Histatin-1 promotes bone regeneration by coordinating osteogenic and angiogenic responses in a sustained-release hydrogel system

The regeneration of critical-sized bone defects is severely hampered by a dual challenge: insufficient vascularization and limited osteogenic activity at the injury site. Histatin-1 (Hst1), a salivary peptide with known pro-angiogenic and regenerative activities, is a hopeful candidate for bone regeneration, yet its dual function in osteogenesis and angiogenesis remains underexplored. Here, we systematically elucidated this dual function. In vitro , Hst1 was demonstrated to stimulate the osteogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs) through the activation of the Wnt/β-catenin signaling pathway. Concurrently, Hst1 promoted tube formation through paracrine signaling. In vivo , the hydrogel formulated from oxidized sodium alginate (OSA), gelatin (GE), and adipic acid dihydrazide (ADH) was employed to ensure the sustained delivery of Hst1. This Hst1-loaded hydrogel was applied to a 5-mm critical-sized cranial defect in rats. Compared to the Control group, Hst1-loaded hydrogel significantly enhanced bone regeneration, with the bone volume fraction (BV/TV) increasing to 20.0 % ( vs. 8.2 % for Control). This was accompanied by a marked increase in vascularization, as evidenced by a 3.0-fold rise in vessel density. In conclusion, this study reveals the dual pro-regenerative function of Hst1 in simultaneously promoting osteogenesis and angiogenesis, demonstrating that harnessing Hst1 within a sustained-release hydrogel is a powerful therapeutic strategy for achieving vascularized bone regeneration.