A preliminary study of the expression of bone morphogenetic protein 9 and epidermal growth factor receptor in the nonunion microenvironment

Abstract:

Objective：To investigate the expression of bone morphogenetic protein 9（BMP9） and epidermal growth factor receptor （EGFR） and the number of osteoblasts and osteoclasts in local tissues in the nonunion microenvironment，and to provide a basis for the etiology and treatment of nonunion. Methods：Twelve 3-month-old healthy New Zealand white rabbits were selected as exper－imental group to develop an animal model of nonunion and six healthy New Zealand white rabbits of the same age were selected as control group. X-ray examination was used to verify the success of modeling. Western blot and immunohistochemistry were used to determine the expression of BMP9 and EGFR in local tissues. Hematoxylin-eosin（HE） staining and tartrate-resistant acid phos－phatase（TRAP） staining were used to count osteoblasts and osteoclasts. Results：X-ray examination indicated that the animal model of nonunion was successfully developed. Western blot and immunohistochemistry showed that the expression of BMP9 and EGFR was significantly reduced from the early stage to the late stage of fracture healing；the expression of BMP9 in the nonunion microen－vironment was significantly lower than that of the control group，while the expression of EGFR was not significantly different from that of the control group. HE staining and TRAP staining showed that the number of osteoblasts was significantly reduced from the early stage to the late stage of fracture healing，and the decrease in osteoblasts in the nonunion microenvironment was greater than that in the control group；however，there was no significant difference in the number of osteoclasts between the experimental group and the control group in both early and late stages of fracture healing. Conclusion：The development of bone nonunion may be associ－ated with decreased expression of BMP9 and EGFR and number of osteoblasts in local tissues.