Application of biomaterials in vascularization of cardiac organoids

Cardiac organoids (COs) are platforms for disease modeling and regenerative medicine, yet inadequate vascularization still limits their function and longevity. This review examines how biomaterial properties-porosity, elasticity, surface chemistry, and bioactivity-regulate endothelial cell behavior and vascular network formation, thereby shaping progress in organoid vascularization. We survey natural, synthetic, and composite systems (e.g., collagen, fibrin, polyethylene glycol [PEG] hydrogels, and poly(ε-caprolactone) [PCL] scaffolds) used to promote vascularization. We also summarize fabrication strategies to improve perfusion, including micro/nanopatterning, scaffold design, and delivery of pro-angiogenic factors, and we outline technical routes for spatially patterned vasculature such as three-dimensional (3D) bioprinting and microfluidics. Ongoing challenges include degradation mismatch and incomplete integration. Future work should emphasize stimuli-responsive and bioactive materials, as well as standardized, scalable scaffold platforms, to strengthen reproducibility and translational efficiency. These directions will help optimize the vascular microenvironment of organoids, enhance functional maturation, and broaden applications in disease modeling, drug evaluation, and regenerative repair.