Vitronectin-GM-CSF fusion protein hydrogel with a recruitment-anchoring-activation strategy accelerates vascularized...

The process of tissue injury repair involves the synergistic effects of angiogenesis and immune regulation, yet a single molecule rarely can regulate both processes. To address this, we designed a fusion protein, VGC, by integrating the potent chemotactic property of granulocyte-macrophage colony-stimulating factor (GM-CSF) with the cell-anchoring domain of vitronectin (VTN). This design yielded an integrated system capable of recruiting, anchoring and activating repair cells. The VGC, connecting VTN and GM-CSF via linker peptides (GGGGSGGGGS), was successfully produced by microbial fermentation and loaded into temperature-sensitive Pluronic F127 hydrogel (F127) for controlled release. In vitro, VGC significantly promoted endothelial cell proliferation, migration and tube formation, while temporally modulated macrophage polarization from the M1 to M2 phenotype to improve the immune microenvironment. In a rat cranial defect model, VGC-loaded hydrogel (F-VGC) accelerated bone regeneration, increasing bone volume (**P < 0.01, vs F-VTN; ***P < 0.01, vs F127) and collagen I deposition (*P < 0.05, vs F127). In mouse full-thickness skin wounds, F-VGC significantly accelerated healing, achieving a 95.78 ± 0.65% closure rate by Day 10 (**P < 0.01, vs F-VTN/F127) through mechanisms involving early angiogenesis, collagen remodeling and re-epithelialization. This study provides a protein-based strategy for synergistically promoting vascularization and immune modulation, offering a new paradigm for functional biomaterial design.