Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Regenerative Nanomedicine Research Group, Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Mater Sci Eng C Mater Biol Appl. 2017 Nov 1;80:213-221. doi: 10.1016/j.msec.2017.05.140. Epub 2017 May 29.
The emerging demand for small caliber vascular grafts to replace damaged vessels has attracted research attention. However, there is no perfect replacement in clinical use yet, mainly due to low patency rate of synthetic small caliber grafts. The main pathology behind low patency rate include thrombosis and graft/vessel hemodynamic mismatch, leading to intimal hyperplasia. Rapid in-situ endothelialization of vascular grafts is considered as one of the best strategies to overcome these complications. In the present study, Heparin and VEGF were immobilized via self-polymerization and deposition of polydopamine (PDA) on polyurethane (PU) nanofibrous scaffolds to improve endothelialization. Polyurethane nanofibrous scaffold (PUNF) that mimics vascular extracellular matrix (ECM) was chosen owing to its biocompatibility, biodegradability. Scanning electron microscopy (SEM), water contact angle (CA) measurement and Raman spectroscopy were used to characterize the surface, and tensile test was used to analyze mechanical properties before and after surface modification of the scaffolds. It was found that tensile strength and young's modulus were significantly increased after PDA coating on PUNF membranes. The hemocompatibility tests revealed that surface heparinization significantly inhibited the adhesion of platelet on the scaffolds. Immobilization of VEGF on the scaffolds significantly enhanced the proliferation of human umbilical vein endothelial cells (HUVECs) through enhanced cells adhesion and improved cell-scaffold interactions. The results suggest that dual-factor immobilization resulted in not only confluent monolayer of endothelial cells but also conferred excellent antithrombotic properties to the surface. This method of surface modification (immobilization of Heparin, VEGF by PDA layer) is suggested as a promising modification technique to increase hemocompatibility of small-diameter vascular grafts.
新兴的小口径血管移植物需求，以取代受损的血管，引起了研究的关注。然而，目前还没有完美的替代品在临床应用，主要是由于合成小口径移植物的通畅率较低。通畅率低的主要病理学包括血栓形成和移植物/血管血流动力学不匹配，导致内膜增生。血管移植物的快速原位内皮化被认为是克服这些并发症的最佳策略之一。在本研究中，肝素和 VEGF 通过在聚多巴胺（PDA）上的自聚合和沉积固定在聚氨酯（PU）纳米纤维支架上，以改善内皮化。选择模仿血管细胞外基质（ECM）的聚氨酯纳米纤维支架（PUNF），是因为其具有生物相容性、可生物降解性。扫描电子显微镜（SEM）、水接触角（CA）测量和拉曼光谱用于表征表面，拉伸试验用于分析支架表面改性前后的机械性能。结果发现，PDA 涂层后 PUNF 膜的拉伸强度和杨氏模量显著增加。血液相容性测试表明，表面肝素化显著抑制了血小板在支架上的黏附。支架上固定 VEGF 显著增强了人脐静脉内皮细胞（HUVEC）的增殖，通过增强细胞黏附和改善细胞-支架相互作用。结果表明，双因素固定不仅导致内皮细胞形成了均匀的单层，而且赋予了表面优异的抗血栓性能。这种表面改性方法（通过 PDA 层固定肝素和 VEGF）被建议作为一种有前途的改性技术，以提高小直径血管移植物的血液相容性。
