Zinc-based metal orchestrates early osteoimmune microenvironment to promote angiogenesis via macrophage-derived extracellular vesicles

Zinc (Zn)-based metals are promising materials for guided bone regeneration due to their controllable degradation and bioactivity. However, the immunomodulatory processes by which Zn influences angiogenesis during bone regeneration remain incompletely understood. This study investigated the role of Zn-based metals in the early osteoimmune microenvironment and its association with angiogenic responses involving macrophage-derived extracellular vesicles (EVs). Compared to the control, Zn membranes were associated with enhanced osteogenesis and angiogenesis during bone defect repair. Single-cell RNA sequencing identified Arg1+ macrophages as a prominent cell population in the early osteoimmune microenvironment. This subset appeared to function as intermediate communication and showed extensive interactions with endothelial cells after implantation. Functional enrichment analysis demonstrated increased metabolic activity and enrichment of pathways associated with vesicle transport in this subset. Conditioned media from Zn-stimulated macrophages enhanced endothelial migration and tube formation, whereas inhibition of EVs release significantly attenuated these effects. The expression of P2Y11 was increased in endothelial cells exposed to the media from Zn-treated macrophages. These findings provided significant information regarding EV-mediated communication between macrophages and endothelial cells for Zn-based implant response.