The effect of carrier for BMP-2 delivery on histological aspects of tissue-engineered bone

Bone morphogenetic protein-2 (BMP-2) that can regenerate bone by recruiting osteo-progenitor cells and inducing osteogenic differentiation has been highlighted as an alternative therapy to treat bone defects. The therapeutic effect of BMP-2 depends considerably on the delivery carriers. Previous studies demonstrated that collagen and fibrin have the potential to serve as a carrier for delivery of BMP-2. The successful bone regeneration by collagen and fibrin with BMP-2 implantation has been shown in animal models. However, those studies were not focused on the effect of the carriers on the quality of the regenerated bone. In this study, we directly compared the quality of regenerated bone when BMP-2 was delivered with collagen or fibrin, both of which are shown to be excellent carrier for BMP-2. The microstructure, surface morphology, BMP-2 release profile was examined in vitro. To evaluate the quality of regenerated bone, both types of BMP-2 carriers were implanted into the dorsal subcutaneous spaces of the mice. Four and six weeks after implantation, the regenerated bone was evaluated by computed tomography, histology, and histomorphometric analysis. The bone regeneration by the collagen with BMP-2 was higher bone density than bone regenerated by the fibrin with BMP-2. The results of this study show that carrier of BMP-2 is an important factor affecting the quality of engineered bone.