Neurological Disorders

Coding Dimension ID: 
303
Coding Dimension path name: 
Neurological Disorders

Molecular mechanisms involved in adult neural stem cell maintenance

Funding Type: 
New Faculty I
Grant Number: 
RN1-00527
ICOC Funds Committed: 
$2 348 520
Disease Focus: 
Aging
Neurological Disorders
Stem Cell Use: 
Adult Stem Cell
Embryonic Stem Cell
Cell Line Generation: 
Adult Stem Cell
oldStatus: 
Active
Public Abstract: 
Statement of Benefit to California: 
Progress Report: 
  • Aging is accompanied by a decline in the number and the function of adult stem cells in several tissues. In the brain, the depletion of adult neural stem cells (NSC) may underlie impaired cognitive performance associated with aging. Discovering the factors that govern the maintenance of adult NSC during aging should allow us to harness their regenerative potential for therapeutic purposes during normal aging and age-related neurodegenerative disorders. We have recently found that two 'longevity genes', Foxo3 and Sirt1, are critical for adult NSC function. In the past year, we have published a manuscript showing that Foxo3 is necessary for the maintenance of NSC in the adult brain. We have also started to explore the critical mechanisms by which Foxo3 maintains adult neural stem cells in the brain. We have used ultra-high throughput sequencing approach to reveal that Foxo3 is recruited to the regulatory regions of 3,000 genes in the adult neural stem cells, thereby triggering a gene expression network that regulates both the ability of neural stem cells to divide and their ability to give rise to progeny. Finally, we have obtained new results in the past year, showing that Sirt1, another 'longevity gene' is critical for the proper function of neural stem cells in the adult brain, and their ability to give rise to differentiated cells. Together, our results will help understand the regulation of neural stem cell maintenance in aging individuals and will provide new avenues to preserve the pool of these cells in the brain. Modulating longevity genes to harness the regenerative power of stem cells will provide new avenues for stem cell therapeutics for neurological and neurodegenerative diseases, most of which are age-dependent.
  • The adult brain contains pools of stem cells called neural stem cells that are critical for
  • the formation of new neurons in the adult brain. During aging, the number of neural stem
  • cells and their ability to give rise to new neurons strikingly decline. This decline could
  • underlie at least in part memory deterioration that occurs during aging and age-related
  • neurodegenerative disease such as Alzheimer’s disease. We have been interested over
  • the years in the importance of genes that regulate overall longevity in the control of the
  • pool of neural stem cells. We made the important discovery that Foxo3, a gene that has
  • been implicated in human exceptional longevity, is necessary for preserving the neural
  • stem cell pool. In the past year, we have made extensive progress in characterizing the
  • ensemble of genes regulated by Foxo3 in adult neural stem cells, a key step in
  • unraveling the mechanisms by which neural stem cells are maintained intact. In the past
  • year, we have observed that in the absence of another gene important for longevity
  • Sirt1, there is an unexpected increase in oligodendrocyte progenitors, which are cells
  • that are important for myelination of neurons, which is important for the proper
  • propagation of the neuronal information. Defects in myelination, which happen for
  • example in multiple sclerosis, have devastating consequences on the neurological
  • function. In the past year, we have made progress to understand the cellular and
  • molecular mechanism of action that enhances the production of oligodendrocytes in the
  • absence of Sirt1. Finally, we have made progress in initiating a project in human stem
  • cells that can be reprogrammed from adult cells, to extend our findings from mice to
  • humans, in particular as it relates to human diseases that have an age-dependent
  • component.
  • The number and function of adult stem cells decrease with age in a number of tissues. In the nervous system, the depletion of functional adult neural stem cells (NSC) may be responsible for impaired cognitive performance associated with normal or pathological aging. Understanding the factors that govern the maintenance of adult NSC should provide insights into their regenerative potential and open new avenues to use these cells for therapeutic purposes during normal aging and age-related neurodegenerative disorders.
  • Clues to key regulators of stem cell functions may come from studies of the genetics of aging, as genes that regulate longevity may do so by maintaining stem cells. To date, the most compelling examples for genes that control aging in a variety of organisms include the insulin-Akt-Foxo transcription factor pathway and the Sirt deacetylases. We have recently found that Foxo3 regulates a network of genes in adult NSC and interact with another transcription factor, called Ascl1, to preserve the integrity of the NSC pool and prevent the premature exhaustion of this important pool of cells. In the past year, we have also made the surprising discovery that inactivating Sirt1 in adult neural stem cells leads to the increased production of oligodendrocyte progenitors, which are cells that are crucial for myelination and could help demyelinating diseases, such as multiple sclerosis, or demyeliating injuries such as spinal cord injuries. Importantly, the enzymatic activity of Sirt1 can be targeted by small molecules, underscoring the potential for Sirt1 as a therapeutic target in stem cell and oligodendrocyte production. In the last year, we have also made significant progress in using cellular reprogramming to investigate the role of longevity genes in human cells. Our work examines the mechanisms by which ‘longevity genes’ regulate stem cell function and maintenance. Harnessing the regenerative power of stem cells by acting on longevity genes will provide a novel angle to identify stem cell therapeutics for regenerative medicine.
  • The adult brain contains reservoirs of neural stem cells that are critical for the formation of new neurons, oligodendrocytes, and astrocytes in the adult brain. During aging, the number of neural stem cells and their ability to give rise to new neurons strikingly decline. This decline could underlie at least in part the decline in memory that occurs during aging. We are interested in the importance of genes that regulate organismal longevity in the control of the reservoir of neural stem cells. We discovered that Foxo3, a transcription factor that has been implicated in human exceptional longevity, is important for regulating the neural stem cell pool pool. In the past year, we have made extensive progress in characterizing the interaction between Foxo3 and specific chromatin states at target genes in adult neural stem cells, which provides us with a mechanistic view onto how longevity genes can affect specific networks of target genes in neural stem cells in adult organisms. In the past year, we have made significant progress in testing the role of a gene involved in healthspan and longevity in a number of organisms, the deacetylase Sirt1, in adult neural stem cell function. We have observed that Sirt1 inactivation, whether genetic or pharmacological, leads to an increase in oligodendrocyte progenitors, which are cells that are important for myelination of axons. We have found that Sirt1 inactivation is beneficial for models of demyelinating injuries and diseases, which has important consequences for multiple sclerosis. Finally, we are making progress in reprogramming adult human fibroblasts into induced pluripotent stem cells and induced NSCs, with the aim to test the importance of longevity genes in this process.

Developmental Candidates for Cell-Based Therapies for Parkinson's Disease (PD)

