OBJECTIVETo investigate the effect of modified bone morphogenetic protein-2 polylactic acid nanospheres (BMP-2-PLA-Ns) sustained-release system on rabbit mandibular defect repair.

METHODSThe polylactic acid s nanospheres (PLA-Ns) and BMP-2-PLA-Ns were prepared by ultrasonic emulsification after graft polymerization. Forty-five rabbits were randomly divided into 3 groups: Blank group, PLA-Ns gel group(control group), and BMP-2-PLA-Ns gel group (experimental group). The rabbit mandibular defect models were established. The defect area of control group was implanted with PLA-Ns gel, meanwhile, the experimental group was implanted with BMP-2-PLA-Ns gel, the blank group experienced no special handling. Rabbits were killed in 1, 2, 4 weeks after operation and the iconography, hematine eosin(HE) staining and PCNA immunohistochemistry were used to detect the reparative effect on rabbit mandible defects.

RESULTSImage observation showed that bone defect repair in the experimental group was well and the shadow was not obvious. Better repair effect was seen compared with the control group and blank group. HE staining showed that the experimental group and the control group had a large number of neovascularization and secondary callus formation, callus in experimental group was obviously higher than that of control group and blank group. Immunohistochemical observation showed that the experimental group's PCNA positive chondrocytes were more than those in the control group and the blank group in the first 2 weeks; all groups of PCNA positive cells were rare in the fourth week, PCNA positive expression rate of the fourth week was lower than that of the first 2 weeks.

CONCLUSIONThe modified BMP-2-PLA-Ns sustained-release system promotes mandibular defect repair obviously.