BACKGROUND: The osteoinduction by biomaterials has been proven in various animal experiments. OBJECTIVE: To investigate the osteoinduction of porous calcium phosphate cement on bone marrow mesenchymal stem cel s. METHODS: Bone marrow mesenchymal stem cel s were isolated from rabbits aged 1 week in vitro and labeled by PKH-67 or PKH-26, respectively. Forty-eight adult New Zealand white rabbits were randomized into four groups and porous calcium phosphate cement was implanted into both sides of gluteus maximus in each rabbit. Then, 1 mL PKH-26-labeled bone barrow mesenchymal stem cel s (1×1010/L) were injected into the superior gluteal artery branch at each side of gluteus maximus near the femur, and 1 mL PKH-67-labeled bone barrow mesenchymal stem cel s (1×1010/L) injected into tissues around the cement (group A); 1 mL PKH-26-labeled bone barrow mesenchymal stem cel s (1×1010/L) were injected into the each side of superior gluteal artery branch (group B); 1 mL PKH-67-labeled bone barrow mesenchymal stem cel s (1×1010/L) were injected into tissues around the cement (group C); the same amount of normal saline was injected into tissues around the cement (group D). At 3, 7 and 12 weeks after implantation, the cement and its surrounding tissues were extracted and detected by fluorescence microscope and Massion staining. Expression of bone morphogenetic protein 2 was analyzed by RT-PCR. RESULTS AND CONCLUSION: Under fluorescence microscope, PKH-26-labeled bone barrow mesenchymal stem cel s attached fast and distributed homogeneously; however, PKH-67-labeled bone barrow mesenchymal stem cel s attached slowly and exhibited a gradual y homogeneous distribution. Massion staining showed that ectopic new bone formation appeared to have an upward trend in al groups, and the area of new bones in groups A, B and C were larger than that of group D at different time points after implantation. There was a significantly higher expression of bone morphogenetic protein 2 in groups A, B and C compared with the group D at different time points after implantation (P < 0.05), and the expression was the highest in the group A (P < 0.05). In conclusion, the porous calcium phosphate cement can induce bone barrow mesenchymal stem cel s chemotaxis and osteogenetic differentiation. Besides, osteoblasts are differentiated from both the surrounding capil aries and body fluid, and capil ary-derived mesenchymal stem cel s occupy the important position.%背景：生物材料的骨诱导现象已在多种动物实验中被证实。目的：探讨骨髓间充质干细胞对多孔磷酸钙人工骨的骨诱导作用。方法：体外分离培养1周龄兔骨髓间充质干细胞，分别以 PKH-67或 PKH-26荧光标记。将48只成年新西兰大白兔随机分为4组，均在两侧臀大肌内置入多孔磷酸钙人工骨，A 组在每侧臀大肌靠近股骨侧臀上动脉分支顺行注入1 mL PKH-26标记的骨髓间充质干细胞，在每侧材料周围注入1 mL PKH-67标记的骨髓间充质干细胞；B 组在每侧臀上动脉分支注入1 mL PKH-26标记的骨髓间充质干细胞；C 组在每侧材料周围注入1 mL PKH-67标记的骨髓间充质干细胞；D 组在每侧材料周围注射同体积生理盐水。置入后3，7，12周取材料及其周围组织，行荧光显微镜观察、骨形态发生蛋白2基因量检测和 Masson 组织学染色。结果与结论：①荧光显微镜观察：PKH-26标记的骨髓间充质干细胞趋化速度快，荧光分布均匀；PKH-67标记的骨髓间充质干细胞趋化速度慢，荧光逐步分布均匀；②Masson 组织学染色观察：4组出现新生类骨质并逐步增多，A 组、B 组、C 组不同时间点的新生类骨质面积大于 D 组；③骨形态发生蛋白2基因量检测：A 组、B 组、C 组不同时间点的基因量多于 D 组(P <0.05)，A 组、不同时间点的基因量多于 B 组、C 组(P <0.05)；④结果表明：多孔磷酸钙人工骨可诱导微环境中骨髓间充质干细胞向材料趋化并增殖分化为成骨细胞，进而形成新生骨；周围毛细血管及体液中的间充质干细胞均是成骨源细胞来源，但毛细血管来源间充质干细胞在其中起主要作用。
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