Effect and Mechanism of Cuttlebone/Bovine Serum Albumin Photocrosslinked Hydrogel on Promoting Bone Healing
Critical-sized bone defects (CSBD) remain a clinical bottleneck due to insufficient osteogenic drive and uncontrolled degradation of current grafts. This study evaluates a photocrosslinked hydrogel composed of cuttlebone (CB) and bovine serum albumin (BSA) for repairing 5 mm rat calvarial CSBD. SD rats were randomized into control, positive control (Bio-Oss® Collagen), BSA, 0.5% CB/BSA, 1.5% CB/BSA, and 3.0% CB/BSA groups (n=6). After 8 weeks, micro-CT revealed no new bone in controls, whereas all CB/BSA groups exhibited significant increases in bone volume fraction, bone mineral density, and trabecular thickness (P<0.05), with reduced bone surface-to-volume ratio (P<0.05). Histology confirmed new bone formation in hydrogel groups versus loose fibrous tissue in controls. Immunohistochemistry and immunofluorescence showed elevated COL1A1, PECAM-1, and OCN expression (P<0.05). qRT-PCR and Western blotting demonstrated upregulation of WNT3A, β-catenin, VEGFA, COL1A1, PECAM-1, and OCN (P<0.05). The 3.0% CB/BSA group exhibited the most pronounced osteogenic effect. Blood routine and serum liver/kidney function tests showed no abnormalities, and major organs displayed no inflammation, necrosis, or fibrosis. These findings indicate that CB/BSA photocrosslinked hydrogel promotes bone repair with favorable in vivo safety, likely through activation of the Wnt/β-catenin signaling pathway.