can introduce specific genes into adult human skin cells and generate cells similar to embryonic stem cells, termed induced pluripotent stem cells (iPSC). These iPSC, when derived from PD patients, can be used as an experimental model to study disease mechanisms that are unique to PD, because when differentiated into DA neurons, these cells are actually pathologically affected with PD. We are using a PD iPSC line called PI-1754 derived from a patient with a severe mutation in the SNCA gene, which encodes alpha-synuclein. The SNCA mutation causes dramatic clinical symptoms of PD, with early-onset progressive disease. For comparison we are using a normal, unaffected sibling iPSC line PI-1761. We are also using a normal human embryonic stem cell (ESC) line H9 as the gold standard for differentiation.
  • The current methods for differentiating iPSC into DA neurons are not adequate in terms of efficiency and reliability. Our hypothesis is that forced expression of certain midbrain-specific genes called transcription factors will direct iPSC to differentiate more effectively into DA neurons in cell culture. We use transcription factors called Lmx1a, Otx2, and FoxA2, abbreviated L, O, and F. In this project, we have developed a new, efficient gene integration technology that allows us rapidly to introduce and express these transcription factor genes in various combinations, in order to test whether they stimulate the differentiation of iPSC into DA neurons.
  • In the first year of the project, we began establishing iPSC and ESC lines that contained a genomic “landing pad” site for insertion of the transcription factor genes. We carefully chose a location for placement of the genes based on previous work in mouse that suggested that a site on human chromosome 22 would provide strong and constant gene expression. We initially used ordinary homologous recombination to place the landing pad into this site. By the end of year 1 of the project, this method was successful in the normal iPSC and in the ESC, but not in the more difficult-to-grow PD iPSC. To solve this problem, in year 2 we introduced a new and more powerful recombination technology, called TALENs, and were successful in placing the landing pad in the correct position in all three of the lines, including the PD iPSC.
  • We were now in a position to insert the midbrain-specific transcription factor genes with high efficiency. For this step, we developed a new genome engineering methodology called DICE, for dual integrase cassette exchange. In this technology, we use two site-specific integrase enzymes, called phiC31 and Bxb1, to catalyze precise placement of the transcription factor genes into the desired place in the genome.
  • We constructed gene cassettes carrying all pair-wise combinations of the L, O, and F transcription factors, LO, LF, and OF, and the triple combination, LOF. We successfully demonstrated the power of this technology by rapidly generating a large set of iPSC and ESC that contained all the above combinations of transcription factors, as well as lines that contained no transcription factors, as negative controls for comparison. Two examples of each type of line for the 1754 and 1761 iPSC and the H9 ESC were chosen for differentiation and functional characterization studies. Initial results from these studies have demonstrated correct differentiation of neural stem cells and expression of the introduced transcription factor genes.
  • In summary, we were successful in obtaining ESC and iPSC lines from normal and PD patient cells that carry a landing pad in a pre-selected genomic location chosen and validated for strong gene expression. These lines are valuable reagents. We then modified these lines to add DA-associated transcription factors in four combinations. All these lines are currently undergoing differentiation studies in accordance with the year two and three timelines. During year three of the project, the correlation between expression of various transcription factors and the level of DA differentiation will be established. Furthermore, functional studies with the PD versus normal lines will be carried out.
  • The objective of this project is to develop approaches and technologies that will improve neuronal differentiation of stem cells into midbrain dopaminergic (DA) neurons. DA neurons are of central importance in the project, because they are that cells that are impaired in patients with Parkinson’s disease (PD). Current differentiation methods typically produce low yields of DA neurons. The methods also give variable results, and cell populations contain many types of cells. These impediments have hampered the study of disease mechanisms for PD, as well as other uses for the cells, such as drug screening and cell replacement therapy. Our strategy is to develop a novel method to introduce genes into the genome at a specific place, so we can rapidly add genes that might help in the differentiation of DA neurons. The genes we would like to add are called transcription factors, which are proteins involved differentiation of stem cells into DA neurons. We have placed the genes for three transcription factors into a safe, active position on human chromosome 22 in the cell lines we are studying. These cells, called pluripotent stem cells, have the potential to differentiate into almost any type of cell. We are using embryonic stem cells in our study, as well as induced pluripotent stem cells (iPSC), which are similar, but are derived from adult cells, rather than an embryo. We are using iPSC derived from a PD patient, as well as iPSC from a normal person, for comparison. By forced expression of these neuronal transcription factors, we may achieve more efficient and reproducible generation of DA neurons. The effects of expressing different combinations of the three transcription factors called Lmx1a, FoxA2, and Otx2 on DA neuronal differentiation will be evaluated in the context of embryonic stem cells (ESC) as the gold standard, as well as in iPSC derived from a PD patient with a severe mutation in alpha-synuclein and iPSC derived from a normal control. Comparative functional assays of the resulting DA neurons will complete the analysis.
  • To date, this project has created a novel technology for modifying the genome. The strategy developed out of the one that we originally proposed, but contains several innovations that make it more powerful and useful. The new methodology, called DICE for Dual Integrase Cassette Exchange, allowed us to generate “master” or recipient cell lines for ESC, normal iPSC, and PD iPSC. These recipient cell lines contain a “landing pad” placed into a newly-identified actively-expressed location on human chromosome 22 called H11 that permits robust expression of genes placed into it. We then generated a series of cell lines by "cassette exchange" at the H11 locus. In cassette exchange, the new genes we want to add take the place of the landing pad we originally put into the cells. Cassette exchange is a good way to introduce various genes into the same place in the chromosomes. We created cell lines expressing three neuronal transcription factors suspected to be involved in DA neuronal differentiation, in all pair-wise combinations, including lines with expression of all three factors, and negative control lines with no transcription factors added. This collection of modified human pluripotent stem cell lines is now being used to study neural differentiation. The modified ESC have undergone differentiation into DA neurons and are being evaluated for the effects of the different transcription factor combinations on DA neuronal differentiation. During the final year of the project, this differentiation analysis will be completed, and we will also analyze functional properties of the differentiated DA neurons, with special emphasis on disease-related features of the cells derived from PD iPSC.

Banking transplant ready dopaminergic neurons using a scalable process

Funding Type: 
Early Translational II
Grant Number: 
TR2-01856
ICOC Funds Committed: 
$6 016 624
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Collaborative Funder: 
Maryland
Stem Cell Use: 
Embryonic Stem Cell
oldStatus: 
Active
Public Abstract: 
Parkinson's disease (PD) is a devastating movement disorder caused by the death of dopaminergic neurons (a type of nerve cells in the central nervous system) present in the midbrain. These neurons secrete dopamine (a signaling molecule) and are a critical component of the motor circuit that ensures movements are smooth and coordinated. All current treatments attempt to overcome the loss of these neurons by either replacing the lost dopamine, or modulating other parts of the circuit to balance this loss or attempting to halt or delay the loss of dopaminergic neurons. Cell replacement therapy (that is, transplantation of dopaminergic neurons into the brain to replace lost cells and restore function) as proposed in this application attempts to use cells as small pumps of dopamine that will be secreted locally and in a regulated way, and will therefore avoid the complications of other modes of treatment. Indeed, cell therapy using fetal tissue-derived cells have been shown to be successful in multiple transplant studies. Work in the field has been limited however, partially due to the limited availability of cells for transplantation (e.g., 6-10 fetuses of 6-10 weeks post-conception are required for a single patient). We believe that human embryonic stem cells (hESCs) may offer a potentially unlimited source of the right kind of cell required for cell replacement therapy. Work in our laboratories and in others has allowed us to develop a process of directing hESC differentiation into dopaminergic neurons. To move forward stem cell-based therapy development it is important to develop scale-up GMP-compatible process of generating therapeutically relevant cells (dopaminergic neurons in this case). The overall goal of this proposal is to develop a hESC-based therapeutic candidate (dopaminergic neurons) by developing enabling reagents/tools/processes that will allow us to translate our efforts into clinical use. We have used PD as a model but throughout the application have focused on generalized enabling tools. The tools, reagents and processes we will develop in this project will allow us to move towards translational therapy and establish processes that could be applied to future IND-enabling projects. In addition, the processes we will develop would be of benefit to the CIRM community.
Statement of Benefit to California: 
Parkinson’s disease affects more than a million patients United States with a large fraction being present in California. California, which is the home of the Parkinson’s Institute and several Parkinson’s related foundations and patient advocacy groups, has been at the forefront of this research and a large number of California based scientists supported by these foundations and CIRM have contributed to significant breakthroughs in this field. In this application we and our collaborators in California aim propose to develop a hESC-based therapeutic candidate (dopaminergic neurons) that will allow us to move towards translational therapy and establish processes that could be applied to future IND-enabling projects for this currently non-curable disorder. We believe that this proposal includes the basic elements that are required for the translation of basic research to clinical research. We believe these experiments not only provide a blueprint for moving Parkinson’s disease towards the clinic for people suffering with the disorder but also a generalized blueprint for the development of stem cell therapy for multiple neurological disorders including motor neuron diseases and spinal cord injury. The tools and reagents that we develop will be made widely available to Californian researchers. We expect that the money expended on this research will benefit the Californian research community and the tools and reagents we develop will help accelerate the research of our colleagues in both California and worldwide.
Progress Report: 
  • Parkinson's disease (PD) is a devastating movement disorder caused by the death of dopaminergic neurons (a type of nerve cells in the central nervous system) present in the midbrain. These neurons secrete dopamine (a signaling molecule) and are a critical component of the motor circuit that ensures movements are smooth and coordinated.
  • All current treatments attempt to overcome the loss of these neurons by either replacing the lost dopamine, or modulating other parts of the circuit to balance this loss or attempting to halt or delay the loss of dopaminergic neurons. Cell replacement therapy (that is, transplantation of dopaminergic neurons into the brain to replace lost cells and restore function) as proposed in this application attempts to use cells as small pumps of dopamine that will be secreted locally and in a regulated way, and will therefore avoid the complications of other modes of treatment. Indeed, cell therapy using fetal tissue-derived cells have been shown to be successful in multiple transplant studies. Work in the field has been limited however, partially due to the limited availability of cells for transplantation (e.g., 6-10 fetuses of 6-10 weeks post-conception are required for a single patient).
  • We believe that human embryonic stem cells (hESCs) may offer a potentially unlimited source of the right kind of cell required for cell replacement therapy. Work in our laboratories and in others has allowed us to develop a process of directing hESC differentiation into dopaminergic neurons. To move forward stem cell-based therapy development it is important to develop scale-up GMP-compatible process of generating therapeutically relevant cells (dopaminergic neurons in this case).
  • The overall goal of this proposal is to develop a hESC-based therapeutic candidate (dopaminergic neurons) by developing enabling reagents/tools/processes that will allow us to translate our efforts into clinical use. We have used PD as a model but throughout the application have focused on generalized enabling tools. The tools, reagents and processes we will develop in this project will allow us to move towards translational therapy and establish processes that could be applied to future IND-enabling projects. In addition, the processes we will develop would be of benefit to the CIRM community.
  • Parkinson's disease (PD) is a devastating movement disorder caused by the death of dopaminergic neurons (a type of nerve cells in the central nervous system) present in the midbrain. These neurons secrete dopamine (a signaling molecule) and are a critical component of the motor circuit that ensures movements are smooth and coordinated.
  • All current treatments attempt to overcome the loss of these neurons by either replacing the lost dopamine, or modulating other parts of the circuit to balance this loss or attempting to halt or delay the loss of dopaminergic neurons. Cell replacement therapy (that is, transplantation of dopaminergic neurons into the brain to replace lost cells and restore function) as proposed in this application attempts to use cells as small pumps of dopamine that will be secreted locally and in a regulated way, and will therefore avoid the complications of other modes of treatment. Indeed, cell therapy using fetal tissue-derived cells have been shown to be successful in multiple transplant studies. Work in the field has been limited however, partially due to the limited availability of cells for transplantation (e.g., 6-10 fetuses of 6-10 weeks post-conception are required for a single patient).
  • We believe that human pluripotent stem cells (PSC) may offer a potentially unlimited source of the right kind of cell required for cell replacement therapy. Work in our laboratories and in others has allowed us to develop a process of directing PSC differentiation into dopaminergic neurons. To move forward stem cell-based therapy development it is important to develop scale-up GMP-compatible process of generating therapeutically relevant cells (dopaminergic neurons in this case).
  • During this grant, we have optimized a step-wise scalable process for generating authentic dopaminergic neurons in defined media from human PSC, and have determined the time point at which dopaminergic neurons can be frozen, shipped, thawed and transplanted without compromising their ability to mature and provide therapeutic benefit in animal models. Our process has been successfully transferred to a GMP facility and we have manufactured multiple lots of GMP-equivalent cells using this process. Importantly, we have shown functional equivalency of the manufactured cells in appropriate models. The tools, reagents and processes we have developed in this project allow us to move towards translational therapy and establish processes that could be applied to future IND-enabling projects. In addition, the processes we have developed would be of benefit to the CIRM community.

