Basic Biology III
Recent technical advancements in human embryonic stem cells have revolutionized their potential applications in regenerative medicine. However, a remaining big hurdle in this process is the need for efficient, effective, and stable generation of specific cell types from such stem cells for therapeutic usage. The proposed research focuses on studying a special cell type in our embryo, called mesoderm. Mesoderm gives rise to a number of tissues and structures including bone, cartilage, muscle, connective tissue, the urinary system, the reproductive system, heart, and the dermis of the skin. For example, heart failure often requires heart transplant, which is limited by the lack of matched donors and severe side effects due to immunosuppressant therapy. Heart regeneration from mesoderm tissues derived from human embryonic stem cells or induced pluripotent stem cells would greatly improve heart failure treatment. To regenerate mesoderm-derived tissues for tissue repair, it is critical to understand what are the genes and signaling pathways that control human mesoderm formation. To date, there is little information on how human mesoderm is formed due to the inability to study this event in embryo. This proposal takes advantage of the use of human embryonic stem cells to develop mesoderm in culture to study mesoderm development. We will first test a group of genes for their roles in mesoderm formation. Then we will develop a novel reporter system to label and purify emerging human mesoderm cells and identify and study novel genes involved in human mesoderm development. Completion of this project would provide valuable insight into the key factors in mesoderm differentiation, which is essential for efficient generation of mesoderm-derived tissues for therapeutic usage.
Statement of Benefit to California:
Stem cell therapy has the potential to revolutionize the treatment of many common diseases that afflict residents of the State of California. For example, thousands of Californians suffer from heart failure and need heart transplant for survival. However, these life-saving measures are limited by a lack of eligible donors and the necessity of finding correctly matched donors. Recent technical advancements in human embryonic stem cell and induced pluripotent stem cell production have revolutionized their potential applications in regenerative medicine and have provided enormous hope for these patients. Producing therapeutically useful differentiated cells from pluripotent stem cells is a critical step in clinical application. Our proposal will provide a better understanding of the mechanisms involved in producing mesoderm, which then gives rise to many critical tissues in our body, including heart, bone, cartilage, and muscle. One long-term benefit of the proposed research is to allow effective generations of various mesoderm-derive cell types and tissues for tissue repair. In addition, the involved work will include the training and education of some of California's bright young minds to become leaders of stem cell research and maintain California as a world leader in regeneration medicine.
Project Synopsis: The goal of this application is to understand the mechanisms regulating human mesoderm formation and patterning using human embryonic stem cell (hESC)-derived embryoid bodies (EBs) as a model system. Mesoderm gives rise to a number of tissues relevant to regenerative medicine including those of the musculoskeletal system and the heart. The application has three specific aims. In Aim 1, the principal investigator (PI) will determine the expression and function of transcription factors that induce epithelial to mesenchymal transition (EMT), a morphogenetic process during human mesoderm formation. In the second aim, the PI will isolate and characterize presumptive mesoderm cells in developing human EBs. In the third aim, the PI will identify and characterize the signaling molecules that control human mesoderm morphogenesis. Significance and Innovation: - The application fails to adequately address published reports describing similar regulation of mesoderm formation and patterning in mouse and human ESCs. This left reviewers unconvinced the project would produce substantial new insights. - Most reviewers deemed EBs to be an inadequate model for embryonic morphogenesis; they may not accurately recapitulate the organized EMT that is observed in the embryo itself. However, one discussant appreciated that EBs circumvent the ethical constraints of utilizing embryos proper. - The proposal focuses on a problem relevant to regenerative medicine. Feasibility and Experimental Design: - The proposal depends on successful generation of knock-in hESC lines, tools the applicants have yet to produce. Further, the method proposed to generate these tools has been challenging to successfully perform in hESCs, presenting a critical feasibility concern. - The preliminary data demonstrate the ability to replicate published work in mESC, but they are neither surprising nor novel. No hESC data are presented, and the quality of the overall experimental plan demonstrates a paucity of experience with hESC research and study of mesoderm formation. - Reviewers found the proposal extremely unfocused and noted that aim 3 could form an independent grant application. - The facilities are sufficient to support the proposed research. Principal Investigator (PI) and Research Team: - The PI is a talented and productive new investigator. Albeit lacking a direct background in either embryonic development or ESC differentiation, s/he has a great deal of experience studying tumor metastasis and EMT and has published important papers in this area. - The research team possesses all the expertise necessary to complete the proposed studies. However, the two key collaborators providing knock-in and differentiation expertise do not commit any time to the program. Responsiveness to the RFA: - The proposal is within the scope of the RFA, although the application fails to clearly justify how this work may improve differentiation of appropriate mesoderm cell types from stem cells.