Establishment of Frontotemporal Dementia Patient-Specific Induced Pluripotent Stem (iPS) Cell Lines with Defined Genetic Mutations
New Cell Lines
$1 708 560
Statement of Benefit to California:
Executive Summary The goal of this proposal is to establish multiple induced pluripotent stem (iPS) cell lines from patients with many forms of frontotemporal dementia (FTD) and differentiate these into neurons, in order to study underlying molecular defects and potentially develop therapies. In Specific Aim 1, fibroblasts from patients with FTD with different mutations and from control will be reprogrammed to generate iPS cells. The applicant will use published protocols, and will collaborate with a leader in the field of somatic cell reprogramming. Microarray analyses will be used to compare patient and control stem cells. In Specific Aim 2, the iPS cells from FTD patients will be assessed for their pluripotent potential, and then differentiated into forebrain neurons. This will allow the applicant to study the effects of FTD mutations on the formation of dendritic spines, and to identify potential biochemical defects in these cells. FTD accounts for 15-20% of all dementia cases and there are no reliable animal or cell-based models of the disease. Thus, the generation of human neurons and a reliable cell-based model of FTD would be a significant advance. Overall, reviewers commented that this proposal is extremely clear, coherent and ultimately appears quite feasible. By looking at a relevant and measurable cellular phenotype, namely the formation and maintenance of dendritic spines, the applicant is very likely to uncover important differences between normal and affected neurons. By combining cellular phenotyping with a biochemical dissection of the disease process, the work may even yield some insight into the pathological mechanism(s) of FTD. Finally, the team that will be collaborating on this project is outstanding, and reviewers were impressed with the clinical aspect of this project as the applicant carefully considers the genetics of the disorder and proposes multiple cell lines for each mutation. If successful, this project would provide the first definitive proof of the hypothesis that dendritic spine abnormalities contribute to FTD. Applicants have clear plans to share their cell lines, which will increase the impact of this work. Reviewers identified weaknesses in the proposal, although overall they were not important enough to outweigh the potential significance of the work. One concern was whether it will be feasible to study late-onset diseases using in vitro culture models. One reviewer questioned whether differentiating iPS cells into generic post-mitotic neurons would be a sufficiently sensitive assay to detect defects in dendrite formation or biochemical changes, or whether it would be necessary to focus on a particular subtype of neurons. Minor concerns over grantsmanship were raised regarding the presentation of preliminary data in the grant application itself, which made it difficult for reviewers to assess some of the data. Finally, the evaluation of gene expression in the FTD patient iPS cells compared to controls was not considered well justified. Reviewer One Comments Significance: The applicant is clearly working with a disorder that is important. The proposal will utilize one of the great promises of iPS cell technology, which is the potential of generating patient-specific cells that are the target in their disease - in the case of FTD, forebrain neurons. Successful derivation of such cells from FTD would be a major advance, provided of course that the molecular/biochemical events that lead to their demise, will occur in the culture dish over the time frame in which they can be studied. This will be a major question in trying to reproduce all late-onset diseases in cells in the culture dish. This proposal has novelty in that it will carry out in vitro studies of potential underlying structural changes in neurons from FTD patients and then correlate these with certain biochemical abnormalities. Deriving neurons from iPS cells from FTD patients that can subsequently be shared with others is important. Feasibility: Much of this proposal is straightforward and given the applicant’s close association with S. Yamanaka it seems certain that he will be successful in generating iPS cells from the FTD patients and controls. The applicant has shown the ability in the preliminary data to generate neurons from the H9 cell line and so it would appear likely that he will do so with those from FTD patients. Demonstration that the iPS cells are pluripotent is appropriately described. The evaluation of gene expression in the FTD patient iPS cells compared to controls (iPS cell and ES cells from the H9 line) is less well justified and might be viewed as a shot-in-the-dark. With the establishment of postmitotic neuronal subtype of choice, the applicant will then be well positioned to study the effect of the different mutations in FTD patients on dendritic morphology. While these studies are acknowledged to be descriptive, they would seem to provide the platform required to screen new therapeutic agents. Whether the particular biochemical defect they have chosen to study will be a key to the pathophysiology of FTD remains to be determined. They do, however cite data that shows that progranulin deficiency leads to intracellular accumulation of TD43, a nuclear nucleotide binding factor. As in many neurodegenerative diseases, there may be a final common pathway to cell death, and this might be the pathway in FTD. The applicant is an accomplished young scientist with an excellent track record. He is very well funded and has a CIRM award that helped initiate the current proposal. His collaborations are particularly strong, firstly in generating iPS cells (S. Yamanaka) and then in the biochemical and molecular bases of neurodegeneration (R. Farese). In addition, Dr. Bruce Miller is a senior neurologist/neuroscientist, who promises access to the appropriate patient population and expresses great enthusiasm for the project. The applicant is located at the Gladstone Institute at USCF where he will have the required facilities and equipment. One weakness with the preliminary data is in Figure 1 which is not well done. The neuroectodermal cells look just like a confluent culture, the neuronal precursors could be anything and the human neurons are not labeled with the antibody used (although noted in the text). Responsiveness to RFA: The research is highly likely to generate pluripotent human stem cell lines that will be appropriately tested and made available to others. Reviewer Two Comments Significance: The proposal seeks to establish FrontoTemporal Dementia (FTD) patient-specific induced pluripotent stem (iPS) cell lines with defined genetic mutations. FTD accounts for 15-20% of all dementia cases and there are no reliable animal or cell-based models of the disease. The creation of FTD iPS cell lines would provide an opportunity to investigate the molecular and genetic basis for this disease as well as perhaps discover novel therapies. The generation of human neurons and a reliable cell based model of FTD would be a significant advance. Feasibility: The design of this proposal is extremely clear, coherent and ultimately appears quite feasible. Given the expertise of the investigators involved including Dr. S. Yamanaka, the goal of creating FTD iPS cell lines from patient fibroblasts as outlined in the first aim is likely to succeed. The second aim of studying post-mitotic neurons derived from FTD iPS cells is also quite feasible given previously published protocols, preliminary results and expertise of Dr. F-B. Gao’s laboratory. Moreover, by looking at a relevant and measurable cellular phenotype, namely the formation and maintenance of dendritic spines, they are very likely to uncover important differences between normal and affected neurons. Finally, by combining cellular phenotyping with a biochemical dissection of the disease process by Dr. R. Farese’s laboratory, the proposal may even yield some insight into the pathological mechanism(s) of FTD. Responsiveness to RFA: The proposal is very responsive to the RFA.