Apoptotic-mimetic nanovesicles orchestrate immune-vascular-osteogenic crosstalk for critical-sized craniofacial bone regeneration.

The management of critical-sized craniomaxillofacial bone defects remains a formidable clinical challenge due to the concomitant issues of prolonged inflammation, inadequate vascularization, and insufficient endogenous osteogenesis. Herein, a novel cell-free bone regeneration strategy is reported based on biomimetic apoptotic nanovesicles (Apo-NVs) derived from apoptotic T-lymphocytes membrane. The Apo-NVs, which mimic the "find-me" and "eat-me" signals of natural apoptotic cells, are engineered into a gelatin methacryloyl (GelMA) hydrogel for sustained localized delivery. In vitro, the Apo-NVs demonstrate superior immunomodulatory efficacy by promoting the repolarization of pro-inflammatory M1 macrophages towards a pro-healing M2 phenotype. Concurrently, they directly enhance the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) and potently stimulate human umbilical vein endothelial cells (HUVECs) proliferation, migration, and tube formation. In vivo, the GelMA-Apo-NVs significantly augments bone regeneration and vascularization compared to GelMA and GelMA-NVs groups, as validated by micro-computed tomography and histological analyses. Mechanistic unraveling through transcriptomic profiling reveals that the regenerative function of Apo-NVs is orchestrated through the activation of Wnt/β-catenin signaling pathway. This activation not only directly drives osteogenic gene expression but also upregulates vegfa, thereby coupling angiogenesis with osteogenesis, while simultaneously inhibiting the NF-κB pathway to inhibit inflammation. This study pioneers a versatile apoptotic vesicle-based platform that harmonizes the immune-osteogenic-vascular triad, presenting a potent and promising therapeutic paradigm for regenerative medicine.