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Medtronic's INFUSE Bone Graft provides surgeons with a potent tool for stimulating bone formation. Current delivery vehicles that rely on Absorbable Collagen Sponges (ACS) require excessive quantities of the active ingredient in INFUSE, recombinant human Bone Morphogenic Protein-2 (rhBMP2), to achieve physiologically relevant concentrations of the growth factor, driving up the cost of the product and increasing the likelihood of undesirable side effects in neighboring tissues. We demonstrate that a simple light-mediated, thiol-ene chemistry can be used to create an effective polymer delivery vehicle for rhBMP2, eliminating the use of xenographic materials and reducing the dose of rhBMP2 required to achieve therapeutic effects. Comprised entirely of synthetic components, this system entraps rhBMP2 within a biocompatible hydrogel scaffold that is degraded by naturally occurring remodeling enzymes, clearing the way for new tissue formation. When tested side-by-side with ACS in a critical-sized bone defect model in rats, this polymeric delivery system significantly increased bone formation over ACS controls. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 401-406, 2013 [ABSTRACT FROM AUTHOR]

UV light irradiation to a photocrosslinkable chitosan (Az-CH-LA) resulted in an insoluble and flexible hydrogel within 30 s. The purpose of this study was to evaluate the ability of the photocrosslinkable chitosan to inhibit bone formation in the bone defects. A 5-mm-diameter defect was made in the rat calvarium, and then photocrosslinkable chitosan was implanted and irradiated with UV for 30 s. Furthermore, a 2-mm defect was made in the fibula of a rat hind leg, and then photocrosslinkable chitosan was implanted and irradiated with UV. Bone formations in the rat skull and fibula defects with photocrosslinkable chitosan hydrogel were significantly prevented for 8 weeks. Thus, the chitosan hydrogel has an inhibitory effect on bone formation. [ABSTRACT FROM AUTHOR]