Expansion of cardiac and hematopoietic progenitors by Wnt and Notch

描述（由申请人提供）： 为了实现再生医学在心肌发生领域的承诺，有必要有效地操纵心脏祖细胞的扩增、分化和维持。无论翻译研究人员是否试图通过体内祖细胞的募集来增强内源性再生能力，或者是否在体外产生和扩增祖细胞用于随后的递送或用于组织工程生物假体的产生，这都是必需的。造血领域的类似进展强调了详细了解对祖细胞扩增和适当分化重要的信号传导途径的重要性，其中调节干细胞扩增的GM-CSF、G-CSF和相关生长因子的临床使用提供了显著的临床影响。在心血管领域，通常缺乏特异性调节祖细胞存活、扩增和分化的能力。此外，用于离体扩增的祖细胞的可用来源仍然难以捉摸。为了克服这一局限性，许多研究集中于从胚胎干细胞以及从非心脏成纤维细胞衍生的诱导多能干细胞的心脏祖细胞的产生和表征，以最终用于组织工程治疗。这些研究表明，心肌细胞可以从这些细胞类型产生，但也揭示了所得的心肌细胞不表现出成人心肌细胞的所有必要特征。因此，从ES或IPS细胞扩增和可控地分化心肌细胞的能力在其应用中受到限制，部分原因是缺乏对心脏祖细胞如何在体内扩增和分化的理解。Penn/UW Consortium申请的基本论点是，进一步阐明胚胎中介导心脏和造血祖细胞发育的信号，为鉴定对祖细胞体外扩增和分化有用的因子提供了逻辑方法。因此，我们的合作项目联合收割机结合了两个最重要的干细胞信号传导途径的分析，Wnt和Notch，在发育过程中，以及在来自多能干细胞（包括ES和iPS细胞）的心脏和血液祖细胞中。然而，这种分析仍然没有开发，Wnt和Notch在发育中的心脏中的相互作用仍然没有探索，尽管已知这些途径在许多其他干细胞群体中相互作用。这些研究将与关于Wnt和Notch在造血干细胞（HSC）扩增和适当分化中的作用的协作链接申请中描述的那些研究相互作用。宾夕法尼亚大学心脏部分的目的将集中在1）Wnt和Notch如何促进发育和ES/iPS细胞中的心脏祖细胞扩增和分化，以及2）定义Wnt和Notch操作的心肌细胞和成熟成人心肌细胞之间的相似性和差异。因此，Penn/UW祖细胞联盟提出表征Wnt和Notch信号传导在体内以及离体扩增祖细胞的能力。

DESCRIPTION (provided by applicant): To fulfill the promise of regenerative medicine in the cardiac myogenesis field, it will be necessary to effectively manipulate expansion, differentiation, and maintenance of cardiac progenitor cells. This will be required regardless of whether translational researchers attempt to augment endogenous regenerative capacity via recruitment of progenitor cells in vivo, or whether progenitors are generated and expanded ex vivo for subsequent delivery or for the generation of tissue engineered bioprostheses. The importance of a detailed understanding of the signaling pathways important for progenitor expansion and proper differentiation is emphasized by analogous advances in the hematopoietic field, where the clinical use of GM-CSF, G-CSF and related growth factors, which regulate stem cell expansion has provided dramatic clinical impact. In the cardiovascular field, the ability to specifically regulate progenitor cell survival, expansion and differentiation is generally lacking. Moreover, a usable source of progenitors for ex vivo expansion remains elusive. To overcome this limitation, many studies have focused on the generation and characterization of cardiac progenitors from embryonic stem cells as well as induced pluripotential stem cells derived from non-cardiac fibroblasts for eventual use in tissue engineering therapies. These studies have shown that cardiac myocytes can be generated from such cell types but have also revealed that the resulting myocytes do not exhibit all of the necessary characteristics of adult cardiac myocytes. The ability to expand and controllably differentiate cardiac myocytes from ES or IPS cells is therefore limited in its uses, in part due to the lack of understanding of how cardiac progenitors expand and differentiate in vivo. The underlying thesis of the Penn/UW Consortium application is that further elucidation of the signals that mediate cardiac and hematopoietic progenitor development in the embryo provides a logical approach for the identification of factors useful for expansion and differentiation of progenitor cells ex vivo. Hence, our collaborative projects combine the analysis of two of the most vital stem cell signaling pathways, Wnt and Notch, during development and in cardiac and blood progenitors derived from pluripotential stem cells including ES and iPS cells. Nevertheless, this analysis remains undeveloped and the interactions of Wnt and Notch in the developing heart remain unexplored, although these pathways are known to interact in many other stem cell populations. These studies will interface with those described in the collaborative linked application on the role of Wnt and Notch in expansion and proper differentiation of hematopoietic stem cells (HSCs). The Aims of the UPenn cardiac portion will focus on 1) how Wnt and Notch promote cardiac progenitor expansion and differentiation in development and in ES/iPS cells and 2) defining the similarities and differences between Wnt and Notch manipulated cardiac myocytes and mature adult myocytes. Thus, the Penn/UW Progenitor Consortium proposes to characterize the ability of Wnt and Notch signaling to expand progenitors in vivo as well as ex vivo.