Funding Type: 
Early Translational I
Grant Number: 
TR1-01267
ICOC Funds Committed: 
$5 416 003
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Collaborative Funder: 
Victoria, Australia
Stem Cell Use: 
Adult Stem Cell
Embryonic Stem Cell
iPS Cell
oldStatus: 
Active
Public Abstract: 
Statement of Benefit to California: 
Progress Report: 
  • Parkinson's Disease (PD) is a devastating disorder, stealing vitality from vibrant, productive adults & draining our health care dollars. It is also an excellent model for studying other neurodegenerative conditions. We have discovered that human neural stem cells (hNSCs) may exert a significant beneficial impact in the most authentic, representative, & predictive animal model of actual human PD (the adult African/St. Kitts Green Monkeys exposed systemically to the neurotoxin MPTP). Interestingly, we have learned that, while some of the hNSCs differentiate into replacement dopamine (DA) neurons, much of the therapeutic benefit derived from a stem cell action we discovered called the “Chaperone Effect” – even hNSC-derived cells that do not become DA neurons contributed to the reversal of severe Parkinsonian symptoms by protecting endangered host DA neurons & their connections, restoring equipoise to the host nigrostriatal system, and reducing pathological hallmark of PD. While the ultimate goal may someday be to replace dead DA neurons, the Chaperone Effect represents a more tractable near-term method of using cells to address this serious condition. However, many questions remain in the process of developing these cellular therapeutic candidates. A major question is what is the best (safest, most efficacious) way to generate hNSCs? Directly from the fetal brain? From human embryonic stem cells? From skin cells reprogrammed to act like stem cells? Also, would benefits be even greater if, in addition to harnessing the Chaperone Effect, the number of stem cell-derived DA neurons was also increased? And could choosing the right stem cell type &/or providing the right supportive molecules help achieve this? This international study – which involves scientists from California, Madrid, Melbourne -- has been seeking to answer these questions. Importantly, we have been doing so using the most representative model of human PD, a model that not only mimics all of the human symptomatology but also all the side-effects of treatment; inattention to this latter aspect plagued earlier clinical trials in PD. A successful therapy for PD would not only be of great benefit for the many patients who now suffer from the disease, or who are likely to develop it as they age, but the results will help with other potential disease applications due to greater understanding of stem cell biology (particularly the Chaperone Effect, which represents “low hanging fruit”) as well as their potential complications and side effects.
  • To date, we have transplanted nearly 40 Parkinsonian non-human primates (NHPs) with a range of the different stem cell types described above. We have been able to generate neurons from some of these stem cells that appear to have the characteristics of the desired A9-type midbrain dopaminergic neuron lost in PD. Following transplantation, some of these stem cell derivatives appear to survive, integrate, & behave like dopaminergic neurons. Preliminary behavioral analysis of some engrafted NHPs offers encouraging results, suggesting an improvement in the Parkinsonism score in some of the animals. These NHPs will need to be followed for 1 year to insure that improvement continues & that no adverse events intervene. Over the next year, more stem cell candidates will be tested as we further optimize their preparation & differentiation.
  • We have made substantial progress in what will amount to the largest and most comprehensive head-to-head behavioral analysis of stem cell transplanted MPTP-NHPs to date and have identified cell types that show dramatic improvement in this model. Compared to the improvement observed with undifferentiated fetal CNS-derived hNSCs (the stem cell type in used Redmond et al, PNAS, 2007), 3 human stem cell candidates have shown a larger improvement in PS.
  • Summary of Achievements for this reporting period
  • • Comprehensive Behavioral data collection of 84 monkeys comprising over 10,000 observation data points
  • • Statistical analysis of Behavioral data collected to date identifies striking and statistically significant improvements in PS for several stem cell types. (Accordingly, NO-GO (or near NO-GO) cell types have been identified via comparison of levels of improvement or no improvement) [Figure 1]
  • • DNA samples collected in order to pursue the first ever complete genome sequencing of the Vervet in collaboration with the Washington University Genome Center
  • • Biochemistry sample processing and data collection of a 2nd large batch of samples completed.
  • The identification and development of an ideal cell-based therapy for a complex neurodegenerative disease requires the rigorous evaluation of both efficacy and safety of different sources and subtypes of hNSCs. The objective of this project has been to fully evaluate and identify the optimal stem cell type for a cell based therapy for refractory Parkinson’s Disease (PD) using the systemically MPTP-lesioned Old World non-human primate (NHP) (the St. Kitts Green Monkey) the most authentic animal model of the actual human disease. Among a list of plausible potentially therapeutic stem cell sources, 7 candidates have been evaluated head-to-head. The intent has been that the stem cell type (and its derivatives) safely producing the largest improvement in behavioral scores (based on a well-established NHP PD score – the Parkinson’s Factor Score [PFS] or ParkScore (which closely parallels the Hoehn–Yahr scale used in human patients, and is an accurate functional read-out of nigrostriatal dopamine [DA] activity) -- as well as a Healthy Behaviors Score [HBS] (similar to the activities-of-daily-living [ADL] on the major Parkinson’s rating scale and allows quantification of adverse events) -- will be advanced towards IND-enabling studies, to an actual IND filing, and ultimately a clinical trial.
  • Candidate cells have been transplanted into specific sub-regions of the nigrostriatal pathway of MPTP-lesioned NHPs. Animals undergo behavioral scoring for analysis of severity of Parkinsonian behavior at multiple time points pre- and post-cell transplantation. At sacrifice, biochemical measurements of DA content are made. Tissue is also analyzed to determine the fate of donor cells; the status of the host nigrostriatal pathway; the number of alpha-synuclein aggregates; degree of inflammation; any evidence of adverse events (e.g., tumor formation, cell overgrowth, emergence of cells inappropriate to the CNS).
  • We have made substantial progress in what will amount to the largest and most comprehensive head-to-head analysis of stem cell transplanted into any disease model to date, let alone behavioral analysis into a primate model of PD. Behavioral data have been collected on ~100 monkeys comprising >10,000 observation data points. We have identified a single Developmental Candidate (DC) that shows consistent and dramatic improvement in severely Parkinsonian NHPs (i.e., a significant decrease in Parkinsonian symptoms over the entire evaluation period), reflecting a restitution of DA function – human embryonic stem cell (hESC-derived) ventral mesencephalic (VM) precursors. We also suggest adding a mechanism to these cells for insuring unambiguous safety and invariant lineage commitment (a construct already generated and inserted into this DC, and recently engrafted into some initial monkeys).
  • We believe are ready for IND-enabling studies, including additional long-term pre-clinical behavioral studies of hESC-derived hVM cells that bear the above-mentioned “safety construct” – combined with additional biochemical assays of DA metabolism, histological assessments, serial profiling to insure genomic stability. Scale-up conditions for this DC are defined and reproducible and a working cell bank has been established.
  • Parkinson's Disease (PD) is a devastating disorder that is caused by the loss of a particular type of neuron in the brain. PD patients show movement abnormalities which worsen over time and significantly reduce the quality of life. Current treatments reduce the severity of these problems but very often the efficacy of these treatments gradually weakens over time leaving patients with few therapeutic options, some of which carry significant unwanted side effects. Since the development of growing undifferentiated human stem cells in the late 1990’s, much has been learned in regards to how to make these cells develop into neuronal cells, in particular the same type of neuron that is lost in a PD patient. Therefore, a cellular therapy has been envisioned for the treatment of PD, however, the complex nature of this disease requires higher level models in which potential therapies can be accurately evaluated before moving a therapy to clinical trials.
  • Previous work using human fetal tissue showed improvement of PD symptoms in an animal model and human clinical trials, however, distinctive movement abnormalities arose from the use of this treatment and combined with the ethical issues, it is not a viable therapeutic strategy. Recent work suggests that the use of embryonic stem cells for the treatment of PD may be possible but a direct comparison of the different types of cells derived from these was lacking. Additionally, tumors caused by these cells have been reported.
  • Our research efforts funded by this CIRM award allowed us to complete the largest stem cell therapy comparison for PD using the most accurate disease model available. Over the last 3 years we have evaluated the efficacy of 8 potential therapeutic cell types and 2 control cell types (in addition to various other control groups to rule out any possibility that the observations may have resulted from something other than cells). From these efforts we have confidently identified a strategy for producing cells that show a dramatic reduction in the PD symptoms in this model and these cells will be developed for clinical trials. Furthermore, we have incorporated a critical step for ensuring the safety of this cell therapy by including a purification technique that removes cells that may give rise to tumors or produce unknown or unwanted effects.

