Parkinson's Disease

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

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.

Modeling Parkinson's Disease Using Human Embryonic Stem Cells

Funding Type: 
SEED Grant
Grant Number: 
RS1-00331
ICOC Funds Committed: 
$758 999
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
Cell Line Generation: 
Embryonic Stem Cell
oldStatus: 
Closed
Public Abstract: 
Parkinson’s disease (PD) is the most frequent neurodegenerative movement disorder caused by damage of dopamine-producing nerve cells (DA neuron) in patient brain. The main symptoms of PD are age-dependent tremors (shakiness). There is no cure for PD despite administration of levodopa can help to control symptoms. Most of PD cases are sporadic in the general population. However, about 10-15% of PD cases show familial history. Genetic studies of familial cases resulted in identification of PD-linked gene changes, namely mutations, in six different genes, including α-synuclein, LRRK2, uchL1, parkin, PINK1, and DJ-1. Nevertheless, it is not known how abnormality in these genes cause PD. Our long-term research goal is to understand PD pathogenesis at cellular and molecular levels via studying functions of these PD-linked genes and dysfunction of their disease-associated genetic variants. A proper experimental model plays critical roles in defining pathogenic mechanisms of diseases and for developing therapy. A number of cellular and animal models have been developed for PD research. Nevertheless, a model closely resembling generation processes of human DA nerve cells is not available because human neurons are unable to continuously propagate in culture. Nevertheless, human embryonic stem cells (hESCs) provide an opportunity to fulfill the task. hESCs can grow and be programmed to generate DA nerve cells. In this study, we propose to create a PD model using hESCs. The strategy is to express PD pathogenic mutants of α-synuclein or LRRK2 genes in hESCs. Mutations in α-synuclein or LRRK2 genes cause both familial and sporadic PD. α-Synuclein is a major component of Lewy body, aggregates found in the PD brain. The model will allow us to determine molecular action of PD pathogenic α-synuclein and LRRK2 mutants during generation of human DA neuron and interactions of PD related genes and environmental toxins in DA neurons derived from hESCs. Our working hypothesis is that PD associated genes function in hESCs-derived DA neurons as in human brain DA neurons. Pathogenic mutations in combination with environmental factors (i.e. aging and oxidative stress) impair hESCs-derived DA function resulting in eventual selective neuronal death. In this study, we will firstly generate PD cellular models via expressing two PD-pathogenic genes, α-synuclein and LRRK2 in hESCs. We will next determine effects of α-synuclein and LRRK2 on hESCs and neurons derived from these cells. Finally, we will determine whether PD-causing toxins (i.e. MPP+, paraquat, and rotenone) selectively target to DA neurons derived from hESCs. Successful completion of this study will allow us to study the pathological mechanism of PD and to design strategies to treat the disease.
Statement of Benefit to California: 
Parkinson’s disease (PD) is the second leading neurodegenerative disease with no cure currently available. Compared to other states, California is among one of the states with the highest 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 is 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 citizen in California.
Progress Report: 
  • Parkinson’s disease (PD) is the most frequent neurodegenerative movement disorder caused by damage of dopamine-producing nerve cells (DA neuron) in patient brain. The main symptoms of PD are age-dependent tremors (shakiness). There is no cure for PD despite administration of levodopa can help to control symptoms.

  • Most of PD cases are sporadic in the general population. However, about 10-15% of PD cases show familial history. Genetic studies of familial cases resulted in identification of PD-linked gene changes, namely mutations, in six different genes, including α-synuclein, LRRK2, uchL1, parkin, PINK1, and DJ-1. Nevertheless, it is not known how abnormality in these genes cause PD. Our long-term research goal is to understand PD pathogenesis at cellular and molecular levels via studying functions of these PD-linked genes and dysfunction of their disease-associated genetic variants.

  • A proper experimental model plays critical roles in defining pathogenic mechanisms of diseases and for developing therapy. A number of cellular and animal models have been developed for PD research. Nevertheless, a model closely resembling generation processes of human DA nerve cells is not available because human neurons are unable to continuously propagate in culture. Nevertheless, human embryonic stem cells (hESCs) provide an opportunity to fulfill the task. hESCs can grow and be programmed to generate DA nerve cells. In this study, we propose to create a PD model using hESCs.

  • During the funding period, we have generated a number of human ES cell lines overexpressing α-synuclein and two disease-associated α-synuclein mutants. These cells are being used to determine the cellular and molecular effects of the disease genes on human ES cells and the PD affected dopaminergic neurons made from these cells. We have found that normal and disease α-synucleins have little effect on hESC growth and differentiation. We will continue to investigate roles of this protein in modulating PD affected dopaminergic neurons. Completion of this study will allow us to study the pathological mechanism of PD and to design strategies to treat the disease.

