Creating Super Stem Cells for Cardiac and Wound Repair

描述(申请人提供)：直到最近，心肌损失和相关的功能恶化被认为是不可逆转的。然而，越来越多的证据表明，注射干细胞可以改善衰竭心脏的功能，从而催生了心脏再生疗法的革命性概念。骨髓(BM)来源的间充质干细胞(MSCs)可以分化为多种组织，在几个临床前模型中显示可以改善心肌功能，导致目前的一项人类临床试验，以提供这些引人注目的新的基于细胞的治疗方法，使用人类MSCs进行心肌修复。因此，了解如何提高干细胞的治疗效果，例如开发“超级”干细胞，将扩大它们的用途，特别是在老年人、心脏功能障碍患者和被描述为干细胞功能障碍的糖尿病人群中。使用一种代表再生光谱上端的菌株，我们分离出了与C57BL/6(野生型，WT)小鼠相比再生能力显著增强的MSCs。在小鼠肉芽组织模型中，“超级”MSCs表现出显著的增殖增加、创面组织重建和血管可塑性。此外，来自这些细胞的可溶性因子显著增加了胎儿心肌细胞的增殖和内皮细胞在对照条件培养液中的迁移。在小鼠心肌梗死模型中，心肌梗死周围肌肉注射这些细胞显示出比WT MSCs和对照组更好的初步功能结果。我们发现，与WT相比，分泌的卷曲相关蛋白和可溶性WNT的表达存在显著的差异，从而显著下调了“超级”MSCs中WNT途径的表达。我们证实了Wnt/-catenin信号在MRLMSCs中的相对下调，以及Wnt途径的抑制促进了MSC的增殖和肉芽组织的形成，暗示这一途径是MSC优越再生表型的分子基础。我们推测，Wnt信号通路的调控对MSC的自我更新和再生能力至关重要。此外，我们认为，调节这一途径的活性将概括“超级干细胞”的表型，是未来心肌损伤和创面再生细胞治疗的良好靶点。

DESCRIPTION (provided by applicant): Until recently, myocardial loss and associated functional deterioration was regarded as irreversible. Yet, accumulating evidence suggests that injected stem cells can improve function of a failing heart, giving birth to a revolutionary concept of regenerative therapy for the heart. Bone marrow (BM)-derived mesenchymal stem cells (MSCs), known to differentiate into a wide variety of tissues, have shown in several preclinical models to result in improved myocardial function leading to a current human clinical trial to provide these dramatic new cell based therapies using human MSCs for myocardial repair. Hence, understanding how to enhance their therapeutic efficacy, e.g. to develop "super" stem cells, would expand their utility, especially in the elderly, patients with cardiac dysfunction, and in the diabetic population in whom stem cell dysfunction has been described. Using a strain that represents the upper end of the regenerative spectrum we isolated MSCs that demonstrate remarkably enhanced regenerative capacity as compared to those from C57Bl/6 (wildtype, WT) mice. The "super" MSCs demonstrated dramatically increased proliferation, vigorous wound tissue reconstitution, and vascular plasticity in a mouse granulation tissue model. Also, soluble factors derived from these cells caused significantly increased proliferation of fetal cardiomyoctyes and migration of endothelial cells over control conditioned media. In a murine myocardial infarct model, intramuscular peri- infarct injection of these cells showed favorable preliminary functional results over WT MSCs and control. We have identified a striking downregulation of the Wnt pathway in the "super" MSCs by differential expression of members of secreted frizzled related proteins and soluble Wnts as compared to WT. We verified both the relative downregulation of Wnt/-catenin signaling in MRLMSCs and that Wnt pathway inhibition enhanced MSC proliferation and granulation tissue formation, implicating this pathway as the molecular basis for the superior regenerative phenotype. We hypothesize that regulation of the Wnt signaling pathway is critical for MSC self-renewal and regenerative capacity. Moreover, we propose that modulating the activity of this pathway will recapitulate the "super stem cell" phenotype and is an excellent future target for cell based therapies for myocardial injuries and wound regeneration.