Crosstalk: Inflammation in Parkinson’s disease (PD) in a humanized in vitro model

Funding Type: 
Early Translational II
Grant Number: 
TR2-01778
ICOC Funds Committed: 
$2 472 839
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Collaborative Funder: 
Germany
Stem Cell Use: 
iPS Cell
Cell Line Generation: 
iPS Cell
oldStatus: 
Active
Public Abstract: 
Parkinson’s Disease (PD) is the most common neurodegenerative movement disorder. It is characterized by motor impairment such as slowness of movements, shaking and gait disturbances. Age is the most consistent risk factor for PD, and as we have an aging population, it is of upmost importance that we find therapies to limit the social, economic and emotional burden of this disease. Most of the studies to find better drugs for PD have been done in rodents. However, many of these drugs failed when tested in PD patients. One problem is that we can only investigate the diseased neurons of the brain after the PD patients have died. We propose to use skin cells from PD patients and reprogram these into neurons and other surrounding cells in the brain called glia. This is a model to study the disease while the patient is still alive. We will investigate how the glial surrounding cells affect the survival of neurons. We will also test drugs that are protective for glial cells and neurons. Overall, this approach is advantageous because it allows for the study of pathological development of PD in a human system. The goal of this project is to identify key molecular events involved at early stages in PD and exploit these as potential points of therapeutic intervention.
Statement of Benefit to California: 
The goal of this proposal is to create human cell-based models for neurodegenerative disease using transgenic human embryonic stem cells and induced pluripotent stem cells reprogrammed from skin samples of highly clinically characterized Parkinson’s Disease (PD) patients and age-matched controls. Given that age is the most consistent risk factor for PD, and we have an aging population, it is of utmost importance that we unravel the cellular, molecular, and genetic causes of the highly specific cell death characteristic of PD. New drugs can be developed out of these studies that will also benefit the citizens of the State of California. In addition, if our strategy can go into preclinical development, this approach would most likely be performed in a pharmaceutical company based in California.
Progress Report: 
  • In the first year of our CIRM Early Translational II Award we have largely accomplished the first two aims put forth in our proposal “Crosstalk: Inflammation in Parkinson’s disease (PD) in a humanized in vitro model.” Dr. Juergen Winkler, in Erlangen, Germany, has enrolled 10 patients and 6 controls in this project, most of which have had a biopsy of their skin cells sent to The Salk Institute in La Jolla. In Dr. Gage’s lab at The Salk Institute these patient fibroblasts are being reprogrammed into induced pluripotent stem cells (iPSCs), and initial attempts at differentiation into dopaminergic neurons are underway. Additionally, patient blood cells have been sent from Dr. Winkler’s clinic to the lab of Dr. Glass at UC San Diego, where their gene expression profile is being determined. In this initial reporting period we are successfully building the cellular tools necessary to investigate the role of nuclear receptors and inflammation in Parkinson’s Disease.
  • In the second year of our CIRM Early Translational II Award we are making substantial progress towards completing all three aims put forth in our proposal. Dr. Juergen Winkler, our German collaborator, has completed the patient recruitment phase of this project, and skin cells from all 16 subjects (10 with PD and six controls) have been reprogrammed into induced pluripotent stem cells (iPSCs) at the Salk Institute in La Jolla. The patient-specific iPSCs have been differentiated into well-characterized neural stem cells, which the Gage lab is further differentiating into both dopaminergic neurons and astrocytes. In addition to collecting patient skin cells, Dr. Winkler’s group has collected blood cells which are currently being analyzed for gene expression differences by Dr. Glass’ lab at UCSD using state-of-the-art RNA sequencing technology. We have identified a compound that is anti-inflammatory in human cells that we will test on the patient-specific cells once we finish building the cellular tools required to investigate the role of nuclear receptors and inflammation in Parkinson’s Disease.
  • In the final year of our CIRM Early Translational II Award we made considerable progress towards completing all three aims put forth in our proposal. Dr. Juergen Winkler, our German collaborator, has completed the patient recruitment phase of this project, and skin cells from all 16 subjects (10 with PD and six controls) have been reprogrammed into induced pluripotent stem cells (iPSCs) at the Salk Institute in La Jolla. The patient-specific iPSCs have been differentiated into well-characterized neural stem cells, which the Gage lab is further differentiating into both dopaminergic neurons and astrocytes. In addition to collecting patient skin cells, Dr. Winkler’s group has collected blood cells which are currently being analyzed for gene expression differences by Dr. Glass’ lab at UCSD using state-of-the-art RNA sequencing technology. We have identified a compound that is anti-inflammatory in human cells that can reduce inflammation in patient-specific cells, and we are beginning to look at its effects on neuronal survival. This award has allowed us to build the cellular tools required to investigate the role of nuclear receptors and inflammation in Parkinson’s disease, which is a model with endless potential.

Genetic Encoding Novel Amino Acids in Embryonic Stem Cells for Molecular Understanding of Differentiation to Dopamine Neurons

Funding Type: 
New Faculty I
Grant Number: 
RN1-00577
ICOC Funds Committed: 
$2 626 937
Disease Focus: 
Parkinson's Disease
Neurological Disorders
oldStatus: 
Closed
Public Abstract: 
Embryonic stem cells have the capacity to self-renew and differentiate into other cell types. Understanding how this is regulated on the molecular level would enable us to manipulate the process and guide stem cells to generate specific types of cells for safe transplantation. However, complex networks of intracellular cofactors and external signals from the environment all affect the fate of stem cells. Dissecting these molecular interactions in stem cells is a very challenging task and calls for innovative new strategies. We propose to genetically incorporate novel amino acids into proteins directly in stem cells. Through these amino acids we will be able to introduce new chemical or physical properties selectively into target proteins for precise biological study in stem cells. Nurr1 is a nuclear hormone receptor that has been associated with Parkinson’s disease (PD), which occurs when dopamine (DA) neurons begin to malfunction and die. Overexpression of Nurr1 and other proteins can induce the differentiation of neural stem cells and embryonic stem cells to dopamine (DA) neurons. However, these DA neurons did not survive well in a PD mouse model after transplantation. In addition, it is unclear how Nurr1 regulates the differentiation process and what other cofactors are involved. We propose to genetically introduce a novel amino acid that carries a photocrosslinking group into Nurr1 in stem cells. Upon illumination, molecules interacting with Nurr1 will be permanently linked for identification by mass spectrometry. Using this approach, we aim to identify unknown cofactors that regulate Nurr1 function or are controlled by Nurr1, and to map sites on Nurr1 that can bind agonists. The function of identified cofactors in DA neuron specification and maturation will be tested in mouse and human embryonic stem cells. These cofactors will be varied in combination to search for more efficient ways to induce embryonic stem cells to generate a pure population of DA neurons. The generated DA neurons will be evaluated in a mouse model of PD. Additionally, the identification of the agonist binding site on Nurr1 will facilitate future design and optimization of potent drugs.
Statement of Benefit to California: 
Parkinson’s disease (PD) is the second most common human neurodegenerative disorder, and primarily results from the selective and progressive degeneration of ventral midbrain dopamine (DA) neurons. Cell transplantation of DA neurons differentiated from neural stem cells or embryonic stem cells raised great hope for an improved treatment for PD patients. However, DA neurons derived using current protocols do not survive well in mouse PD models, and the details of DA neuron development from stem cells are unclear. Our proposed research will identify unknown cofactors that regulate the differentiation of embryonic stem cells to DA neurons, and determine how agonists activate Nurr1, an essential nuclear hormone receptor for DA neuron specification and maturation. This study may yield new drug targets and inspire novel preventive or therapeutic strategies for PD. These discoveries may be exploited by California’s biotech industry and benefit Californians economically. In addition, we will search for more efficient methods to differentiate human embryonic stem cells into DA neurons, and evaluate their therapeutic effects in PD mouse models. Therefore, the proposed research will also directly benefit California residents suffering from PD.
Progress Report: 
  • Patients with Parkinson’s disease have malfunctioning or dying dopaminergic (DA) neurons. Human embryonic stem cells can be differentiated into DA neurons for transplantation with the potential to cure this disease, yet the differentiation mechanism is not very clear. A nuclear hormone receptor named Nurr1 is found to regulate the differentiation process. To study the regulation mechanism, we proposed to genetically incorporate nonnatural amino acids into Nurr1 in stem cells, and use the novel properties of these amino acids to identify the interacting protein partners of Nurr1. Once these partners are discovered, effective protocols can be developed to generate high purity DA neurons for therapeutic purposes. In the past year, we made significant progress in genetically inserting nonnatural amino acids in stem cells. We are in the process of making stem cell lines that have this capacity. We also set up functional assays for studying Nurr1 and its mutants containing nonnatural amino acids. These results paved the way for our future identification of Nurr1 interacting networks in stem cells.
  • Patients with Parkinson’s disease have malfunctioning or dying dopaminergic (DA) neurons. Human embryonic stem cells can be differentiated into DA neurons for transplantation with the potential to cure this disease, yet the differentiation mechanism is not very clear. A nuclear hormone receptor named Nurr1 is found to regulate the differentiation process. To study the regulation mechanism, we proposed to genetically incorporate nonnatural amino acids into Nurr1 in stem cells, and use the novel properties of these amino acids to identify the interacting protein partners of Nurr1. Once these partners are discovered, effective protocols can be developed to generate high purity DA neurons for therapeutic purposes. In the past year, we figured out several mechanisms that prevent the efficient incorporation of nonnatural amino acids into proteins in stem cells. We now have developed new strategies to overcome these difficulties. In the meantime, we developed another complementary approach in order to detect unknown proteins that interact with Nurr1 during the differentiation process of stem cells. We are employing these new methods to identify Nurr1 interacting networks in stem cells.
  • Patients with Parkinson’s disease have malfunctioning or dying dopaminergic (DA) neurons. Human embryonic stem cells can be differentiated into DA neurons for transplantation with the potential to cure this disease, yet the differentiation mechanism is not very clear. The differentiation of embryonic stem cells to DA neurons has been found to be regulated by a nuclear hormone receptor Nurr1, but how Nurr1 involves in this complicated process remains unclear - no ligands or protein partners have been uncovered for Nurr1. To understand the regulation mechanism in molecular details, we proposed to incorporate non-natural amino acids into Nurr1 directly in stem cells, and use the novel properties of these amino acids to identify the protein partners of Nurr1. Once these partners are discovered, effective protocols can be developed to generate high purity DA neurons for therapeutic purposes. In the past year, we figured out a right solution for generating stem cell lines capable of incorporating non-natural amino acids. We also created a novel bacterial strain for efficient producing Nurr1 proteins with the non-natural amino acids inserted. With these progresses we are now probing proteins that interact with Nurr1 during the differentiation of stem cells, which should eventually enable us to come up with new strategies for making DA neurons from embryonic stem cells.
  • Patients with Parkinson’s disease have malfunctioning or dying dopaminergic (DA) neurons. Human embryonic stem cells can be differentiated into DA neurons for transplantation with the potential to cure this disease, yet the differentiation mechanism is not very clear. The differentiation of embryonic stem cells to DA neurons has been found to be regulated by a nuclear hormone receptor Nurr1, but how Nurr1 is involved in this complicated process remains unclear - no ligands or protein partners have been uncovered for Nurr1. To understand the regulation mechanism in molecular details, we proposed to incorporate non-natural amino acids into Nurr1 directly in stem cells, and use the novel properties of these amino acids to identify the protein partners of Nurr1. Once these partners are discovered, effective protocols can be developed to generate high purity DA neurons for therapeutic purposes. In the past year, after testing numerous conditions in various cell lines, we discovered that photo-crosslinking is inefficient in capturing proteins interacting with Nurr1, possibly because the affinity between the unknown target protein and Nurr1 is too low. To overcome this challenge, we developed a new strategy of capture interacting proteins based on a novel class of non-natural amino acids, which do not require additional reagents nor external stimuli to function. We demonstrated the ability of these amino acids to crosslink proteins in the process of interacting with other proteins in live cells. We have also generated stable cell lines that are able to incorporate such non-natural amino acids. Using these new methods, we have been probing proteins that interact with Nurr1 during the differentiation of stem cells, which should eventually enable us to come up with new strategies for making DA neurons from embryonic stem cells.