Sustained siRNA production from human MSC to treat Huntingtons Disease and other neurodegenerative disorders

Funding Type: 
Early Translational I
Grant Number: 
TR1-01257
ICOC Funds Committed: 
$2 753 559
Disease Focus: 
Huntington's Disease
Neurological Disorders
Stem Cell Use: 
Adult Stem Cell
Embryonic Stem Cell
Cell Line Generation: 
Adult Stem Cell
oldStatus: 
Closed
Public Abstract: 
Statement of Benefit to California: 
Progress Report: 
  • During the first year of funding we have made significant progress toward the goals of the funded CIRM grant TR1-01257: Sustained siRNA production from human MSC to treat Huntington’s disease and other neurodegenerative disorders.
  • The overall goal of the grant is to use human mesenchymal stem cells (MSC) as safe delivery vehicles to knock down levels of the mutant Huntingtin (htt) RNA and protein in the brain. There is mounting evidence in trinucleotide repeat disorders that the RNA, as well as the protein, is toxic and thus we will need to significantly reduce levels of both in order to have a durable impact on this devastating disease.
  • This year we have shown that human MSC engineered to produce anti-htt siRNA can directly transfer enough RNA interfering molecules into neurons in vitro to achieve significant reduction in levels of the htt protein. This is a significant achievement and a primary goal of our proposed studies, and demonstrates that the hypothesis for our proposed studies is valid. The transfer occurs through direct cell-to-cell transfer of siRNA, and we have filed an international patent for this process, working closely with our Innovation Access Program at UC Davis. A manuscript documenting the results of these studies is in preparation.
  • We continue to explore the precise methods by which the cell-to-cell transfer of small RNA molecules occurs, working in close collaboration with the national Center for Biophotonics Science and Technology at UC Davis. This Center is located across the street from our CIRM-funded Institute for Regenerative Cures (IRC) where our laboratory is located, and has equipment that allows visualization of protein-protein interactions in high clarity and detail. The proximity of our HD team researchers in the IRC to the Center for Biophotonics has been an important asset to our project and a collaborative manuscript is in preparation.
  • During year two of the proposed studies we will continue to document levels of reduction of the toxic htt protein in different types of neurons, including medium spiny neurons (MSN) derived from HD patient induced pluripotent stem cells (iPSC). We have made significant advances in developing the tools for these studies, including HD iPSC line generation and MSN maturation from human pluripotent cells in culture. A manuscript on improved techniques for generating MSN from pluripotent cells is in preparation. We have also worked closely with our colleagues at the UC Davis MIND Institute to achieve improved maturation and electrical activity in neurons derived from human pluripotent stem cells in vitro, and we are examining the impact of human MSC on enhancing survival of damaged human neurons.
  • In the second year of funding we will test efficacy of the siRNA-mediated knockdown of the mutant human htt RNA and protein in the brains of our newly developed strain of immune deficient Huntington's disease mice. This strain was developed by our teams at UC Davis to allow testing of human cells in the mice, since the current strains of HD mice will reject human stem cells. A manuscript describing generation of this novel HD mouse strain is in preparation, in collaboration with our nationally prominent Center for Mouse Biology.
  • Behavioral studies will be conducted in this strain with and without the MSC/siRNA-mediated knockdown of the mutant protein, through years 2-3, in collaboration with our well established mouse neurobehavioral core at the UC Davis Center for Neurosciences. We have documented the safety of intrastriatal injection of human MSC in immune deficient mice and will next test the efficacy of human MSC engineered to continually produce the siRNA to knock down the mutant htt protein in vivo.
  • As added leverage for this grant program, and supported entirely by philanthropic donations from the community committed to curing HD, we have performed IND-enabling studies in support of an initial planned clinical trial that will use normal donor MSC (non-engineered) to validate their significant neurotrophic effects in the brain. These trophic effects have been documented in animal models. The planned study will be a phase 1 safety trial. We have completed the clinical protocol design and have received feedback from the Food and Drug Administration. We will be conducting additional studies in response to their queries, over the next 6-10 months, through a pilot grant obtained from our Clinical Translational Science Center (CTSC), which is located in the same building as our Institute. Upon completion of these additional studies we will submit the updated IND application to the FDA. MSCs for this project have been expanded and banked using standard operating procedures in place in the Good Manufacturing Practice Facility in the CIRM/UC Davis Institute for Regenerative Cures.
  • From the funded studies 4 manuscripts are now in preparation, a chapter is in press and a review paper on MSC to treat neurodegenerative diseases is in press.
  • During the second year of funding we have made significant progress toward the goals of the funded CIRM grant TR1-01257: Sustained siRNA production from human MSC to treat Huntington’s disease and other neurodegenerative disorders.
  • The overall goal of the grant is to use human mesenchymal stem cells (MSC) as safe delivery vehicles to knock down levels of the mutant Huntingtin (htt) RNA and protein in the brain. During the second year we have more fully characterized our development candidate; MSC/anti-htt. We have documented that normal human donor MSC engineered to produce anti-htt siRNA can directly transfer enough RNA interfering molecules into neurons in vitro to achieve significant reduction in levels of the htt protein. We reported this work at the Annual meeting of the American Academy of Neurology (G Mitchell, S Olson, K Pollock, A Kambal, W Cary, K Pepper, S Kalomoiris, and J Nolta. Mesenchymal Stem Cells as a Delivery Vehicle for Intercellular Delivery of RNAi to Treat Huntington's disease. AAN IN10-1.010, 2011) and have recently completed and submitted a manuscript describing these results (S Olson, A Kambal, K Pollock, G Mitchell, H Stewart, S Kalomoiris, W Cary, C Nacey, K Pepper, J Nolta. Mesenchymal stem cell-mediated RNAi transfer to Huntington's disease affected neuronal cells for reduction of huntingtin. Submitted, In Review, July 2011).
  • We have explored the molecular methods by which the cell-to-cell transfer of small RNA molecules occurs, working in close collaboration with the national Center for Biophotonics Science and Technology at UC Davis. This Center is located across the street from our CIRM-funded Institute for Regenerative Cures (IRC) where our laboratory is located, and has equipment that allows visualization of protein-siRNA interactions in high clarity and detail. The proximity of our HD team researchers in the IRC to the Center for Biophotonics has been an important asset to our project. This work was also presented at AAN 2011, and a collaborative manuscript is in preparation for submission (S Olson, G McNerny, K Pollock, F Chuang, T Huser and J Nolta, Visualization of siRNA Complexed to RISC Machinery: Demonstrating Intercellular siRNA Transfer by Imaging Activity. MS in preparation, Presented at AAN 2011: IN4-1.014).
