Lin Li-Han, Lee Hung-Pang, Yeh Ming-Long
Department of Biomedical Engineering, National Cheng Kung University, Tainan 701, Taiwan.
Biomedical Engineering, Dwight Look College of Engineering, Texas A&M University, College Station, TX 77843, USA.
Materials (Basel). 2020 Dec 4;13(23):5538. doi: 10.3390/ma13235538.
Absorbable magnesium stents have become alternatives for treating restenosis owing to their better mechanical properties than those of bioabsorbable polymer stents. However, without modification, magnesium alloys cannot provide the proper degradation rate required to match the vascular reform speed. Gallic acid is a phenolic acid with attractive biological functions, including anti-inflammation, promotion of endothelial cell proliferation, and inhibition of smooth muscle cell growth. Thus, in the present work, a small-molecule eluting coating is designed using a sandwich-like configuration with a gallic acid layer enclosed between poly (d,l-lactide-co-glycolide) layers. This coating was deposited on ZK60 substrate, a magnesium alloy that is used to fabricate bioresorbable coronary artery stents. Electrochemical analysis showed that the corrosion rate of the specimen was ~2000 times lower than that of the bare counterpart. The released gallic acid molecules from sandwich coating inhibit oxidation by capturing free radicals, selectively promote the proliferation of endothelial cells, and inhibit smooth muscle cell growth. In a cell migration assay, sandwich coating delayed wound closure in smooth muscle cells. The sandwich coating not only improved the corrosion resistance but also promoted endothelialization, and it thus has great potential for the development of functional vascular stents that prevent late-stent restenosis.
由于可吸收镁支架比生物可吸收聚合物支架具有更好的机械性能，已成为治疗再狭窄的替代方案。然而，未经改性的镁合金无法提供与血管重塑速度相匹配的合适降解速率。没食子酸是一种具有吸引人的生物学功能的酚酸，包括抗炎、促进内皮细胞增殖和抑制平滑肌细胞生长。因此，在本研究中，设计了一种小分子洗脱涂层，采用三明治结构，没食子酸层夹在聚（d，l-丙交酯-共-乙交酯）层之间。该涂层沉积在ZK60基底上，ZK60是一种用于制造生物可吸收冠状动脉支架的镁合金。电化学分析表明，试样的腐蚀速率比未涂层的对照物低约2000倍。从三明治涂层释放的没食子酸分子通过捕获自由基抑制氧化，选择性地促进内皮细胞增殖，并抑制平滑肌细胞生长。在细胞迁移试验中，三明治涂层延缓了平滑肌细胞的伤口愈合。三明治涂层不仅提高了耐腐蚀性，还促进了内皮化，因此在开发预防晚期支架再狭窄的功能性血管支架方面具有巨大潜力。
