Investigation of the Potential of Mouse Embryonic Stem Cells to Develop into Neuroendocrine Cells in Vitro
New Faculty II
Neuroendocrine cells are a set of specialized neurons located in the hypothalamus. They are called neuroendocrine because rather than forming synapses with other neurons, their major function is to release their product, neurohormones, into the blood circulation to act on their endocrine targets. The neuroendocrine system consists of eight neuronal populations, each expressing a specific complement of neurohormones and receptors. They are important because they control most of our vital functions, such as growth, reproduction, nutrition, sleep, stress responses and homeostasis via hormonal balance. Moreover, the neuroendocrine hypothalamus is susceptible to a variety of developmental diseases or syndromes such as Kallmann’s, Prader-Willi, or Rubenstein-Taybi. Although neuroendocrine cells are an important component in the regulation of homeostasis and behavior, very little is understood about the mechanisms that control their differentiation. This is mainly due to a lack of an in vitro model of development. The differentiation of embryonic stem cells in culture recapitulates a number of normal developmental processes that occur in mammalian embryos. This proposal aims at coaxing embryonic stem cells into becoming neuroendocrine in order to provide an in vitro model for further investigating the cellular and molecular mechanisms that control differentiation of hypothalamic neuroendocrine cells in early embryonic development. The biology of mouse stem cells mirrors that of human stem cells and, therefore, this work in mouse stem cells will ultimately provide a methodology for studying human embryonic stem cell differentiation into neuroendrocrine neurons, and thus serve as a means for therapeutic investigations. Finally, this project will also provide the opportunity to generate a core of highly skilled undergraduate students trained to maintain and manipulate embryonic stem cells, who can use their skills in laboratories of both academia and biotechnology immediately upon graduation. This will provide them with critical skills in the expanding scientific field of stem cell biology research, to which the state of California is financially, politically, and socially dedicated.
Statement of Benefit to California:
The State of California and its citizens would benefit at two levels from this proposed work. The first is therapeutic and the second is educational: 1- Therapeutic benefits: Hypothalamic neuroendocrine cells are a set of specialized hormone-secreting neurons that integrate and control several homeostatic processes that are required for our survival. Disruption of the development of neuroendocrine systems thus has the potential of perturbing important physiological processes with lifelong consequences. However, little is know about the mechanisms that control the development of such a critical component of homeostatic and behavioral control. The success of this work with mouse stem cells will ultimately provide a template for research into the development of human neuroendocrine cells and, therefore, serve as a means for therapeutic investigations of a variety of neuroendocrine-related developmental diseases or syndrome including obesity and high blood pressure. 2- Training of a skilled workforce in the field of stem cell research: This project will also be used as a template for semester-long individual projects in several upper division laboratory classes including cell and developmental biology, and research methodology class that is part of our undergraduate curriculum. This project will, therefore, provide the opportunity to generate a core of undergraduates trained in techniques of stem cell culture as well as fluorescence microscopy imaging of cells, who can function in laboratories of both academia and biotechnology soon after graduation. In addition, embryonic stem cells are of great interest to science and medicine because of their potential use as a tool to grow and replace damaged tissues in regenerative therapies. Therefore, training my students to successfully grow, maintain and manipulate embryonic stem cells in culture will provide them with critical skills in the expanding scientific field of stem cell biology research, to which the state of California is financially, politically, and socially dedicated.
Neuroendocrine cells are a set of specialized neurons in the hypothalamus that release neural hormones to control growth, reproduction, nutrition and other biological functions. Very little is understood about the mechanisms that control development and differentiation of neuroendocrine cells. The main goal of this proposal is to promote the in vitro differentiation of mouse embryonic stem cells (mESCs) into neuroendocrine cells in order to develop a cell culture model for studying the molecular mechanisms that control formation of hypothalamic neuroendocrine systems. The principal investigator (PI) also intends to help train a new generation of technically skilled personnel as part of research electives for undergraduates at his/her university. The proposed research plan is straightforward, consisting of five aims that propose the differentiation of mESC lines and the exploration of their functional states. Reviewers felt that the research plan is weak and not well described with respect to understanding the development and differentiation of these unique neurons, and they found the aims of this proposal very limited in their scope. For example, the plan to assay the functional state of these neurons is based on a single test with a fluorescent dye that marks secretory activity. Reviewers felt that the proposal to develop neurosecretory cells is not particularly innovative. Although limited in scope, one reviewer considered the use of the dye to be of interest, but thought that the use of another marker, which the applicant proposes as a tool for analysis of all neurosecretory neurons, is not well supported in the proposal. Finally, reviewers felt that the goal to train undergraduate students is novel and much needed at smaller institutions, but is suited better for a different funding mechanism. Overall, the applicant did not provide a compelling rationale for pursuing the proposed research, there seems to be no clinical need to which any findings can be applied, and there is no plan to induce the differentiation of human ESC into neuroendocrine cell types. The principal investigator (PI) is well trained in neuroendocrinology and has an impressive publication record, especially up to 2003. She/he has published three papers since, two as a co-author and one as a senior author. The PI is a co-investigator on a shared laboratory award with a PI in another California institution, but does not list other current support for his/her research. Furthermore, the applicant’s prior work with stem cells is limited. Consequently, reviewers did not find evidence that the applicant will develop into a leader in the field as required by this RFA. Institutional support appears to be strong and a mentoring plan is in place. However, reviewers commented that the scientific environment at the applicant’s institution is not equivalent to that of a research-oriented medical school or college. Furthermore, there is no information provided in the supporting letter or the text of the application of the track record of the university in promoting the development of new biomedical research faculty. The applicant’s laboratory is located in a new Science Center and it appears that the institution is making a genuine effort to enhance research opportunities for its faculty and students, which is commendable. Overall, reviewers did not find this application suitable for funding under this RFA.