Experimental Studies On HA/TCP With RhBMP-2 For Bone Defect Repair In Osteoporotic Rats

The research has done by 3 serial experiments.1.The effect of experimental osteoporosis on bone defect physio-healing in rats.Base on the model of osteoporosis was established,cylindrical defect which diameter is 3.0mm and depth is the co-width of cortical bone and cavitas medullaris were performed on both condyles of femur and non graft.To investigate whether osteoporosis influences the physio-healing of bone defect.The defect can not healing completely in 12^thweek after operation.Meanwhile, especially in the 4^thweek,the healing of defect can be delayed by osteoporosis,degrade the quality of neoformative bone tissue.2.Experimental studies on HA/TCP diphase bioceramic for bone defect repair in osteoporotic rats.Base on the model of osteoporotic defects was established,then HA/TCP bioceramic were been implanted in the defect site.The effect of bone defect healing was evaluated in the 4^th,8^thand 12^thweek postoperatively by radiograph,bone mineral density (BMD),histomorphology,transmission electron microscope(TEM)and vitodynamics,and to compare with normal rats.Osteoporosis delayed degradation of the material,especially in the 4^th week,neoformative bone tissue decreased obviously in experimental group.But the X-ray gray scale,BMD and ultimate stress of defect site in experimental group were non difference obviously compared to control group.In 12^thweek the function of osteoblast in bone callus was degraded,but osteoclast was active.Immuhistochemistry analysis showed the expression of BMP-2 declined and delayed significantly in osteoporotic rats.It indicated that BMP-2 plays an important roles in bone regeneration.3.Experimental studies on HA/TCP with rhBMP-2 for bone defect repair in osteoporotic rats.rhBMP-2 growth factor were compounded with HA/TCP in vitro,then implanted in the defect site described in first part.At 4^th,8^thand 12^thweek after implantation,histomorphometric analysis revealed that HA/TCP compounded with rhBMP-2 has a quicker degradation.The X-ray gray scale,BMD and ultimate stress of defect site were all significantly increase in experimental BMP/HA-TCP group,and close to the control BMP/HA-TCP group.In this paper,base on the model of osteoporosis was successfully established,investigate osteoporosis delays the physio-healing of bone defect in rats,discover simple HA/TCP can better healing the defects on certain degree.But osteoporosis delayed degradation of the material and healing of the defect.Meanwhile,rhBMP-2 growth factor were compounded with HA/TCP in vitro and implanted in the defect to speed up the degradation of the material,to promote the healing of the defect in osteoporotic rats.This indicate HA/TCP with rhBMP-2 growth factor may allow for successful treatment of large bone defects in osteoporotic patients.