Effect Of Bone Formation Of Vertebral Body In Ovariectomized Rat By HBMP-7 Gene Induced By Adenovirus

Objective: To study the effect of bone formation of vertebral body in ovariectomized rat by hBMP-7 gene Induced by adenovirus. Background: Morphogenetic protein (BMP)-7, a member of the BMP family, plays an important role hi the onset of endochondral bone formation in humans, and a reduction in BMP-7 expression has been associated with a variety of bone diseases. Osteoporosis is a common problem of aging and results from a failure of homeostatic, it can cause dangerous of old woman's fracture, increase morbidity and mortality of old women. Current treatment on this disease included drug therapy such as bisphosphonates, calcitonin, estrogen and related compounds, vitamin D analogues, statins and complication treatment such as vertebralplasty . However, drug therapy has lots of side effects, and vertebraplasty is difficult to operate, furthermore, likely to cause operation complication. Therefore, it would be desirable to have a satisfactory and relatively safety treatment to osteoporosis. Bone morphogenetic protein gene therapy has currently being developed to promote osteogersesis for clinical indications such as spinal fusions, craniofkcial bone loss, and other osteapenia diseases. According to this, we used BMP-7 gene therapy in local osteoporotic vertebral body to observe bone formation of the osteoporotic vertebral bodies, which we called biovertebralpasty. Methods: in this study, the full-length hBMP-7 cDNA, including secretion signal peptide coding region was recloned into adenovirus transfer vector. The AdBMP-7 gene was then transfected into 293 cells for amplification, in vitro we assessed the secretion activity of these cells quantitatively by western blot. Furthermore, the secreted products of Ad-BMP-7 were injected into vertebral body in ovariectomized rat (3 month after ovariectomy). At 7day after surgery, rats were sacrificed and the marrow cavities of the vertebral bodies were rinsed, the solution was tested by fluorescence microscope. At 30 days after surgery the rats were killed and the vertebral bodies were excised, histology and histomorphometry of the vertebral body was performed using a confocal laser scanning microscope and animage analyzer. The sampling site was divided into two regions for analysis: (1) a "sub-endplate region," formed by the region connected to endplate; and (2) a "central region," formed by the region beneath the former. The changes in these two regions were analyzed separately. Results: by bistological observation, compared with sham injected vertebral bodies and control vertebral bodies, the trabecular of vertebral bodies injected with Ad-BMP-7 were aligned more density at 1 month after operation (1 month after injected). At histomorphometric level, in the sub-endplate region and central region, the vertebral bodies' section injected with adenovirus-BMP-7 of ovariectomized rat compared with sham injected vertebral bodies and control, The mean trabecular thickness, the fraction of labeled osteoid surfece, the number of the osteoblast, the bone volume, and the fraction of labeled trabecular surface increased significantly 1 month after injection of the Ad-BMP-7 in the sub-endplate region, the difference in statistics is significant. Conclusions: This study show: 1) Ovariectomized rat is a successful animal model of postmenopausal osteoporosis. 2) The rBMP-7 recloned into adenovirus transfer vector, and transfected into 293 cells may express active rBMP-7. 3) Osteoblastic differentiation is an essential part of bone formation that compensates resorbed bone matrix to maintain its structural integrity, these Ad-BMP-7 injected into vertebral bodies of ovariectomized rats may induce bone formation of vertebral bodies in osteoporosis. 4) This bio-vertebralpiasty is a potential method to treat osteoporosis of postmenopausal.