含内皮祖细胞的组织工程皮肤体外构建及裸鼠移植研究

目的构建含内皮祖细胞（EPC）和成纤维细胞的组织工程复合皮，初步研究EPC在组织工程皮肤移植中促血管发生的作用。方法采用免疫磁珠法从人脐血中分离培养CD133＋血管内皮祖细胞，以聚羟基乙酸（PGA）为真皮基质，接种EPC和成纤维细胞，其上覆盖表皮细胞膜片，构建组织工程复合皮，覆盖裸鼠背部全层皮肤缺损创面。结果EPC和成纤维细胞能均匀贴附于PGA支架纤维材料上，并逐渐伸展为梭形或多极状。裸鼠移植实验表职，实验组创面愈合早于对照组，可见EPC参与大量新生小血管形成，真皮支架5周完全降解。结论EPC参与血管重建，具有促进血管新生，加速缺血组织血管化的作用。应用PGA＋纤维蛋白凝胶，制备含EPC和成纤维细胞的活性真皮替代物，具有良好的生物相容性、降解特性。

Construction and transplantation of tissue engineering skin with EPCs in athymic mice

Objective To establish the methods of seeding endothelial progenitor cells (EPC) in porous biodegradable scaffold PGA (the polyglycolic acid) by leading EPC into tissue engineering skin and study EPC biological characteristics and its neovascularization in tissue engineering skin by constructing tissue engineering skin with EPC and fibroblast. Methods CD133+ cells were enriched from human umbilical cord blood by immunomagnetic sorting. EPC and fibroblasts were seeded into dermal substitute constructed by mixing PGA with fibronogen. When EPC and fibroblasts in PGA-collagen gel showed better morphological character and a network form,the surface of the substitute was covered with a thin layer keratinocyte sheet to construct tissue engineering skin. This compound skin was cultured in vitro,then transplanted to repair the athymic mouse full-thickness wound, at last biopsied to be observed for its structure and vascularization. Results The EPC and fibroblasts could evenly distribute the dermal scaffold, while attaching to the PGA and stretching into the spindle or multiangular shape gradually, then there were large amounts of them growing in the compound skin. After athymic mice transplanting,histo-logical analysis revealed that EPC participated in neovascularization and the dermal substitute was completely degraded within 5 weeks. Conclusion EPC may contribute to angiogenesis and promote ischemic tissue vascularization. PGA combined with fibrinogen seeding EPC and bibroblasts.as dermal substitute, has good biological compatibility and biodegradable characteristics.