Optimization of guidance response in human embryonic stem cell derived midbrain dopaminergic neurons in development and disease

Funding Type: 
SEED Grant
Grant Number: 
RS1-00271
ICOC Funds Committed: 
$633 170
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
oldStatus: 
Closed
Public Abstract: 
A promising approach to alleviating the symptoms of Parkinson’s disease is to transplant healthy dopaminergic neurons into the brains of these patients. Due to the large number of transplant neurons required for each patient and the difficulty in obtaining these neurons from human tissue, the most viable transplantation strategy will utilize not fetal dopaminergic neurons but dopaminergic neurons derived from human stem cell lines. While transplantation has been promising, it has had limited success, in part due to the ability of the new neurons to find their correct targets in the brain. This incorrect targeting may be due to the lack of appropriate growth and guidance cues as well as to inflammation in the brain that occurs in response to transplantation, or to a combination of the two. Cytokines released upon inflammation can affect the ability of the new neurons to connect, and thus ultimately will affect their biological function. In out laboratory we have had ongoing efforts to determine the which guidance molecules are required for proper targeting of dopaminergic neurons during normal development and we have identified necessary cues. We now plan to extend these studies to determine how these critical guidance cues affect human stem cell derived dopaminergic neurons, the cells that will be used in transplantation. In addition, we will examine how these guidance cues affect both normal and stem cell derived dopaminergic neurons under conditions that are similar to the diseased and transplanted brain, specifically when the brain is inflamed. Ultimately, an understanding of how the environment of the transplanted brain influences the ability of the healthy new neurons to connect to their correct targets will lead to genetic, and/or drug-based strategies for optimizing transplantation therapy.
Statement of Benefit to California: 
The goal of our work is to further optimize our ability to turn undifferentiated human stem cells into differentiated neurons that the brain can use as replacement for neurons damaged by disease. We focus onParkinson’s disease, a neurodegenerative disease that afflicts 4-6 million people worldwide in all geographical locations, but which is more common in rural farm communities compared to urban areas (Van Den Eeden et al., 2003), a criteria important for California’s large farming population. In Parkinson’s patients, a small, well-defined subset of neurons, the midbrain dopaminergic neurons have died, and one therapeutic strategy is to transplant healthy replacement neurons to the patient. Our work will further our understanding of the biology of these neurons in normal animals. This will allow us to refine the process of turning human ES cells onto biologically active dopaminergic neurons that can be used in transplantation therapy. Our work will be of benefit to all Parkinson’s patients including afflicted Californians. In addition to the direct benefit in improving PD therapies, discoveries from this work are also likely to generate substantial intellectual property and further boost clinical and biotechnical development efforts in California.
Progress Report: 
  • A promising approach to alleviating the symptoms of Parkinson's disease is to transplant healthy dopaminergic neurons into the brains of these patients. Due to the large number of transplant neurons required for each patient and the difficulty in obtaining these neurons from human tissue, the most viable transplantation strategy will utilize not fetal dopaminergic neurons but dopaminergic neurons derived from human stem cell lines. While transplantation has been promising, it has had limited success, in part due to the ability of the new neurons to find their correct targets in the brain. This incorrect targeting may be due to the lack of appropriate growth and guidance cues as well as to inflammation in the brain that occurs in response to transplantation, or to a combination of the two. Cytokines released upon inflammation can affect the ability of the new neurons to connect, and thus ultimately will affect their biological function. In out laboratory we have been examining which guidance molecules are required for proper targeting of dopaminergic neurons during normal development and have identified necessary cues. We have now extended these studies to determine that two of the molecules have dramitc effects on dopaminergic neurons made from human embryonic stem cellls and that at least in vitro, cytokines do not mask these effects. Ultimately, an understanding of how the environment of the transplanted brain influences the ability of the healthy new neurons to connect to their correct targets will lead to genetic, and/or drug-based strategies for optimizing transplantation therapy.

Identifying small molecules that stimulate the differentiation of hESCs into dopamine-producing neurons

Funding Type: 
SEED Grant
Grant Number: 
RS1-00215
ICOC Funds Committed: 
$564 309
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
oldStatus: 
Closed
Public Abstract: 
In this application, we propose to identify small molecule compounds that can stimulate human embryonic stem cells to become dopamine-producing neurons. These neurons degenerate in Parkinson’s disease, and currently have very limited availability, thus hindering the cell replacement therapy for treating Parkinson’s disease. Our proposed research, if successful, will lead to the identification of small molecule compounds that can not only stimulate cultured human embryonic stem cells to become DA neurons, but may also stimulate endogenous brain stem cells to regenerate, since the small molecule compounds can be made readily available to the brain due to their ability to cross the blood-brain barrier. In addition, these small molecule compounds may serve as important research tools, which can tell us the fundamental biology of the human embryonic stem cells.
Statement of Benefit to California: 
The proposed research will potentially lead to a cure for the devastating neurodegenerative, movement disorder, Parkinson’s disease. The proposed research will potentially provide important research tools to better understand hESCs. Such improved understanding of hESCs may lead to better treatments for a variety of diseases, in which a stem-cell based therapy could make a difference.
Progress Report: 
  • Parkinson’s disease is the most common movement disorder due to the degeneration of brain dopaminergic neurons. One strategy to combat the disease is to replenish these neurons in the patients, either through transplantation of stem cell-derived dopaminergic neurons, or through promoting endogenous dopaminergic neuronal production or survival. We have carried out a small molecule based screen to identify compounds that can affect the development and survival of dopaminergic neurons from pluripotent stem cells. The small molecules that we have identified will not only serve as important research tools for understanding dopaminergic neuron development and survival, but potentially could also lead to therapeutics in the induction of dopaminergic neurons for treating Parkinson’s disease.

