Spatially heterogeneous microgel-annealed PRP-derived fibrin hydrogel promotes coordinated vasculogenesis and angiogenesis after myocardial infarction

Blood vessel reconstruction is key for ischemic disease treatment by restoring microvascular perfusion and mitigating pathological tissue stiffening. During neovascularization, the mechanical and biochemical cues presented by the cellular-scale spatial heterogeneity of extracellular matrix (ECM) facilitate the endothelial cells (ECs) spreading and mechanotransduction, thereby driving angiogenesis. Therefore, developing ECM-mimetic proangiogenic biomaterials with compartmentalized spatial heterogeneity is highly desirable but challenging. Here, inspired by the spatially heterogeneous mechanical properties of natural tissues, we designed a series of microgel-annealed hydrogels (GMP) with compartmentalized stress heterogeneity. By integrating microfluidic-synthesized rigid microgels, the soft PRP-derived fibrin matrix was annealed with spatially mechanical domains that direct ECs-guided vascular morphogenesis through mechanotransduction, where rigid microdomains provide anchorage sites for cells adhesion, while soft interstitial matrix permits stalk cells migration and morphogenesis. In vitro, heterogeneous GMP hydrogel augmented ECs mechanotransduction via activating integrin β1-p-FAK-p-MLC signaling pathway and stabilizing VE-CAD/β-cat junctions, promoting 3D vasculogenesis and angiogenesis. In a rat myocardial infarction (MI) model, treatment with the heterogeneous hydrogel enhanced myocardial neovascularization, attenuated ventricular dilation and enhanced cardiac function. These findings not only provide valuable guidance for engineering proangiogenic biomaterials via ECM biomechanical mimicry, but also highlight the promise of spatially heterogeneous hydrogel with engineered mechanical cues essential for de novo blood vessel formation in the treatment of ischemic disease. STATEMENT OF SIGNIFICANCE: This work develops a proangiogenic hydrogel that mimics the spatially heterogeneous mechanical properties of the native extracellular matrix (ECM). By annealing rigid microgels into a soft fibrin matrix, we create a biomaterial with compartmentalized stress domains that guide endothelial cell behavior. This engineered heterogeneity promotes 3D vascular network formation by enhancing key mechanotransduction pathways and stabilizing cell-cell junctions. Significantly, in a rat model of myocardial infarction, the hydrogel enhances neovascularization, attenuates tissue damage, and improves cardiac function. Our findings highlight that recapitulating ECM biomechanical heterogeneity is a transformative strategy for engineering biomaterials to drive functional blood vessel regeneration, offering a promising therapeutic approach for treating ischemic diseases.