Using patient-specific iPSC derived dopaminergic neurons to overcome a major bottleneck in Parkinson's disease research and drug discovery

Funding Type: 
Early Translational I
Grant Number: 
TR1-01246
ICOC Funds Committed: 
$3 701 766
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Collaborative Funder: 
Germany
Stem Cell Use: 
iPS Cell
Cell Line Generation: 
iPS Cell
oldStatus: 
Closed
Public Abstract: 
The goals of this study are to develop patient-specific induced pluripotent cell lines (iPSCs) from patients with Parkinson’s disease (PD) with defined mutations and sporadic forms of the disease. Recent groundbreaking discoveries allow us now to use adult human skin cells, transduce them with specific genes, and generate cells that exhibit characteristics of embryonic stem cells, termed induced pluripotent stem cells (iPSCs). These lines will be used as an experimental pre-clinical model to study disease mechanisms unique to PD. We predict that these cells will not only serve an ‘authentic’ model for PD when further differentiated into the specific dopaminergic neurons, but that these cells are pathologically affected with PD. The specific objectives of these studies are to (1) establish a bank of iPSCs from patients with idiopathic PD and patients with defined mutations in genes associated with PD, (2) differentiate iPSCs into dopaminergic neurons and assess neurochemical and neuropathological characteristics of PD of these cells in vitro, and (3) test the hypothesis that specific pharmacologic agents can be used to block or reverse pathological phenotypes. The absence of cellular models of Parkinson’s disease represents a major bottleneck in the scientific field of PD, which, if solved in this collaborative effort, would be instantly translated into a wide range of clinical applications, including drug discovery. This research is highly translational, as the final component is aimed at testing lead compounds that could be neuroprotective, and ultimately at developing a high-throughput drug screening program to discover new disease modifying compounds. This is an essential avenue if we want to offer our patients a new therapeutic approach that can give them a near normal life after being diagnosed with this progressively disabling disease.
Statement of Benefit to California: 
Approx. 36,000-60,000 people in the State of California are affected with Parkinson’s disease (PD), a common neurodegenerative disease that causes a high degree of disability and financial burden for our health care system. It is estimated that the number of PD cases will double by the year 2030. We have a critical need for novel therapies that will prevent or even reverse neuronal cell loss of specific neurons in the brain of patients. This collaborative proposal will provide real benefits and values to the state of California and its citizens in providing new approaches for understanding disease mechanisms, diagnostic tools and drug discovery of novel treatment for PD. Reprogramming of adult skin cells to a pluripotent state is the underlying mechanism upon which this application is built upon and offers an attractive avenue of research in this case to develop an ‘authentic’ pre-clinical model of PD. The rationale for the proposed research is that differentiated pluripotent stem cells from patients with known genetic forms of PD will recapitulate in vitro one or more of the key molecular aspects of neural degeneration associated with PD and thus provide an entirely novel human cellular system for investigation PD-related disease pathways and for drug discovery. The impact of this collaborative research project, if successful, is difficult to over-estimate. The scientific field has been struggling with the inability to directly access cells that are affected by the disease process that underlies PD and therefore all research and drug discovery has relied on ”best guess” models of the disease. Thus, the absence of cellular models of Parkinson’s disease represents a huge bottleneck in the field.
Progress Report: 
  • In the first year of the CIRM Early translational research award, we established a bank of 51 cell lines derived from skin cells of patients with Parkinson’s disease that carry specific mutations in known genes that cause PD as well as sporadic PD patients. We also recruited matched healthy individuals that serve as controls.
  • In a next step, we reprogrammed (‘rejunivated’) 17 samples of skin cells to derive pluripotent stem cells (iPSC) that closely resemble human embryonic stem cells characterized by biochemical and molecular techniques. We also optimize this process by introducing factors the will be removed after successful reprogramming.
  • We have now built a foundation for the next milestones and made already progress on the differentiation into authentic dopamine producing cells, and we have developed assays to assess the Parkinson’s disease-specific pathological phenotype of the dopamine neurons.
  • The goal of this CIRM early translational grant is to develop a model for “Parkinson’s disease (PD) in a culture dish” using patient-specific induced pluripotent stem cell lines (iPS). The underlying idea is to utilize these lines as an experimental pre-clinical model to study disease mechanisms unique to PD that could lay the foundation for drug discovery.
  • Over the last year, we have expanded our patient skin cell bank to 57 cell lines and the iPS cell bank to 39 well-characterized pluripotent stem cell lines from PD patients and healthy controls individuals. We have improved current protocols of neuronal differentiation from patient-derived iPS lines into dopamine producing neurons and can show consistency and reproducibility of making midbrain dopamine expressing nerve cells.
  • In our first publication (Nguyen et al. 2011), we describe for the first time differences in iPS-derived neurons from a PD patient with a common causative mutation in the LRRK2 gene. These patient cells are more susceptible for cellular toxins leading ultimately to more cell degeneration and cell death.
  • We are also investigating a common disease mechanism implicated in PD, which is mitochondrial dysfunction. In skin cells of a patient we were able to find profound deficits of mitochondrial function compared to control lines and we are now in the process of confirming these results in neural precursors and mature dopamine neurons.
  • Overall, we have made substantial progress towards the goal of this grant which is the a new cell culture model of PD which can replicate PD-related cellular pathology.
  • The goal of this CIRM early translational grant is to develop a model for “Parkinson’s disease (PD) in a culture dish” using patient-specific induced pluripotent stem cell lines (iPS). The underlying idea is to utilize these lines as an experimental pre-clinical model to study disease mechanisms unique to PD that could lay the foundation for drug discovery.
  • Over the last year, we have expanded our patient skin cell bank to 61 cell lines and the iPS cell bank to 51 well-characterized pluripotent stem cell lines from PD patients and healthy controls individuals. We have improved current protocols of neuronal differentiation from patient-derived iPS lines into dopamine producing neurons and can show consistency and reproducibility of making midbrain dopamine expressing nerve cells. This has been now published in Mak et al. 2012. Furthermore, we also develop new protocols to also derive other neuronal subtypes and glia, which are the support cells in the brain, to build co-culture systems. These co-cultures might represent closer the physiological conditions in the brain.
  • In our first publication (Nguyen et al. 2011), we describe for the first time differences in iPS-derived neurons from a PD patient with a common causative mutation in the LRRK2 gene. These patient cells are more susceptible for cellular toxins leading ultimately to more cell degeneration and cell death. In a second publication Byers et al. 2011, we describe similar findings for a different mutation in the alpha-synuclein gene where the normal protein is overexpressed due to a triplication of the gene locus.
  • We are also investigating a common disease mechanism implicated in PD, which is mitochondrial dysfunction. In skin cells of a patient we were able to find profound deficits of mitochondrial function compared to control lines and we are now in the process of confirming these results in neural precursors and mature dopamine neurons.
  • We are expanding the assay development to other disease-related mechanisms such as deficits in outgrowth of neuronal projections and protein aggregation.
  • Overall, through this program we have developed an invaluable resource of patient-derived cell lines that will be crucial for understanding disease mechanisms and drug discovery. We also showed proof that these cell lines can indeed recapitulates important aspects of disease and are therefore valuable assets as research tools.

