Effects of Immobilized rhBMP-2/atelocollagen in vivo and in vitro

The use of recombinant human bone morphogenetic protein - 2 (rhBMP-2) to induce ectopic bone formation requires a carrier. Atelocollagen, a biomaterial with a porous structure, excellent operational features and biocompatibility, is known to be an effective carrier for rhBMP-2. However, conventionally used lyophilized rhBMP-2/atelocollagen mixture does not necessarily give adequate bone induction effect. In the present study, we evaluated the effect of immobilizing rhBMP-2 to succinylated type I atelocollagen on the cellular activity of ST2 cells and immobilized rhBMP-2/ atelocollagen and non immobilized rhBMP-2/atelocollagen implanted in subcutaneous pockets of Wister rats. Our results revealed that 1) Alkaline phosphatase activity confirmed the effectiveness of rhBMP-2/ succinylated type I atelocollagen immobilization in augmenting cellular activity. 2) Intracellular signaling continued for prolonged period when rhBMP-2 was immobilized to succinylated type I atelocollagen. 3) In rhBMP-2/atelocollagen implants were completely fully with new bone formation and cell proliferation. Whereas, in non immobilized rhBMP-2/atelocollagen implants showed new hard tissue in the periphery of the carrier with only collagen membrane in its center. This study indicated that immobilizing rhBMP-2 is an efficient method to increase bone induction.