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RN1-00570-1: Investigation of the molecular pathways that integrate self-renewal and cell structure in embryonic stem cells.
Recommendation: Not recommended for funding
Public Abstract (provided by applicant)
Human embryonic stem cells (hESCs) can give rise to virtually all types of specialized adult cells in human body. Thus they are thought to be the potential source of the cell-transplantation therapy for the treatment of diseases such as Parkinson’s disease, myocardial infarction, and diabetes mellitus. While hESC research has made a considerable progress in developing methods to generate specialized cell types including neurons, cardiomyocytes, and insulin-secreting cells, studies to identify the key mechanisms that allow hESCs to maintain such an enormous differentiation capacity (pluripotency) have just begun. Because obtaining the pure undifferentiated cell population establishes the basis of hESCs-based therapeutic approach, these studies are essential to find the way to grow hESCs without losing their pluripotency.
The goal of the proposed study is to determine the core mechanism to maintain pluripotency in ESCs. Our preliminary data have indicated that a specific signaling pathway (like a hormone that mediates various biological information) may be responsible for supporting the differentiation capacity in hESCs. Based on this finding, we will focus on investigating the role of the signaling pathway in hESCs through a series of molecular experiments, and developing novel technologies which enable us to grow hESCs as a pure population of undifferentiated cells that would further standardize the hESCs-based therapeutic strategy.
Statement of Benefit to California (provided by applicant)
Our research will focus on identifying the mechanism that regulates the multiple differentiation capacity (pluripotency) in hESCs. With the knowledge obtained through the project, we will concentrate on developing novel technologies that will allow us to culture uniformly pluripotent hESCs which is not possible under the current culture protocols. The establishment of such a new method would impact virtually all hESCs-based application programs as it involves a common basic process to expand hESCs before turning into any type of adult cells for the therapeutic purposes. It is therefore predictable that the new methodology will be promptly translated as an intellectual property to be commercialized, and would substantially activate the biotechnology field in the State of California. More importantly, the new methodology will be provided to the Institutes in California at the highest priority where the method will accelerate the process to apply the hESCs-based transplantation approach for the clinical settings that would further substantiate the enhancement of the medical environment for California citizens.
Review
SYNOPSIS: The general goal of this research proposal is to test the role of a specific regulatory protein in stem cell self-renewal and stem cell cytoskeletal structure, using murine and human embryonic stem cell (mESC, hESC) systems. Previous work by the Principal Investigator (PI) has shown that activation of a specific signaling pathway can help sustain ES cell self-renewal. Since a member of that pathway, a second regulatory protein, also plays a role in energy metabolism, the PI considered whether there is a general link between energy metabolism and developmental processes such as regulation of stem cell fate. S/he proposes that other regulators of energy metabolism, specifically the regulatory protein under investigation for this proposal, might have additional roles in cell fate specification. S/he focuses on this regulatory protein because studies in fruit flies have implicated its homolog in maintenance of cell structure. It is therefore proposed that an effect of the regulatory protein under investigation on stem cell self-renewal will be mediated via regulation of cell structure.
STRENGTHS AND WEAKNESSES OF THE RESEARCH PLAN: The PI presents an interesting hypothesis, proposing a link between energy metabolism and self-renewal, based on an understanding of the developmental biology that brings model systems’ work to bear on hESC. However, the proposed experiments for the most part are either excessively speculative, or relatively derivative. For instance, it is unclear what the basis is for the hypothesis that regulation of energy metabolism in general, and of the regulatory protein under investigation in particular, is a key to understanding stem cell self-renewal. To use this as a basis for studying the regulatory protein under investigation is tenuous. Moreover, much of Aim 2 is largely derivative of recently published work from others showing that this regulatory protein controls cell structure in the fruit fly. The applicant proposes to do similar experiments in ES cells. The rest of Aim 2 proposes unjustified leaps to test the roles of additional regulatory pathways in stem cell self-renewal. Several assumptions are made that seem hypothetical and indirect. No specific links are cited by the PI to justify these experiments.
A major weakness of the proposal is that it reads much like a compilation of a large number of descriptive assays, design strategies are hard to discern, and it is not clear that upon completion of the proposed projects the field will have been moved much beyond what is already shown in the preliminary data. Several of the proposed experiments are likely to generate predictable outcomes that do not provide new insights. The overall hypothesis is interesting, but it will be important to clarify whether the observed effects are quite direct, or reflect late downstream phenotypes that are only correlative with the disruption of the self-renewal phenotype.
The reviewers listed several specific suggestions for improvements of the research plan. One reviewer pointed out that the PI would find the work in mesenchymal stem cell differentiation fate choice based largely on energetic considerations to be informative for the proposed ESC work, and it is somewhat surprising that the work is not mentioned in this proposal, especially since fate choice based on constraining cell structure is an important part of this literature.
QUALIFICATIONS AND POTENTIAL OF THE PRINCIPAL INVESTIGATOR: The PI earned an MD in 1987 and a PhD in 1996. S/he was a research fellow in medicine from 1996-2000 and then held a variety of short research associate or staff scientist positions at various institutions until being appointed an Assistant Professor at the applicant institution in 2006. Prior to this appointment, s/he published two papers in good journals on hESC, but since 2004, s/he has published only two methods papers. There is no current outside support.
The PI is very well qualified for this project. S/he is fully capable of mESC and hESC cultures and most of the assays will not be particularly challenging for him/her. The PI is clearly committed to the study of stem cell fate and describes a plan to focus on how this relates to cell structure. This does provide him/her with a potential niche to develop within the field.
INSTITUTIONAL COMMITMENT TO PRINCIPAL INVESTIGATOR: The applicant institution has benefited from CIRM funding and now has several investigators involved in stem cell research. The institution is looking to the applicant to be a leader in a new endeavor, thus they have an investment in his/her success.
The description of facilities and interactions suggests that the investigator is in an appropriately supportive environment to carry out the planned experiments. S/he occupies appropriate independent lab space, and the start up package included new equipment and access to core facilities, but no mention is made of research and salary support. The PI is also a member of a stem cell research center. A designated mentor would be a good idea, even though the PI has independence, to help with grantsmanship.
DISCUSSION: During a brief discussion, a reviewer stated that the PI pulled together disparate literature to come up with the interesting hypothesis that a specific regulatory protein involved in energy regulation plays a role in stem cell self-renewal. However, there was consensus among the reviewers that the proposal simply consists of a list of experiments with no endpoints of analysis proposed. Overall, the proposal was not viewed as competitive.
The following Working Group members had a conflict of interest with this application and were therefore recused from participating in review of, discussion of, and voting on the application:
- Brivanlou, Ali