Porcine Bone Extracellular Matrix Hydrogel as a Promising Graft for Bone Regeneration

Bone defects resulting from trauma, tumors, or congenital conditions pose significant challenges for natural healing and often require grafting solutions. While autografts remain the gold standard, their limitations, such as restricted availability and donor site complications, underscore the need for alternative approaches. The present research investigates the potential of porcine-derived bone extracellular matrix (pbECM) hydrogel as a highly promising bioactive scaffold for bone regeneration, comparing it to the human-derived bECM (hbECM). Porcine and human cancellous bones were decellularized and characterized in terms of their composition and structure. Further, the ECMs were processed into hydrogels, and their rheological properties and cytocompatibility were studied in vitro while their biocompatibility was studied in vivo using a mouse model. The potential of the pbECM hydrogel as a bone graft was evaluated in vivo using a rat femoral defect model. Our results demonstrated the excellent preservation of essential ECM components in both the pbECM and hbECM with more than 90% collagen out of all proteins. Rheological analyses revealed the superior mechanical properties of the pbECM hydrogel compared to the hbECM, with an approximately 10-fold higher storage modulus and a significantly later deformation point. These stronger gel properties of the pbECM were attributed to the higher content of structural proteins and residual minerals. Both the pbECM and hbECM effectively supported mesenchymal stem cell adhesion, viability, and proliferation, achieving a 20-fold increase in cell number within 10 days and highlighting their strong bioactive potential. In vivo, pbECM hydrogels elicited a minimal immunogenic response. Most importantly, when implanted in a rat femoral defect model, pbECM hydrogel had significantly enhanced bone regeneration through graft integration, stem cell recruitment, and differentiation. New bone formation was observed at an average of 50% of the defect volume, outperforming the commercial demineralized bone matrix (DBM), in which the new bone filled only 35% of the defect volume. These results position pbECM hydrogel as a highly effective and biocompatible scaffold for bone tissue engineering, offering a promising alternative to traditional grafting methods and paving the way for future clinical applications in bone repair.