摘要：背景:利用缓释系统释放生长因子,是目前生物活性因子应用研究的方向之一。目的:应用离子交联沉淀法制备壳聚糖-转化生长因子β1缓释微球,观察其体外缓释性能以及细胞相容性。设计、时间及地点:观察性实验,于2006-10/2007-09在华中科技大学同济医学院附属协和医院中心实验室完成。材料:壳聚糖,脱乙酰度90%,由清华大学化学工程系提供;转化生长因子β1,由晶美公司提供;大鼠由华中科技大学同济医学院实验动物中心提供。方法:①离子交联沉淀法制备壳聚糖微球,并包裹转化生长因子β1,制备可体外缓释转化生长因子β1的壳聚糖-转化生长因子β1缓释微球。②选择传代二三次、生长良好的大鼠胸降主动脉中层肌成纤维细胞,调节细胞密度至1×108L-1,分别加入不同浓度(4,2,1g/L)壳聚糖微球浸提液,不含浸提液的培养基作为对照培养。主要观察指标:扫描电镜、激光粒度分析仪、Elisa法观察微球表面形态,测定药物载药率、包封率、体外缓释效率等指标;四甲基偶氮唑盐法观察细胞增殖情况,评估壳聚糖微球体外细胞相容性。结果:所得微球球形良好,表面光滑,粒径分布集中,平均粒径272nm。壳聚糖微球有较高的药物包封率,达80.60%。体外释放试验提示,转化生长因子β1初期存在突释现象,前24h释放达27%,其后可从壳聚糖微球中稳定释放,7d累计释放达41%。四甲基偶氮唑盐法提示该壳聚糖微球对细胞体外生长无不良影响,相容性好。结论:离子交联沉淀法制备壳聚糖缓释微球方法简单易行,所得壳聚糖-转化生长因子β1微球具有良好的缓释效能及细胞相容性。

摘要：The aim of this study was to fabricate biomatrix/polymer hybrid scaffolds using an electrospinning technique. Then tissue engineered heart valves were engineered by seeding mesenchymal stromal cells （MSCs） onto the scaffolds. The effects of the hybrid scaffolds on the proliferation of seed cells, formation of extracellular matrix and mechanical properties of tissue engineered heart valves were investigated. MSCs were obtained from rats. Porcine aortic heart valves were decellularized, coated with poly（3-hydroxybutyrate-co-4-hydroxybutyrate） using an electrospinning technique, and reseeded and cultured over a time period of 14 days. In control group, the decellularized valve scaffolds were reseeded and cultured over an equivalent time period. Specimens of each group were examined histologically （hematoxylin-eosin [HE] staining, immunohistostaining, and scanning electron microscopy）, biochemically （DNA and 4-hydroxyproline） and mechanically. The results showed that recellularization was comparable to the specimens of hybrid scaffolds and controls. The specimens of hybrid scaffolds and controls revealed comparable amounts of cell mass and 4-hydroxyproline （P〉0.05）. However, the specimens of hybrid scaffolds showed a significant increase in mechanical strength, compared to the controls （P〈0.05）. This study demonstrated the superiority of the hybrid scaffolds to increase the mechanical strength of tissue engineered heart valves. And compared to the decellularized valve scaffolds, the hybrid scaffolds showed similar effects on the proliferation of MSCs and formation of extracellular matrix. It was believed that the hybrid scaffolds could be used for the construction of tissue engineered heart valves.