Basic Biology V
$1 127 369
Recommended if funds allow
Understanding fundamental aspects of stem cell biology is essential to develop regenerative medicine therapies. Unacceptable outcomes include inadequate functionality, exhaustion, immune rejection, cancer development, and others. Our studies strongly support our core hypothesis that mitochondrial function determines stem cell quality and safety. Dysfunctional mitochondria foster cancer, diabetes, obesity, neurodegeneration, immunodeficiency, and cardiomyopathy. Unlike whole genome approaches, methodological hurdles for evaluating mitochondria in human embryonic stem cells (hESCs) and in reprogrammed human induced pluripotent stem cells (hiPSCs) are significant and techniques developed or adapted for stem cells are almost non-existent. With a CIRM-supported grant, we developed new approaches for analyzing respiration in hESCs. We also describe the function of stem cell mitochondria in low oxygen (hypoxia), in normoxia (room air), and during differentiation. The mitochondrial network structure changes between fragmented and fused appearances with differentiation or reprogramming, and that a mitochondrial quality control system is activated as hESCs differentiate. Our studies are providing new basic and clinical insights into stem cell biology and hold promise for developing applications to common diseases, such as Parkinson and Alzheimer neurodegenerative disorders and cancer. These CIRM-supported advances provide the underpinnings for our current proposal.
Statement of Benefit to California:
Our proposal benefits California by adding new essential knowledge on mitochondrial mechanisms that control human pluripotent stem cell (hPSC) fate and function to support the taxpayers' commitment to personalized cell therapies. This work builds on highly successful 2-year CIRM Seed and 3-year Basic Biology I awards. CIRM funds to date resulted in 20+ published studies, numerous conference presentations, and the training of 14 individuals including post-docs, graduate students, undergraduates, and CIRM Bridges to Stem Cell Biology program trainees, some of whom have now entered the California workforce. Those studies provided the first methods and thorough characterizations of the function of mitochondria in stem and differentiated cells. This new CIRM BBV proposal is groundbreaking for revealing how mitochondrial quality control and dynamics layered with epigenetic mechanisms drive hPSC differentiation, which has implications for regenerative medicine. Our ongoing work underpins therapy development in California’s major academic centers and will provide data for many of California's biotechnology companies in the growing stem cell industry, whose success will propel hiring and increased economic prosperity for the state. With success, tangible health and economic impact on California, its academic institutions and companies, and the rest of the nation will be achieved as California leads the way forward with personalized medicine for the 21st century and beyond.
The goal of this project is to determine the role mitochondria play in controlling the renewal and differentiation of human pluripotent stem cells (hPSC). The hypothesis proposed is that mitochondria play an active role in the regulation of fate decisions that control self-renewal and differentiation of human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs). To achieve their goal, the applicants will pursue two specific aims. In Aim 1, the investigators will dissect the role of a mitochondrial protein in the survival and apoptosis of human pluripotent stem cells (hPSC) using conventional molecular biology approaches. Aim 2 will focus on determining the role of mitochondrial network dynamics and quality control in hESC and hiPSC differentiation. To address this aim, the applicants will observe the mitochondrial network in hPSCs and differentiated cells expressing activating or inhibitory forms of three proteins that are known to regulate mitochondrial network structure. Significance and Innovation - The project addresses an important unresolved problem in stem cell biology: the cellular control of hPSC fate decisions. - The hypothesis that mitochondrial activity plays an active, rather than passive, role in stem cell fate determination was considered highly innovative. - Reviewers expressed concern that the project was primarily observational and descriptive rather than mechanistic. Although a great deal of data would be obtained, it was not clear how it would be analyzed to gain insight into the mechanistic details and test the proposed hypothesis. - The relationship between Specific Aims 1 and 2 was not clear: these aims appeared to be separate, unlinked projects. Feasibility and Experimental Design - Specific Aim 1 was supported by extensive preliminary data and a rational plan. However, there was concern that the approaches to be used might not adequately address the hypothesis or provide deep mechanistic insight. - The observation that a small molecule inhibitor of a mitochondrial protein killed hPSC but not differentiated cells is an interesting and important finding, but reviewers questioned the proposed role of this protein as a gatekeeper of differentiation. - Specific Aim 2 was considered unfocused, and the rationale for many of the proposed experiments was unclear. - Reviewers questioned the proposed causal linkage between the mitochondrial network morphology and stem cell differentiation; preliminary data supporting many of the experiments in Aim 2 were not convincing. - The research environment was considered suitable for conducting the project. Principal Investigator (PI) and Research Team - There was very strong enthusiasm for the PI and co-PI, both of whom have strong research records and excellent, relevant expertise. - The members of the team have the necessary expertise in mitochondria; this was considered a strength of the proposal. Responsiveness to the RFA - The proposal was considered responsive to the RFA.