Using Digested and Lyophilized Bone Matrices for Enhanced Retention and Sustained Release of BMP-2 for Bone Regeneration Background Human recombinant bone morphogenetic protein 2 (rhBMP-2) is an FDA-approved growth factor that promotes bone formation but includes safety risks like inflammation and ectopic bone formation. Current research aims to enhance rhBMP-2 delivery strategies, as prolonged, controlled release improves bone healing and reduces side effects compared to short-term release. Currently, collagen sponges are often used for the delivery of rhBMP-2 but suffer from poor structural stability and inadequate release profiles. A previous study developed a sponge- like matrix from decellularized, demineralized, and enzymatically digested porcine bone, demonstrating biocompatibility and bone regeneration. In this study, we created a similar digested and lyophilized bone matrix (DLBM) while adding synthetic BMP2 (sBMP2) and stabilizing with glutaraldehyde (GL) crosslinking in the hopes of creating a safe and efficacious BMP2 delivery system. Methods The digested and lyophilized bone matrix (DLBM) was fabricated using established methods, with synthetic BMP2 peptide (sBMP2) infused and stabilized through glutaraldehyde (GL) crosslinking. This DLBM/BMP2/GL construct was compared to a DLBM/BMP2 scaffold without crosslinking. Over four weeks, we assessed in vitro degradation and BMP2 release of both constructs at various time points. The in vivo efficacy of the DLBM/BMP2/GL scaffold was evaluated using a non-healing tibial defect model in a rat model, analyzing bone growth via CT and histology after eight weeks. Results In vitro degradation experiments showed that the DLBM/BMP2/GL scaffold retained significantly more of its original mass (~40%) compared to the non-GL scaffold (~17%). Additionally, we found significantly higher retention of sBMP2 in the DLBM/BMP2/GL scaffold at all time points. CT analysis and histological examinations further indicated that the DLBM/BMP2/GL scaffold exhibited enhanced regenerative capability over the DLBM scaffold in vivo, demonstrating improved efficacy.

Conclusion Our study underscores the potential of the DLBM/BMP2/GL scaffold as a promising platform for bone tissue engineering. We found that a sponge-like matrix, comprised of the digested and lyophilized bone matrix (DLBM) of pig bone, could effectively retain BMP2 peptide after chemical crosslinking using glutaraldehyde (DLBM/BMP2/GL). Further, we found a much more sustainable and controllable release profile of the BMP2 from the DLBM/BMP2/GL matrix when compared to the same BMP2-infused DLBM structure without any chemical crosslinking applied. Our in vivo evaluations demonstrate the improved biocompatibility, osteogenicity, and bone regenerative capacity of the DLBM/BMP2/GL scaffold compared to DLBM alone. Overall, our findings contribute to advancing innovative strategies for optimizing bone tissue engineering outcomes, thereby enhancing clinical efficacy and safety in bone repair and regeneration applications.