目的:探索以人脂肪基质细胞(human adipose-derived stromal cells,hASCs)为基础的组织工程骨在体内成骨过程中hASCs发挥的作用,为深入研究其体内成骨机制奠定基础。方法:酶消化法分离原代hASCs,进行传代培养。体内实验使用16只裸鼠,于其背部正中做皮肤切口,向两侧分离出4个皮下植入腔,分别植入:(1)空白;(2)单纯β-磷酸三钙(β-tricalcium phosphate,β-TCP)支架(支架对照组);(3)β-TCP支架+人成纤维细胞(阴性细胞对照组);(4)β-TCP支架+hASCs(实验组)。植入后1周、2周、4周、6周进行取材,每时间点取4只裸鼠,其中2只裸鼠的标本经处理后进行扫描电镜(scanning electron microscope,SEM)观察,另外2只裸鼠的标本制成组织学切片,进行HE染色分析。结果:SEM观察可见实验组植入2周后,hASCs周围即出现大量细胞外基质,至4周时细胞外基质开始出现明显的矿化,6周时可见矿化基质进一步增多。HE染色分析可见实验组植入2周后hASCs即开始分泌嗜酸性较强的均质细胞外基质,至4周时细胞外基质中出现了强嗜酸性的类骨组织,6周时新生类骨组织面积明显增大,结构更加典型。在其他组均未见矿化基质和类骨组织生成。结论:人脂肪基质细胞在体内成骨过程中发挥了关键的作用,包括分泌大量细胞外基质,促进细胞外基质矿化和引导新生类骨组织形成。
Objective:To explore the effect of human adipose-derived stromal cells(hASCs) on the osteogenesis during the process of bone formation in vivo,and to lay the foundation of further investigations on the mechanism of in vivo osteogenesis of hASCs.Methods:hASCs were isolated from adipose tissue by the method of collagenase digestion,and were routinely proliferated and passaged.In the in vivo study 16 nude mice were used and 4 groups were set and implanted subcutaneously into the back of nude mice:(1) blank;(2) β-tricalcium phosphate(β-TCP) scaffold only(scaffold control group);(3) β-TCP scaffold with human fibroblasts(negative cell control group);(4) β-TCP scaffold with hASCs(test group).After 1 week,2 weeks,4 weeks and 6 weeks of implantation,samples from the 4 nude mice were collected at each time point.Scanning electron microscope(SEM) observation and histological staining were performed to evaluate the in vivo osteogenesis of hASCs.Results:SEM images showed that large amount of extracellular matrix(ECM) could be observed around hASCs in test group after 2 weeks of implantation.At the time point of 4 weeks,mineral deposit was found in ECM.At the time point of 6 weeks,the mineral deposit was observed to increase significantly.HE staining showed that the ECM with eosinophilic staining could be observed around hASCs after 2 weeks of implantation.At the time point of 4 weeks,newly-formed bone-like tissue could be found in ECM around the scaffold materials.At the time point of 6 weeks,more bone-like tissues were observed in ECM with typical structure of bone tissue.In comparison,no obvious mineralization and bone-like tissue were found in other groups.Conclusion:hASCs play important roles in the process of osteogenesis in vivo,including secretion of large amount of ECM,acceleration of the mineralization of ECM and guidance for the formation of bone-like tissues.