Funding opportunities

MicroRNAs as regulators of pluripotence and reprogramming

Funding Type: 
Basic Biology I
Grant Number: 
RB1-01350
Funds requested: 
$1 647 486
Funding Recommendations: 
Not recommended
Grant approved: 
No
Public Abstract: 
Human pluripotent stem cells, both embryo-derived and induced from adult cells, will play an important role in the future of human health. In particular, recent breakthroughs in technology for reprogramming cells from an individual's skin and hair have opened the door to significant improvements in the efficiency of drug discovery and the potential of cell therapy. However, there are shortcomings in the current approaches: researchers originally used viruses to make adult cells pluripotent. These genetic engineering approaches have improved incrementally in recent years, but the successful modifications of the technology still use introduction of human genes into cells. We propose to short-circuit the genetic engineering approach by developing a new reprogramming method based on the mechanisms that cells themselves use to transition from one developmental state to another. We have shown that human embryonic stem cells have a unique complement of microRNAs, which are short stretches of RNA that do not code for proteins, but rather play a key regulatory role in the activity of protein-coding genes. MicroRNAs can control the balance of proteins in cells by inhibiting the synthesis of some, while allowing the production of others. They are powerful controllers of transition states in cells; such transitions occur when cells are differentiating into specific cell types. And, they work swiftly, not requiring intermediate signals to have their effects. Base on our observations, and because of their powerful regulatory activities, we propose to develop a microRNA-based strategy to change the fate of cells. In the proposed project, we plan to reprogram adult cells using only microRNAs, obviating the need for introducing viruses or DNA into cells. The project is risky, but all of the elements are in place, and we have crafted a straightforward plan for research and development of this new technology. Success would mean that we could provide researchers and clinicians with an efficient and safe approach for converting patient-specific adult cells into pluripotent stem cells.
Statement of Benefit to California: 
California’s large diverse population presents a challenge for the future of healthcare. In these uncertain economic times, California’s investment in the future, through education and science, has become increasingly important. Support for basic research and development has put the state at the forefront of new technological advances and groundbreaking medical research. Human pluripotent stem cells, both embryo-derived and induced from adult cells, will play an important role in the future of both human and economic health in California. With support from CIRM, researchers have made tremendous progress toward clinical and biotechnological applications of these remarkable cells by developing new ways to generate them and to differentiate them into cell types that can be used in drug development and to replace damaged tissues. Our proposed research builds on our previous research as well as that of our colleagues in the field, and takes the next logical step forward in the development of new pluripotent stem cell lines. We have shown that human embryonic stem cells have a unique complement of microRNAs, which are short stretches of RNA that do not code for proteins, but rather play a key regulatory role in the activity of protein-coding genes. MicroRNAs can control the balance of proteins in cells by inhibiting the synthesis of some, while allowing the production of others. They are powerful controllers of transition states in cells; such transitions occur when cells are differentiating into specific cell types. And, they work swiftly, not requiring intermediate signals to have their effects. Base on our observations, and because of their powerful regulatory activities, we propose to develop a microRNA-based strategy to change the fate of cells. In the proposed project, we plan to reprogram adult cells using only microRNAs, obviating the need for introducing viruses or DNA into cells. The project is risky, but all of the elements are in place, and we have crafted a straightforward plan for research and development of this new technology. Success would mean that we could provide researchers and clinicians with an efficient and safe approach for converting patient-specific cells into pluripotent stem cells. In carrying out this research, we also will be contributing to California's economy. Almost all of the supplies we will be using for this project will be sourced from California companies. In addition, we plan to train and hire new personnel, through our partnership with the CIRM Bridges internship program
Review Summary: 
The overall goal of this proposal is to develop microRNA-based strategies for reprogramming somatic cells into pluripotent stem cells and potentially differentiating them into specific lineages. The applicant suggests that such methodologies would obviate the need for introducing viruses or DNA into cells and could therefore ameliorate the risks that are associated with those techniques. The first aim entails the use of microarrays to determine whether pluripotent cells induced via transcription factors (iPS) express a characteristic microRNA profile that has previously been described for human embryonic stem cells (hESCs). Next, a selection of candidate microRNAs will be chosen for manipulation at the cellular level in an effort to induce pluripotency in somatic cells. For the final aim, the applicants will attempt to identify differentiation-specific microRNA programs and use them to guide differentiation of pluripotent cells towards a desired lineage. In general, reviewers appreciated the mechanistic focus of this application and found it to be logical, well written and highly responsive to the RFA. Nonetheless, they were not convinced that it would have a substantial impact on the field of stem cell biology. While intrigued by the concept, reviewers were not persuaded that microRNA-based approaches would prove superior to alternative reprogramming methodologies. Several questioned the premise that such methods would be safer, especially in light of recent publications linking aberrant microRNA expression to cancer. Others were not convinced that it would be possible to achieve adequate control of the microRNA program without reliance on viral vectors, thereby eliminating one of the key advantages of the proposed technique. In terms of feasibility, the reviewers were encouraged by the strong preliminary data and impressive track record of the applicant team. Nonetheless, several serious weaknesses were identified that significantly tempered their overall enthusiasm. While Aim 1 employed clever strategies for identifying microRNAs linked to the pluripotent state, the applicant failed to provide adequate contingency plans in the event of failure, despite the fact that much of the remaining effort would depend on these findings. Reviewers also criticized this aim for being non-hypothesis driven and worried that a successful outcome might only lead to a list of microRNAs that may or may not reveal insights into iPS cells or relevant biology. In addition to these concerns, reviewers were puzzled by the inclusion of Aim 3, which appeared to be at odds with the rest of the proposal. Most considered Aim 3 to be risky, fairly speculative, and unlikely to yield meaningful results. The PI was praised as an established stem cell biologist and a leader in the field with an excellent track record to support his/her capabilities. The assembled research team was judged to be well qualified and fully capable of executing the proposed experiments. In summary, the reviewers felt that this application addressed an important topic, but was limited in potential for impact due to an uncompelling rationale, a lack of contingency plans, and an unfavorable risk-to-reward ratio.
Conflicts: 

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