  • In the second year of funding we developed the models for in vivo efficacy testing of the siRNA-mediated knockdown of the mutant human htt RNA and protein in the brains of established and new strains of Huntington's disease mice. Behavioral studies were conducted in two strains, the R6/2 immune competent mice and our new immune deficient strain, the NSG/HD, in comparison to normal littermate controls that are not affected by HD. We established the batteries of behavioral tests that are now needed to test efficacy of our development candidate in the brain, in year three. Established tests include rotarod, treadscan, pawgrip, spontaneous activity, nesting, locomotor activity, and the characteristic HD mouse hindlimb clasping phenotype. In addition we monitor the status of weight and tremor, grooming, eyes, hair, body position, and tail position, which all change over time in HD mice. These tests are conducted at 48 hour intervals by two highly trained technicians who are blinded to the treatment that the mouse had received. These behavioral and phenotypic tests have been established at the level of Good laboratory practices in our new Institute for Regenerative Cures shower-in barrier facility vivarium. We have documented the biosafety of intrastriatal injection of human MSC in immune deficient mice and are now examining the in vivo efficacy of the development candidate: human MSC engineered to continually produce the siRNA to knock down the mutant htt protein in vivo, which will be completed in year three.
  • As added leverage for this funded grant program, and supported entirely by philanthropic donations from the community committed to curing HD, we have performed IND-enabling studies in support of an initial planned clinical trial that will use normal donor MSC (non-engineered) to validate their significant neurotrophic effects in the brain. These trophic effects have been documented in animal models. The planned study will be a phase 1 safety trial. We have completed the clinical protocol design and have received feedback from the Food and Drug Administration. We will be conducting additional studies in response to their queries, over the next 6-10 months, through a pilot grant obtained from our Clinical Translational Science Center (CTSC), which is located in the same building as our Institute. Upon completion of these additional studies we will submit the updated IND application to the FDA. MSCs for this project have been expanded and banked using standard operating procedures in place in the Good Manufacturing Practice Facility in the CIRM/UC Davis Institute for Regenerative Cures.
  • During the three years of funding we made significant progress toward the goals of the funded CIRM grant TR1-01257: Sustained siRNA production from human MSC to treat Huntington’s disease and other neurodegenerative disorders.
  • The overall goal of the grant is to use human mesenchymal stem cells (MSC) as safe delivery vehicles to knock down levels of the mutant Huntingtin (htt) RNA and protein in the brain. There is mounting evidence in trinucleotide repeat disorders that the RNA, as well as the protein, is toxic and thus we will need to significantly reduce levels of both in order to have a durable impact on this devastating disease.
  • We initially demonstrated that human MSC engineered to produce anti-htt siRNA can directly transfer enough RNA interfering molecules into neuronal cells in vitro to achieve significant reduction in levels of the htt protein. This is a significant achievement and a primary goal of our proposed studies, and demonstrates that the hypothesis for our proposed studies is valid. The transfer occurs either through direct cell-to-cell transfer of siRNA or through exosome transfer, and we filed an international patent for this process, working closely with our Innovation Access Program at UC Davis. This patent has IP sharing with CIRM.
  • An NIH transformative grant was awarded to Dr. Nolta to further explore these exciting findings. This provides funding for five years to further define and optimize the siRNA transfer mechanism.
  • A manuscript documenting the results of these studies was published:
  • S Olson, A Kambal, K Pollock, G Mitchell, H Stewart, S Kalomoiris, W Cary, C Nacey, K Pepper, J Nolta. Examination of mesenchymal stem cell-mediated RNAi transfer to Huntington's disease affected neuronal cells for reduction of huntingtin. Molecular and Cellular Neuroscience; 49(3):271-81, 2012.
  • Also a review was published with our collaborator Dr. Gary Dunbar:
  • S Olson, K Pollock, A Kambal, W Cary, G Mitchell, J Tempkin, H Stewart, J McGee, G Bauer, T Tempkin, V Wheelock, G Annett, G Dunbar and J Nolta, Genetically Engineered Mesenchymal Stem Cells as a Proposed Therapeutic for Huntington’s disease. Molecular Neurobiology; 45(1):87-98, 2012.
  • We examined the potential efficacy of injecting relatively small numbers of MSCs engineered to produce ant-htt siRNA into the striata of the HD mouse strain R6/2, in three series of experiments. Results of these experiments did not reach significance for the test agent as compared to controls. The slope of the decline in rotarod performance was less with the test agent, and development of clasping behavior was slightly delayed after injection of MSC/aHtt, but this caught up to the controls and was not significant after day 60.
  • Our conclusions are that the R6/2 strain is too rapidly progressing to see efficacy with the test agent, and also that improved methods of siRNA transfer from cell to cell are needed. We are currently working on this problem through the NIH transformative award, and will use the YAC 128 strain, which has a more slowly progressing phenotype, for all future studies. These mice are now bred and in use in our vivarium, for the MSC/BDNF studies funded through our disease team grant.
  • Through this translational grant funding we have also developed in vitro potency assays, using human embryonic stem cell-derived neurons and medium spiny neurons, as we have described in prior reports. The differentiation techniques (funded through other grants to our group) have now been published:1-3
  • 1. Liu J, Githinji J, McLaughlin B, Wilczek K, Nolta J. Role of miRNAs in Neuronal Differentiation from Human Embryonic Stem Cell-Derived Neural Stem Cells. Stem Cell Rev;8(4):1129-37, 2012.
  • 2. Jun-feng Feng, Jing Liu, Xiu-zhen Zhang, Lei Zhang, Ji-yao Jiang, Nolta J, Min Zhao. Guided Migration of Neural Stem Cells Derived from Human Embryonic Stem Cells by an Electric Field. Stem Cells. Feb; 30(2):349-55, 2012.
  • 3. Liu J, Koscielska KA, Cao Z, Hulsizer S, Grace N, Mitchell G, Nacey C, Githinji J, McGee J, Garcia-Arocena D, Hagerman RJ, Nolta J, Pessah I, Hagerman PJ. Signaling defects in iPSC-derived fragile X premutation neurons. Hum Mol Genet. 21(17):3795-805. 2012.

