Recently, we devised and reported a new regenerative medicine paradigm that entails temporal/transient overexpression of induced pluripotent stem cell based reprogramming factors in skin cells, leading to the rapid generation of “activated” cells, which can then be directed by specific growth factors and small molecules to “relax” back into various defined and homogenous tissue-specific precursor cell types (including nervous cells, heart cells, blood vessel cells, and pancreas and liver progenitor cells), which can be expanded and further differentiated into mature cells entirely distinct from fibroblasts.
In this proposal, combined with small molecules that can functionally replace reprogramming transcription factors as well as substantially improve reprogramming efficiency and kinetics, we aim to further develop and mechanistically characterize chemically defined, non-integrating approaches (e.g., mRNA, miRNA, episomal plasmids and/or small molecule-based) to robustly and efficiently reprogram skin fibroblast cells into expandable heart precursor cells. Specifically, we will: determine if we can use non-integrating methods to destabilize human fibroblasts and facilitate their direct reprogramming into the heart precursor cells; characterize of heart cells generated by the direct programming methods, both in the tissue culture dish and in a mouse model of heart attack; and characterize newly identified reprogramming enhancing small molecules mechanistically.
This study will develop and mechanistically characterize a new method of generating safe patient specific heart cells that could be useful in treating heart failure which afflicts millions of Californians and accounts for billions of dollars in healthcare spending annually. Additionally, the small molecules discovered in this study could be good candidates for future drug development as well as being broadly useful for other regenerative medicine applications. These advances could also be a platform for new personalized medicine/ cell banking businesses which could bring economic growth in addition to improving the health of Californians.
The goal of the research described by this proposal is to derive patient-specific cardiac cells via direct reprogramming of fibroblasts. Such cells might be appropriate for transplantation and for the development of novel therapies for heart disease. Proposed experiments will investigate different approaches for the derivation of cardiac precursor cells (CPCs) and will characterize cellular and molecular mechanisms that underlie the reprogramming process. The first specific aim will focus on developing non-integrating methods for the direct conversion of human fibroblasts to CPCs. This effort will include a screen to identify small-molecule enhancers of this process. The second aim will be to molecularly and functionally characterize the CPCs derived by direct reprogramming. The third specific aim will be to analyze reprogramming-enhancing small molecules to gain further insight into the mechanistic basis of the transdifferentiation process.
Significance and Innovation
- The application describes an innovative, high risk ñ high impact proposal with potential to significantly contribute to regenerative medicine strategies.
- The project could provide novel insights into cell plasticity.
- Reviewers asserted that even partial success of the study is likely to have significant impact on understanding of reprogramming and yield useful new chemical tools.
Feasibility and Experimental Design
- Reviewers found the experimental design to be comprehensive, relatively straightforward and adequate for the proposed work.
- Project aims were presented logically, with a clear progression of appropriate goals.
- Although there was concern that the proposal lacked many specific experimental details, reviewer confidence in the project's feasibility was bolstered by the quality of the PI's track-record and previous accomplishments.
- Reviewers were uncertain about how CPCs were defined and encouraged the PI to develop a clearer specification of the desired phenotype of a human CPC to guide experimental progress.
Principal Investigator (PI) and Research Team
- The PI is an outstanding investigator with an excellent track record of transformative research that has had a major impact on the field.
- The proposed research team has all needed expertise.
- The proposed collaborator is excellent and appropriate.
- Reviewers expressed some concern that the PI and collaborator may be overextended by current commitments to a large number of projects.
Responsiveness to the RFA
- The project was viewed as entirely responsive to the RFA.
- James Ellis