Recommended if funds allow
Statement of Benefit to California:
SYNOPSIS: In this proposal the investigators plan to develop a library of small molecules that can induce hESCs to differentiate into cardiomyocytes. Studies will be done wherein optimized compounds will be generated based on the structure of established hits. This library will then be screened on hESCs already engineered to express fluorochromes from the Nkx5.2 and MHC promoters. Hits will then be further optimized taking into account absorption, metabolization, etc. SIGNIFICANCE AND INNOVATION: The use of hESCs to understand human cardiomyogensis and generate drugs that can induce such differentiation are of great importance in developing therapies for human cardiac diseases. Therefore, this work would be very significant if new molecules can be found to direct hESCs into cardiomyocyte lineages. STRENGTHS: The chemical genetics approach with high-throughput screening is a major strength, as is the PI's expertise in both of these areas. The collaboration with Dr. Mercola for hES cell expertise, who has developed lineage marked hESCs, is also a plus. The PI has some preliminary hits from screening the chemical libraries. WEAKNESSES: There is some weakness in the biological characterization of lead compounds. There are limited plans to identify the cellular targets of the lead compounds, a limited description of gene array studies to be conducted with compounds, and an inadequate analysis of what fraction of cells give the cardiomyocyte signal, or express non-cardiomyocyte cell fates in the assays. The ambitiousness of the proposal is another weakness, and it is not clear what the funding exactly will be used for as this is an ongoing project. DISCUSSION: This proposal represents a collaborative program involving two strong investigators who will expand a library screen to find new molecules that promote the differentiation of cardiomyocytes. The facilities seem appropriate, but the robotics and the experiments are not well described. The experiments are presented in a cursory manner with respect to how the data will be interpreted. Also, this looks like an ongoing program. The PI has already screened one library and found four hits, and this proposal is for screening a second library. This makes the proposal somewhat less innovative, but finding these small molecules is very important. How new is this work? Is this truly a SEED grant? A massive amount of work is proposed and it is unclear if it can be completed in 2 years. The proposal is weak in the biological characterization of lead compounds. One concern is that a positive readout in the cell based assay for a desired cell type does not necessarily speak to the efficiency of generating that desired cell type due to heterogeneity. What percentage of cells would become cardiomyocytes? This heterogeneity of the indicator cell population was not considered a major problem given the investigators involved, but this complication diminished enthusiasm for this project. More positively, the work is well underway, and chemical genetics approaches with hESCs should be supported as they are unlikely to be supported by NIH.