Funding opportunities

Molecular determinants of placodal competence in non-neural ectoderm

Funding Type: 
Basic Biology V
Grant Number: 
Funds requested: 
$1 178 370
Funding Recommendations: 
Not recommended
Grant approved: 
Public Abstract: 
The sense organs of the mammalian head and the anterior pituitary, a major endocrine gland, originate to a great extent from embryonic structures called cranial placodes. These placodes arise from the ectoderm, one of the three germ layers, which is known to give rise to brain, spinal cord, and epidermis. Placodes develop in the head of the embryo in a narrow region that is flanked by the developing brain and epidermis. Generation of placodal cells from human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) has been difficult because as the stem cells differentiate into ectodermal cells, they favor developing into brain, spinal cord, or epidermis. This research project aims to understand the mechanisms that restrict but also enable ectodermal cells from developing into placodal cells. In a second aim, it is proposed to investigate the molecular mechanisms that enable placodal cells generated from hESCs/hiPSCs to develop into distinct placodal cell types. These distinct placodal lineages encompass cells that play crucial roles in smell, vision, hearing, balance, touch, pain, and endocrine processes such as growth, reproduction, lactation, and stress. The overarching goal of the research is to provide a deeper understanding of the molecular mechanisms that can be used to advance human stem cell-based applications to numerous sensory as well as endocrinological disorders.
Statement of Benefit to California: 
Millions of Californians suffer from disorders of the sensory and endocrinological systems of the head. These disorders range from the loss of smell, chronic sinusitis, vision loss, hearing loss, tinnitus, vertigo, touch perception disorders, chronic pain, and endocrinological dysfunction. Although most of these disorders to not directly cause death, they can contribute to morbidity and they play substantial roles in diminishing the quality of life, especially in an aging population. The US statistics for each individual of these disorders reveals that they affect a large percentage of the population, which reflected to the state of California means millions of people costing the health care system multiple billions of dollars each year. Quality of life interventions for the aging population are a major market, and biological as well as pharmacological interventions arising from the proposed research has the potential to create jobs in the biotech and pharmaceutical industry. The Principal Investigator has previous experience of licensing discoveries made in his laboratory to industrial partners located in CA, which already led to creation of new jobs and the potential to bring novel treatments that would help millions of Californians to live healthier and longer lives.
Review Summary: 
Sensory organs of the mammalian head, such as those involved in smell, sight, and hearing, originate primarily from embryonic structures known as cranial placodes, which in turn derive from the ectoderm. Generation of placodal cells from human embryonic stem cells (hESCs) and human-induced pluripotent stem cells (hiPSCs) has been challenging, however, because as the stem cells differentiate into ectodermal cells, they are biased towards developing into brain, spinal cord and epidermal cell types at the expense of the placodal lineage. The goal of this Fundamental Mechanisms proposal is to elucidate mechanisms that enable ectodermal cells to develop into placodal cells, and to define conditions in which hESCs/hiPSCs can be directed towards the pre placodal fate (Aim 1). The applicant will also test the role of key pathways in restricting placodal cell fates to specific sub-lineages (Aim 2). Significance and Innovation - The proposed studies address an understudied and significant area of research. If successful, the biological insights obtained could represent an important advance towards the production of placodal cell types for in vitro modeling and potential cellular therapy applications. - The scientific rationale for this project is sound, with a logical basis in developmental biology. - The proposed studies should produce useful data on the combinatorial effects of signaling pathway regulation on the differentiation of pluripotent stem cells. Feasibility and Experimental Design - While recognizing the power and innovation of the platform technology to be employed, reviewers were strongly concerned that the proposed approaches would not adequately recapitulate the complex microenvironment that is likely key to successful differentiation of various placodal cell types. - Differentiation of ESCs to a placodal lineage has been reported by several groups, including that of the applicant, albeit with the major limitation of low efficiency. It is not apparent that this limitation has been successfully addressed through the proposed studies. - A major concern is that with the low frequency of placodal cell generation, the heterogeneity of the resulting populations will be difficult to quantify. While acknowledged by the applicant, reviewers worried that this issue would compromise identification of relevant mechanisms and cell types at the single-cell level. - The facilities and environment for conducting the proposed research are outstanding. Principal Investigator (PI) and Research Team - The PI is an accomplished researcher with an excellent track record of publications and highly relevant expertise. - The budget and level of PI commitment are appropriate. Responsiveness to the RFA - The proposal is fully responsive to the RFA, as the studies are aimed at elucidating the molecular mechanisms of human pluripotent stem cell differentiation towards specific fates.

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