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A composite of recombinant human bone morphogenetic protein-2 (rhBMP-2) and collagen was implanted beneath the cranial periosteum of 10-month-old rats to observe bone development and absorbent change of carrier collagen. The rhBMP-2/collagen onlay implant resulted in active bone formation and the augmented bone was connected directly with the original bone, whereas the collagen alone resulted in neither bone nor cartilage. The ossification process in the rhBMP-2/collagen occurred directly through bone formation, similar to intramembranous ossification. The carrier collagen fibers were found in the woven bone and were completely absorbed at 8 weeks in the presence of rhBMP-2, while the collagen alone implant remained encapsulated by a thin, fibrous connective tissue. Our results indicate that rhBMP-2/collagen is an effective material as a biological onlay implant, showing osteoinductive properties and being completely replaced by new bone. Carrier collagen not only plays a role in rhBMP-2 delivery, but also provides a cell anchorage for cell differentiation and remains as an artificial matrix in woven bone.

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Concentrated growth factor (CGF) is 100% blood-derived, cross-linked fibrin glue with platelets and growth factors. Human CGF clot is transformed into membrane by a compression device, which has been widely used clinically. However, the mechanical properties of the CGF membranes have not been well characterized. The aims of this study were to measure the tensile strength of human CGF membrane and observe its behavior as a scaffold of BMP-2 in ectopic site over the skull. The tensile test of the full length was performed at the speed of 2mm/min. The CGF membrane (5 × 5 × 2 mm3) or the CGF/BMP-2 (1.0 μg) membrane was grafted onto the skull periosteum of nude mice (5-week-old, male), and harvested at 14 days after the graft. The appearance and size of the CGF membranes were almost same for 7 days by soaking at 4 °C in saline. The average values of the tensile strength at 0 day and 7 days were 0.24 MPa and 0.26 MPa, respectively. No significant differences of both the tensile strength and the elastic modulus were found among 0, 1, 3, and 7 days. Supra-periosteal bone induction was found at 14 days in the CGF/BMP-2, while the CGF alone did not induce bone. These results demonstrated that human CGF membrane could become a short-term, sticky fibrin scaffold for BMP-2, and might be preserved as auto-membranes for wound protection after the surgery.

No abstract