Enhancing healing via Wnt-protein mediated activation of endogenous stem cells

Funding Type: 
Early Translational I
Grant Number: 
TR1-01249
ICOC Funds Committed: 
$6 762 954
Disease Focus: 
Bone or Cartilage Disease
Stroke
Neurological Disorders
Heart Disease
Neurological Disorders
Skin Disease
Stem Cell Use: 
Adult Stem Cell
oldStatus: 
Active
Public Abstract: 
Statement of Benefit to California: 
Progress Report: 
  • In the first year of CIRM funding our objectives were to optimize the activity of the Wnt protein for use in the body and then to test, in a variety of injury models, the effects of this lipid-packaged form of Wnt. We have made considerable progress on both of these fronts. For example, in Roel Nusse and Jill Helms’ groups, we have been able to generate large amounts of the mouse form of Wnt3a protein and package it into liposomal vesicles, which can then be used by all investigators in their studies of injury and repair. Also, Roel Nusse succeeded in generating human Wnt3a protein. This is a major accomplishment since our ultimate goal is to develop this regenerative medicine tool for use in humans. In Jill Helms’ lab we made steady progress in standardizing the activity of the liposomal Wnt3a formulation, and this is critically important for all subsequent studies that will compare the efficacy of this treatment across multiple injury repair scenarios.
  • Each group began testing the effects of liposomal Wnt3a treatment for their particular application. For example, in Theo Palmer’s group, the investigators tested how liposomal Wnt3a affected cells in the brain following a stroke. We previously found that Wnt3A promotes the growth of neural stem cells in a petri dish and we are now trying to determine if delivery of Wnt3A can enhance the activity of endogenous stem cells in the brain and improve the level of recovery following stroke. Research in the first year examined toxicity of a liposome formulation used to deliver Wnt3a and we found it to be well tolerated after injection into the brains of mice. We also find that liposomal Wnt3a can promote the production of new neurons following stroke. The ongoing research involves experiments to determine if these changes in stem cell activity are accompanied by improved neurological function. In Jill Helms’ group, the investigators tested how liposomal Wnt3a affected cells in a bone injury site. We made a significant discovery this year, by demonstrating that liposomal Wnt3a stimulates the proliferation of skeletal progenitor cells and accelerates their differentiation into osteoblasts (published in Science Translational Medicine 2010). We also started testing liposomal Wnt3a for safety and toxicity issues, both of which are important prerequisites for use of liposomal Wnt3a in humans. Following a heart attack (i.e., myocardial infarction) we found that endogenous Wnt signaling peaks between post-infarct day 5-7. We also found that small aggregates of cardiac cells called cardiospheres respond to Wnt in a dose-responsive manner. In skin wounds, we tested the effect of boosting Wnt signaling during skin wound healing. We found that the injection of Wnt liposomes into wounds enhanced the regeneration of hair follicles, which would otherwise not regenerate and make a scar instead. The speed and strength of wound closure are now being measured.
  • In aggregate, our work on this project continues to move forward with a number of great successes, and encouraging data to support our hypothesis that augmenting Wnt signaling following tissue injury will provide beneficial effects.
  • In the second year of CIRM funding our objectives were to optimize packaging of the developmental candidate, Wnt3a protein, and then to continue to test its efficacy to enhance tissue healing. We continue to make considerable progress on the stated objectives. In Roel Nusse’s laboratory, human Wnt3a protein is now being produced using an FDA-approved cell line, and Jill Helms’ lab the protein is effectively packaged into lipid particles that delay degradation of the protein when it is introduced into the body.
  • Each group has continued to test the effects of liposomal Wnt3a treatment for their particular application. In Theo Palmer’s group we have studied how liposomal Wnt3a affects neurogenesis following stroke. We now know that liposomal Wnt3a transiently stimulates neural progenitor cell proliferation. We don’t see any functional improvement after stroke, though, which is our primary objective.
  • In Jill Helms’ group we’ve now shown that liposomal Wnt3a enhances fracture healing and osseointegration of dental and orthopedic implants and now we demonstrate that liposomal Wnt3a also can improve the bone-forming capacity of bone marrow grafts, especially when they are taken from aged animals.
  • We’ve also tested the ability of liposomal Wnt3a to improve heart function after a heart attack (i.e., myocardial infarction). Small aggregates of cardiac progenitor cells called cardiospheres proliferate to Wnt3a in a dose-responsive manner, and we see an initial improvement in cardiac function after treatment of cells with liposomal Wnt3a. the long-term improvements, however, are not significant and this remains our ultimate goal. In skin wounds, we tested the effect of boosting Wnt signaling during wound healing. We found that the injection of liposomal Wnt3a into wounds enhanced the regeneration of hair follicles, which would otherwise not regenerate and make a scar instead. The speed of wound closure is also enhanced in regions of the skin where there are hair follicles.
  • In aggregate, our work continues to move forward with a number of critical successes, and encouraging data to support our hypothesis that augmenting Wnt signaling following tissue injury will provide beneficial effects.
  • Every adult tissue harbors stem cells. Some tissues, like bone marrow and skin, have more adult stem cells and other tissues, like muscle or brain, have fewer. When a tissue is injured, these stem cells divide and multiply but only to a limited extent. In the end, the ability of a tissue to repair itself seems to depend on how many stem cells reside in a particular tissue, and the state of those stem cells. For example, stress, disease, and aging all diminish the capacity of adult stem cells to respond to injury, which in turn hinders tissue healing. One of the great unmet challenges for regenerative medicine is to devise ways to increase the numbers of these “endogenous” stem cells, and revive their ability to self-renew and proliferate.
  • The scientific basis for our work rests upon our demonstration that a naturally occurring stem cell growth factor, Wnt3a, can be packaged and delivered in such a way that it is robustly stimulates stem cells within an injured tissue to divide and self-renew. This, in turn, leads to unprecedented tissue healing in a wide array of bone injuries especially in aged animals. As California’s population ages, the cost to treat such skeletal injuries in the elderly will skyrocket. Thus, our work addresses a present and ongoing challenge to healthcare for the majority of Californians and the world, and we do it by mimicking the body’s natural response to injury and repair.
  • To our knowledge, there is no existing technology that displays such effectiveness, or that holds such potential for the stem cell-based treatment of skeletal injuries, as does a L-Wnt3a strategy. Because this approach directly activates the body’s own stem cells, it avoids many of the pitfalls associated with the introduction of foreign stem cells or virally reprogrammed autologous stem cells into the human body. In summary, our data show that L-Wnt3a constitutes a viable therapeutic approach for the treatment of skeletal injuries, especially those in individuals with diminished healing potential.
  • This progress report covers the period between Sep 01 2012through Aug 31 2013, and summarizes the work accomplished under ET funding TR1-01249. Under this award we developed a Wnt protein-based platform for activating a patient’s own stem cells for the purpose of tissue regeneration.
  • At the beginning of our grant period we generated research grade human WNT3A protein in quantities sufficient for all our discovery experiments. We then tested the ability of this WNT protein therapeutic to improve the healing response in animal models of stroke, heart attack, skin wounding, and bone fracture. These experimental models recapitulated some of the most prevalent and debilitating human diseases that collectively, affect millions of Californians.
  • At the end of year 2, we assembled an external review panel to select the promising clinical indication. The scientific advisory board unanimously selected skeletal repair as the leading indication. The WNT protein is notoriously difficult to purify; consequently in year 3 we developed new methods to streamline the purification of WNT proteins, and the packaging of the WNT protein into liposomal vesicles that stabilized the protein for in vivo use.
  • In years 3 and 4 we continued to accrue strong scientific evidence in both large and small animal models that a WNT protein therapeutic accelerates bone regeneration in critical size bony non-unions, in fractures, and in cases of implant osseointegration. In this last year of funding, we clarified and characterized the mechanism of action of the WNT protein, by showing that it activates endogenous stem cells, which in turn leads to faster healing of a range of different skeletal defects.
  • In this last year we also identified a therapeutic dose range for the WNT protein, and developed a route and method of delivery that was simultaneously effective and yet limited the body’s exposure to this potent stem cell factor. We initiated preliminary safety studies to identify potential risks, and compared the effects of WNT treatment with other commercially available bone growth factors. In sum, we succeeded in moving our early translational candidate from exploratory studies to validation, and are now ready to enter into the IND-enabling phase of therapeutic candidate development.
  • This progress report covers the period between Sep 01 2013 through April 30 2014, and summarizes the work accomplished under ET funding TR101249. Under this award we developed a Wnt protein-based platform for activating a patient’s own stem cells for purposes of tissue regeneration.
  • At the beginning of our grant period we generated research grade human WNT3A protein in quantities sufficient for all our discovery experiments. We then tested the ability of this WNT protein therapeutic to improve the healing response in animal models of stroke, heart attack, skin wounding, and bone fracture. These experimental models recapitulated some of the most prevalent and debilitating human diseases that collectively, affect millions of Californians. At the conclusion of Year 2 an external review panel was assembled and charged with the selection of a single lead indication for further development. The scientific advisory board unanimously selected skeletal repair as the lead indication.
  • In year 3 we accrued addition scientific evidence, using both large and small animal models, demonstrating that a WNT protein therapeutic accelerated bone healing. Also, we developed new methods to streamline the purification of WNT proteins, and improved our method of packaging of the WNT protein into liposomal vesicles (e.g., L-WNT3A) for in vivo use.
  • In year 4 we clarified the mechanism of action of L-WNT3A, by demonstrating that it activates endogenous stem cells and therefore leads to accelerated bone healing. We also continued our development studies, by identifying a therapeutic dose range for L-WNT3A, as well as a route and method of delivery that is both effective and safe. We initiated preliminary safety studies to identify potential risks, and compared the effects of L-WNT3A with other, commercially available bone growth factors.
  • In year 5 we initiated two new preclinical studies aimed at demonstrating the disease-modifying activity of L-WNT3A in spinal fusion and osteonecrosis. These two new indications were chosen by a CIRM review panel because they represent an unmet need in California and the nation. We also initiated development of a scalable manufacturing and formulation process for both the WNT3A protein and L-WNT3A formulation. These two milestones were emphasized by the CIRM review panel to represent major challenges to commercialization of L-WNT3A; consequently, accomplishment of these milestones is a critical yardstick by which progress towards an IND filing can be assessed.

