RhBMP-2-Induced Osteogenesis Research Of The Sustained-release System Of /Center Porous Allogeneic Bone

Aim: Serious skeletal defects result from diverse carses including trauma, birth defects, oncologic resections, and disease pathoses which have been more emergent.The recombinant human Bone morphogengtic protein has been isolated, identified, cloned, and expressed by Wany et al, and rhBMP can induce bone when it was implanted with a certain carrier into ectopic eissues such as skin or mscle and the rhBMP-2-induced osteo- and chondrogenesis is highly dependent upon the carrier. Thus scientists have developed and tested more than ten different carriers to impoving the BMP-induced bone formation.In this experiment, we design the center porous allogeneic bone as the carrier, additionally, we add the mixture of the rhBMP-2 with collagen and gelatin into the center hole to compare which one is better.Material and Method: (1) The allogeneic bone is made to cylinder as diameter 8mm, length 5mm, and the half of them is drilled to center hole as diameter 3mm. There are three group: center porous allogeneic bone / gelatin / collagen/ rhBMP-2 (PGB) , solid allogeneic bone / gelatin / collagen/ rhBMP-2 (SGB) , center porous allogeneic bone/ rhBMP-2 (PB), and the allogeneic bone is as the control group.(2)In the vitro bioassay for PGB and SGB, conditioned medium(l Ml per interval) was collected at 1 hour, 1 day, 2 days, 3 days, 6 days and 9 days after immerged the PGB and SGB. respectively. The ALP activity is checked to compare the release of rhBMP-2.(3)In the vivo, 15 rats were implanted the PGB, PB and SGB respectively. Animals were examined 2weeks, 4 weeks, Sweeks after implantation by radiography, histology and ALP.Results: In the vitro, ALP of the PGB and SGB both greatly increasedIn X-ray, PGB were observed the large high density shadow in the outside and the edge is not clear in the center hole, PB can be seen some same, hi contrast, SGB only were observed some high density shadow in the outside and no big change in the center at 2 weeks. The same thing can been observed at 4 weeks. At 8 weeks, PGB were observed the lower density compared 4 weeks, SGB were observed a little high density shadow in the outside, PB were observed paint high density at the center.In histology, for PGB, the regeneration of bone is active, a number of mesenchymal cel were observed, and the capillaries invaded the center pore at 8 weeks, on contrast, SGB only were seen fewer bone formation and no capillaries invaded.ALP activity at 4 weeks PGB, SGB and PB all increase compared with the control, and the significant differences were observed with PGB, SGB, PB and the CONs (P<0.05) , additionally, PGB increase to highest, and the significant differences also were observed with PGB and PB, PGB and SGB.Conclusion:1. The center pore benefit for bone formation. PGB's bone formation is more as same rhBMP-2 dose compared SGB's.2. The collagen and gelatin benefit the bone formation, the bone formantion is more as same frame carrier when collagen and gelatin are added.