载荷角质细胞生长因子聚乳酸-羟基乙酸共聚物纳米缓释微球在组织工程皮肤构建中的应用

背景：聚乳酸-羟基乙酸共聚物具有良好的生物相容性和可降解性性。目的：制备载荷角质细胞生长因子聚乳酸-羟基乙酸共聚物控释载药系统用于组织工程皮肤。方法：采用乳化-溶剂挥发法、冷冻干燥法制备载有角质细胞生长因子的聚乳酸-羟基乙酸共聚物纳米微球，并构建组织工程皮肤。扫描电镜、倒置显微镜、纳米粒度分析仪、紫外分光及ELISA法对微球评价其特性。结果与结论：纳米微球载药量为(14.05±0.56)%，包封率为(59.86±2.38)%，角质细胞生长因子活性保留率(78.26±5.63)%，体外释放30 d的累积释药率达75%以上，微球形态规则圆润。微球形态规整，在脱细胞真皮表面分布均匀，与其联接良好。毛囊干细胞群在荷载聚乳酸-羟基乙酸共聚物纳米微囊脱细胞真皮上生长活跃，细胞形态良好，并呈克隆团生长。说明实验用组织工程材料制备工艺合理，材料相容性好，可用于构建新型组织工程皮肤。

Preparation and characterization of keratinocyte growth factor loaded poly(lactic-co-glycolic) acid nanocapsules and their applications in reconstruction of tissue-engineered skin

BACKGROUND: Poly(lactic-co-glycolic) acid (PLGA) has good biocompatible and biodegradable properties.OBJECTIVE: To prepare keratinocyte growth factor (KGF) loaded PLGA nanocapsules as the controlled-release drug carrier system suitable for skin-tissue engineering. METHODS: The KGF-nanocapsules were prepared by double emulsion-solvent evaporation and freeze drying methods. Then, tissue-engineered technology was used to construct cell membrane. The morphology of nanocapsules as well as the growth and dermal connections of the cells were observed by scanning electron microscope (SEM) and inverted microscope. Mean diameter and particle size distribution were determined by particle size analyzer. The drug loading rate and encapsulation efficiency, as well as the release profile of KGF in the nanocapsules was evaluated indirectly by ultraviolet spectrometry and ELISA. RESULTS AND CONCLUSION: Inverted microscope and SEM showed the nanocapsules spherical particles seemed to be smooth and uniform, distributed evenly on acellular dermal matrix (ADM) surface and linked tightly to ADM. The hair follicle stem cells grew well on the KGF-PLGA-ADM and formed clones. Both of them had a good compatibility. The drug-loading rate, encapsulation efficiency and KGF activity retention rate were (14.05±0.56)%, (59.86±2.38)% and (78.26±5.63)%, respectively. The released from nanocapsules appeared to be consistent with initial rapid-release and later slow- release. Accumulative release ratio was up to 75% in the continuous period of 30 days. It is indicated that KGF loaded PLGA nanocapsules prepared reasonably, which had good biocompatible and biodegradable properties and could be used to construct a new kind of tissue-engineered skin.