Hydrogel biomaterials to support and guide vascularization

Biomaterials can be intentionally designed to support and even guide vascularization for applications ranging from engineered organs to treatment of ischemic diseases like myocardial infarction and stroke. In order to appropriately design bioactive biomaterials for vascularization, it is important to understand the cellular and molecular events involved in angiogenesis and vasculogenesis. Cell-matrix and signaling biomolecule interactions that initiate and promote formation of vasculature in vivo can often be mimicked in biomaterial platforms. Hydrogels are frequently used in these applications because they are soft and hydrated with mechanical properties similar to soft tissues and because many synthetic hydrogels are essentially bioinert, allowing one to engineer in specific cell-material interactions. A variety of both naturally-derived and synthetic hydrogel bases are used for supporting vascularization, and these gels are tailored to possess mechanical properties, biodegradation, cell adhesive interactions, biochemical signaling, and/or architectural properties that can promote assembly and tubulogenesis by vascular cells. This article serves to review current hydrogel materials and the innovative design modifications implemented to guide and support the vascularization process.