Understanding Pancreatic Progenitors for Diabetes Cell-Replacement Therapy

简介（由申请人提供）：糖尿病是一个日益严重的全球性健康问题。1型和2型糖尿病都会导致产生胰岛素的β细胞逐渐减少。我们的长期目标是开发β细胞替代策略来克服糖尿病患者的胰岛素缺乏症。为了实现这一目标，我们开发了新的、更安全的方法，利用化学物质和遗传因素将患者成纤维细胞转化为诱导多能干细胞（iPSCs）。利用人类胚胎干细胞（hESCs）开发的方案，这些iPSCs可以分化为多能胰腺祖细胞，即β细胞的前体。然而，我们对胰腺祖细胞的基本生物学的理解仍然是初级的，这为开发有效的策略来扩大和进一步分化这些祖细胞进行治疗带来了障碍。我们自己的研究和其他实验室的研究证据表明，胰腺祖细胞是异质的，可能由具有不同生理功能的亚群组成。然而，这些亚群之间的分子和功能差异知之甚少。目前尚不清楚发育中的胰腺中哪个亚群能够产生功能性β细胞，以及特定亚群在多大程度上能够自我更新。对hESCs分化的胰腺祖细胞的生理功能和自我更新特性的了解就更少了。我们的目标是在这项建议中解决这些关键问题。我们假设体内胰腺祖细胞区室包含异质亚群：(i)一个共同的多能胰腺祖细胞负责产生所有三种胰腺谱系；（ii）不同的谱系特异性祖细胞负责产生一个或两个特定的胰腺谱系。基于这一假设，本建议的总体目标是定义胰腺祖细胞

DESCRIPTION (provided by applicant): Diabetes mellitus is an escalating global health problem. Both Type 1 and Type 2 diabetes lead to the gradual loss of insulin-producing beta cells. Our long-term goal is to develop beta cell replacement strategies to overcome the insulin deficiency in diabetic patients. To achieve this goal, we have developed novel, safer approaches to convert patient fibroblasts to induced pluripotent stem cells (iPSCs) using chemicals together with genetic factors. These iPSCs can be differentiated into multipotent pancreatic progenitors, the precursors to beta cells, using protocols developed for human embryonic stem cells (hESCs). However, our understanding of the basic biology of pancreatic progenitor cells is still rudimentary, which presents hurdles in the development of effective strategies to expand and further differentiate these progenitor cells for therapy. Evidence emerged from our own studies and from those of other laboratories suggests that pancreatic progenitor cells are heterogeneous, and likely consist of subpopulations with different physiological functions. Yet, molecular and functional distinctions between these subpopulations are poorly understood. It is unclear which subpopulation(s) in the developing pancreas is(are) capable of generating functional beta cells, and to which extent a specific subpopulation is capable of self-renewal. Even less is known about the physiological functions and self-renewal properties of pancreatic progenitor cells differentiated from hESCs. We aim to address these critical questions in this proposal. We hypothesize that the pancreatic progenitor cell compartment in vivo contains heterogeneous subpopulations: (i) a common multipotent pancreatic progenitor responsible for generating all three pancreatic lineages; and (ii) distinct lineage-specific progenitors responsible for generating one or two specific pancreatic lineages. Based on this hypothesis, the overall objective of this proposal is to define pancreatic progenitor subpopulations in terms of their molecular characteristics and physiological functions, as well as to identify mechanisms for self-renewal. We anticipate that our study will yield the following outcomes. Aim 1 will reveal the presence of distinct pancreatic progenitor subpopulations both during embryo development and in hESC differentiation culture. This will identify the progenitor subpopulation(s) capable of generating functional cells. Aim 2 will identify cell surface markers for enrichment of the appropriate progenitor subpopulation(s) for further ¿ differentiation into ¿ cells, and set the stage for studies on expansion of progenitor cells. Aim 3 will elucidate the mechanism of self-renewal of distinct progenitor subpopulations, which are critical for the development of novel, effective strategies to expand pancreatic progenitors for beta cell replacement therapy. Additionally, the ability to generate a large quantity of human pancreatic progenitor cells will provide a new way to study the biology of these cells to complement mouse genetics approaches. Broadly, the proposed research will lead to novel findings to fill in critical gaps in our current knowledge of human pancreatic development.