Institute of Mechanobiology & Medical Engineering, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, China.
FEBS J. 2020 Dec;287(23):5196-5217. doi: 10.1111/febs.15293. Epub 2020 Mar 28.
Intimal injury is an early stage of several cardiovascular diseases. Endothelial progenitor cells (EPCs) play a significant role in endothelial repair following vascular injury. Once the intima is damaged, EPCs are mobilized from the bone marrow to the injury site. Meanwhile, the injury to the intimal surface triggers platelet degranulation, aggregation, and adhesion to the damaged endothelium, and exposed collagen stimulates platelet to secrete platelet-derived microvesicles (PMVs). However, the role of PMVs in EPC function during this process remains unknown. In an in vivo study, EPCs and platelets were found to adhere to the injury site in Sprague-Dawley (SD) rat vascular injury model. In vitro, collagen stimulation induced the release of PMVs, and collagen-activated PMVs (ac.PMVs) significantly promoted EPC proliferation. Transforming growth factor-β1 (TGF-β1) content was increased in ac.PMVs. Activated PMVs significantly upregulated Smad3 phosphorylation in EPCs and increased Smad3 nuclear translocation from the cytoplasm. TGF-β1 knockdown ac.PMVs downregulated EPC proliferation. Recombinant TGF-β1 enhanced EPC proliferation. The TGF-β1 inhibitor SB431542 significantly repressed the intracellular signal triggered by ac.PMVs. Furthermore, the Smad3-specific phosphorylation inhibitor SIS3 effectively reversed the cell proliferation induced by ac.PMVs. Smad3 translocated to the nucleus and enhanced EPC proliferation via its downstream genes tenascin C (TNC), CDKN1A, and CDKN2A. r-TGF-β1 promoted reendothelialization and EPC proliferation in vivo. Our data demonstrate that activated PMVs deliver TGF-β1 from collagen-activated platelets to EPCs, which in turn activates Smad3 phosphorylation and regulates TNC, CDKN1A, and CDKN2A expression to promote EPC proliferation, suggesting that PMVs act as a key transporter and a potential therapeutic target for vascular injury.
内膜损伤是几种心血管疾病的早期阶段。内皮祖细胞（EPCs）在血管损伤后的内皮修复中起着重要作用。一旦内膜受损，EPCs 就会从骨髓动员到损伤部位。同时，内膜表面的损伤会触发血小板脱颗粒、聚集和黏附到受损的内皮细胞上，暴露的胶原蛋白会刺激血小板分泌血小板衍生的微泡（PMVs）。然而，在这个过程中，PMVs 在 EPC 功能中的作用尚不清楚。在一项体内研究中，发现 EPCs 和血小板在 Sprague-Dawley（SD）大鼠血管损伤模型中黏附在损伤部位。在体外，胶原蛋白刺激诱导 PMVs 的释放，而胶原蛋白激活的 PMVs（ac.PMVs）显著促进 EPC 增殖。转化生长因子-β1（TGF-β1）含量在 ac.PMVs 中增加。激活的 PMVs 显著上调 EPC 中的 Smad3 磷酸化，并增加 Smad3 从细胞质向核内的转位。TGF-β1 敲低 ac.PMVs 下调 EPC 增殖。重组 TGF-β1 增强 EPC 增殖。TGF-β1 抑制剂 SB431542 显著抑制 ac.PMVs 触发的细胞内信号。此外，Smad3 特异性磷酸化抑制剂 SIS3 有效逆转了 ac.PMVs 诱导的细胞增殖。Smad3 转位到核内，并通过其下游基因 tenascin C（TNC）、CDKN1A 和 CDKN2A 增强 EPC 增殖。r-TGF-β1 促进体内再内皮化和 EPC 增殖。我们的数据表明，激活的 PMVs 将 TGF-β1 从胶原蛋白激活的血小板传递到 EPCs，进而激活 Smad3 磷酸化，并调节 TNC、CDKN1A 和 CDKN2A 的表达，以促进 EPC 增殖，这表明 PMVs 作为一种关键的转运体和血管损伤的潜在治疗靶点。
