基质金属蛋白酶-2敏感型聚乙二醇复合水凝胶的制备及性质

Preparation of matrix metalloproteinases-2 sensitive polyethylene glycols hydrogel

目的采用相对分子质量20000Da分枝状聚乙二醇（fourarmedPEG-Ac）和基质金属蛋白酶-2（MMP-2）敏感型底物肽制备一种可降解复合水凝胶，并检测其性能。方法以制备浓度为10％（w／v）的酶敏感型复合PEG水凝胶为实验A组，单纯PEG水凝胶为对照B组，比较两种水凝胶在37℃磷酸盐缓冲液（PBS）和血清的降解，并检测细胞毒性。在制胶过程中包埋转化生长因子（TGF-β1），观察两组水凝胶对TGF-β1的缓释效果。结果PBS中A、B两组4周累计降解率分别为78．36％、76．28％，两者差异无统计学意义（P〉0．05）；分别添加正常人体血清，A组4周累计降解率为88．35％，降解速度加快，B组则变化不明显。噻唑蓝（MTT）比色法检测复合PEG水凝胶无细胞毒性。A、B两组水凝胶TGF-β1 7d累计释放率分别为50．63％、44．36％，两者差异无统计学意义（P〉0．05），分别添加MMP-2后，A组对TGF-β1的释放速度明显加快。结论MMP-2敏感型PEG水凝胶结构稳定，对细胞无毒性，包埋TGF-β1有良好的控释效果，有望应用于新型组织工程心脏瓣膜支架材料的研制。

Objective To construct a biodegradable compound gel by four-armed polyethylene glycols （PEG） and matrix metalloproteinases-2 （MMP-2） sensitive substrate peptide, and investigate its properties. Methods Trials were randomly designed into two groups： MMP-2 enzymatically degradable PEG hydrogel （group A） and simple PEG hydrogel （group B）. Degradation in different media was analyzed and the cell toxicity was observed. Transforming growth factor （TGF）-β1 was embedded into hydrogel during production process and its release rate was calculated. Results Compound gel had excellent stability. The degradation rate in phosphate buffer solution for four weeks was 78.36% and 76.28% in groups A and B respectively and had no significant difference between two groups （ P 〉 0. 05 ）. After addition of the normal human serum, the degradation rate of group A reached 88.35%, and that of group B had no significant change. No cell toxicity of composite hydrogel was detected by methyl thiazol tetrazolium （MTT） test. TGF-β1 accumulative release rate at 7th day was 50. 63% and 44. 36% in groups A and B respectively （P 〉0. 05）. After addition of MMP-2, TGF-β1 release rate of group A was obviously increased. Conlusion This MMP-2 enzymatically degradable PEG hydrogel has stable structure and no cell toxicity, and can effectively control the release of TGF-β1. It is a potential material to fabricate new hybrid scaffold for tissue engineering of heart valves