Amyotrophic lateral sclerosis (ALS) is an idiopathic adult-onset degenerative disease characterized by progressive weakness from loss of upper and lower motor neurons. Onset is insidious, progression is essentially linear, and death occurs within 3-5 years in 90% of patients. In the US, 5,000 deaths occur per year and in the world, 100,000. In October, 2011, the causative gene defect in a long sought after locus on chromosome 9 for ALS, frontotemporal dementia (FTD) and overlap ALS-FTD was identified to be a expansion of a hexanucleotide repeat in the uncharacterized C9ORF72 gene. The goal of the proposed research is to generate human stem cell models from cells derived from ALS patients with the C9ORF72 expanded repeats and relevant control cells using genome-editing technology. We will also generate a stem cell model expressing the repeat independent of the C9ORF72 gene to study if the repeat alone is causing neural defects. Using advanced genome technologies, biochemical and cellular approaches, we will study the molecular pathways affected in motor neurons derived from these stem cell models. Finally, we will use innovative technologies to rescue the abnormal phenotypes that arise from the expanded repeat in human motor neurons. Completion of the proposed research is expected to transform our understanding of the regulatory and pathogenetic mechanisms underlying ALS and FTD, and establish therapeutic options for these debilitating diseases.
Our research provides the foundation for decoding the mechanisms that underlie the single most frequent genetic mutation found to contribute to both ALS and FTD, debilitating neurological diseases that impact many Californians. In California, the expected prevalence of ALS (the number of total existing cases) is 2,200 to 3,000 cases at any one time, and the incidence is 750-1,100 new cases each year. The number of FTD cases is five times as many. Our research has and will continue to serve as a basis for understanding deviations from normal and disease patient neuronal cells, enabling us to make inroards to understanding neurological disease modeling using neurons differentiated from reprogammed patient-specific lines. Such disease modeling will have great potential for California health care patients, pharmaceutical and biotechnology industries in terms of improved human models for drug discovery and toxicology testing. Our improved knowledge base will support our efforts as well as other Californian researchers to study stem cell models of neurological disease and design new diagnostics and treatments, thereby maintaining California's position as a leader in clinical research.
This proposal is focused on the development and characterization of in vitro models of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) from patient-derived induced pluripotent stem cells (iPSCs). The applicant specifically proposes to study cells with mutations in the C9ORF72 gene, which were recently discovered as the most prevalent known cause of ALS and FTD. There are three Specific Aims: (1) to generate iPSCs and differentiated motor neurons from patients with C9ORF72 mutations along with appropriate control cells; (2) to perform in-depth analyses of these cells to interrogate disease mechanisms; and (3) to test strategies to rescue C9ORF72 mutation-induced defects in iPSC-derived motor neurons.
Significance and Innovation
- The proposal is timely and highly significant. The recent discovery of mutations in the C9ORF72 gene as a prevalent cause of ALS and FTD was an important breakthrough and invites additional research to determine how these mutations lead to disease.
- The project is innovative in its use of state-of-art technologies to generate stem cell models and control cell lines, comprehensively address potential disease mechanisms, and attempt to rescue disease phenotypes.
- If successful, the project will have a major impact on the fields of ALS and FTD. It could also have a broader impact on our understanding of other neurodegenerative diseases caused by similar mutations in different genes.
Feasibility and Experimental Design
- The proposed studies are feasible, although the scope of proposed activities in the grant is ambitious for a three-year timeframe.
- Reviewers emphasized the importance of generating stem cell lines from a number of patients that have been clinically well characterized and possess mutations with different repeat lengths. They also suggested that determining repeat length may be challenging with the methods proposed and should be validated using another technique.
- Reviewers noted that the low yield of motor neurons differentiated from pluripotent cells could pose challenges given the large number of cells required for some of the techniques proposed.
Principal Investigator (PI) and Research Team
- The PI is an outstanding young investigator with a strong funding record.
- Reviewers were concerned that the PI may be overcommitted, given the amount of effort already devoted to other projects.
- Reviewers felt the team would benefit from greater clinical collaboration to assist in patient characterization, disease modeling and potential translational applications.
Responsiveness to the RFA
- The project is highly responsive to the RFA.