Accelerated bony defect healing by chitosan/silica hybrid membrane with localized bone morphogenetic protein-2 delivery. 
Therapeutic agents such as growth factors have been widely applied to promote bone regeneration with implantable biomaterials.  In this study, a hybrid of chitosan-xerogel membrane was combined with bone morphogenetic protein-2 (BMP-2) for enhancing bone regeneration.  The characteristics of the hybrid membrane as a carrier of BMP-2 were compared with that of the pure chitosan membrane, and the effect of combining the hybrid membrane with BMP-2 on its bone healing ability was evaluated using in vitro and in vivo animal tests.  The amount of BMP-2 adsorbed on the pure chitosan membrane was less than that on the hybrid membrane and, therefore, the cellular behaviors of the pure chitosan membrane were only slightly improved by the protein treatment.  In contrast, the hybrid membrane showed excellent affinity toward BMP-2, and the adsorption of BMP-2 elicited a dramatic improvement in the cellular responses of the hybrid membrane.  Moreover, the in vivo study demonstrated that bone regeneration was significantly enhanced when using the hybrid membrane with BMP-2 as compared to the hybrid membrane without BMP-2.  These results suggest that the hybrid membrane is very efficient in carrying BMP-2 and accelerates the bone healing process through the successful delivery of BMP-2 and its osteoconductive composition.