Directed Evolution of Novel AAV Variants for Enhanced Gene Targeting in Pluripotent Human Stem Cells and Investigation of Dopaminergic Neuron Differentiation

Funding Type: 
Tools and Technologies I
Grant Number: 
RT1-01021
ICOC Funds Committed: 
$918 000
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
Cell Line Generation: 
iPS Cell
oldStatus: 
Closed
Public Abstract: 
Human embryonic stem cells (hESCs) and induced pluripotent stem (iPS) cells have considerable potential as sources of differentiated cells for numerous biomedical applications. The ability to introduce targeted changes into the DNA of these cells – a process known as gene targeting – would have very broad implications. For example, mutations could readily be introduced into genes to study their roles in stem cell propagation and differentiation, to analyze mechanisms of human disease, and to develop disease models to aid in creating new therapies. Unfortunately, gene targeting efficiency in hESCs is very low. To meet this urgent need, we propose to develop new molecular tools and novel technologies for high efficiency gene targeting in hES and iPS cells. Importantly, this approach will be coupled with genome-wide identification and functional analysis of genes involved in the process in dopaminergic neuron development, work with fundamental implications for Parkinson's disease. Barriers to targeted genetic modification include the effective delivery of gene targeting constructs into cells and the introduction of defined changes into the genome. We have developed a high throughput approach to engineer novel properties into a highly promising, safe, and clinically relevant gene delivery vehicle. For example, we have engineered variants of this vehicle with highly efficient gene delivery to neural stem cells (NSCs), and the resulting vehicles can mediate efficient gene targeting. We now propose to engineer novel gene delivery and targeting vehicles optimized for use in hESCs and iPS cells. One application of such an improved vector system will be to study the mechanism of ESC differentiation into dopaminergic neurons aided by the key transcription factor Lmx1a. We propose to identify target genes that are regulated by Lmx1a during dopaminergic neuron differentiation using the newly developed technique of ChIP-seq, in combination with RNA expression and bioinformatics analysis. This work will identify essential control genes that drive dopaminergic neuron differentiation. Furthermore, our improved gene delivery and targeting system will be used for overexpressing candidate genes, knocking them down via RNA interference, and knocking in reporter genes to analyze gene expression networks during neuronal differentiation. The generation of efficient targeting technologies, in combination with genome wide analysis of gene regulation networks, will provide a general method for identifying and testing key regulatory genes for stem cell self-renewal and differentiation, as well as generating stem cell-based models of human disease. This blend of bioengineering and cell biology therefore has strong potential to create an important new capability for basic and applied stem cell research.
Statement of Benefit to California: 
This proposal will develop novel molecular tools and methodologies that will strongly enhance the scientific, technological, and economic development of stem cell therapeutics in California. The most important net benefit will be for the treatment of human diseases. Efficiently introducing specific genetic modifications into a stem cell genome is a greatly enabling technology that would impact many downstream medical applications. This capability will further enable investigations of self-renewal and differentiation, two defining properties of human stem cells. New tools to introduce targeted alterations of ES and iPS cells will also yield key model systems to elucidate mechanisms of human disease, and most importantly enable the generation of mutant cell lines to serve as models of human disease and systems for high throughput screening to develop novel therapies. Finally, the reverse process, the repair of genetic lesions responsible for disease, can in the long run enable the generation of patent-specific stem cell lines for therapeutic application. Each of these applications will directly benefit biomedical knowledge and human health. Furthermore, this proposal directly addresses several research targets of this RFA – the development and utilization of efficient homologous recombination techniques for gene targeting in human stem cells, the development of safer and more effective viral vectors for gene transduction in human stem cells, and the development and analysis of human embryonic stem cell lines with reporter genes inserted into key loci – indicating that CIRM believes that the proposed capabilities are a priority for California’s stem cell effort. While the potential applications of the proposed technology are broad, we will apply it to a specific and urgent biomedical problem: elucidating mechanisms of ES cell differentiation into dopaminergic neurons, part of a critical path towards developing therapies for Parkinson’s disease. While hESCs clearly have this capacity, the underlying mechanisms are incompletely understood, and the efficiency of this process must be improved. We will elucidate transcriptional networks that underlie this process, and utilize our novel gene targeting system to identify and analyze key components of these networks. This work will lead to a better fundamental understanding of mechanisms regulating stem cell differentiation, as well as enhance our ability to control this complex process for biomedical application. The co-investigators have a strong record of translating basic science and engineering into practice through interactions with industry, including the founding of biotech companies in California. Finally, this collaborative project will focus diverse research groups with many students on an important interdisciplinary project at the interface of science and engineering, thereby training future employees and contributing to the technological and economic development of California.
Progress Report: 
  • The central goal of this is to develop enhanced vehicles for gene delivery to human embryonic stem cells, both to modulate gene expression and to edit the cellular genome via homologous recombination. We have been using a novel directed evolution technology to improve the properties of a promising viral vehicle, and we are in the progress of progressively increasing gene delivery efficiency. In particular, we have isolated several viral vector variants with enhanced gene delivery to human embryonic stem cells.
  • In parallel, we have a strong interest in understanding and elucidating mechanisms of human pluripotent stem cell differentiation into dopaminergic neurons, with implications for Parkinson's Disease. In particular, the transcription factor Lmx1a plays a role in this fate specification, but the underlying mechanisms are largely unknown. We are conducting chromatin immunoprecipitation coupled with next generation DNA sequencing to identify the genes in the cellular genome that this factor regulates. We have generated an antibody to isolate this protein from cells and are in the process of pulling down DNA bound to this factor within cells undergoing dopaminergic specification. Once we have identified relevant target genes, we will use the new gene delivery technology to study their functional role in dopaminergic specification of human embryonic stem cells.
  • The central goal of this is to develop enhanced vehicles for gene delivery to human embryonic stem cells, both to modulate gene expression and to edit the cellular genome via homologous recombination. We have been using a novel directed evolution technology to improve the properties of a promising viral vehicle, and we are in the progress of progressively increasing gene delivery efficiency. In particular, we have isolated several viral vector variants with enhanced gene delivery to human embryonic stem cells.
  • In parallel, we have a strong interest in understanding and elucidating mechanisms of human pluripotent stem cell differentiation into dopaminergic neurons, with implications for Parkinson's Disease. In particular, the transcription factor Lmx1a plays a role in this fate specification, but the underlying mechanisms are largely unknown. We are conducting chromatin immunoprecipitation coupled with next generation DNA sequencing to identify the genes in the cellular genome that this factor regulates. We have generated an antibody to isolate this protein from cells and are in the process of pulling down DNA bound to this factor within cells undergoing dopaminergic specification. Once we have identified relevant target genes, we will use the new gene delivery technology to study their functional role in dopaminergic specification of human embryonic stem cells.
  • The central goal of this project is to develop enhanced vehicles for gene delivery to human embryonic stem cells, both to modulate gene expression and to edit the cellular genome via homologous recombination. Harnessing a novel directed evolution technology we have developed to improve the properties of a promising viral vehicle, we have significantly increased its gene delivery efficiency to human embryonic and human induced pluripotent stem cells. Furthermore, this advance resulted in considerable improvements in the efficiency of gene targeting (i.e. editing) in the genomes of these cells.
  • In parallel, we have a strong interest in understanding and elucidating mechanisms of luripotent stem cell differentiation into neurons, with for example implications for Parkinson's Disease. In particular, the transcription factor Lmx1a plays a role in this fate specification, but the underlying mechanisms are largely unknown. We attempted chromatin immunoprecipitation coupled with next generation DNA sequencing to identify the genes in the cellular genome that this factor regulates. Progress in this objective was ultimately hampered by the lack of a suitable antibody against Lmx1a. However, in parallel we have used an analogous approach to investigate mechanisms by which RNA transcription is regulated during the differentiation of embryonic stem cells into neurons, including motor neurons. These basic results can now be applied to enhance the efficiency of neuronal differentiation.

Derivation of Parkinson's Disease Coded-Stem Cells (PD-SCs)

