Yan Jing, Wang Wen-Bin, Fan Yang-Jing, Bao Han, Li Na, Yao Qing-Ping, Huo Yun-Long, Jiang Zong-Lai, Qi Ying-Xin, Han Yue
School of Life Sciences and Biotechnology, Institute of Mechanobiology and Medical Engineering, Shanghai Jiao Tong University, Shanghai, China.
Front Cell Dev Biol. 2020 Dec 9;8:606989. doi: 10.3389/fcell.2020.606989. eCollection 2020.
Endothelial progenitor cells (EPCs) play a vital role in endothelial repair following vascular injury by maintaining the integrity of endothelium. As EPCs home to endothelial injury sites, they may communicate with exposed vascular smooth muscle cells (VSMCs), which are subjected to cyclic stretch generated by blood flow. In this study, the synergistic effect of cyclic stretch and communication with neighboring VSMCs on EPC function during vascular repair was investigated. study revealed that EPCs adhered to the injury site and were contacted to VSMCs in the Sprague-Dawley (SD) rat carotid artery injury model. , EPCs were cocultured with VSMCs, which were exposed to cyclic stretch at a magnitude of 5% (which mimics physiological stretch) and a constant frequency of 1.25 Hz for 12 h. The results indicated that stretched VSMCs modulated EPC differentiation into mature endothelial cells (ECs) and promoted angiogenesis. Meanwhile, cyclic stretch upregulated the mRNA expression and secretion level of connective tissue growth factor (CTGF) in VSMCs. Recombinant CTGF (r-CTGF) treatment promoted endothelial differentiation of EPCs and angiogenesis, and increased their protein levels of FZD8 and β-catenin. CTGF knockdown in VSMCs inhibited cyclic stretch-induced EPC differentiation into ECs and attenuated EPC tube formation via modulation of the FZD8/β-catenin signaling pathway. FZD8 knockdown repressed endothelial differentiation of EPCs and their angiogenic activity. Wnt signaling inhibitor decreased the endothelial differentiation and angiogenetic ability of EPCs cocultured with stretched VSMCs. Consistently, an Matrigel plug assay demonstrated that r-CTGF-treated EPCs exhibited enhanced angiogenesis; similarly, stretched VSMCs also induced cocultured EPC differentiation toward ECs. In a rat vascular injury model, r-CTGF improved EPC reendothelialization capacity. The present results indicate that cyclic stretch induces VSMC-derived CTGF secretion, which, in turn, activates FZD8 and β-catenin to promote both differentiation of cocultured EPCs into the EC lineage and angiogenesis, suggesting that CTGF acts as a key intercellular mediator and a potential therapeutic target for vascular repair.
内皮祖细胞（EPCs）通过维持内皮的完整性，在血管损伤后的内皮修复中发挥着至关重要的作用。由于EPCs归巢至内皮损伤部位，它们可能与暴露的血管平滑肌细胞（VSMCs）进行通讯，而这些血管平滑肌细胞会受到血流产生的周期性拉伸。在本研究中，我们探究了周期性拉伸以及与相邻VSMCs通讯对血管修复过程中EPC功能的协同作用。研究表明，在Sprague-Dawley（SD）大鼠颈动脉损伤模型中，EPCs粘附于损伤部位并与VSMCs接触。然后，将EPCs与VSMCs共培养，VSMCs受到幅度为5%（模拟生理拉伸）、频率为1.25 Hz的恒定周期性拉伸，持续12小时。结果表明，受拉伸的VSMCs调节EPCs分化为成熟内皮细胞（ECs）并促进血管生成。同时，周期性拉伸上调了VSMCs中结缔组织生长因子（CTGF）的mRNA表达和分泌水平。重组CTGF（r-CTGF）处理促进了EPCs的内皮分化和血管生成，并增加了它们的FZD8和β-连环蛋白的蛋白水平。VSMCs中CTGF基因敲低抑制了周期性拉伸诱导的EPCs分化为ECs，并通过调节FZD8/β-连环蛋白信号通路减弱了EPCs的管腔形成。FZD8基因敲低抑制了EPCs的内皮分化及其血管生成活性。Wnt信号抑制剂降低了与受拉伸VSMCs共培养的EPCs的内皮分化和血管生成能力。同样，基质胶栓实验表明，r-CTGF处理的EPCs表现出增强的血管生成能力；类似地，受拉伸的VSMCs也诱导共培养的EPCs向ECs分化。在大鼠血管损伤模型中，r-CTGF提高了EPCs的再内皮化能力。目前的结果表明，周期性拉伸诱导VSMC分泌CTGF，进而激活FZD8和β-连环蛋白，促进共培养的EPCs分化为EC谱系并促进血管生成，这表明CTGF作为关键的细胞间介质和血管修复的潜在治疗靶点。
