From the Cardiovascular Division, King's College London BHF Centre, London, United Kingdom.
Arterioscler Thromb Vasc Biol. 2013 Oct;33(10):2397-406. doi: 10.1161/ATVBAHA.113.301595. Epub 2013 Aug 8.
Sirolimus-eluting stent therapy has achieved considerable success in overcoming coronary artery restenosis. However, there remain a large number of patients presenting with restenosis after the treatment, and the source of its persistence remains unclarified. Although recent evidence supports the contribution of vascular stem/progenitor cells in restenosis formation, their functional and molecular responses to sirolimus are largely unknown.
Using an established technique, vascular progenitor cells were isolated from adventitial tissues of mouse vessel grafts and purified with microbeads specific for stem cell antigen-1. We provide evidence that vascular progenitor cells treated with sirolimus resulted in an induction of their migration in both transwell and wound healing models, clearly mediated by CXCR4 activation. We confirmed the sirolimus-mediated increase of migration from the adventitial into the intima side using an ex vivo decellularized vessel scaffold, where they form neointima-like lesions that expressed high levels of smooth muscle cell (SMC) markers (SM-22α and calponin). Subsequent in vitro studies confirmed that sirolimus can induce SMC but not endothelial cell differentiation of progenitor cells. Mechanistically, we showed that sirolimus-induced progenitor-SMC differentiation was mediated via epidermal growth factor receptor and extracellular signal-regulated kinase 1/2 activation that lead to β-catenin nuclear translocation. The ablation of epidermal growth factor receptor, extracellular signal-regulated kinase 1/2, or β-catenin attenuated sirolimus-induced SM-22α promoter activation and SMC differentiation.
These findings provide direct evidence of sirolimus-induced progenitor cell migration and differentiation into SMC via CXCR4 and epidermal growth factor receptor/extracellular signal-regulated kinase/β-catenin signal pathways, thus implicating a novel mechanism of restenosis formation after sirolimus-eluting stent treatment.
西罗莫司洗脱支架治疗在克服冠状动脉再狭窄方面取得了相当大的成功。然而，仍有大量患者在治疗后出现再狭窄，其持续存在的原因尚不清楚。尽管最近的证据支持血管干细胞/祖细胞在再狭窄形成中的作用，但它们对西罗莫司的功能和分子反应在很大程度上尚不清楚。
使用已建立的技术，从小鼠血管移植物的外膜组织中分离血管祖细胞，并使用针对干细胞抗原-1的微珠进行纯化。我们提供的证据表明，西罗莫司处理的血管祖细胞在 Transwell 和划痕愈合模型中均诱导其迁移，这显然是由 CXCR4 激活介导的。我们通过使用体外去细胞化血管支架证实了西罗莫司介导的从外膜到内膜侧的迁移增加，在那里它们形成表达高水平平滑肌细胞（SMC）标志物（SM-22α 和钙调蛋白）的新生内膜样病变。随后的体外研究证实，西罗莫司可诱导祖细胞向 SMC 分化，而不是内皮细胞分化。从机制上讲，我们表明，西罗莫司诱导祖细胞-SMC 分化是通过表皮生长因子受体和细胞外信号调节激酶 1/2 的激活介导的，导致β-连环蛋白核易位。表皮生长因子受体、细胞外信号调节激酶 1/2 或β-连环蛋白的消融减弱了西罗莫司诱导的 SM-22α 启动子激活和 SMC 分化。
这些发现提供了直接证据，表明西罗莫司通过 CXCR4 和表皮生长因子受体/细胞外信号调节激酶/β-连环蛋白信号通路诱导祖细胞迁移和向 SMC 分化，从而提示了西罗莫司洗脱支架治疗后再狭窄形成的新机制。
