ABSTRACT
BACKGROUND:Bone marrow stem cels combined with traditional surgery regimen can significantly improve the therapeutic effects on bone nonunion, which are considered to have an important application value. OBJECTIVE:To explore therapeutic effect of bone marrow mesenchymal stem cels on bone nonunion under micro-damage environment. METHODS:Forty New Zealand white rabbits were selected and randomized into experimental and control groups, 20 rabbits in each group. Bone marrow of the tibia was extracted to isolate and culture bone marrow mesenchymal stem cels. Passage 3 cels with the order of magnitudes of 107 were labeled by superparamagnetic iron oxide nanoparticles. A 15-mm bone defect was made at the middle of the radius of the rabbit forelimb. Bone nonunion appeared at 6 weeks after bone defects. Bone marrow mesenchymal stem cels combined with iliac particles were implanted into the bone defect of rabbits in the experimental group, and only iliac particles were implanted into the bone defect of rabbits in the control group. Within 12 weeks after implantation, the bone nonunion was observed through gross morphology, X-ray observation, and pathological observation. RESULTS AND CONCLUSION:After implantation, a remarkable calus was found in the experimental group, and the bone defect recovered gradualy until it was completely healed; in the control group, there was no calus, and the bone marrow cavity was closed and ful of granulation tissues. In the experimental group, there were actively proliferated cartilage tissues, bone particles were fused, osteoid structures appeared, and osteoblasts proliferated progressively; in the control group, poor cartilage hyperplasia was found, and there were a large amount of dead bone tissues but no fused bone particles and osteoblasts. In the experimental group, X-ray films on the defected radium showed cloudiness-like shadow, the bone marrow cavity was recanalized, and the skeleton was shaped wel; in the control group, few bone particles were absorbed, the bone marrow cavity was partly recanalized, and the injured bone was not healed with osteosclerosis. These findings indicate that under the micro-damage environment, bone marrow mesenchymal stem cels can differentiate into osteoblasts to repair bone defects-induced bone nonunion.