Funding Type: 
New Cell Lines
Grant Number: 
RL1-00682
ICOC Funds Committed: 
$1 589 760
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
iPS Cell
Cell Line Generation: 
iPS Cell
oldStatus: 
Closed
Public Abstract: 
Parkinson's disease (PD) is currently the most common neurodegenerative movement disorder, severely debilitating approximately 1-2% of the US population. The disease is caused by a selective loss of dopamine-producing neurons located in a specific region of the brain. This loss leads to significant motor function impairment and age-dependent tremors. Unfortunately there is currently no cure for PD, however a synthetic dopamine treatment (L-DOPA), temporarily alleviates symptoms. The mechanisms of PD progression are currently unknown. However, genetic studies have identified that mutations (changes) in seven genes, including ?-synuclein, LRRK2, uchL1, parkin, PINK1, DJ-1 and ATP13A2 cause familial PD. Although the familial form of PD only affects a small portion of PD cases, uncovering the function of these genes may provide insight into the mechanisms that lead to the majority of PD cases. One of the best strategies to study PD mechanisms is to generate experimental models that mimic the initiation and progression of PD. A number of cellular and animal models have been developed for PD research. However, a model, which closely resembles the human degeneration process of PD, is currently not available because human neurons are unable to continuously propagate (grow) in culture. Human stem cells provide an opportunity to fulfill this task because these cells can grow and be programmed to generate dopamine nerve cells (the neurons under assault in PD patients). In this study, we propose to create stem cell lines that possess PD-associated mutations in two causative genes, PINK1 and parkin, using either rejected early stage embryos or cultured patient fibroblasts. These cell lines will in effect, represent a model of human PD degeneration of dopaminergic neurons. Our working hypothesis is that PD-associated abnormal parkin or PINK1 genes cause degeneration of stem cell-derived dopaminergic neurons, and dopaminergic neurons in vivo via the same mechanism. We will fulfill three tasks in this study; 1/ To generate the PD-stem cell (PD-SCs) line which harbor abnormal or mutant parkin or PINK1 genes; 2/ To determine the whether the PD-SCs cell lines can form into midbrain dopaminergic nerve cells; 3/ To determine whether mutations in parkin and PINK1 effect the survival of dopaminergic neurons which are derived from the PD-SCs cells. Successful completion of this study will yield novel cellular models for studying the mechanisms involved in PD initiation and progression, and further screening remedies for PD treatment.
Statement of Benefit to California: 
Parkinson's disease (PD) is the second leading neurodegenerative disease with no current cure available. Compared to other states, California is the highest in the incidence of this particular disease. First, California growers use approximately 250 million pounds of pesticides annually, about a quarter of all pesticides used in the US (Cal Pesticide use reporting system). A commonly used herbicide, paraquat, has been shown to induce parkinsonism in both animals and human. Other pesticides are also proposed as potential causative agents for PD. Studies have shown increased PD-caused mortality in agricultural pesticide-use counties in comparison to those non-use counties in California. Second, California has the largest Hispanic population. Studies suggest that incidence of PD is the highest among Hispanics (Van Den Eeden et al, American Journal of Epidemiology, Vol 157, pages 1015-1022, 2003). Thus, finding effective treatments of PD will significantly benefit citizens in California.
Progress Report: 
  • Parkinson’s disease (PD) is currently the most common neurodegenerative movement disorder, severely debilitating approximately 1-2% of the US population. The disease is caused by a selective loss of dopamine-producing neurons located in a specific region of the brain. This loss leads to significant motor function impairment and age-dependent tremors. Unfortunately there is currently no cure for PD, however a synthetic dopamine treatment (L-DOPA), temporarily alleviates symptoms.
  • The mechanism of PD progression are currently unknown. However, genetic studies have identified that mutations (changes) in multiple genes, including α-synuclein, LRRK2, uchL1, parkin, PINK1, DJ-1 and ATP13A2 cause familial PD. Although the familial form of PD only affects a small portion of PD cases, uncovering the function of these genes may provide insight into the mechanisms that lead to the majority of PD cases.
  • One of the best strategies to study PD mechanisms is to generate experimental models that mimic the initiation and progression of PD. A number of cellular and animal models have been developed for PD research. However, a model, which closely resembles the human degeneration process of PD, is currently not available because human neurons are unable to continuously propagate (grow) in culture. Human stem cells provide an opportunity to fulfill this task because these cells can grow and be programmed to generate dopamine nerve cells (the neurons under assault in PD patients).
  • In this study, we propose to create stem cell lines that possess PD-associated mutations in two causative genes, PINK1 and parkin, using either rejected early stage embryos or cultured patient fibroblasts. These cell lines will in effect, represent a model of human PD degeneration of dopaminergic neurons. Our working hypothesis is that PD-associated abnormal parkin or PINK1 genes cause degeneration of stem cell-derived dopaminergic neurons, and dopaminergic neurons in vivo via the same mechanism. We will fulfill three tasks in this study; 1/ To generate the PD-stem cell (PD-SCs) line which harbor abnormal or mutant parkin or PINK1 genes; 2/ To determine the whether the PD-SCs cell lines can form into midbrain dopaminergic nerve cells; 3/ To determine whether mutations in parkin and PINK1 effect the survival of dopaminergic neurons which are derived from the PD-SCs cells. Successful completion of this study will yield novel cellular models for studying the mechanisms involved in PD initiation and progression, and further screening remedies for PD treatment.
  • During last year, we have successfully generated primary skin fibroblast cultures from PD patients harboring mutations of parkin, PINK1, and DJ-1 genes, as well as sporadic PD patients and normal individuals. By using these cells, we have already generated four induced stem cell lines expressing multiple pluripotent markers (two from PD patients and two from normal individuals. These lines can also form teratomas with cells from three germ layers using mouse as host. These findings suggest that the induced pluripotent cell lines generated in the lab are likely PD patient specific stem cells.
  • During the next report year, we will continue to generate more PD patient-specific induced pluripotent stem cells. We will carefully characterize all lines generated in the lab as proposed. Furthermore, we will adapt protocols to differentiate the new lines into dopaminergic neurons.
  • Public Summary of Scientific Progress
  • Parkinson’s disease (PD) is currently the most common neurodegenerative movement disorder affecting approximately 1-2% of the US population. The disease is caused by a selective loss of dopamine-producing neurons located in a specific region of the brain. This loss leads to significant motor function impairment and age-dependent tremors. Unfortunately, there is currently no cure for PD, however a synthetic dopamine treatment (L-DOPA), temporarily alleviates symptoms.
  • Genetic studies have identified that mutations (changes) in multiple genes cause familial PD. Although the familial form of PD only affects a small portion of PD cases, uncovering the function of these genes in PD-affected dopamine-secretion neurons may provide insight into the mechanisms that lead to the majority of PD cases.
  • One of the best strategies to study PD mechanisms is to generate experimental models that mimic the initiation and progression of PD. A number of cellular and animal models have been developed for PD research. However, a model, which closely resembles the human degeneration process of PD, is currently not available because human neurons are unable to continuously propagate (grow) in culture. Human stem cells provide an opportunity to fulfill this task because these cells can grow and be programmed to generate dopamine nerve cells (the neurons under assault in PD patients).
  • In this study, we propose to create stem cell lines that possess PD-associated mutations in two causative genes, PINK1 and parkin, using either rejected early stage embryos or cultured patient fibroblasts. These cell lines will in effect, represent a model of human PD degeneration of dopaminergic neurons. Our working hypothesis is that PD-associated abnormal parkin or PINK1 genes cause degeneration of stem cell-derived dopaminergic neurons, and dopaminergic neurons in vivo via the same mechanism. We will fulfill three tasks in this study; 1/ To generate the PD-stem cell (PD-SCs) line which harbor abnormal or mutant parkin or PINK1 genes; 2/ To determine the whether the PD-SCs cell lines can form into midbrain dopaminergic nerve cells; 3/ To determine whether mutations in parkin and PINK1 effect the survival of dopaminergic neurons which are derived from the PD-SCs cells. Successful completion of this study will yield novel cellular models for studying the mechanisms involved in PD initiation and progression, and further screening remedies for PD treatment.
  • During last year, we have successfully obtained more primary skin fibroblast cultures from PD patients harboring mutations of parkin, PINK1, DJ-1 and PLA2G6 genes, as well as sporadic PD patients and normal control individuals. By using these cells, we have already generated 9 induced stem cell lines expressing multiple pluripotent markers (7 from PD patients and 2 from normal individuals). These lines can also form teratomas with cells from three germ layers using mouse as host. These findings suggest that the induced pluripotent cell lines generated in the lab are likely PD patient specific stem cells.
  • During the next report year, we will continue to generate more PD patient-specific induced pluripotent stem cells. We will carefully characterize all lines generated in the lab as proposed. Furthermore, we will adapt protocols to differentiate the new lines into dopaminergic neurons.
  • Parkinson’s disease (PD) is currently the most common neurodegenerative movement disorder, severely debilitating approximately 1-2% of the US population. The disease is caused by a selective loss of dopamine-producing neurons located in a specific region of the brain. This loss leads to significant motor function impairment and age-dependent tremors. Unfortunately there is currently no cure for PD, however a synthetic dopamine treatment (L-DOPA), temporarily alleviates symptoms.
  • The mechanism of PD progression is currently unknown. However, genetic studies have identified that mutations (changes) in multiple genes, including α-synuclein, LRRK2, uchL1, parkin, PINK1, DJ-1 and ATP13A2 cause familial PD. Although the familial form of PD only affects a small portion of PD cases, uncovering the function of these genes may provide insight into the mechanisms that lead to the majority of PD cases.
  • One of the best strategies to study PD mechanisms is to generate experimental models that mimic the initiation and progression of PD. A number of cellular and animal models have been developed for PD research. However, a model, which closely resembles the human degeneration process of PD, is currently not available because human neurons are unable to continuously propagate (grow) in culture. Human stem cells provide an opportunity to fulfill this task because these cells can grow and be programmed to generate dopamine nerve cells (the neurons under assault in PD patients).
  • In this study, we propose to create stem cell lines that either have the genetic background of sporadic PD patients or possess PD-associated mutations using cultured patient fibroblasts. These cell lines will in effect, represent a model of human PD degeneration of dopaminergic neurons. Our working hypothesis is that the degeneration of stem cell-derived dopaminergic neurons and dopaminergic neurons in vivo via the same mechanism. We will fulfill three tasks in this study; 1/ To generate the PD-stem cell (PD-SCs) line which either have the genetic background of sporadic PD patients or harbor PD specific gene mutantions; 2/ To determine the whether the PD-SCs cell lines can form into midbrain dopaminergic nerve cells; 3/ To determine whether mutations in parkin and PINK1 effect the survival of dopaminergic neurons which are derived from the PD-SCs cells. Successful completion of this study will yield novel cellular models for studying the mechanisms involved in PD initiation and progression, and further screening remedies for PD treatment.
  • During last year, we have finished to develop 15 lines of iPSCs. These include 5 lines from normal control individuals, 5 lines from sporadic Parkinson disease patients, and 5 lines from Parkinson disease patients harboring disease related mutations of PINK1, DJ-1 and PLA2G6 genes. These lines provide an unique opportunity to systematically study comparative pathophysiology of Parkinson disease using sporadic and genetic cases. Moreover, we indeed spent more than a year in optimizing the condition for differentiation of these lines. It is recognized that iPSCs are more difficult to differentiate than the hESCs. We are now able to finalize the protocols to have all lines be differentiated in vitro. Therefore, we will be able to compare differences among the controls, sporadic PD and genetic PD at the level of cell biology and molecular biology.
  • During the next report year, we will differentiate all lines into DA neurons and carefully the functional changes of these cells. We hope that the results will reveal some molecular basis of PD pathogenesis from these human neurons.
  • Parkinson’s disease (PD) is currently the most common neurodegenerative movement disorder, severely debilitating approximately 1-2% of the US population. The disease is caused by a selective loss of dopamine-producing neurons located in a specific region of the brain. This loss leads to significant motor function impairment and age-dependent tremors. Unfortunately there is currently no cure for PD, however a synthetic dopamine treatment (L-DOPA), temporarily alleviates symptoms.
  • The mechanism of PD progression is currently unknown. However, genetic studies have identified that mutations (changes) in multiple genes, including α-synuclein, LRRK2, uchL1, parkin, PINK1, DJ-1 and ATP13A2 cause familial PD. Although the familial form of PD only affects a small portion of PD cases, uncovering the function of these genes may provide insight into the mechanisms that lead to the majority of PD cases.
  • One of the best strategies to study PD mechanisms is to generate experimental models that mimic the initiation and progression of PD. A number of cellular and animal models have been developed for PD research. However, a model, which closely resembles the human degeneration process of PD, is currently not available because human neurons are unable to continuously propagate (grow) in culture. Human stem cells provide an opportunity to fulfill this task because these cells can grow and be programmed to generate dopamine nerve cells (the neurons under assault in PD patients).
  • In this study, we propose to create stem cell lines that either have the genetic background of sporadic PD patients or possess PD-associated mutations using cultured patient fibroblasts. These cell lines will in effect, represent a model of human PD degeneration of dopaminergic neurons. Our working hypothesis is that the degeneration of stem cell-derived dopaminergic neurons and dopaminergic neurons in vivo via the same mechanism. We will fulfill three tasks in this study; 1/ To generate the PD-stem cell (PD-SCs) line which either have the genetic background of sporadic PD patients or harbor PD specific gene mutantions; 2/ To determine the whether the PD-SCs cell lines can form into midbrain dopaminergic nerve cells; 3/ To determine whether mutations in parkin and PINK1 effect the survival of dopaminergic neurons which are derived from the PD-SCs cells. Successful completion of this study will yield novel cellular models for studying the mechanisms involved in PD initiation and progression, and further screening remedies for PD treatment.
  • During last four years, we have finished to develop 15 lines of iPSCs. These include 5 lines from normal control individuals, 5 lines from sporadic Parkinson disease patients, and 5 lines from Parkinson disease patients harboring disease related mutations of PINK1, DJ-1 and PLA2G6 genes. These iPS lines are shown to have biochemical and genomic characteristics of human ES cells. These lines provide an unique opportunity to systematically study comparative pathophysiology of Parkinson disease using sporadic and genetic cases. Using these lines, we have identified a group of genes differentially expressed and differentially methylated between iPS cells derived from PD patients and iPS cells derived from normal control individuals. However, we recognize that iPSCs are more difficult to differentiate than the hESCs. We are yet to finalize the protocols to have all lines be differentiated in vitro. Our goal is to compare differences among the controls, sporadic PD and genetic PD at the level of cell biology and molecular biology.

