Carrier systems for bone morphogenetic proteins

Bone deficits can regenerate inherently, although when the amount of bone l oss exceeds a critical limit, pseudarthrosis and fibrosis occur. Therapeuti c intervention either with an autograft or allogeneic bank bone are traditi onal options to promote regeneration to overcome critical limits. However, liabilities with traditional treatments have inspired investigators to deve lop alternatives, such as combinations of biomimetic scaffolds and osteogen ic regulatory molecules. The class of osteogenic regulatory molecules known as the bone morphogenetic proteins has several members that stimulate bone regeneration. Therapeutic applications of bone morphogenetic proteins requ ire a well characterized carrier system to ensure safe and effective presen tation at the implant site. Several carrier systems have been used to evalu ate the sustained release and implant retention of recombinant human bone m orphogenetic protein-2, The carrier systems used in this study include type I collagen, poly(D,L-lactide), and deorganified bovine bone. Pharmacokinet ics of recombinant human bone morphogenetic protein-2 released from these s ystems were characterized in the rat ectopic assay, Pharmacokinetics were i nfluenced by the implant carrier. For example, sustained release occurred w ith the collagen sponge. The recombinant human bone morphogenetic protein-2 from deorganified bovine bone resulted in a burst release at the first col lection interval, but thereafter, appeared to bind irreversibly to the morp hogen. The poly (D,L-lactide) systems showed a dose dependent sustained rel ease pattern. These results indicate the physicochemical characteristics of a carrier system for recombinant human bone morphogenetic protein-2 impact the release kinetics and may have a profound influence on clinical outcome .