Identification and characterization of human ES-derived DA neuronal subtypes

Funding Type: 
Basic Biology I
Grant Number: 
RB1-01358
ICOC Funds Committed: 
$1 407 076
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
oldStatus: 
Closed
Public Abstract: 
Parkinson’s disease (PD) is a neurodegenerative movement disorder that affects 1 in 100 people over the age of 60, one million people in the US and six million worldwide. Patients show a resting tremor, slowness of movement (bradykinesia), postural instability and rigidity. Parkinson's disease results primarily from the loss of neurons deep in the middle part of the brain (the midbrain), in particular neurons that produce dopamine (referred to as “dopaminergic”). There are actually two groups of midbrain dopaminergic (DA) neurons, and only one, those in the substantia nigra (SN) are highly susceptible to degeneration in Parkinson’s patients. There is a relative sparing of the second group and these are called ventral tegmental area (VTA) dopaminergic neurons. These two groups of neurons reside in different regions of the adult ventral midbrain and importantly, they deliver dopamine to their downstream neuronal targets in different ways. SN neurons deliver dopamine in small rapid squirts, like a sprinkler, whereas VTA neurons have a tap that provides a continuous stream of dopamine. A major therapeutic strategy for Parkinsons’ patients is to produce DA neurons from human embryonic stem cells for use in transplantation therapy. However early human trials were disappointing, since a number of patients with grafts of human fetal neurons developed additional, highly undesirable motor dyskinesias. Why this occurred is not known, but one possibility is that the transplant mixture, which contained both SN and VTA DA neurons, provided too much or unregulated amounts of DA (from the VTA neurons), overloading or confusing the target region in the brain that usually receives dopamine from SN neurons in small, regular quantities. Future human trials will likely utilize DA neurons that have been made from human embryonic stem cells (hES). Since stem cells have the potential to develop into any type of cell in the body, these considerations suggest that we should devise a way to specifically produce SN neurons and not VTA neurons from stem cells for use in transplantation. However, although we can produce dopaminergic neurons from hES cells, to date the scientific community cannot distinguish SN from VTA neurons outside of their normal brain environment and therefore has no ability to produce one selectively and not the other. We do know, however, that these two populations of neurons normally form connections with different regions in the brain, and we propose to use this fact to identify molecular markers that distinguish SN from VTA neurons and to determine optimal conditions for the differentiation of hES to SN DA neurons, at the expense of VTA DA neurons. Our studies have the potential to significantly impact transplantation therapy by enabling the production of SN over VTA neurons from hES cells, and to generate hypotheses about molecules that might be useful for coaxing SN DA neurons to form appropriate connections within the transplanted brain.
Statement of Benefit to California: 
The goal of our work is to further optimize our ability to turn undifferentiated human stem cells into differentiated neurons that the brain can use as replacement for neurons damaged by disease. We focus on Parkinson’s disease, a neurodegenerative disease that afflicts 4-6 million people worldwide in all geographical locations, but which is more common in rural farm communities compared to urban areas, a criteria important for California's large farming population. In Parkinson’s patients, a small, well-defined subset of neurons, the midbrain dopaminergic neurons have died, and one therapeutic strategy is to transplant healthy replacement neurons to the patient. Our work will further our understanding of the biology of these neurons in normal animals. This will allow us to refine the process of turning human embryonic stem cells onto biologically active dopaminergic neurons that can be used in transplantation therapy. Our work will be of benefit to all Parkinson's patients including afflicted Californians. Further, this project will utilize California goods and services whenever possible.
Progress Report: 
  • Parkinson's disease results primarily from the loss of neurons deep in the middle part of the brain (the midbrain), in particular neurons that produce dopamine (referred to as “dopaminergic”). In this region of the midbrain there are actually two different groups of dopaminergic (DA) neurons, and only one of them, the neurons of the substantia nigra (SN) are highly susceptible to degeneration in patients with PD. There is a relative sparing of the second group of midbrain dopaminergic neurons, called the ventral tegmental area (VTA) dopaminergic neurons. These two groups of neurons reside close to each other in the brain and both make dopamine. They are virtually indistinguishable except for one major functional difference—they release dopamine, the transmitter that is lost in Parkinson’s patients, to their downstream neuronal targets in different ways. SN neurons deliver dopamine in small rapid squirts, like a sprinkler, whereas VTA neurons have a tap that provides a continuous stream of dopamine.
  • A major therapeutic strategy for patients with PD is to make new DA neurons from human embryonic stem cells (hES). As stem cells have the potential to develop into any type of cell in the body, these considerations suggest that we should devise a way to produce SN neurons in the absence of VTA neurons from stem cells for use in transplantation. At present although we can produce dopaminergic neurons from hES cells, the scientific community cannot distinguish SN from VTA neurons in vitro due to lack of molecular markers or a bioassay, and we are therefore unable to identify culture conditions that favor the production of one over the other,
