目的：探讨新型成骨诱导生长因子骨形态发生蛋白2/7异二聚体（bone morphogenetic protein 2/7 heterodimer，BMP-2/7）在诱导人脂肪间充质干细胞（human adipose-derived stem cells，hASCs）成骨分化中的作用。方法：体外培养hASCs，以成骨诱导培养基（osteogenic medium，OM）中添加150 μg/L BMP-2/7为实验组，以单纯OM为阳性对照组（OM组）， 以常规增殖培养基（proliferation medium，PM）为阴性对照组（PM组）。体外诱导的第1、4和7天检测细胞DNA含量，第7和14天进行碱性磷酸酶（alkaline phosphatase，ALP）染色及定量检测，第21和28天进行茜素红染色及定量检测，第1、4、7和14天分别进行成骨相关基因的检测。体内实验使用6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）单纯β磷酸三钙（β-tricalcium phosphate，β-TCP）支架（支架对照组）；（2）β-TCP支架+hASCs（体外PM培养1周）（增殖细胞对照组）；（3）β-TCP支架+hASCs（体外OM培养1周）（诱导细胞对照组）；（4）β-TCP支架+hASCs（体外OM+150 μg/L BMP-2/7培养1周）（实验组）。植入后4周进行取材，标本制成组织学切片，进行HE和Masson三色染色分析。结果：体外诱导后第1天，实验组细胞DNA含量与PM组差异没有统计学意义（P>0.05），第4天时实验组细胞DNA含量较PM组升高（P<0.05），第7天时组间DNA含量没有明显差异（P>0.05）。诱导7天和14天后，实验组的ALP染色及定量检测均高于OM组和PM组（P<0.05）；第21和28天矿化结节染色及钙沉积定量检测均高于OM和PM组（P<0.05）。诱导第1天时实验组的成骨相关基因（Runx2、ALP、COL-1A1）的表达量即高于PM组 (P<0.05)，诱导第4天时骨钙素（osteocalcin，OC）基因表达量即开始升高，第4、7和14天的基因表达量较OM和PM组显著升高（P<0.05）。HE染色分析可见实验组和诱导细胞对照组的hASCs能分泌出嗜酸性较强的均质细胞外基质，出现了强嗜酸性的类骨组织；与诱导细胞对照组相比，实验组的细胞外基质嗜酸性更强，类骨组织的面积更大，结构更加典型；其他两对照组均未见矿化基质和类骨组织生成。Masson三色染色分析可见实验组呈强阳性表现，细胞基质中充满绿染的胶原；诱导细胞对照组和增殖细胞对照组的细胞基质中有不同程度的阳性表现，但较之实验组，胶原的数量明显减少；单纯支架组未见胶原的表达。结论：BMP-2/7在hASCs的成骨分化过程中发挥了重要作用，能够有效促进hASCs的体外和体内成骨分化。

Objective：To investigate the role of bone morphogenetic protein 2/7 heterodimer (BMP-2/7) in the osteogenesis of human adipose-derined stem cells (hASCs). Methods: hASCs were exposed to three different treatments in vitro: osteogenic medium with 150 μg/L BMP-2/7 (experimental group), osteogenic medium alone (OM group) and proliferation medium (PM group). After 1, 4 and 7 days of osteogenic induction, the amount of cellular DNA was measured to investigate the cytotoxicity. After 7 and 14 days, alkaline phosphatase (ALP) staining and quantification were performed to test the activity of ALP. After 21 and 28 days, the calcification deposition was determined by Alizarin Red S (ARS) staining and quantification. The expressions of the osteoblast-related genes were tested on days 1, 4, 7 and 14. In the in vivo study, 6 nude mice were used and 4 groups were set and implanted subcutaneously into the back of nude mice: (1) β-TCP scaffold only (scaffold control group); (2) β-TCP scaffold with hASCs cultured by PM in vitro for 1 week (PM control group); (3) β-TCP scaffold with hASCs cultured by OM in vitro for 1 week (OM control group); (4) β-TCP scaffold with hASCs cultured by OM with 150 μg/L BMP-2/7 in vitro for 1 week (test group). After 4 weeks of implantation, histological staining was performed to evaluate the in vivo osteogenesis of hASCs. Results: After induction for 1 day, there was no significant difference between the experimental group and the PM group on the cellular DNA content (P>0.05). After 4 days, the cellular DNA content increased under the stimulation of BMP-2/7 (P<0.05). On day 7, there was no significant difference among the three groups (P>0.05). ALP activity was higher by the induction of BMP-2/7 than in OM alone and PM (P<0.05). More mineralization deposition and more expressions of osteoblast-related genes such as Runx2, ALP, COL-1A1 and OC were determined in the experimental group at different time points (P<0.05). HE staining showed that, in the test group and OM control group, the extracellular matrix (ECM) with eosinophilic staining were observed around hASCs, and newly-formed bone-like tissues could be found in ECM around the scaffold materials. Moreover, compared with the OM control group, more bone-like tissues could be observed in ECM with typical structure of bone tissue in the test group. Masson’s trichrome staining showed that more expression of collagen could be observed in ECM in the test group compared with the other groups. There was small amount of expression of collagen in the OM and PM control groups. No obvious positive results were found in the scaffold group. Conclusion: BMP-2/7 heterodimer plays a significant role in the osteogenesis of hASCs and is able to enhance the osteogenic differentiation of hASCs in vitro and in vivo.