Derivation of Inhibitory Nerve Cells from Human Embryonic Stem Cells

Funding Type: 
Comprehensive Grant
Grant Number: 
RC1-00346
ICOC Funds Committed: 
$2 507 223
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
oldStatus: 
Closed
Public Abstract: 
Parkinson’s disease (PD) is caused by degeneration of a specific population of dopamine-producing nerve cells in the brain and is chronic, progressive, and incurable. Loss of dopamine-containing cells results in profound physiological disturbances producing tremors, rigidity, and severe deterioration of gate and balance. In the United States, approximately 1.5 million people suffer with PD and it is estimated that 60,000 new cases are diagnosed each year. Drugs can modify some of the disease symptoms, but many patients develop disabling drug-induced movements that are unresponsive to medication. Deep brain stimulation can alleviate motor symptoms in some patients but is not a cure. We plan an entirely novel approach to treat PD. We propose to utilize a specific class of inhibitory nerve cells found in the embryonic brain, known as MGE cells, as donor transplant cells to inhibit those brain regions whose activity is abnormally increased in PD. In preliminary studies we have demonstrated that this approach can relieve symptoms in an animal model of PD. To turn this approach into a patient therapy, we will need to develop methods to obtain large numbers of human cells suitable for transplantation. This proposal seeks to address this problem by producing unlimited numbers of exactly the right type of MGE nerve cell using human embryonic stem cells. The inhibitory nerve cells we seek to produce will reduce brain activity in target regions. They may therefore be used to treat other conditions characterized by excessive brain activity, such as epilepsy. Epilepsy can be a life threatening and disabling condition. Nearly two million Americans suffer with some form of epilepsy. Unfortunately, modulation of brain excitability using antiepileptic drugs can have serious side-effects, especially in the developing brain, and many patients can only be improved by surgically removing areas of the brain containing the seizure focus. Using MGE cells made from human embryonic stem cell lines, we hope to develop a novel epilepsy treatment that could replace the need for surgery or possibly even drug therapy. We propose an integrated approach that combines the complementary expertise of four UCSF laboratories to achieve our goals. We have already determined that mouse MGE cells can improve the symptoms of PD and epilepsy when grafted into animal models. We now need to develop methods to obtain large numbers of human cells suitable for grafting. We need to ensure that when delivered, the cells will migrate and integrate in the target brain regions, and we need to evaluate therapeutic efficacy in animal models of Parkinson’s disease and epilepsy. This proposal addresses these goals. If successful, this accomplishment will set the stage for studies in primates and hasten the day when MGE cells may be used as patient therapy for a wide variety of debilitating neurological disorders.
Statement of Benefit to California: 
This collaborative proposal promises to accelerate progress toward a novel cell based therapeutic agent with potentially widespread benefit for the treatment of a variety of grave neurological disorders. The promise of this work to eventually help our patients is our primary motivation. Additionally, our studies, if successful, could form the basis of a new stem cell technology to produce unlimited numbers of cellular therapeutic products of uniform quality and effectiveness. The production of neurons from stable nerve cell lines derived from human embryonic stem cells is a much-needed biotechnology and a central challenge in embryonic stem (ES) cell biology. Current methods are inefficient at producing neurons that can effectively migrate and integrate into adult brain, and available cell lines generally lack the ability to differentiate into specific neuronal subtypes. Moreover, while many cells resist neuronal differentiation others often take on a glial cell fate. Identification of key factors driving ES cells into a specific neuronal lineage is the primary focus of the current proposal, and if achieved, will generate valuable intellectual property. As such, it may attract biotechnology interest and promote local business growth and development. Moreover, the inhibitory nerve cell type that is the goal of this proposal would be a potentially valuable therapeutic agent. This achievement could attract additional funding from state or industry to begin primate studies and ultimately convert any success into a safe and effective product for the treatment of patients. To produce and distribute stable medicinal-grade cells of a purity and consistency appropriate for therapeutic use will require partnering with industry. Industry participation would be expected to provide economic benefits in terms of job creation and tax revenues. Hopefully, there may ultimately be health benefits for the citizens of California who are suffering from neurological disease.
Progress Report: 
  • Our goal is to develop a novel cell-based therapy to treat patients with epilepsy, Parkinson’s disease and brain injury. The strategy is to use human embryonic stem cells to produce inhibitory nerve cells for transplantation and therapeutic modulation of neural circuits, an approach that may have widespread clinical application. In preliminary studies using inhibitory neuron precursors from embryonic rodent brains, we have demonstrated that this approach can relieve symptoms in animal models of Parkinson’s disease and epilepsy. To turn this approach into a patient therapy we need to develop methods to obtain large numbers of human cells suitable for transplantation. The object of this proposal is to develop methods for producing unlimited numbers of exactly the right type of inhibitory nerve cell using human embryonic stem (ES) cells as the starting material.
  • One strategy to make large numbers of inhibitory neurons would be to convert human ES cells into neural stem (NS) cell lines that could be stably propagated indefinitely, and then to convert the NS cells into inhibitory nerve cells. However, we discovered that NS cell lines do not retain the capacity to generate neurons after extended culture periods but instead produce only glial cells. We have therefore begun to create neurons directly from ES cells, without interrupting the differentiation to amplify cell number at the neural progenitor phase. Using this approach, we have been successful at specifying the right pathway to produce the specific neural progenitor cell we need during the process of differentiation from ES cells. Because there are multiple subytpes of inhibitory neuron, we are testing various cell culture manipulations to enrich for the specific neuron subtype that matches our desired cell type. In addition, we are developing reporter cell lines that will allow us to observe differentiation from ES cell to inhibitory neuron in real time and purify the cells of interest for transplantation. Finally, we are also testing whether artificially expressing key proteins that regulate gene expression and are required for inhibitory neuron production during brain development can more efficiently drive a high percentage of ES cells to differentiate into the desired cell type.
  • With these tools in place, we hope to begin animal transplantation studies using human ES-derived inhibitory nerve cells within the coming year. If successful, this accomplishment will set the stage for studies in primates, and hasten the day when inhibitory nerve cells may be used as patient therapy for a wide variety of debilitating neurological disorders including Parkinson’s disease, epilepsy, and brain injury.
  • This past year, we have made significant strides toward the production of inhibitory nerve cells and precursor (MGE) cells from human embryonic stem (ES) and induced pluripotent stem (iPS) cells. These stem cell-derived MGE progenitor cells appropriately mature into inhibitory neurons upon further culture and following transplantation into the newborn mouse brain. Additionally, human ES cell-derived inhibitory neurons possess active membrane properties by electrophysiology analysis. Work is ongoing to determine their functional potential following transplantation: whether these cells can make connections, or synapses, with each other and with neurons in the host brain in order to elevate inhibitory tone in the transplanted animals. Following successful completion of this aim in the coming year, we will be well positioned to examine the therapeutic potential of these cells in pre-clinical epilepsy and Parkinson's disease animal models.
  • Inhibitory nerve cell deficiencies have been implicated in many neurological disorders including epilepsy. The decreased inhibition and/or increased excitation lead to hyper-excitability and brain imbalance. We are pursuing a strategy to re-balance the brain by injecting inhibitory nerve precursor cells. Most inhibitory nerve cells come from the medial ganglionic eminence (MGE) during fetal development. We have previously documented that mouse MGE transplants reduce seizures in animal models of epilepsy and ameliorate motor symptoms in a rat model of Parkinson’s disease. This project aims to develop human MGE cells from human embryonic stem (ES) cells and to investigate their function in animal models of human disease. In the past year, we have successfully developed a robust and reproducible method to generate human ES cell-derived MGE cells and have performed extensive gene expression and functional analyses. The gene expression profiles of these ES-derived MGE cells resemble those of mouse and human fetal MGE. They appropriately mature into inhibitory nerve cells in culture and following injection into rodent brain. Also, the ES-derived inhibitory cells exhibit active electrical properties and establish connections (synapses) with other nerve cells in culture and in the rodent brain. Thus, we have succeeded in deriving inhibitory human MGE cells from human ES cells and are now transplanting these cells into animal models of disease.