  • In addition to releasing dopamine differently, SN and VTA neurons have axons that project to different regions of the striatum. It has been shown over the last decade that specific classes of guidance cues guide axons to their particular targets. One approach we have taken has been to investigate whether differences in axon guidance receptor expression and or responses to guidance cues in vitro might provide both markers and a bioassay that will distinguish SN from VTA neurons. Over the last year we have shown that VTA and SN neurons respond differentially to Netrin-1 and express different markers associated with the guidance cue family. We now have a bioassay and markers that distinguish these two populations of neurons in vitro and in the coming year we plan to utilize this information to identify cultures conditions that favor the production of SN over VTA neurons, from hES cells.
  • Parkinson’s disease results primarily from the loss of neurons deep in the middle part of the brain (the midbrain), in particular neurons that produce dopamine (referred to as “dopaminergic”). In this region of the midbrain there are actually two different groups of dopaminergic (DA) neurons, and only one of them, the neurons of the substantia nigra (SN) are highly susceptible to degeneration in patients with PD. There is a relative sparing of the second group of midbrain dopaminergic neurons, called the ventral tegmental area (VTA) dopaminergic neurons. These two groups of neurons reside close to each other in the brain and both make dopamine. They are virtually indistinguishable except for one major functional difference—they release dopamine, the transmitter that is lost in Parkinson’s patients, to their downstream neuronal targets in different ways. SN neurons deliver dopamine in small rapid squirts, like a sprinkler, whereas VTA neurons have a tap that provides a continuous stream of dopamine. 
A major therapeutic strategy for patients with PD is to make new DA neurons from human embryonic stem cells (hES). As stem cells have the potential to develop into any type of cell in the body, these considerations suggest that we should devise a way to produce SN neurons in the absence of VTA neurons from stem cells for use in transplantation. At present although we can produce dopaminergic neurons from hES cells, the scientific community cannot distinguish SN from VTA neurons in vitro due to lack of molecular markers or a bioassay, and we are therefore unable to identify culture conditions that favor the production of one over the other, 
In addition to releasing dopamine differently, SN and VTA neurons have axons that project to different regions of the striatum. It has been shown over the last decade that specific classes of guidance cues guide axons to their particular targets. One approach we have taken has been to investigate whether differences in axon guidance receptor expression and or responses to guidance cues in vitro might provide both markers and a bioassay that will distinguish SN from VTA neurons. We showed previously that VTA and SN neurons respond differentially to Netrin-1 and express different markers associated with the guidance cue family. Also, in this year using backlabeling, laser capture and microarray analysis of SN vs VTA neurons, we have identified a number of genes expressed in on or the other population. We now have a bioassay and markers that distinguish these two populations of neurons in vitro and in the coming year we plan to utilize this information to identify cultures conditions that favor the production of SN over VTA neurons, from hES cells.
  • Parkinson's disease (PD) is a neurodegenerative movement disorder that affects more than six million people worldwide. The main symptoms of the disease result from the loss of neurons from the midbrain that produce dopamine (referred to as "dopaminergic" or DA neurons).Human embryonic stem cells (hESC) offer an exciting opportunity to treat Parkinson’s disease by transplanting hESC-derived DA neurons to replace those that have died. There are actually two groups of midbrain DA neurons in the human brain. Those from the substantia nigra (SN) are highly susceptible to degeneration in Parkinson's patients while those from the ventral tegmental area (VTA) are not. These two types of neurons have similar features but have different functions and it is important to ensure that DA neurons from hESC are the correct SN type before they are used in therapy. The primary goal of this research was to study these two neuronal types in animals and determine if the distinguishing features discovered in mice or rats can be used to more easily recognize and purify SN-type DA neurons made from hESC.
  • One of the discoveries made in this research is that SN and VTA neurons show differences in how they make connections within the brain. We have been able to identify some of the molecules that guide each neuron to connect to it appropriate target and have found that SN and VTA neurons placed in the petri dish can be distinguished from each other by their response to guidance molecules. Work in the final period of this grant has focused on testing guidance response in hESC-derived DA neurons and we have found that many of the neurons produced from hESC do show SN-like responses to guidance molecules. This discovery is being further developed as a screening tool to help guide our ongoing efforts to make increasingly pure populations of DA neurons from hESC.
  • Future human trials will likely utilize such DA neurons but since embryonic stem cells have the potential to develop into any type of cell in the body, it is important to ensure that the production methods used to make a therapeutic product for Parkinson’s disease do indeed specifically produce SN neurons. Prior to the research supported under this CIRM grant, the scientific community was not able to distinguish SN from VTA neurons outside of their normal brain environment and therefore had no ability to confirm whether a method produced one type selectively and not the other. Further refinements of the assay tools developed in our research may provide a practical means of quantifying the purity of a DA neuron preparation. This would have a significant impact transplantation therapy as well as provide useful insights into the molecular mechanisms that underlie proper connectivity and function of SN and VTA DA neurons in humans.

