ANGIONEOGENESIS AROUND INDUCED BONE WITH RECOMBINANT HUMAN BMP-2 IN A LATISSIMUS DORSI MUSCLE FLAP

Bony tissue induced with recombinant human bone morphogenetic protein-2 (rhBMP-2) in the latissimus dorsi muscle flap (LDMF) of rats was investigated in angiography and histological examination. In five rats, rhBMP-2 with atelopeptide type I collagen (CL) as a carrier was implanted in the muscle pocket of LDMF. In five controls, only CL was implanted in the same manner. Three weeks after the implant, contrast medium was injected into the assending aorta. The LDMF was cut off at the base and exposed in soft X-ray. The implant and the surrounding tissue were then histologically examined. In the rhBMP-2-implant group, the vascularity was richer, especially around the implant, and radiated to the induced bony tissue. Contrast medium was observed in the vascular cavities of the marrow inside the trabeculae. In the controls, the vascularity was relatively poor and the remnant CL occupied the whole implant space. This study indicated that rhBMP-2 does not only induce trabeculae in muscle tissue, but also in the marrow, including vessels in the implant and the vascular system around the implant. Then, the induced bony tissue is supported in the circulation by the circulation by the vascular system, as a functional osseous tissue. This phenomenon may be highly beneficial in endogenous tissue engineering and regenerative medicene for skeletal reconstruction using BMP in the future.