Engineering Multiscale Vasculature: Biological Principles, Design Constraints, and Advanced Biofabrication Strategies...

Creating functional multiscale vascular networks remains a major challenge in tissue engineering and regenerative medicine. Native vasculature spans a wide range of diameters, from large elastic arteries to microscale capillaries, supporting vital functions such as perfusion, barrier regulation, mechanotransduction, and immune surveillance. Replicating this complexity requires biomaterials and fabrication techniques that enable hierarchical branching, preserve endothelial and mural cell phenotypes, and withstand physiological hemodynamic forces. We review biophysical design constraints, including diffusion limits, shear stress, mechanical compliance, and endothelial specialization, in the context of vascular developmental biology to outline a multiscale engineering framework for vascular graft design. Several promising scaffold systems are evaluated including electrospun fibers, decellularized matrices, cell-sheet constructs, and 3D bioprinting methods such as sacrificial-template fabrication, based on their respective advantages, limitations, and translational progress. Microvascular and organ-on-a-chip models are evaluated as high-fidelity platforms for studying human vascular physiology and disease. Finally, we discuss cellular sources for vascularization, including primary endothelial cells and iPSC-derived vascular lineages, as well as coculture and preconditioning strategies to enhance vessel maturation. While previous reports have reviewed individual vascular biofabrication methods, we integrate vascular biology, biophysical design constraints, fabrication strategies, and cell sources across macrovascular and microvascular scales. A multiscale approach is critical for selecting and combining approaches to meet vessel-specific requirements. Collectively, these advances may facilitate the development of perfusable, stable, and tissue-specific vascular networks and support the translation of multiscale vascular grafts toward clinical applications.