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

Funding Type: 
Early Translational I
Grant Number: 
TR1-01246
ICOC Funds Committed: 
$3 701 766
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Collaborative Funder: 
Germany
Stem Cell Use: 
iPS Cell
Cell Line Generation: 
iPS Cell
oldStatus: 
Closed
Public Abstract: 
Statement of Benefit to California: 
Progress Report: 
  • In the first year of the CIRM Early translational research award, we established a bank of 51 cell lines derived from skin cells of patients with Parkinson’s disease that carry specific mutations in known genes that cause PD as well as sporadic PD patients. We also recruited matched healthy individuals that serve as controls.
  • In a next step, we reprogrammed (‘rejunivated’) 17 samples of skin cells to derive pluripotent stem cells (iPSC) that closely resemble human embryonic stem cells characterized by biochemical and molecular techniques. We also optimize this process by introducing factors the will be removed after successful reprogramming.
  • We have now built a foundation for the next milestones and made already progress on the differentiation into authentic dopamine producing cells, and we have developed assays to assess the Parkinson’s disease-specific pathological phenotype of the dopamine neurons.
  • The goal of this CIRM early translational grant is to develop a model for “Parkinson’s disease (PD) in a culture dish” using patient-specific induced pluripotent stem cell lines (iPS). The underlying idea is to utilize these lines as an experimental pre-clinical model to study disease mechanisms unique to PD that could lay the foundation for drug discovery.
  • Over the last year, we have expanded our patient skin cell bank to 57 cell lines and the iPS cell bank to 39 well-characterized pluripotent stem cell lines from PD patients and healthy controls individuals. We have improved current protocols of neuronal differentiation from patient-derived iPS lines into dopamine producing neurons and can show consistency and reproducibility of making midbrain dopamine expressing nerve cells.
  • In our first publication (Nguyen et al. 2011), we describe for the first time differences in iPS-derived neurons from a PD patient with a common causative mutation in the LRRK2 gene. These patient cells are more susceptible for cellular toxins leading ultimately to more cell degeneration and cell death.
  • We are also investigating a common disease mechanism implicated in PD, which is mitochondrial dysfunction. In skin cells of a patient we were able to find profound deficits of mitochondrial function compared to control lines and we are now in the process of confirming these results in neural precursors and mature dopamine neurons.
  • Overall, we have made substantial progress towards the goal of this grant which is the a new cell culture model of PD which can replicate PD-related cellular pathology.
  • The goal of this CIRM early translational grant is to develop a model for “Parkinson’s disease (PD) in a culture dish” using patient-specific induced pluripotent stem cell lines (iPS). The underlying idea is to utilize these lines as an experimental pre-clinical model to study disease mechanisms unique to PD that could lay the foundation for drug discovery.
  • Over the last year, we have expanded our patient skin cell bank to 61 cell lines and the iPS cell bank to 51 well-characterized pluripotent stem cell lines from PD patients and healthy controls individuals. We have improved current protocols of neuronal differentiation from patient-derived iPS lines into dopamine producing neurons and can show consistency and reproducibility of making midbrain dopamine expressing nerve cells. This has been now published in Mak et al. 2012. Furthermore, we also develop new protocols to also derive other neuronal subtypes and glia, which are the support cells in the brain, to build co-culture systems. These co-cultures might represent closer the physiological conditions in the brain.
  • In our first publication (Nguyen et al. 2011), we describe for the first time differences in iPS-derived neurons from a PD patient with a common causative mutation in the LRRK2 gene. These patient cells are more susceptible for cellular toxins leading ultimately to more cell degeneration and cell death. In a second publication Byers et al. 2011, we describe similar findings for a different mutation in the alpha-synuclein gene where the normal protein is overexpressed due to a triplication of the gene locus.
  • We are also investigating a common disease mechanism implicated in PD, which is mitochondrial dysfunction. In skin cells of a patient we were able to find profound deficits of mitochondrial function compared to control lines and we are now in the process of confirming these results in neural precursors and mature dopamine neurons.
  • We are expanding the assay development to other disease-related mechanisms such as deficits in outgrowth of neuronal projections and protein aggregation.
  • Overall, through this program we have developed an invaluable resource of patient-derived cell lines that will be crucial for understanding disease mechanisms and drug discovery. We also showed proof that these cell lines can indeed recapitulates important aspects of disease and are therefore valuable assets as research tools.

Neural Stem Cells as a Developmental Candidate to Treat Alzheimer Disease

Funding Type: 
Early Translational I
Grant Number: 
TR1-01245
ICOC Funds Committed: 
$3 599 997
Disease Focus: 
Aging
Alzheimer's Disease
Neurological Disorders
Collaborative Funder: 
Victoria, Australia
Stem Cell Use: 
Adult Stem Cell
Embryonic Stem Cell
oldStatus: 
Closed
Public Abstract: 
Statement of Benefit to California: 
Progress Report: 
  • Over the past decade, the potential for using stem cell transplantation as a therapy to treat neurological disorders and injury has been increasingly explored in animal models. Studies from our lab have shown that neural stem cell transplantation can improve cognitive deficits in mice resulting from extensive neuronal loss and protein aggregation, both hallmarks of Alzheimer’s Disease pathology. Our results support the justification for exploring the use of human derived stem cells for the treatment of Alzheimer’s patients.
  • During the past few months, we have begun studies aimed at taking human derived stem cells from the bench top to the bed side. To identify the best possible human stem cells to use in our future studies, we have conducted comparisons between a wide array of human stem cells and a mouse neural stem cell line (the same mouse stem cells used in the studies mentioned above). Using these results, we have selected a cohort of human stem cell candidates to which we will continue to study in upcoming experiments involving our AD model mice.
  • In addition to identifying the best human stem cells to conduct further studies, we have also performed experiments to determine the optimal immune suppression regimen to use in our human stem cell engraftment studies. Similar to organ transplants in humans, we will need to administer immune suppressants to mice which receive our candidate human stem cells. Our group has identified a potential suppressant, also found to work in humans, which we will use in future studies.
  • Over the past decade, the potential for using stem cell transplantation as a therapy to treat neurological disorders and injury has been increasingly explored in animal models. Studies from our lab have shown that neural stem cell transplantation can improve cognitive deficits in mice resulting from extensive neuronal loss and protein aggregation, both hallmarks of Alzheimer’s Disease pathology. Our results support the justification for exploring the use of human derived stem cells for the treatment of Alzheimer’s patients.
  • During the past few months, we have begun studies aimed at taking human derived stem cells from the bench top to the bed side. To identify the best possible human stem cells to use in our future studies, we have conducted comparisons between a wide array of human stem cells and a mouse neural stem cell line (the same mouse stem cells used in the studies mentioned above). Using these results, we have selected a cohort of human stem cell candidates to which we will continue to study in upcoming experiments involving our AD model mice.
  • In addition to identifying the best human stem cells to conduct further studies, we have also performed experiments to determine the optimal immune suppression regimen to use in our human stem cell engraftment studies. Similar to organ transplants in humans, we will need to administer immune suppressants to mice which receive our candidate human stem cells. Our group has identified a potential suppressant, also found to work in humans, which we will use in future studies.
  • During the last reporting period the lab has made substantial advancements in determining the effects of long term human neural stem cells engraftment on pathologies associated with the advancement of Alzheimer's disease. In addition, data obtained by our lab has may provide additional insight on ways to target the immune system as a means of prolonging neural stem cell survival and effectiveness.

