Advances in GelMA Hydrogel-Enabled Angiogenic-Osteogenic Coupling: From Structural Programming to Exogenous Cue...

Vascular-osteogenic coupling plays a central regulatory role in bone regeneration, but it is frequently impaired under pathological conditions, including aging, ischemia, and chronic inflammation, which compromises efficient bone repair. Gelatin methacryloyl (GelMA) hydrogels, which combine extracellular matrix-like bioactivity, adjustable mechanical properties, and compatibility with three-dimensional biomanufacturing, have become a widely used material platform for vascularized bone regeneration. From the perspective of vascular-osteogenic coupling, this review reframes and synthesizes GelMA-based approaches for vascularized bone regeneration, grouping existing strategies into three categories: (i) intrinsic material design, in which pore architecture, microchannels, dynamic networks, and interfacial functionalization are used to guide vascular ingrowth; (ii) exogenous bioactive delivery, involving growth factors, extracellular vesicles, cells, and inorganic ions to enhance vascularization; and (iii) smart responsive strategies, including ROS/pH-responsive systems, sequential release, and external stimulation, which aim to recapitulate the evolving microenvironment during bone repair. This review further compares these strategies in terms of evidence level, reproducibility, and translational potential. Exogenous delivery systems currently have the strongest preclinical support, but issues related to dose standardization, burst release, and long-term safety remain unresolved. Intrinsic material programming is less extensively studied, yet may be more compatible with manufacturing consistency, sterilization, and engineering translation. Most stimuli-responsive systems, by contrast, remain largely at the small-animal or proof-of-concept stage. Future GelMA-based systems should therefore shift from increasing functional complexity toward improving predictability, reproducibility, and clinical feasibility. Compositionally defined and structurally controllable GelMA composites that integrate vascular regulation with mechanical support may provide a more realistic path for vascularized bone regeneration.