MEF2C-Directed Neurogenesis From Human Embryonic Stem Cells

Funding Type: 
Comprehensive Grant
Grant Number: 
RC1-00125
ICOC Funds Committed: 
$3 035 996
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Stroke
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
Cell Line Generation: 
Embryonic Stem Cell
oldStatus: 
Closed
Public Abstract: 
Understanding differentiation of human embryonic stem cells (hESCs) provides insight into early human development and will help directing hESC differentiation for future cell-based therapies of Parkinson’s disease, stroke and other neurodegenerative conditions. The PI’s laboratory was the first to clone and characterize the transcription factor MEF2C, a protein that can direct the orchestra of genes to produce a particular type of cell, in this case a nerve cell (or neuron). We have demonstrated that MEF2C directs the differentiation of mouse ES cells into neurons and suppresses glial fate. MEF2C also helps keep new nerve cells alive, which is very helpful for their successful transplantation. However, little is known about the role of MEF2C in human neurogenesis, that is, its ability to direct hESC differentiation into neuronal lineages such as dopaminergic neurons to treat Parkinson’s disease and its therapeutic potential to promote the generation of nerve cells in stem cell transplantation experiments. The goal of this application is to fill these gaps. The co-PI’s laboratory has recently developed a unique procedure for the efficient differentiation of hESCs into a uniform population of neural precursor cells (NPCs), which are progenitor cells that develop from embryonic stem cells and can form different kinds of mature cells in the nervous system. Here, we will investigate if MEF2C can instruct hESC-derived NPCs to differentiate into nerve cells, including dopaminergic nerve cells for Parkinson’s disease or other types of neurons that are lost after a stroke. Moreover, we will transplant hESC-NPCs engineered with MEF2C to try to treat animal models of stroke and Parkinson’s disease. We will characterize known and novel MEF2C target genes to identify critical components in the MEF2C transcriptional network in the clinically relevant cell population of hESC-derived neural precursor cells (hESC-NPCs). Specifically we will: 1) determine the function of MEF2C during in vitro neurogenesis (generation of new nerve cells) from hESC-NPCs; 2) investigate the therapeutic potential of MEF2C engineered hESC-NPCs in Parkinson’s and stroke models; 3) determine the MEF2C DNA (gene) binding sites and perform a “network” analysis of MEF2C target genes in order to understand how MEF2C works in driving the formation of new nerve cells from hESCs.
Statement of Benefit to California: 
Efficient and controlled neuronal differentiation from human embryonic stem cells (hESCs) is mandatory for developing future clinical cell-based therapies. Strategies to direct differentiation towards neuronal vs. glial fate are critical for the development of a uniform population of desired neuronal specificities (e.g., dopaminergic neurons for Parkinson’s disease (PD)). Our laboratory was the first to clone and characterize the transcription factor MEF2C, the major isoform of MEF2 found in the developing brain. Based on our encouraging preliminary results that were obtained with mouse (m)ESC-derived and human fetal brain-derived neural precursors, we propose to investigate if MEF2C enhances neurogenesis from hESCs. In addition to neurogenic activity, we have shown that MEF2C exhibits an anti-apoptotic (that is, anti-death) effect and therefore increases cell survival. This dual function of MEF2C is extremely valuable for the purpose of transplantation of MEF2C-engineererd neural precursors. Additionally, we found MEF2 binding sites in the Nurr1 promoter region, which in the proper cell context, should enhance dopaminergic (DA) neuronal differentiation. We hypothesize that hESC-derived neural precursors engineered with MEF2C will selectively differentiate into neurons, which will be resistant to apoptotic death and not form tumors such as teratomas. We believe that our proposed research will lead us to a better understanding of the role of MEF2C in hESC differentiation to neurons. These results will lead to novel and effective means to direct hESCs to become neurons and to resist cell death. This information will ultimately lead to novel, stem cell-based therapies to treat stroke and neurodegenerative diseases such as Parkinson’s. We also believe that an effective, straightforward, and broadly understandable way to describe the benefits to the citizens of the State of California that will flow from the stem cell research we propose to conduct is to couch the work in the familiar, everyday business concept of “Return on Investment.” The novel therapies and reconstructions that will be developed and accomplished as a result of our research program and the many related programs that will follow will provide direct benefits to the health of California citizens. In addition, this program and its many complementary programs will generate potentially very large, tangible monetary benefits to the citizens of California. These financial benefits will derive directly from two sources. The first source will be the sale and licensing of the intellectual property rights that will accrue to the state and its citizens from this and the many other stem cell research programs that will be financed by CIRM. The second source will be the many different kinds of tax revenues that will be generated from the increased bio-science and bio-manufacturing businesses that will be attracted to California by the success of CIRM.
Progress Report: 
  • In Year 02 of this grant, we have continued to refine the techniques developed for producing nerve cells from human embryonic stem cells (hESC). Central to our grant proposal is the expression of an active form of a protein called MEF2C, which we insert into the stem cells at a young age. MEF2C is a transcription factor, which is a molecule that regulates how RNA is converted to a protein. MEF2C regulates the production of proteins that are specifically found in neurons, and it plays an important role in making a stem cell into a nerve cell. Specific improvements this year in culture conditions have resulted in our being able to direct a much higher percentage of hESCs into precursors of nerve cells, and it is at this stage that the cells are most appropriate for insertion of MEF2C. Following this, we can transplant the stem cells, destined to become nerve cells, in to the brain in rodent models of stroke and Parkinson’s disease. We have also made very good progress in producing dopaminergic nerve cells, the specific type of cell that dies in Parkinson’s disease. In addition, our improved methods are completely free of any animal products, so they represent a step forward in developing cells as a treatment for human diseases.
  • Building upon these advances in our techniques, we have transplanted cells into a rat model of Parkinson’s disease and shown that a large percentage of the cells become dopaminergic nerve cells in the brain. Additionally, rats receiving these cell transplants show greater improvements in motor skills compared to rats receiving similar cells without the inserted MEF2C factor. These findings complement our results presented in the first year’s progress report showing that transplantation of these MEF2C-expressing cells into a mouse model of stroke resulted in less damage to the brain. Together these results indicate the utility and versatility of these cells “programmed” by expression of the inserted MEF2C gene.
  • Finally, in Year 02 we report on our efforts to discover the mechanism by which the MEF2C gene prevents cell death and drives stem cells to become nerve cells. We have performed microarray analyses, which measure the expression levels of various genes, e.g., how much of each protein is produced from a gene. This approach includes 24,000 of the possible ~30,000 gene sequences expressed in human cells and tissues. These experiments were performed on stem cells with the inserted MEF2C gene just as the cells were making the decision to become a nerve cell. We observed a decrease in the activity of several genes that are known to make stem cells proliferate (divide and multiply), rather than becoming a differentiated nerve cell. This finding is consistent with the known role of MEF2C, which causes cells to stop proliferating and start differentiating into nerve cells. Without insertion of MEF2C into the stem cells, they mostly continue proliferating. We also saw that many genes, which are not expressed in mature nerve cells, were coordinately down regulated. These results may suggest a new role of MEF2C as a factor for shutting down gene expression, thereby helping to promote the formation of new nerve cells. We are continuing our investigations into the mechanism of MEF2C actions in neuronal differentiation and function as well as our transplantation experiments in stroke and Parkinson’s disease models in the coming year.
  • We initially discovered that mouse embryonic stem cell (ESC)-derived neural progenitor cells forced to express the transcription factor MEF2C were protected from dying and were also given signals to differentiate almost exclusively into neurons (J Neurosci 2008; 28:6557-68). Under the CIRM grant, we have investigated the role of MEF2C and consequences of its forced expression in neural differentiation of human ES cells, including identification of specific genes under MEF2C regulation. We have also used rodent models of Parkinson’s disease and stroke to evaluate the therapeutic potential of human ESC-derived neural progenitors forced to express active MEF2C (MEF2CA).
  • In the third year of the CIRM grant, we continued to refine our procedures for differentiating MEF2CA-expressing human ES cells growing in culture into neural progenitor cells (NPC) and fully developed neurons. We also investigated their electrophysiological characteristics and potential to develop into specific types of neurons. We found that not only do the MEF2CA-expressing NPCs become almost exclusively neurons, as we previously showed, but they also had a strong bias to develop into dopaminergic neurons, the type of neuron that dies in Parkinson’s disease. We also found that MEF2CA-expressing NPCs differentiated to maturity in culture dishes showed a wide variety of electrophysiological responses of normal mature neurons. We were able to record sodium currents and action potentials indicating that the neurons were capable of transmitting chemo-electrical signals. They also responded to GABA and NMDA (a glutamate mimic), which shows that the neurons can respond to the major signal-transmitting molecules in the brain.
  • Previously we showed that transplantation of the MEF2CA-expressing human ESC-derived NPCs into the brains of a rat model of Parkinson’s disease resulted in a much higher number of dopaminergic (DA) neurons and positive behavioral recovery compared to controls. We now report that evaluation of the MEF2CA-expressing cells showed a much higher expression level of a variety of proteins known to be important in DA neuron differentiation and that none of these cells become tumors or hyper proliferative. We have also transplanted NPCs into the brains of a rat stroke model. Our preliminary data analysis shows an improvement in the ability to walk a tapered beam in the rats transplanted with MEF2CA-expressing cells compared to controls. These results are evidence there may be a great advantage in the use of NPC expressing MEF2C for transplantation into various brain diseases and injuries.
  • We have also continued our investigations into the mechanisms of MEF2C activities in the hope of finding new drug targets to mimic it effects. We have identified interactive pathways in which MEF2C plays a role and found correlations between MEF2C expression levels and a variety of diseases. These will hopefully lead us to a better understanding of how to leverage our results to produce effective therapies for a broad spectrum of neurological diseases and traumas.
  • Our goals for this grant were to determine the role of the transcription factor MEF2C in neurogenesis, including all of the targets of this factor in the genome, use this knowledge to direct differentiation of human embryonic stem cells (hESC) into specific types of neurons, and investigate the transplantation of these cells into rodent models of Parkinson’s disease (PD) and stroke. During the tenure of this grant, we accomplished these goals to a very significant degree. Our investigations into the role of MEF2C in neurogenesis produced a large body of knowledge pertinent to its essential role in this process. This knowledge base was achieved through both monitoring expression levels of MEF2C during the entire process of neurogenesis and by knocking down its expression by use of siRNA. We now have a very detailed view of the temporal contribution of MEF2C as stem cells differentiate into neurons. Using this knowledge, we optimized a differentiation protocol for directing hESC into neuronal precursor cells and then initiated expression of a constitutively active MEF2 transcription factor (MEF2CA) via lentiviral technology. We discovered that the forced expression of MEF2CA provided a strong bias to neurons to differentiate along a dopaminergic (DA) lineage. Our network analysis for MEF2C confirmed that many of the known effector proteins for DA neurons are indeed targets for this transcription factor. Histological and electrophysiological investigations into the nature of these cells grown in vitro showed that they are indeed functional neurons displaying the anticipated qualities during the various stages of differentiation.
  • Our in vivo transplantation studies have been equally productive. Owing to the strong tendency of the MEF2CA-expressing cells to differentiate into DA neurons, we first investigated their effects on a rat PD model where the dopaminergic cells of the substantia nigra are ablated on one side of the brain by injection of 6-hydroxydopamine. In response to an injection of the dopamine analog apomorphine, these rats will turn in a circle and the readout is the number of turns in a 30 minute period measured on a rotometer. Fewer turns indicate that the rat has less pathology, i.e., is getting better. We transplanted hESC-derived neural progenitor cells (hESC-NPC) either expressing MEF2CA or not and monitored recovery of the rats. While rats receiving both preparations of stem cells showed considerable improvement, the ones receiving MEF2C-expressing cells did significantly better on the rotometer. Also, histologically the MEF2CA-expressing cells could all be seen to differentiate, whereas those that did not express MEF2CA were often found in an undifferentiated state, which potentially posses a problem of continuing proliferation in the brain and tumor formation. Thus, the forced expression of MEF2CA forced the cells to differentiate and prevented uncontrolled cell division. An additional advantage was that the remaining endogenous DA neurons showed much greater density of fibers in the vicinity of the transplanted cells, suggesting that there was an additional benefit of factor secretion. Thus, the MEF2CA genetically modified cells appear to have significant advantages for transplantation for PD.
  • We are also investigating the use of the MEF2CA-expressing hESC-NPC in rat and mouse models of stroke. Preliminary data shows that in both systems we see behavioral improvements following the transplantations with these cells. In the period of the no cost extension, we will complete these studies and characterize the types of neurons these transplanted cells become and their role in reversing the pathology caused by the brain ischemia from stroke. Our hypothesis is that there is a strong bias toward the DA neuron phenotype produced by the expression of MEF2CA, but that this is overridden by the context within the brain. Therefore, in a stroke model, the context of damage to the cortex provides signals to the newly transplanted cells that they should migrate to the damaged area and become cells appropriate to that region, not DA neurons. We will test this hypothesis in the remaining months of the grant.
  • Our goals for this grant were to determine the role of the transcription factor MEF2C in neurogenesis, including all of the targets of this factor in the genome, use this knowledge to direct differentiation of human embryonic stem cells (hESC) into specific types of neurons, and investigate the transplantation of these cells into rodent models of Parkinson’s disease (PD) and stroke. During the tenure of this grant, we accomplished these goals to a very significant degree. Our investigations into the role of MEF2C in neurogenesis produced a large body of knowledge pertinent to its essential role in this process. This knowledge base was achieved through both monitoring expression levels of MEF2C during the entire process of neurogenesis and by knocking down its expression by use of siRNA. We now have a very detailed view of the temporal contribution of MEF2C as stem cells differentiate into neurons. Using this knowledge, we optimized a differentiation protocol for directing hESC into neuronal precursor cells and then initiated expression of a constitutively active MEF2 transcription factor (MEF2CA) via lentiviral technology. We discovered that the forced expression of MEF2CA provided a strong bias to neurons to differentiate along a dopaminergic (DA) lineage. Our network analysis for MEF2C confirmed that many of the known effector proteins for DA neurons are indeed targets for this transcription factor. Histological and electrophysiological investigations into the nature of these cells grown in vitro showed that they are indeed functional neurons displaying the anticipated qualities during the various stages of differentiation.
  • Our in vivo transplantation studies have been equally productive. Owing to the strong tendency of the MEF2CA-expressing cells to differentiate into DA neurons, we first investigated their effects on a rat PD model where the dopaminergic cells of the substantia nigra are ablated on one side of the brain by injection of 6-hydroxydopamine. In response to an injection of the dopamine analog apomorphine, these rats will turn in a circle and the readout is the number of turns in a 30 minute period measured on a rotometer. Fewer turns indicate that the rat has less pathology, i.e., is getting better. We transplanted hESC-derived neural progenitor cells (hESC-NPC) either expressing MEF2CA or not and monitored recovery of the rats. While rats receiving both preparations of stem cells showed considerable improvement, the ones receiving MEF2C-expressing cells did significantly better on the rotometer. Also, histologically the MEF2CA-expressing cells could all be seen to differentiate, whereas those that did not express MEF2CA were often found in an undifferentiated state, which potentially posses a problem of continuing proliferation in the brain and tumor formation. Thus, the forced expression of MEF2CA forced the cells to differentiate and prevented uncontrolled cell division. An additional advantage was that the remaining endogenous DA neurons showed much greater density of fibers in the vicinity of the transplanted cells, suggesting that there was an additional benefit of factor secretion. Thus, the MEF2CA genetically modified cells appear to have significant advantages for transplantation for PD.
  • We are also investigating the use of the MEF2CA-expressing hESC-NPC in rat and mouse models of stroke. Preliminary data shows that in both systems we see behavioral improvements following the transplantations with these cells. In the period of the no cost extension, we will complete these studies and characterize the types of neurons these transplanted cells become and their role in reversing the pathology caused by the brain ischemia from stroke. Our hypothesis is that there is a strong bias toward the DA neuron phenotype produced by the expression of MEF2CA, but that this is overridden by the context within the brain. Therefore, in a stroke model, the context of damage to the cortex provides signals to the newly transplanted cells that they should migrate to the damaged area and become cells appropriate to that region, not DA neurons. We will test this hypothesis in the remaining months of the grant.