Role of HLA in neural stem cell rejection using humanized mice

Funding Type: 
Transplantation Immunology
Grant Number: 
RM1-01735-A
ICOC Funds Committed: 
$1 472 634
Disease Focus: 
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
Cell Line Generation: 
Embryonic Stem Cell
Public Abstract: 
One of the key issues in stem cell transplant biology is solving the problem of transplant rejection. Despite over three decades of research in human embryonic stem cells, little is known about the factors governing immune system tolerance to grafts derived from these cells. In order for the promise of embryonic stem cell transplantation for treatment of diseases to be realized, focused efforts must be made to overcome this formidable hurdle. Our proposal will directly address this critically important issue by investigating the importance of matching immune system components known as human leukocyte antigens (HLA). Because mouse and human immune systems are fundamentally different, we will establish cutting-edge mouse models that have human immune systems as suitable hosts within which to conduct our stem cell brain transplant experiments. Such models rely on immunocompromised mice as recipients for human blood-derived stem cells. These mice go on to develop a human immune system, complete with HLAs, and can subsequently be used to engraft embryonic stem cell-derived brain cells that are either HLA matched or mismatched. Due to our collective expertise in the central nervous system and animal transplantation studies for Parkinson’s disease, our specific focus will be on transplanting embryonic stem cell-derived neural stem cells into brains of both healthy and Parkinson's diseased mice. We will then detect: 1) abundance of brain immune cell infiltrates, 2) production of immune molecules, and 3) numbers of brain-engrafted embryonic stem cells. Establishing this important system would allow for a predictive model of human stem cell transplant rejection based on immune system matching. We would then know how similar HLAs need to be in order to allow for acceptance stem cell grafts.
Statement of Benefit to California: 
In this project, we propose to focus on the role of the human immune system in human embryonic stem cell transplant rejection. Specifically, we aim to develop cutting-edge experimental mouse models that possess human immune systems. This will allow us to determine whether immune system match versus mismatch enables embryonic stem cell brain transplant acceptance versus rejection. Further, we will explore this key problem in stem cell transplant biology both in the context of the healthy and diseased brain. Regarding neurological disease, we will focus on neural stem cell transplants for Parkinson's disease, which is one of the most common neurodegenerative diseases, second only to Alzheimer's disease. If successful, our work will pave the way toward embryonic stem cell-based treatment for this devastating neurological disorder for Californians and others. In order to accomplish these goals, we will utilize two of the most common embryonic stem cell types, known as WiCell H1 and WiCell H9 cells. It should be noted that these particular stem cells will likely not be reauthorized for funding by the federal government due to ethical considerations. This makes our research even more important to the State of California, which would not only benefit from our work but is also in a unique position to offer funding outside of the federal government to continue studies such as these on these two important types of human embryonic stem cells.
Progress Report: 
  • In order for the promise of stem cell transplantation therapy to treat or cure human disease to be realized, the key problem of stem cell transplant rejection must be solved. Yet, despite over three decades of research in human embryonic stem cells, little is known about the factors governing immune system tolerance to grafts derived from these cells.
  • The goal of our CIRM Stem Cell Transplantation Immunology Award is to overcome this formidable hurdle by generating pre-clinical mouse models that have human immune systems. This next-generation model system will provide a testing platform to evaluate the importance of matching immune system components known as human leukocyte antigens (HLAs). Because mouse and human immune systems are fundamentally different, these cutting-edge ‘humanized’ mice are currently the only animal models within which to conduct our stem cell brain transplant experiments. Such models rely on immunocompromised mice as recipients for human umbilical cord blood stem cells (HSCs). These mice go on to develop a human immune system, complete with HLAs, and can subsequently be used to engraft embryonic stem cell-derived brain cells that are either HLA matched or mismatched and to monitor for graft acceptance vs. rejection.
  • During this first year of CIRM funding, we have accomplished three main goals leading to completion of Specific Aim 1: To establish mouse models with human immune systems (year 1). Firstly, we have increased purity of HSCs from 75% to 93%. This has enabled us to complete our second goal of generating 10 mice bearing 50% or more human immune cells. Thirdly, we have characterized the human adaptive immune systems of these mice and have found presence of 40-60% of human T lymphocytes in lymphoid organs of ‘humanized’ mice.
  • For the promise of stem cell transplantation therapy to treat or cure human disease to be realized, the key problem of stem cell transplant rejection must be solved. Yet, despite over three decades of research in human embryonic stem cells, little is known about the factors involved in immune system tolerance to grafts derived from embryonic stem cells.
  • The goal of our CIRM Stem Cell Transplantation Immunology Award is to overcome this formidable hurdle by generating pre-clinical mouse models that have human immune systems. This cutting-edge model system will provide a testing platform to evaluate the importance of matching immune system components, known as human leukocyte antigens (HLAs), between the human embryonic stem (hES) cell-derived neural stem cell (NSC) graft and the patient. Because mouse and human immune systems are fundamentally different, these next-generation ‘humanized’ mice are currently the only animal models within which to conduct our stem cell brain transplant experiments. Such models rely on immunocompromised mice as recipients for human umbilical cord blood stem cells (HSCs). These mice go on to develop a human immune system, complete with HLAs, and can subsequently be used to engraft embryonic stem cell-derived brain cells that are either HLA matched or mismatched and to monitor for graft acceptance vs. rejection.
  • During this second year of CIRM funding, we have accomplished three main goals leading to completion of Specific Aim 2, which is designed to perform HLA haplotype ‘mix and match’ experiments using hES cell-derived NSCs as donors and ‘humanized’ mice as recipients (year 2). Firstly, we have now successfully generated ‘humanized’ mice that have 50% or more engraftment of human immune cells in lymphoid organs, defined as percentage of human immune cells within the mouse. Secondly, we have successfully HLA haplotyped these human donor CD34+ HSCs, and have additionally transplanted hES cell-derived NSCs with known HLA haplotypes. Finally, we have ‘mixed and matched’ HLA haplotypes in adoptive transfer experiments using human HSC reconstituted mice as recipients and human NSCs as donors. This critically important new tool will allow for a predictive model of human stem cell transplant acceptance vs. rejection.

Role of HLA in neural stem cell rejection using humanized mice

Funding Type: 
Transplantation Immunology
Grant Number: 
RM1-01735-B
ICOC Funds Committed: 
$1 472 634
Disease Focus: 
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
Cell Line Generation: 
Embryonic Stem Cell
oldStatus: 
Active
Public Abstract: 
One of the key issues in stem cell transplant biology is solving the problem of transplant rejection. Despite over three decades of research in human embryonic stem cells, little is known about the factors governing immune system tolerance to grafts derived from these cells. In order for the promise of embryonic stem cell transplantation for treatment of diseases to be realized, focused efforts must be made to overcome this formidable hurdle. Our proposal will directly address this critically important issue by investigating the importance of matching immune system components known as human leukocyte antigens (HLA). Because mouse and human immune systems are fundamentally different, we will establish cutting-edge mouse models that have human immune systems as suitable hosts within which to conduct our stem cell brain transplant experiments. Such models rely on immunocompromised mice as recipients for human blood-derived stem cells. These mice go on to develop a human immune system, complete with HLAs, and can subsequently be used to engraft embryonic stem cell-derived brain cells that are either HLA matched or mismatched. Due to our collective expertise in the central nervous system and animal transplantation studies for Parkinson’s disease, our specific focus will be on transplanting embryonic stem cell-derived neural stem cells into brains of both healthy and Parkinson's diseased mice. We will then detect: 1) abundance of brain immune cell infiltrates, 2) production of immune molecules, and 3) numbers of brain-engrafted embryonic stem cells. Establishing this important system would allow for a predictive model of human stem cell transplant rejection based on immune system matching. We would then know how similar HLAs need to be in order to allow for acceptance stem cell grafts.
Statement of Benefit to California: 
In this project, we propose to focus on the role of the human immune system in human embryonic stem cell transplant rejection. Specifically, we aim to develop cutting-edge experimental mouse models that possess human immune systems. This will allow us to determine whether immune system match versus mismatch enables embryonic stem cell brain transplant acceptance versus rejection. Further, we will explore this key problem in stem cell transplant biology both in the context of the healthy and diseased brain. Regarding neurological disease, we will focus on neural stem cell transplants for Parkinson's disease, which is one of the most common neurodegenerative diseases, second only to Alzheimer's disease. If successful, our work will pave the way toward embryonic stem cell-based treatment for this devastating neurological disorder for Californians and others. In order to accomplish these goals, we will utilize two of the most common embryonic stem cell types, known as WiCell H1 and WiCell H9 cells. It should be noted that these particular stem cells will likely not be reauthorized for funding by the federal government due to ethical considerations. This makes our research even more important to the State of California, which would not only benefit from our work but is also in a unique position to offer funding outside of the federal government to continue studies such as these on these two important types of human embryonic stem cells.
Progress Report: 
  • For the promise of stem cell transplantation therapy to treat or cure human disease to be realized, the key problem of stem cell transplant rejection must be solved. Yet, despite over three decades of research in human embryonic stem cells, little is known about the factors involved in immune system tolerance to grafts derived from embryonic stem cells.
  • The goal of our CIRM Stem Cell Transplantation Immunology Award is to overcome this formidable hurdle by generating pre-clinical mouse models that have human immune systems. This cutting-edge model system will provide a testing platform to evaluate the importance of matching immune system components, known as human leukocyte antigens (HLAs), between the human embryonic stem (hES) cell-derived neural stem cell (NSC) graft and the patient. Because mouse and human immune systems are fundamentally different, these next-generation ‘humanized’ mice are currently the only animal models within which to conduct our stem cell brain transplant experiments. Such models rely on immunocompromised mice as recipients for human umbilical cord blood stem cells (HSCs). These mice go on to develop a human immune system, complete with HLAs, and can subsequently be used to engraft embryonic stem cell-derived brain cells that are either HLA matched or mismatched and to monitor for graft acceptance vs. rejection.
  • During the third year of CIRM funding, we have addressed two specific questions that have arisen during the completion of Specific Aim 2: 1) which component of the HLA haplotype is most important to match in order to prevent brain stem cell rejection, and 2) can we expand blood stem cells obtained from a single umbilical cord blood sample? In response to question 1, we have determined that HLA-A is expressed at significantly higher levels in NSCs than the other HLA components, which makes this HLA type the critical player in immune system acceptance-rejection. As evidence of this, ‘humanized’ mice transplanted with NSCs expressing completely mismatched HLA-A elicited an immune response. Regarding question 2, we were able to accomplish ex vivo expansion of HSCs while maintaining their ‘stem-ness’ properties, which allows us to coordinate between the birth of mouse pups and the isolation of HSCs from umbilical cord blood samples, and also to significantly increase cell numbers to generate more ‘humanized’ mice. Additionally, in collaboration with Dr. George Liu from Cedars-Sinai Medical Center, we utilized ‘humanized’ mice to successfully model another disease that has become a threat to Californians’ health: skin infection by Staphylococcus aureus. While mice are generally not susceptible to this ‘human selective’ disease, ‘humanized’ mice did respond to the infection, closely mimicking the skin lesions observed in humans.

