基于3D打印技术制备多肽修饰的多孔仿生可降解支架及其促内皮化研究

Vascular stent implantation was widely used in arteriosclerosis obliteration of lower extremity. Biodegradable stent had good biocompatibility, providing support for blood vessel in a short period of time and then disappearing completely to achieve the goal of revascularization. However, such stent still faced the problem of delayed vascular reendothelialization. Therefore, the formation of the endothelium through the enhancement of endothelial cell migration and proliferation became the key to the treatment of disease. Based on the principles of tissue engineering, the project designed a porous biodegradable stent with collagen and REDV peptide modified poly(lactic-co-glycolic acid) (PLGA) by 3D printing technology which could promote endothelialization. Because of the good selectivity of REDV peptide to alpha 4 beta 1 receptor on the surface of endothelial cells, REDV peptide on the stent surface could promote vascular endothelialization. Meanwhile, the porous structure and the exposed collagen due to degradation of the scaffold could provide good microenvironment for the adhesion and proliferation of the endothelial cell to complete endothelialization process and reduce the occurrence of restenosis. Therefore, the project provides a new strategy for targeted therapy to promote endothelialization and vascularization. The results of this study are of great significance for the treatment of arteriosclerosis obliterans of lower extremities.

血管介入治疗在下肢动脉硬化闭塞症中应用广泛，而生物可降解支架具有较好的生物相容性，短期内扩张狭窄血管，随后在体内逐渐被降解，达到血运重建的目的，然而此类支架依旧面临着植入后血管再内皮化迟缓的问题，因此增强内皮细胞的迁移与增殖，促进内皮层的形成，成为治疗支架内再狭窄的关键。基于此，本项目分别制备了胶原改性以及REDV肽改性的聚乳酸-羟基乙酸共聚物，利用3D打印技术制备了能够促进内皮化的多孔仿生可降解血管支架，REDV肽能够特异性结合内皮细胞表面高表达的α4β1受体，从而使得经REDV肽修饰的支架具有特异性促进内皮细胞黏附的能力，同时支架的多孔结构以及因支架降解而暴露出来的胶原能够为内皮细胞的生长提供良好的微环境，因而能够帮助支架更好地完成内皮化过程，继而减小支架内再狭窄的发生。因此本项目为促进内皮化提供了一个新思路，研究结果对介入治疗下肢动脉硬化闭塞症具有重要意义。

血管支架植入在下肢动脉硬化闭塞症介入治疗中应用广泛，而生物可降解支架具有良好的组织相容性和生物降解性，在血管狭窄部位植入可降解支架后，既可在前期有效扩张血管又可被逐渐降解，降解产物可通过代谢排出体外或被人体吸收而不影响远期血管功能，然而此类支架依旧面临着植入后血管再内皮化迟缓的问题，因此增强内皮细胞的迁移与增殖，促进内皮层的形成，成为治疗支架内再狭窄的关键。基于此，本项目分别制备了胶原改性以及REDV肽改性的聚乳酸-羟基乙酸共聚物，利用3D打印技术制备了能够促进内皮化的仿生可降解血管支架，扫描电镜下可见支架表面光滑；支架体外降解实验显示在前8个月中支架的降解率较小，8个月后支架的降解速度明显开始上升， 14个月后支架的降解率仍在继续增加，但降解速度较之前逐渐减缓；体外细胞实验显示支架对细胞活性无明显影响，并且随着培养时间的增加，HUVECs以及HUASMCs细胞数量也在不断增加，同时细胞逐渐在支架上铺展开；细胞FDA染色实验显示REDV肽修饰的可降解支架上的HUVEC细胞数量明显多于未修饰的支架；细胞竞争性粘附实验显示REDV肽修饰的可降解支架上的HUVECs细胞数量明显多于HUASMCs细胞。综上所述，REDV肽能够特异性结合内皮细胞表面高表达的α4β1受体，从而使得经REDV肽修饰的支架具有特异性促进内皮细胞黏附的能力，同时支架的多孔结构以及因支架降解而暴露出来的胶原能够为内皮细胞的生长提供良好的微环境，因而能够帮助支架更好地完成内皮化过程，继而减小支架内再狭窄的发生。因此本项目为促进内皮化提供了一个新思路，研究结果对介入治疗下肢动脉硬化闭塞症具有重要意义。