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目的:观察成骨分化后的去分化骨髓间质干细胞（differentiation osteogenic bone marrow mesenchymal stem cells，De-BMSCs）移植对前十字韧带（anterior cruciate ligament，ACL）重建术后腱骨界面骨形成的促进作用，并探索De-BMSCs成骨分化效应增强的分子机制。方法:从家兔胫骨和股骨中提取BMSCs，经成骨诱导分化后用普通培养基进行去分化培养制备De-BMSCs，鉴定De-BMSCs的干细胞特性。建立家兔ACL重建模型，分为3组：腱骨界面注射海藻酸钠凝胶（对照组）；腱骨界面注射复合BMSCs海藻酸钠凝胶（BMSCs组）；腱骨界面注射复合De-BMSCs海藻酸钠凝胶（De-BMSCs组）。术后4周和12周取膝关节标本，进行组织学、影像学、生物力学检测，评估腱骨界面骨形成情况。De-BMSCs体外成骨诱导分化，给予活化T细胞核转录因子1（nuclear factor of activated T cells 1，NFATc1）RNA干扰处理，检测成骨分化标志基因及Nanog/NFATc1/Osterix信号通路的表达，明确De-BMSCs成骨分化效应增强的分子机制。结果:De-BMSCs可向成骨、成脂、成软骨分化，具有干细胞特性（均n P<0.05）。术后4周De-BMSCs组BV/TV值为0.36±0.01，较对照组0.24±0.03和BMSCs组0.30±0.02明显增加（n P<0.05），最大负荷（40.34±1.19）N和刚度（20.67±2.14）N/mm较对照组[（14.88±2.74）N，（8.67±2.19）N/mm]和BMSCs组[（26.31±1.76）N，（13.81±2.14）N/mm]明显升高（均n P<0.05）；术后12周De-BMSCs组BV/TV值0.47±0.02较对照组0.30 ± 0.02和BMSCs组0.35 ± 0.03明显增加（均n P<0.05），最大负荷（64.46±6.69）N和刚度（25.18±3.11）N/mm较对照组[（41.01±6.12）N，（11.59±2.54）N/mm]和BMSCs组[（48.21±4.12）N，（15.89±2.94）N/mm]明显升高（均n P<0.05）；De-BMSCs成骨分化过程中，Nanog的表达增加（n P<0.05），NFATc1的表达上升且其与Osterix的相互作用增强（n P<0.05），成骨分化标志基因COL1A、OCN、OPN的表达增加（均n P<0.05）。n 结论:De-BMSCs移植可促进ACL重建后的腱骨界面骨形成，其作用机制可能是Nanog/NFATc1/Osterix信号通路介导了De-BMSCs成骨分化效应增强。“,”Objective:This study aimed to investigate the effect of differentiation osteogenic bone marrow mesenchymal stem cells (De-BMSCs) transplantation on the promotion of bone formation at the tendon-bone interface after anterior cruciate ligament reconstruction (ACLR), and further explored the molecular mechanism of the enhanced osteogenic effect of De-BMSCs.Methods:BMSCs from femur and tibia of New Zealand White rabbit were subjected to osteogenic induction and then cultured in no osteogenic factor medium; the obtained cell population was termed De-BMSCs. De-BMSCs were induced into osteo-, chondro-and adipo-differentiation in vitro to examine the characteristics of primitive stem cells. ACLR model with a semitendinosus tendon were performed in 48 adult rabbits, three groups were established: control group with alginate gel injectionat the tendon-bone interface, BMSCs group with the injection of alginate gel containing BMSCs, De-BMSCs group with the injection of alginate gel containing De-BMSCs. At 4 and 12 weeks after surgery, rabbits in each group were sacrificed to evaluate tendon-bone healing by histologic staining, micro-CT examination, and biomechanical test. During osteogenic differentiation of De-BMSCs, si-RNA of nuclear factor of activated T cells 2 (NFATc2) si-RNA of nuclear factor of activated T cells 1 (NFATc1) were used to verify the molecular mechanism of enhanced osteogenic effect of De-BMSCs.Results:De-BMSCs exhibited some properties similar to BMSCs including multiple differentiation potential and cell surface marker. At 4 weeks after surgery, the BV/TV value of the De-BMSCs group 0.36±0.01 was significantly higher than that of the control group 0.24±0.03 and BMSCs group 0.30±0.02 (all n P<0.05), and the maximum load 40.34±1.19 N and stiffness 20.67±2.14 N/mm were significantly higher than those in the control group 14.88±2.74N, 8.67±2.19 N/mm and the BMSCs group 26.31±1.76 N, 13.81±2.14 N/mm (alln P<0.05). At 12 weeks after surgery, the BV/TV value of the De-BMSCs transplantation group 0.47±0.02 was significantly higher than that of the control group 0.30±0.02 and the BMSCs group 0.35±0.03 (alln P<0.05), and the maximum load 64.46±6.69 N and stiffness 25.18±3.11 N/mm were significantly higher than those in the control group 41.01±6.12 N, 11.59±2.54 N/mm and the BMSCs group 48.21±4.12 N, 15.89±2.94 N/mm (alln P<0.05). During the osteogenic differentiation of De-BMSCs, the expressions of Nanog and NFATc1 were synergistically increased which promoted interaction of NFATc1 and Osterix (n P< 0.05), resulting in the increased expression of osteoblast marker genessuch as COL1A, OCN, OPN (alln P< 0.05).n Conclusion:De-BMSCs transplantation could promote bone formation at the tendon-bone interface after ACLR,Nanog/NFATc1/Osterix signaling pathway mediated the enhancement of the osteogenic differentiation effect of De-BMSCs.