Molecular and Cellular Transitions from ES Cells to Mature Functioning Human Neurons

Funding Type: 
Comprehensive Grant
Grant Number: 
RC1-00115
ICOC Funds Committed: 
$2 879 210
Disease Focus: 
Amyotrophic Lateral Sclerosis
Neurological Disorders
Parkinson's Disease
Genetic Disorder
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
oldStatus: 
Closed
Public Abstract: 
Human embryonic stem cells (hESCs) are pluripotent entities, capable of generating a whole-body spectrum of distinct cell types. We have developmental procedures for inducing hESCs to develop into pure populations of human neural stem cells (hNS), a step required for generating authentic mature human neurons. Several protocols have currently been developed to differentiate hESCs to what appear to be differentiated dopaminergic neurons (important in Parkinson’s disease (PD) and cholinergic motor neurons (important in Amyolateral Sclerosis (ALS) in culture dishes. We have developed methods to stably insert new genes in hESC and we have demonstrated that these transgenic cells can become mature neurons in culture dishes. We plan to over express alpha synuclein and other genes associated with PD and superoxide dismutase (a gene mutated in ALS) into hESCs and then differentiate these cells to neurons, and more specifically to dopaminergic neurons and cholinergic neurons using existing protocols. These transgenic cells can be used not only for the discovery of cellular and molecular causes for dopaminergic or cholinergic cell damage and death in these devastating diseases, but also can be used as assays to screen chemical libraries to find novels drugs that may protect against the degenerative process. Until recently the investigation of the differentiation of these human cells has only been observed in culture dishes or during tumor formation. Our recent results show that hESC implanted in the brains of mice can survive and become active functional human neurons that successfully integrate into the adult mouse forebrain. This method of transplantation to generate models of human disease will permit the study of human neural development in a living environment, paving the way for the generation of new models of human neurodegenerative and psychiatric diseases. It also has the potential to speed up the screening process for therapeutic drugs.
Statement of Benefit to California: 
We plan to develop procedures to induce human ES cells into mature functioning neurons that carry genes that cause the debilitating human neurological diseases, Parkinson’s disease and Amyolateral Sclerosis (ALS). We will use the cells to reveal the genes and molecular pathways inside the cells that are responsible for how the mutant genes cause damage to specific types of brain cells. We also will make the cells available to other researchers as well as biotech companies so that other investigators can use these cells to screen small molecule and chemical libraries to discover new drugs that can interfere with the pathology caused by these mutant cells that mimic human disease, in hopes of accelerating the pace of discovery.
Progress Report: 
  • Our research is focused on studying two debilitating diseases of the nervous system: Parkinson’s disease (PD) and Amyotrophic Lateral Sclerosis (ALS) also known as Lou Gehrig’s disease. While the causes and symptoms of these two conditions are very different, they share one aspect in common: patients gradually lose specific types of nerve cells, namely the so-called dopaminergic neurons in PD, and motor neurons in ALS. If we can find ways to protect the neurons from dying, we might be able to slow or even halt disease progression in ALS and PD patients. In the past two years, our lab has developed robust procedures to generate these two classes of neurons from human embryonic stem cells and we have been studying the molecular changes that govern their specialization. Since last year, we have been using neurons to elucidate the molecular mechanisms that underlie the demise of these cells.
  • ALS is one of the most common neuromuscular diseases, afflicting more than 30,000 Americans. Patients rapidly lose their motor neurons – the nerve cells that extend from the brain through the spinal cord to the muscles, thereby controlling their movement. Therapy options are extremely limited and people with ALS usually succumb to respiratory failure or pneumonia within three to five years from the onset of symptoms. Most ALS patients have no family history of ALS and carry no known genetic defects that may help explain why they develop the disease. However, a small number of ALS patients have mutations in the superoxide dismutase 1 (SOD1) gene, which encodes an enzyme that scavenges so-called free radicals – aggressive oxidizing molecules that are by-products of the cells’ normal metabolism. Researchers therefore believe that accumulation of these free radicals may damage motor neurons in ALS and contribute to their death.
  • To test this idea, we introduced the mutated form of the SOD1 gene into astrocytes – cells that provide metabolic and structural support to neurons – and cultured our stem cell-derived motor neurons along with these SOD1-mutant astrocytes. Indeed, while motor neurons grown on ‘normal’ astrocytes were fully viable, we saw widespread death of motor neurons in cocultures with ‘mutant’ astrocytes, along with elevated levels of free radicals. We think that this is due to our mutant astrocytes being causing inflammation, and so our future efforts are focused on understanding the role of the immune system, specifically the function of microglia – the resident immune cells of the brain and spinal cord – in our co-cultures with human motor neurons. We are very excited about these results because they show that our cocultures may be a very useful tool to screen drugs that may counteract the neurotoxicity caused by inflammation and free radicals. We have already begun testing several known antioxidants, and found some of them to be very effective in improving motor neuron survival in the culture dish. Such compounds may ultimately improve the condition of ALS patients.
  • PD is the second most common neurodegenerative disease and develops when neurons in the brain, and in particular, in a part of the brain known as the substantia nigra die. These neurons are called dopaminergic because they produce dopamine, a molecule that is necessary for coordinated body movement. Many dopaminergic neurons are already lost when patients develop PD symptoms, which include trembling, stiffness, and slow movement. Around one million Americans are currently suffering from PD, and 60,000 new cases are diagnosed each year. While several surgical and pharmacological treatment options exist, they cannot slow or halt disease progression and are instead aimed at treating the symptoms. The exact causes for neuron death in PD are unknown but among others inflammation in the affected brain area may play a role in disease progression.
  • In a joint effort with the laboratories of Christopher Glass and Michael Rosenfeld at the University of California, San Diego, we showed using animal experiments that a protein called Nurr1 is crucial for the development and survival of dopaminergic neurons. We found that the Nurr1 gene is turned on by inflammatory signals and suppresses genes that encode neurotoxic factors. Microglia are the major initiators of the neurotoxic response to inflammatory stimuli, which is then amplified by astrocytes. Thus our findings reveal an important role for Nurr1 in microglia and astrocytes to protect dopaminergic neurons from exaggerated production of inflammation-induced neurotoxic mediators. We are now using human embryonic stem cell-derived dopaminergic neurons, cultured along with human atrocytes and microglia to test whether we can demonstrate this positive role of Nurr1 in a culture dish as well.
  • We are investigating the molecular mechanisms underlying two major neurological diseases: Parkinson’s disease (PD) and Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig’s disease. In the past year, we have taken our previously developed human embryonic stem cell (hESC)-based cell culture model for PD and ALS another step further: we have begun building an assay system that may eventually allow both the identification of biomarkers for early diagnosis and the screening of drug candidates for ALS and PD. By transplanting hESC-derived neurons into live animals and brain slices, we have also made first inroads into recapitulating the disease processes in animal model systems.
  • While the causes and symptoms of ALS and PD are very different, they share one aspect in common: in both, patients gradually lose specific types of nerve cells, namely, the so-called dopaminergic neurons in PD, and motor neurons in ALS; it this neuron death that causes both diseases. Previously, we showed with our hESC-based cell culture system that an inflammatory response in astrocytes (the brain cells that provide metabolic and structural support to neurons) is involved in loss of motor neurons. Similarly, we demonstrated that microglia (the brain’s immune cells) and astrocytes together protect dopaminergic neurons from exaggerated production of inflammation-induced neurotoxic mediators. This function of astrocytes and microglia was dependent on a protein called Nurr1: we found that the Nurr1 gene is turned on by inflammatory signals and suppresses genes that encode neurotoxic factors.
  • We have now begun to characterize in depth the specific signaling molecules that communicate the inflammation cue from the glial cells to neurons. To do this, we cultured astrocytes and microglia in the petri dish, induced inflammation and collected cell culture supernatants from the ‘inflamed’ and normal cells. We then measured the levels of specific so-called cytokines, the inflammatory signaling molecules secreted by the glial cells. Once we have obtained a characteristic cytokine ‘signature’ of disease-associated glial cells, we can begin to unravel the molecular pathways that lead to inflammation. Thus our research may lead to the discovery of early diagnostic markers and enable drug screening for compounds that suppress or prevent these neurotoxic inflammatory processes.
  • Our cell culture assays have provided a great deal of insight into the signaling cascades that eventually lead to neuron death. However, they probably cannot fully recapitulate the complex interplay between the neurons and the cellular environment in which they reside within the brain. We have therefore begun to transplant hESC-derived neurons into the brains of mice. Our results indicate that the neurons rapidly extended processes and developed dendritic branches and axons that integrated into the existing neuronal network. In the coming year, we plan to build on these results, using our hESC-derived neuronal models of PD and ALS to better understand mechanisms of dysregulation. Specifically, we will examine alterations in synapse formation, cell survival, and neuron maturation. We will also devise strategies for functional recovery and rescue in the context of the living animal.
  • We are investigating the molecular mechanisms underlying two major neurological diseases: Parkinson’s disease (PD) and Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig’s disease. In the past year, we took our human embryonic stem cell (hESC)-based neural cell culture model for PD and ALS another step further and built sensitive and quantitative assays that can allow for the screening of drug candidates for ALS and PD. We have also consistently improved our transplanting techniques and are now able to detect functional, electrophysiologically active, hESC-derived neurons in live animals. This experiment was crucial to show that, under our culture conditions, human neurons derived from embryonic stem cells were able to integrate and form meaningful connections with other neurons in a given adult brain environment.
  • Moreover, we are now performing an in-depth characterization of the specific signaling molecules that communicate the inflammation cues from the glial cells to neurons in the presence of ALS-causing mutations (SOD1G37R) and PD-causing mutations (recombinant alfa-synuclein). In this report we have explored another functional assay to measure glial function and inflammatory response using astrocytes that express ALS-causing mutations. In addition, we report here that adding PD-causing mutagens to mixed cultures of human neurons and astrocytes results in the death of dopaminergic neurons, the type of neurons affected in PD. We are currently testing new compounds that can decrease the neuronal toxicity observed.
  • Our research may not only lead to the discovery of early diagnostic markers but also enable drug screening for compounds that suppress or prevent these neurotoxic inflammatory processes.

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