Cardiovascular Center & Department of Internal Medicine, Seoul National University, Seoul, Korea.
Mol Ther. 2012 Sep;20(9):1750-1766. doi: 10.1038/mt.2012.109. Epub 2012 Jun 19.
Loss of cardiomyocytes impairs cardiac function after myocardial infarction (MI). Recent studies suggest that cardiac stem/progenitor cells could repair the damaged heart. However, cardiac progenitor cells are difficult to maintain in terms of purity and multipotency when propagated in two-dimensional culture systems. Here, we investigated a new strategy that enhances potency and enriches progenitor cells. We applied the repeated sphere formation strategy (cardiac explant → primary cardiosphere (CS) formation → sphere-derived cells (SDCs) in adherent culture condition → secondary CS formation by three-dimensional culture). Cells in secondary CS showed higher differentiation potentials than SDCs. When transplanted into the infarcted myocardium, secondary CSs engrafted robustly, improved left ventricular (LV) dysfunction, and reduced infarct sizes more than SDCs did. In addition to the cardiovascular differentiation of transplanted secondary CSs, robust vascular endothelial growth factor (VEGF) synthesis and secretion enhanced neovascularization in the infarcted myocardium. Microarray pathway analysis and blocking experiments using E-selectin knock-out hearts, specific chemicals, and small interfering RNAs (siRNAs) for each pathway revealed that E-selectin was indispensable to sphere initiation and ERK/Sp1/VEGF autoparacrine loop was responsible for sphere maturation. These results provide a simple strategy for enhancing cellular potency for cardiac repair. Furthermore, this strategy may be implemented to other types of stem/progenitor cell-based therapy.
心肌细胞的丢失会损害心肌梗死后的心脏功能。最近的研究表明，心脏干/祖细胞可以修复受损的心脏。然而，当在二维培养系统中进行传代时，心脏祖细胞很难保持其纯度和多能性。在这里，我们研究了一种增强效力和丰富祖细胞的新策略。我们应用了重复球体形成策略（心脏组织→原代心脏球体（CS）形成→球体衍生细胞（SDC）在贴壁培养条件下→通过三维培养形成次级 CS）。与 SDC 相比，次级 CS 中的细胞具有更高的分化潜能。当移植到梗死的心肌中时，次级 CS 大量植入，改善左心室（LV）功能障碍，并比 SDC 更能减少梗死面积。除了移植的次级 CS 的心血管分化外，强大的血管内皮生长因子（VEGF）合成和分泌增强了梗死心肌中的新生血管形成。微阵列通路分析和使用 E-选择素敲除心脏、特定化学物质和针对每个通路的小干扰 RNA（siRNA）的阻断实验表明，E-选择素对于球体起始是必不可少的，ERK/Sp1/VEGF 自分泌环负责球体成熟。这些结果为增强心脏修复的细胞效力提供了一种简单的策略。此外，该策略可应用于其他类型的基于干细胞/祖细胞的治疗。