Induction of immune tolerance after spinal grafting of human ES-derived neural precursors

Funding Type: 
Transplantation Immunology
Grant Number: 
RM1-01720
ICOC Funds Committed: 
$1 387 800
Disease Focus: 
Spinal Cord Injury
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
iPS Cell
oldStatus: 
Closed
Public Abstract: 
Previous clinical studies have shown that grafting of human fetal brain tissue into the CNS of adult recipients can be associated with long-term (more then 10 years) graft survival even after immunosuppression is terminated. These clinical data represent in part the scientific base for the CNS to be designated as an immune privilege site, i.e., immune response toward grafted cells is much less pronounced. With rapidly advancing cell sorting technologies which permit effective isolation and expansion of neuronal precursors from human embryonic stem cells, these cells are becoming an attractive source for cell replacement therapies. Accordingly, there is great need to develop drug therapies or other therapeutic manipulations which would permit an effective engraftment of such derived cells with only transient or no immunosuppression. Accordingly, the primary goal in our studies is to test engraftment of 3 different neuronal precursors cell lines of human origin once grafted into spinal cord in transiently immunosuppressed minipigs. In addition, because the degree of cell engraftment can differ if cells are grafted into injured CNS tissue, the survival of cells once grafted into previously injured spinal cord will also be tested. Second, we will test the engraftment of neuronal cells generated from pig skin cells (fibroblasts) after genetic reprogramming (i.e., inducible pluripotent stem cells, iPS). Because these cells will be transplanted back to the fibroblast donor, we expect stable and effective engraftment in the absence of immunosuppression. Jointly by testing the above technologies (transient immunosuppression and iPS-derived neural precursors), our goal is to define the optimal neuronal precursor cell line(s) as well as immunosuppressive (or no) treatment which will lead to stable and permanent engraftment of spinally transplanted cells.
Statement of Benefit to California: 
Brain or spinal cord neurodegenerative disorders, including stroke, amyotrophic lateral sclerosis, multiple sclerosis or spinal trauma, affect many Californians. In the absence of a functionally effective cure, the cost of caring for patients with such diseases is high, in addition to a major personal and family impact. Our major goal is to develop therapeutic manipulations which are well tolerated by patients and which will lead to stable survival of previously spinal cord-grafted cells generated from human embryonic stem cells. If successful, this advance can serve as a guidance tool for CNS cell replacement therapies in general as it will define the optimal immune tolerance-inducing protocols. In addition, the development of this type of therapeutic approach (pharmacological or cell-replacement based) in California will serve as an important proof of principle and stimulate the formation of businesses that seek to develop these types of therapies (providing banks of inducible pluripotent stem cells) in California with consequent economic benefit.
Progress Report: 
  • The use of autologous, induced pluripotent stem cell-derived cell lines in replacement therapies holds great promise in future clinical use. No need for immunosuppression, otherwise required to prevent transplanted cell rejection, would represent a substantial advance in the current clinical utilization of cell replacement therapies. In our recently completed studies we have found that autologous porcine iPSC-derived neural precursors (NPCs) grafted back to the donor animal spinal cord in the absence of immunosuppression was associated with a poor cell survival and extensive inflammation at cell-grafted sites. Our data raises immunological concerns on the use of autologous iPS-cell derivatives for future regenerative medicine in humans.
  • The use of autologous, induced pluripotent stem cell-derived cell lines in replacement therapies holds great promise in future clinical use. No need for immunosuppression, otherwise required to prevent transplanted cell rejection, would represent a substantial advance in the current clinical utilization of cell replacement therapies. In our recently completed studies we have found that autologous porcine iPSC-derived neural precursors (NPCs) grafted back to the donor animal spinal cord in the absence of immunosuppression was associated with a poor cell survival and extensive inflammation at cell-grafted sites. In more recent study we have determined that the same cell population of iPS-NPCs survive and mature once grafted spinally in immunosupressed pigs.The mechanism of the immunogenicity of iPS-NPCs is being currently determined.
  • The use of autologous, induced pluripotent stem cell-derived cell lines in replacement therapies holds great promise in future clinical use. No need for immunosuppression, otherwise required to prevent transplanted cell rejection, would represent a substantial advance in the current clinical utilization of cell replacement therapies. In our recently completed studies, we have found that autologous porcine iPSC-derived neural precursors (NPCs) trigger a positive T-cell mediated reaction in vitro and that this response is not present if autologous T-cells are co-cultured with autologous fibroblasts. These data show that the reprogramming step induces a potent immunogenicity and that extensive screening of clonally-derived iPS-NPCs will be needed to identify clones of autologous NPCs with acceptable immunogenicity profile. Identification of differences in gene activity in differentially derived iPS-NPCs is currently in progress.

Generation of disease models for neurodegenerative disorders in hESCs by gene targeting

Funding Type: 
Tools and Technologies I
Grant Number: 
RT1-01107
ICOC Funds Committed: 
$869 262
Disease Focus: 
Amyotrophic Lateral Sclerosis
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
Cell Line Generation: 
Embryonic Stem Cell
oldStatus: 
Closed
Public Abstract: 
Statement of Benefit to California: 
Progress Report: 
  • The overall objectives for this proposal are to create in vitro human neurodegenerative disease models and to elucidate pathogenesis of amyotrophic lateral sclerosis (ALS), an adult onset fatal motoneuron disease. Using gene targeting and reprogramming technology, we have created ALS disease models in human pluripotent stem cells and are generating neural lineage reporters which will facilitate the downstream efforts on systemic characterization of these diseased cell lines, at undifferentiated stage and after induced lineage differentiation toward motoneurons and astrocytes. These experiments will not only provide direct clues for ALS pathogenesis but also serve as a proof of principle for general disease research using human pluripotent stem cells as a model system. We also aim to provide optimized protocols for easy to access gene targeting which eventually facilitate the development of personalized medicine, the future of regenerative medicine. The novel targeting protocol combined with our experience on directed differentiation along the neural lineage will not only will make tools to move the pathogenesis research for ALS, but also can be reliably extended to other neural and non-neural diseases, of which genetic defects have been identified, including Huntington's disease and Parkinson’s disease.
  • The overall objectives for this proposal are to create in vitro human neurodegenerative disease models for amyotrophic lateral sclerosis (ALS), an adult onset fatal motoneuron disease. Using gene targeting, site-specific integration and reprogramming technology, we have created ALS disease models in human pluripotent stem cells and generated neural lineage reporters which will facilitate the downstream efforts on systemic characterization of these diseased cell lines, at undifferentiated stage and after forced lineage differentiation toward motoneurons and astrocytes. We have optimized protocols for gene targeting using homologous recombination and site-specific integration and insertion. The novel targeting protocol combined with our experience on directed differentiation along the neural lineage are useful tools to pathogenesis research for ALS, as well as to other neural and non-neural diseases, including Huntington's disease and Parkinson’s disease.

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