Zhang Jianfeng, Chen Anqing, Wu Yicheng, Zhao Qiang
Department of Cardiac Surgery, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Cell Physiol Biochem. 2015;36(3):947-55. doi: 10.1159/000430269. Epub 2015 Jun 12.
BACKGROUND/AIMS: Transplantation of mesenchymal stem cells (MSCs) improves post-injury cardiac muscle repair using ill-defined mechanisms. Recently, we have shown that production and secretion of placental growth factor (PLGF) by MSCs play a critical role in the MSCs-mediated post-injury cardiac muscle repair. In this study, we addressed the underlying molecular mechanisms, focusing specifically on the interactions between MSCs, macrophages and endothelial cells.
We isolated macrophages (BM-MΦ) from mouse bone-marrow derived cells based on F4/80 expression by flow cytometry. BM-MΦ were treated with different doses of PLGF. Cell number was analyzed by a MTT assay. Macrophage polarization was examined based on CD206 expression by flow cytometry. PLGF levels in macrophage subpopulations were analyzed by RT-qPCR and ELISA. Effects of macrophages on vascularization were evaluated by a collagen gel assay using Human umbilical vein endothelial cells (HUVECs) co-cultured with PLGF-treated macrophages.
PLGF did not increase macrophage number, but dose-dependently polarized macrophages into a M2 subpopulation. M2 macrophages expressed high levels of PLGF. PLGF-polarized M2 macrophages significantly increased tubular structures in the collagen gel assay.
Our data suggest that MSCs-derived PLGF may induce macrophage polarization into a M2 subpopulation, which in turn releases more PLGF to promote local neovascularization for augmenting post-injury cardiac muscle repair. This study thus sheds novel light on the role of PLGF in cardiac muscle regeneration.
背景/目的：间充质干细胞（MSCs）移植可通过尚不明确的机制改善损伤后的心肌修复。最近，我们发现MSCs产生和分泌胎盘生长因子（PLGF）在MSCs介导的损伤后心肌修复中起关键作用。在本研究中，我们探讨了潜在的分子机制，特别关注MSCs、巨噬细胞和内皮细胞之间的相互作用。
我们通过流式细胞术基于F4/80表达从小鼠骨髓来源的细胞中分离巨噬细胞（BM-MΦ）。用不同剂量的PLGF处理BM-MΦ。通过MTT法分析细胞数量。通过流式细胞术基于CD206表达检测巨噬细胞极化。通过RT-qPCR和ELISA分析巨噬细胞亚群中的PLGF水平。使用与经PLGF处理的巨噬细胞共培养的人脐静脉内皮细胞（HUVECs），通过胶原凝胶试验评估巨噬细胞对血管生成的影响。
PLGF未增加巨噬细胞数量，但剂量依赖性地将巨噬细胞极化为M2亚群。M2巨噬细胞表达高水平的PLGF。在胶原凝胶试验中，PLGF极化的M2巨噬细胞显著增加了管状结构。
我们的数据表明，MSCs来源的PLGF可能诱导巨噬细胞极化为M2亚群，后者进而释放更多PLGF以促进局部新生血管形成，从而增强损伤后心肌修复。因此，本研究为PLGF在心肌再生中的作用提供了新的见解。
