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

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
Award Value: 
$3,698,646
Disease Focus: 
Parkinson's Disease
Neurological Disorders
Collaborative Funder: 
Germany
Stem Cell Use: 
iPS Cell
Cell Line Generation: 
iPS Cell
Status: 
Closed
Public Abstract: 
The goals of this study are to develop patient-specific induced pluripotent cell lines (iPSCs) from patients with Parkinson’s disease (PD) with defined mutations and sporadic forms of the disease. Recent groundbreaking discoveries allow us now to use adult human skin cells, transduce them with specific genes, and generate cells that exhibit characteristics of embryonic stem cells, termed induced pluripotent stem cells (iPSCs). These lines will be used as an experimental pre-clinical model to study disease mechanisms unique to PD. We predict that these cells will not only serve an ‘authentic’ model for PD when further differentiated into the specific dopaminergic neurons, but that these cells are pathologically affected with PD. The specific objectives of these studies are to (1) establish a bank of iPSCs from patients with idiopathic PD and patients with defined mutations in genes associated with PD, (2) differentiate iPSCs into dopaminergic neurons and assess neurochemical and neuropathological characteristics of PD of these cells in vitro, and (3) test the hypothesis that specific pharmacologic agents can be used to block or reverse pathological phenotypes. The absence of cellular models of Parkinson’s disease represents a major bottleneck in the scientific field of PD, which, if solved in this collaborative effort, would be instantly translated into a wide range of clinical applications, including drug discovery. This research is highly translational, as the final component is aimed at testing lead compounds that could be neuroprotective, and ultimately at developing a high-throughput drug screening program to discover new disease modifying compounds. This is an essential avenue if we want to offer our patients a new therapeutic approach that can give them a near normal life after being diagnosed with this progressively disabling disease.
Statement of Benefit to California: 
Approx. 36,000-60,000 people in the State of California are affected with Parkinson’s disease (PD), a common neurodegenerative disease that causes a high degree of disability and financial burden for our health care system. It is estimated that the number of PD cases will double by the year 2030. We have a critical need for novel therapies that will prevent or even reverse neuronal cell loss of specific neurons in the brain of patients. This collaborative proposal will provide real benefits and values to the state of California and its citizens in providing new approaches for understanding disease mechanisms, diagnostic tools and drug discovery of novel treatment for PD. Reprogramming of adult skin cells to a pluripotent state is the underlying mechanism upon which this application is built upon and offers an attractive avenue of research in this case to develop an ‘authentic’ pre-clinical model of PD. The rationale for the proposed research is that differentiated pluripotent stem cells from patients with known genetic forms of PD will recapitulate in vitro one or more of the key molecular aspects of neural degeneration associated with PD and thus provide an entirely novel human cellular system for investigation PD-related disease pathways and for drug discovery. The impact of this collaborative research project, if successful, is difficult to over-estimate. The scientific field has been struggling with the inability to directly access cells that are affected by the disease process that underlies PD and therefore all research and drug discovery has relied on ”best guess” models of the disease. Thus, the absence of cellular models of Parkinson’s disease represents a huge bottleneck in the field.
Progress Report: 

Year 1

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.

Year 2

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.

Year 3

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.

© 2013 California Institute for Regenerative Medicine