Stem Cell Pathologies in Parkinson’s disease as a key to Regenerative Strategies

Funding Type: 
Research Leadership 10
Grant Number: 
LA1_C10-06535
ICOC Funds Committed: 
$6 718 471
Disease Focus: 
Parkinson's Disease
Neurological Disorders
oldStatus: 
Closed
Public Abstract: 
Protection and cell repair strategies for neurodegenerative diseases such as Parkinson’s Disease (“PD”) depend on well-characterized candidate human stem cells that are robust and show promise for generating the neurons of interest following stimulation of inherent brain stem cells or after cell transplantation. These stem cells must also be expandable in the culture dish without unwanted growth and differentiation into cancer cells, they must survive the transplantation process or, if endogenous brain stem cells are stimulated, they should insinuate themselves in established brain networks and hopefully ameliorate the disease course. The studies proposed for the CIRM Research Leadership Award have three major components that will help better understand the importance and uses of stem cells for the treatment of PD, and at the same time get a better insight into their role in disease repair and causation. First, we will characterize adult human neural stem cells from control and PD brain specimens to distinguish their genetic signatures and physiological properties of these cells. This will allow us to determine if there are stem cells that are pathological and fail in their supportive role in repairing the nervous system. Next, we will investigate a completely novel disease initiation and propagation mechanism, based on the concept that secreted vesicles from cells (also known as “exosomes”) containing a PD-associated protein, alpha-synuclein, propagate from cell-to cell. Our hypothesis is that these exosomes carry toxic forms of alpha-synuclein from cell to cell in the brain, thereby accounting disease spread. They may do the same with cells transplanted in patients with PD, thereby causing these newly transplanted cells designed to cure the disease, to be affected by the same process that causes the disease itself. This is a bottleneck that needs to be overcome for neurotransplantation to take its place as a standard treatment for PD. Our studies will address disease-associated toxicity of exosomal transmission of aggregated proteins in human neural precursor stem cells. Importantly, exosomes in spinal fluid or other peripheral tissues such as blood might represent a potentially early and reliable disease biomarker as well as a new target for molecular therapies aimed at blocking transcellular transmission of PD-associated molecules. Finally, we have chosen pre-clinical models with α-synucleinopathies to test human neural precursor stem cells as cell replacement donors for PD as well as interrogate, for the first time, their potential susceptibility to PD and contribution to disease transmission. These studies will provide a new standard of analysis of human neural precursor cells at risk for and contributing to pathology (so-called “stem cell pathologies”) in PD and other neurodegenerative diseases via transmission of altered or toxic proteins from one cell to another.
Statement of Benefit to California: 
According to the National Institute of Health, Parkinson’s disease (PD) is the second most common neurodegenerative disease in California and the United States (one in 100 people over 60 is affected) second only to Alzheimer’s Disease. Millions of Americans are challenged by PD, and according to the Parkinson’s Action Network, every 9 minutes a new case of PD is diagnosed. The cause of the majority of idiopathic PD is unknown. Identified genetic factors are responsible for less than 5% of cases and environmental factors such as pesticides and industrial toxins have been repeatedly linked to the disease. However, the vast majority of PD is thought to be etiologically multi-factorial, resulting from both genetic and environmental risk factors. Important events leading to PD probably occur in early or mid adult life. According to the Michael J. Fox Foundation, “…there is no objective test, or reliable biomarker for PD, so rate of misdiagnosis is high, and there is a seriously pressing need to develop better early detection approaches to be able to attempt disease-halting protocols at a non-symptomatic, so-called prodromal stage.” The proposed innovative and transformative research program will have a major direct impact for patients who live in California and suffer from PD and other related neurodegenerative diseases. If these high-risk high-pay-off studies are deemed successful, this new program will have tackled major culprits in the PD field. They could lead to a better understanding of the role of stem cells in health and disease. Furthermore they could greatly advance our knowledge of how the disease spreads throughout the brain which in turn could lead to entire new strategies to halt disease progression. In a similar manner these studies could lead to ways to prevent the disease from spreading to cells that have been transplanted to the brain of Parkinson’s patients in an attempt to cure their disease. This is critical for neurotransplantation to thrive as a therapeutic approach to treating PD. In addition, if we extend the cell-to-cell transmissible disease hypothesis to other neurodegenerative diseases, and cancer, the studies proposed here represent a new diagnostic approach and therapeutic targets for many diseases affecting Californians and humankind in general. This CIRM Research Leadership Award will not only have an enormous impact on understanding the cause of PD and developing new therapeutic strategies using stem cells and its technologies, this award will also be the foundation of creating a new Center for Translational Stem Cell Research within California. This could lead to further growth at the academic level and for the biotechnology industry, particularly in the area regenerative medicine.

