聚乳酸-聚羟基乙酸/Ⅰ型胶原复合支架的生物相容性研究

BIOCOMPATIBILITY OF POLY-LACTIDE-CO-GLYCOLIDE/COLLAGEN TYPE Ⅰ SCAFFOLD WITH RAT VAGINAL EPITHELIAL CELLS

目的观察聚乳酸-聚羟基乙酸（poly-lactide-co-glycolide,PLGA）/Ⅰ型胶原复合支架的生物相容性,探讨其作为组织工程阴道支架的可行性。方法取经多聚赖氨酸包被的PLGA置于含0.25%Ⅰ型胶原的醋酸水溶液,制备PLGA/Ⅰ型胶原复合支架。取10～12周龄雌性SD大鼠阴道组织,采用酶消化法分离培养阴道上皮细胞,取第2代细胞进行实验。取复合支架浸提液培养阴道上皮细胞,观察材料细胞毒性。将阴道上皮细胞与复合支架共培养48 h（实验组）,检测细胞黏附率;以单纯PLGA支架接种细胞作为对照组。将细胞-支架复合物埋植至SD大鼠皮下,于2、4、8周取材行HE染色、免疫组织化学染色,观察细胞在支架上生长情况。将细胞-支架复合物移植至6只切除阴道组织的SD大鼠阴道部位,于术后3、6个月观察阴道生长情况,6个月后取阴道组织进行组织学观察。结果大鼠阴道上皮细胞在PLGA/Ⅰ型胶原复合支架材料浸提液中生长、增殖良好,细胞毒性为1级。实验组细胞黏附率为71.8%±9.2%,显著高于对照组的63.4%±5.7%（t=2.195,P=0.005）。阴道上皮细胞能在PLGA/Ⅰ胶原复合支架材料上黏附、生长;大鼠皮下埋植2周后,细胞在支架孔隙内生长增殖,成纤维细胞生长;4周支架材料表面形成1～3层上皮;8周后支架材料部分降解,上皮层次增加,呈极性排列,角蛋白免疫组织化学染色呈阳性。细胞-支架复合物原位移植3个月后,大鼠阴道黏膜呈粉红色,有光泽,支架材料大部分降解;6个月时阴道深约1.2 cm,无明显狭窄,阴道黏膜外观类似正常阴道黏膜,皱襞较少,组织学观察示上皮层与正常阴道无明显区别,基底层可见钉状突起,数量少于正常阴道,角蛋白免疫组织化学染色呈阳性。结论 PLGA/Ⅰ型胶原复合支架具有良好的生物相容性,可作为构建组织工程阴道的支架材料。

Objective To explore the biocompatibility of the poly-lactide-co-glycolide（PLGA）/collagen type I scaffold with rat vaginal epithelial cells, and the feasibility of using PLGA/collagen type I as scaffold to reconstruct vagina by the tissue engineering. Methods PLGA/collagen type I scaffold was prepared with PLGA covered polylysine and collagen type I. The vaginal epithelial cells of Sprague Dawley rat of 10-12 weeks old were cultured by enzyme digestion method. The vaginal epithelial cells of passage 2 were cultured in the leaching liquor of scaffold for 48 hours to detect its cytotoxicity by MTT. The vaginal epithelial cells were inoculated on the PLGA/collagen type I scaffold（experimental group） and PLGA scaffold（control group） to calculate the cell adhesion rate. Epithelial cells-scaffold complexes were implanted subcutaneously on the rat back. At 2, 4, and 8 weeks after implantation, the epithelial cells-scaffold complexes were harvested to observe the cell growth by HE staining and immunohistochemical analysis. The epithelial cells-scaffold complexes were transplanted to reconstruct vagina in 6 rats with vaginal defect. After 3 and 6 months, the vaginal length was measured and the appearance was observed. The neovagina tissues were harvested for histological evaluation after 6 months. Results The epithelial cells grew and proliferated well in the leaching liquor of PLGA/collagen type I scaffold, and the cytotoxicity was at grade 1. The cell adhesion rate on the PLGA/collagen type I scaffold was 71.8%±9.2%, which significantly higher than that on the PLGA scaffold（63.4%±5.7%）（t=2.195, P=0.005）. The epithelial cells could grow and adhere to the PLGA/collagen type I scaffolds. At 2 weeks after implanted subcutaneously, the epithelial cells grew and proliferated in the pores of scaffolds, and the fibroblasts were observed. At 4 weeks, 1-3 layers epithelium formed on the surface of scaffold. At 8 weeks, the epithelial cells increased and arranged regularly, which formed the membrane-like layer on the scaffold. The keratin expression of the epithelium was positive. At 3 months after transplantation in situ, the vaginal mucosa showed pink and lustrous epithelialization, and the majority of scaffold degraded. After 6 months, the neovagina length was 1.2 cm, without obvious stenosis; the vaginal mucosa had similar appearance and epithelial layer to normal vagina, but it had less duplicature; there were nail-like processes in the basal layer, but the number was less than that of normal vagina. The immunohistochemistry staining for keratin was positive. Conclusion The PLGA/collagen type I scaffolds have good cytocompatibility with the epithelial cells, and can be used as the biodegradable polymer scaffold of the vaginal tissue engineering.