Vascularization of PEG-grafted macroporous hydrogel sponges: A three-dimensional in vitro angiogenesis model using human microvascular endothelial cells

Vascular tissue can penetrate implants that have an interconnected porous structure. The extent of vascularization is heavily dependent on a number of factors, including the nature of the material as well as the size and porosity of the implant's pore morphology. Currently, it is still not clear what mechanisms are controlling this response. In this work, in vitro human microvascular endothelial cell (HMVEC) experiments employed in angiogenesis research have been adapted as a screening technique for biomaterial vascularization. Hydrogels composed of poly(2-hydroxy ethyl methacrylate) (PHEMA) containing poly(ethylene glycol) (PEG) grafts were capable of supporting in vitro tubule formation. The sizes and lengths of tubules were dependent upon the porosity of the polymer network and pore sizes. When compared to the pure PHEMA sponges, PEG-grafted networks possessed a more lattice-type structure, with greater pore interconnection. As a result, these polymers were better suited to supporting tubule formation.