Migration of endothelial cells into photo-responsive hydrogels with tunable modulus under the presence of pro-inflammatory macrophages

Cell migration in three-dimensional environment is extremely important for tissue regeneration and other biological processes. In this work, a model system was developed to study how endothelial cells (ECs) migrate into photo-responsive hydrogels under the presence of pro-inflammatory macrophages. The hydrogel was synthesized from hyaluronic acid grafted with coumarin and methacrylate moieties by both carbon–carbon covalent linking and coumarin dimerization under UV irradiation at 365 nm. The structure of the hydrogel was conveniently modulated by UV irradiation at 254 nm to decompose the coumarin dimers, leading to the significant decrease of modulus and increase of swelling ratio and mesh size. Under the presence of M1 macrophages, ECs were induced to migrate into the hydrogels with a different degree. A significant larger net displacement of ECs was found in the softer hydrogel obtained by irradiation with UV at 254 nm than in the stiffer original one at day 7.