Experimental Study On The Osteoinductive Chang In Bone Of Ovarictomized Rat

Objective To study the cause of healing difficulty in osteoporotic fracture, and to explore feasible approach and method for clinical treatment of osteoporotic fracture.Methods Donor animals Forty female SD (Sprague-Dawley) rats, as donor animals, were divided into two groups, the ovariectomized group and the control group at random , each with 20 rats. The ovariectomized group were subjected to bilateral ovariectomy in order to set up osteoporosis model, and the control group were subjected to sham operation. Four months after surgery, the rats were killed, and long bones of extremities were taken out for determination of bone mineral content(BMC) and preparation of bone matrix gelatin(BMG).Preparation of BMG implants The periosteum and bone marrows were removed from the bones harvested from ovariectomized and normal rats, then the bones were treated for preparation of BMG implants respectively in terms of Urist's method. (3) Implantation in vivo Seventeen female SD rats, as host animals, were subjected to bilateral femurs incision. BMG implants obtained from previously ovariectomized and sham-operated on rats were implanted in left and right femoral muscle pouches of each animal respectively. The host rats were killed after 14 days, and the tissue masses of implants were taken out for assay of alkaline phosphatase(ALP) activity, calcium content and histologic study respectively.Results (D Four months after the operation, the BMD determinated from ovariectomized group was 0.1426+0.0297g/cm2, and 0.1808+0.047g/cm2 from control group. There was significant difference between the two groups(p<0.01). It demonstrated that the model of animal osteoporosis was established successfully.Two weeks after implantation of BMG, ALP activity in tissue masses of BMG implants from ovariectomized group was 7.2236+2.5945IU/g, and 12.0121+ 6.1782IU/g from control group. Significant difference was found between the two groups also (p<0.01). Furthermore, the calcium content from ovariectomized group and from control group were 224.3641+195.9690^g/g and 422.1159+ 386.1820ug/g respectively. There was significant difference between the two groups(p<0.05). (3)Histologic observation showed that there were much larger cartilaginous islands formation around the BMG implants from control group, whereas there were scanty cartilaginous tissue formation from ovariectomized group.Conclusion The osteoinductive potential of osteoporotic bone is decreased apparently in comparison with normal conditions. This implies that the absence or deficiency of bone growth factors in osteoporosis are related to the fact that fracture healing in osteoporosis is difficulty, and further suggests that it maybe an effectual method of treating osteoporotic fracture to enhance bone induction by means of supplement of exogenous bone growth factors or promotion of expression of endogenous bone growth factors.