Engineering Defined and Scaleable Systems for Dopaminergic Neuron Differentiation of hPSCs

Funding Type: 
Tools and Technologies II
Grant Number: 
RT2-02022
ICOC Funds Committed: 
$1 493 928
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
iPS Cell
oldStatus: 
Active
Public Abstract: 
Human pluripotent stem cells (hPSC) have the capacity to differentiate into every cell in the adult body, and they are thus a highly promising source of differentiated cells for the investigation and treatment of numerous human diseases. For example, neurodegenerative disorders are an increasing healthcare problem that affect the lives of millions of Americans, and Parkinson's Disease (PD) in particular exacts enormous personal and economic tolls. Expanding hPSCs and directing their differentiation into dopaminergic neurons, the cell type predominantly lost in PD, promises to yield cells that can be used in cell replacement therapies. However, developing technologies to create the enormous numbers of safe and healthy dopaminergic neurons required for clinical development and implementation represents a bottleneck in the field, because the current systems for expanding and differentiating hPSCs face numerous challenges including difficulty in scaling up cell production, concerns with the safety of some materials used in the current cell culture systems, and limited reproducibility of such systems. An emerging principle in stem cell engineering is that basic advances in stem cell biology can be translated towards the creation of “synthetic stem cell niches” that emulate the properties of natural microenvironments and tissues. We have made considerable progress in engineering bioactive materials to support hESC expansion and dopaminergic differentiation. For example, basic knowledge of how hESCs interact with the matrix that surrounds them has led to progress in synthetic, biomimetic hydrogels that have biochemical and mechanical properties to support hESC expansion. Furthermore, biology often presents biochemical signals that are patterned or structured at the nanometer scale, and our application of materials chemistry has yielded synthetic materials that imitate the nanostructured properties of endogenous ligands and thereby promise to enhance the potency of growth factors and morphogens for cell differentiation. We propose to build upon this progress to create general platforms for hPSC expansion and differentiation through two specific aims: 1) To determine whether a fully defined, three dimensional (3D) synthetic matrix for expanding immature hPSCs can rapidly and scaleably generate large cell numbers for subsequent differentiation into potentially any cell , and 2) To investigate whether a 3D, synthetic matrix can support differentiation into healthy, implantable human DA neurons in high quantities and yields. This blend of stem cell biology, neurobiology, materials science, and bioengineering to create “synthetic stem cell niche” technologies with broad applicability therefore addresses critical challenges in regenerative medicine.
Statement of Benefit to California: 
This proposal will develop novel tools and capabilities 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 expanding immature hPSCs in a scaleable, safe, and economical manner is a greatly enabling capability that would impact many downstream medical applications. The development of platforms for scaleable and safe cell differentiation will benefit therapeutic efforts for Parkinson’s Disease. Furthermore, the technologies developed in this proposal are designed to be tunable, such that they can be readily adapted to numerous downstream applications. The resulting technologies have strong potential to benefit human health. Furthermore, this proposal directly addresses several research targets of this RFA – the development and validation of stem cell scale-up technologies including novel cell expansion methods and bioreactors for both human pluripotent cells and differentiated cell types – 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: developing systems for generating clinically relevant quantities of dopaminergic neurons from hPSCs, part of a critical path towards developing therapies for Parkinson’s disease. This proposal would therefore work towards developing capabilities that are critical for hPSC-based regenerative medicine applications in the nervous system to clinically succeed. The principal investigator and co-investigator have a strong record of translating basic science and engineering into practice through interactions with industry, particularly within 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: 
  • Human pluripotent stem cells (hPSC) have the capacity to differentiate into every cell in the adult body, and they are thus a highly promising source of differentiated cells for the investigation and treatment of numerous human diseases. For example, neurodegenerative disorders are an increasing healthcare problem that affect the lives of millions of Americans, and Parkinson's Disease (PD) in particular exacts enormous personal and economic tolls. Expanding hPSCs and directing their differentiation into dopaminergic neurons, the cell type predominantly lost in PD, promises to yield cells that can be used in cell replacement therapies. However, developing technologies to create the enormous numbers of safe and healthy dopaminergic neurons required for clinical development and implementation represents a bottleneck in the field, because the current systems for expanding and differentiating hPSCs face numerous challenges including difficulty in scaling up cell production, concerns with the safety of some materials used in the current cell culture systems, and limited reproducibility of such systems.
