Characterization of an Injectable Poly(vinyl alcohol)‐gelatin Hydrogel for Growth Factor Delivery in an Orthopedic Application

Injectable hydrogels have attracted considerable interest because of their minimally invasive delivery and adaptability to patient-specific defects. This study aimed to investigate the suitability of a photo-crosslinkable tyraminated poly(vinyl alcohol)-gelatin (PVA-GT) polymer network as an injectable platform for tissue engineering and growth factor delivery. Two formulations were developed by varying the concentration of ruthenium/sodium persulfate (Ru/SPS), resulting in formulation-specific physical properties with fast (18 days) and slow (36 days) degradation rates. Their injectability was confirmed across a range of needle sizes (14 to 22G), ensuring versatility for multiple applications. Cytokine release from peripheral blood mononuclear cells and THP-1 demonstrated no inflammatory response due to residual ruthenium. When injected subcutaneously into a mouse model, the fast-degrading formulation exhibited greater cellular and vascular infiltration compared to the slow-degrading one. By leveraging bi-phenol bond formation within the polymer network, the fast-degrading injectable hydrogels were used as a growth factor delivery platform for bone morphogenetic protein-2 (BMP-2). BMP-2-loaded hydrogels were injected into the femoral head of a Legg-Calvé-Perthes disease swine model, preventing the necrosis progression and improving piglets' mobility relative to the sham. These findings highlight the potential of injectable PVA-GT hydrogels as tunable platforms for regenerative therapies, with implications for personalized orthopedic treatments.