This proposal aims to define fundamental mechanisms that underlie the production of human pancreas and liver cells. The proposed research seeks to advance the development of stem cell-based therapies for diabetes and chronic liver disease. Diabetes is characterized by insulin deficiency due to destruction and/or malfunction of insulin-producing beta cells in the pancreas. Diabetic patients would benefit tremendously from the availability of transplantable replacement beta cells produced from stem cells. Similarly, stem cell-derived replacement liver cells could help improve liver function in patients with chronic liver disease and/or help identify drugs that protect the liver form damage. Despite some progress, it is at present not possible to produce functional beta or liver cells from stem cells. During embryonic development, the pancreas and liver arise from a common precursor cell. To produce functional beta or liver cells from stem cells in culture, cells have to transition through this pancreas/liver precursor step. We propose to identify mechanisms by which stem cell-derived precursors acquire the ability to develop into beta or liver cells. Knowledge gained from this proposal will have several important applications. First, it will help devise strategies to produce functional replacement beta and liver cells from stem cells. Second, it will inform approaches aimed at directly converting other tissues, such as skin, into insulin-producing or liver cells.
This proposal will have relevance to finding cures for two major diseases: diabetes and liver disease. Diabetes is a metabolic disorder that affects 8.3% of the U.S. population. Average medical expenditures among people with diabetes are 2.3 times higher than those of people without diabetes. The disease is characterized by insulin deficiency due to destruction and/or malfunction of insulin-producing beta cells in the pancreas. An ultimate treatment for diabetes would be to replace lost beta cells with transplantable insulin-producing cells. Similarly, replacing damaged liver cells could have major impact on alleviating the consequences of chronic liver disease. One in ten people in the U.S. have liver disease and chronic liver diseases such as hepatitis, non-alcoholic fatty liver disease and liver cancer are on the rise. Thus, deriving pancreatic beta cells or liver cells from stem cells could have major impact on improving the life of people with diabetes or liver disease. Stem cell-derived beta or liver cells could also be used in drug discovery screens with the hope of identitying drugs that can improve cell function. This proposal seeks to identify strategies for deriving functional pancreatic and liver cells from stem cells; a goal that remains to be been achieved. Given the high prevalence of diabetes and liver disease in California, we believe that the proposed research will have tremendous benefit to the State of California and its citizens.
The differentiation of human embryonic stem cells (hESCs) toward particular cell types correlates with defined epigenetic changes in the chromatin. This Fundamental Mechanisms proposal seeks to better understand the function of these chromatin dynamics during endoderm differentiation. The application is based on preliminary data that suggest substantial differences in the pattern of epigenetic modifications in different endodermal derivatives and differences in their responsiveness to lineage-specific induction factors at different stages. The applicant will determine whether the pattern of epigenetic modifications is responsible for establishing developmental competence and whether exposure to lineage-specific inductive factors controls the chromatin dynamics during differentiation. In addition, the applicant will determine the role of lineage-specific transcription factors in establishing epigenetic remodeling of the chromatin during differentiation.
Significance and Innovation
- The proposal is highly significant in that it addresses the function of epigenetic modifications that occur during differentiation of definitive endoderm to pancreas, liver and lung.
- The insights gained from the proposed studies may provide new strategies for reprogramming as well as the knowledge needed to differentiate fully functional endocrine pancreas, liver and lung tissues from pluripotent stem cells.
- Although previous work has described epigenetic changes that occur during differentiation, this proposal is innovative in that it will study the functional relevance of those changes.
Feasibility and Experimental Design
- The entire experimental design was well thought out and well presented. The two specific aims were interlinked and well justified and the proposed experimental design utilized cutting-edge technology. The feasibility of the project is very high.
- The applicant provided strong preliminary data in support of the application.
- There was some concern was that it might prove to be difficult to tease out functional importance of the changes that occur during differentiation, and that any heterogeneity in cell populations being analyzed could confound the results.
Principal Investigator (PI) and Research Team
- The PI is an outstanding scientist who has made a number of important contributions in developmental biology of the endocrine pancreas and is highly qualified to lead the project.
- A co-investigator brings extensive expertise on computational biology that is needed for this project.
Responsiveness to the RFA
- This proposal is highly responsive to the RFA in that it focuses on the molecular mechanisms of human ESC differentiation to specific endodermal lineages.