  • This project has two central aims: 1) To determine whether a fully defined, three dimensional (3D) synthetic matrix for expanding immature hPSCs can rapidly and scaleably generate large cell numbers for subsequent differentiation into potentially any cell , and 2) To investigate whether a 3D, synthetic matrix can support differentiation into healthy, implantable human DA neurons in high quantities and yields. In the first year of this project, we have made progress in both aims. Specifically, we are conducting high throughput studies to optimize matrix properties in aim 1, and we have developed a material formulation in aim 2 that supports a level of DA differentiation that we are now beginning to optimize with a high throughput approach.
  • This blend of stem cell biology, neurobiology, materials science, and bioengineering to create “synthetic stem cell niche” technologies with broad applicability therefore addresses critical challenges in regenerative medicine.
  • Human pluripotent stem cells (hPSC) have the capacity to differentiate into every cell in the adult body, and they are thus a highly promising source of differentiated cells for the investigation and treatment of numerous human diseases. For example, neurodegenerative disorders are an increasing healthcare problem that affect the lives of millions of Americans, and Parkinson's Disease (PD) in particular exacts enormous personal and economic tolls. Expanding hPSCs and directing their differentiation into dopaminergic neurons, the cell type predominantly lost in PD, promises to yield cells that can be used in cell replacement therapies. However, developing technologies to create the enormous numbers of safe and healthy dopaminergic neurons required for clinical development and implementation represents a bottleneck in the field, because the current systems for expanding and differentiating hPSCs face numerous challenges including difficulty in scaling up cell production, concerns with the safety of some materials used in the current cell culture systems, and limited reproducibility of such systems.
  • This project has two central aims: 1) To determine whether a fully defined, three dimensional (3D) synthetic matrix for expanding immature hPSCs can rapidly and scaleably generate large cell numbers for subsequent differentiation into potentially any cell , and 2) To investigate whether a 3D, synthetic matrix can support differentiation into healthy, implantable human DA neurons in high quantities and yields. In the first year of this project, we have made progress in both aims. Specifically, we are conducting high throughput studies to optimize matrix properties in aim 1, and we have developed a material formulation in aim 2 that supports a level of DA differentiation that we are now beginning to optimize with a high throughput approach.
  • This blend of stem cell biology, neurobiology, materials science, and bioengineering to create “synthetic stem cell niche” technologies with broad applicability therefore addresses critical challenges in regenerative medicine.
  • Human pluripotent stem cells (hPSC) have the capacity to differentiate into every cell in the adult body, and they are thus a highly promising source of differentiated cells for the investigation and treatment of numerous human diseases. For example, neurodegenerative disorders are an increasing healthcare problem that affect the lives of millions of Americans, and Parkinson's Disease (PD) in particular exacts enormous personal and economic tolls. Expanding hPSCs and directing their differentiation into dopaminergic neurons, the cell type predominantly lost in PD, promises to yield cells that can be used in cell replacement therapies. However, developing technologies to create the enormous numbers of safe and healthy dopaminergic neurons required for clinical development and implementation represents a bottleneck in the field, because the current systems for expanding and differentiating hPSCs face numerous challenges including difficulty in scaling up cell production, concerns with the safety of some materials used in the current cell culture systems, and limited reproducibility of such systems.
  • This project has two central aims: 1) To determine whether a fully defined, three dimensional (3D) synthetic matrix for expanding immature hPSCs can rapidly and scaleably generate large cell numbers for subsequent differentiation into potentially any cell , and 2) To investigate whether a 3D, synthetic matrix can support differentiation into healthy, implantable human DA neurons in high quantities and yields. In the first year of this project, we have made progress in both aims. Specifically, we are conducting high throughput studies to optimize matrix properties in aim 1, and we have developed a material formulation in aim 2 that supports a level of DA differentiation that we are now beginning to optimize with a high throughput approach.
  • This blend of stem cell biology, neurobiology, materials science, and bioengineering to create “synthetic stem cell niche” technologies with broad applicability therefore addresses critical challenges in regenerative medicine.

