3D Printing of Phase‐Separating Hydrogels with Tunable Microachitecture for Mechanoregulated Bone Regeneration

Abstract 3D printing has emerged as a transformative technology for fabricating patient‐specific scaffolds with macroscopic precision for maxillofacial bone reconstruction. Yet, current designs fail to replicate the microscale topological cues of the native bone extracellular matrix (ECM), which are critical for orchestrating the sequential cellular events that drive effective bone regeneration. Here, digital light processing (DLP) 3D printing is integrated with polymerization‐induced phase separation (PIPS) to fabricate gelatin methacrylate (GelMA) hydrogel scaffolds that recapitulate ECM‐mimetic topographies within anatomically accurate constructs. PIPS affords robust, precise control over pore morphology while maintaining DLP's high‐resolution fidelity for patient‐specific mandibular repair. The resulting microporous architecture acts as a potent mechanotransductive cue, amplifying phosphorylated‐focal adhesion kinase (pFAK) activation, cytoskeletal remodeling, and Yes‐associated protein (YAP) nuclear localization. This cascade enhances bone marrow mesenchymal stem cells (BMSCs) adhesion, osteogenic differentiation, and pro‐angiogenic paracrine signaling, leading to rapid and functional bone regeneration in vivo. By integrating microscale phase‐separation thermodynamics with macroscale additive manufacturing, this study presents a proof‐of‐concept approach for mechano‐instructive scaffold design, validated in a rabbit mandibular defect model and offering potential relevance to future clinical applications in regenerative medicine.