Editing of Parkinson’s disease mutation in patient-derived iPSCs by zinc-finger nucleases

Funding Type: 
Tools and Technologies II
Grant Number: 
RT2-01965
ICOC Funds Committed: 
$1 327 983
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Stem Cell Use: 
iPS Cell
Cell Line Generation: 
iPS Cell
oldStatus: 
Active
Public Abstract: 
The goal of this proposal is to establish a novel research tool to explore the molecular basis of Parkinson’s disease (PD) - a critical step toward the development of new therapy. To date, a small handful of specific genes and associated mutations have been causally linked to the development of PD. However, how these mutations provoke the degeneration of specific neurons in the brain remains poorly understood. Moreover, conducting such genotype-phenotype studies has been hampered by two significant experimental problems. First, we have historically lacked the ability to model the relevant human cell types carrying the appropriate gene mutation. Second, the genetic variation between individuals means that the comparison of a cell from a disease-carrier to a cell derived from a normal subject is confounded by the many thousands of genetic changes that normally differentiate two individuals from one another. Here we propose to combine two powerful techniques – one genetic and one cellular – to overcome these barriers and drive a detailed understanding of the molecular basis of PD. Specifically, we propose to use zinc finger nucleases (ZFNs) in patient-derived induced pluripotent stem cells (iPSC) to accelerate the generation of a panel of genetically identical cell lines differing only in the presence or absence of a single disease-linked gene mutation. iPSCs have the potential to differentiate into many cell types – including dopaminergic neurons that become defective in PD. Merging these two technologies will thus allow us to study activity of either the wild-type or the mutant gene product in cells derived from the same individual, which is critical for elucidating the function of these disease-related genes and mutations. We anticipate that the generation of these isogenic cells will accelerate our understanding of the molecular causes of PD, and that such cellular models could become important tools for developing novel therapies.
Statement of Benefit to California: 
Approx. 36,000-60,000 people in the State of California are affected with Parkinson’s disease (PD) – a number that is estimated to double by the year 2030. This debilitating neurodegenerative disease causes a high degree of disability and financial burden for our health care system. Importantly, recent work has identified specific gene mutations that are directly linked to the development of PD. Here we propose to exploit the plasticity of human induced pluripotent stem cells (iPSC) to establish models of diseased and normal tissues relevant to PD. Specifically, we propose to take advantage of recent developments allowing the derivation of stem cells from PD patients carrying specific mutations. Our goal is to establish advanced stem cell models of the disease by literally “correcting” the mutated form of the gene in patient cells, therefore allowing for direct comparison of the mutant cells with its genetically “repaired” yet otherwise identical counterpart. These stem cells will be differentiated into dopaminergic neurons, the cells that degenerate in the brain of PD patients, permitting us to study the effect of correcting the genetic defect in the disease relevant cell type as well as provide a basis for the establishment of curative stem cells therapies. This collaborative project provides substantial benefit to the state of California and its citizens by pioneering a new stem cell based approach for understanding the role of disease causing mutations via “gene repair” technology, which could ultimately lead to advanced stem cell therapies for Parkinson’s disease – an unmet medical need without cure or adequate long-term therapy.
Progress Report: 
  • The goal of this proposal was to establish a novel research tool to explore the molecular basis of Parkinson’s disease (PD) - a critical step toward the development of new therapy. To date, a small handful of specific genes and associated mutations have been causally linked to the development of PD. However, how these mutations provoke the degeneration of specific neurons in the brain remains poorly understood.
  • In the first year of the grant, we have successfully modified the LRRK2 G2019S mutation in patient-derived induced pluripotent stem cells (iPSC) using zinc-finger technology. We created several clonal lines with the gene correction and also with a knockdown of the LRRK2 gene.
  • We characterized these lines for pluripotency, karyotype, and differentiation potential and currently, we are testing the lines for functional differences in the next reporting period and will generate iPSCs with specific LRRK2 mutations introduced using zinc-finger technology.
  • Despite the growing number of diseases linked to single gene mutations, determining the molecular mechanisms by which such errors result in disease pathology has proven surprisingly difficult. The ability to correlate disease phenotypes with a specific mutation can be confounded by background of genetic and epigenomic differences between patient and control cells. To address this problem, we employed zinc finger nucleases-based genome editing in combination with a newly developed high-efficiency editing protocol to generate isogenic patient-derived induced pluripotent stem cells (iPSC) differing only at the most common mutation for Parkinson's disease (PD), LRRK2 p.G2019S. We show that correction of the LRRK2 p.G2019S mutation rescues a panel of neuronal cell phenotypes including reduced dopaminergic cell number, impaired neurite outgrowth and mitochondrial dysfunction. These data reveal that PD-relevant cellular pathophysiology can be reversed by genetic repair, thus confirming the causative role of this prevalent mutation – a result with potential translational implications.
  • The goal of this proposal has been to establish a novel research tool to explore the molecular basis of Parkinson’s disease (PD) - a critical step toward the development of new therapies. To date, a small handful of specific genes and associated mutations have been causally linked to the development of PD. However, how these mutations provoke the degeneration of specific neurons in the brain remains poorly understood.
  • Moreover, conducting such genotype-phenotype studies has been hampered by two significant experimental problems. First, we have historically lacked the ability to model the relevant human cell types carrying the appropriate gene mutation. Second, the genetic variation between individuals means that the comparison of a cell from a disease-carrier to a cell derived from a normal subject is confounded by the many thousands of genetic changes that normally differentiate two individuals from one another.
  • We proposed to use zinc finger nucleases (ZFNs) in patient-derived induced pluripotent stem cells (iPSC) to accelerate the generation of a panel of genetically identical cell lines differing only in the presence or absence of a single disease-linked gene mutation.
  • To this end, we have successfully generated a panel of LRRK2 isogenic cell lines that differ only in "one building block" in the genomic DNA of a cell which can cause PD, therefore we genetically 'cured' the cells in the culture dish. These lines are invaluable because they are a set of tools that allow to study the effect of this mutation in the context of neurodegeneration and cell death. We received interest from many outside academic laboratories and industry to distribute these novel tools and these cell lines will hopefully lead to the discovery of new drugs that can halt or even reverse PD.

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.

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.

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