Photosynthetic co‐culture system of algae and human umbilical vein endothelial cells: The effect on alleviating hypoxia and hypoxia/reoxygenation injury

It is a developed photosynthetic co‐culture system to alleviate the hypoxia and hypoxia/reoxygenation (H/R)‐injured human umbilical vein endothelial cells (HUVECs). The algae, Chlorella vulgaris, were encapsulated to slow their growth while not affecting the photosynthetic oxygen‐producing capacity by Layer‐by‐layer (LbL) using gelatin and sodium alginate as the positive and negative charges materials, respectively. Then, the photosynthetic co‐culture system of HUVECs and self‐oxygenating alginate hydrogel (Algae‐gel) was constructed in which the optimal ratios between algae and HUVECs were 5:1 and 20:1 for a 2D or 3D co‐cultured manner, respectively. It indicated that the 3D co‐cultured manner of HUVECs needed more O2 by the production of algae than it did in a 2D co‐cultured manner. The co‐cultured Algae‐gel could alleviate hypoxia and the oxidative stress injury of hypoxia and hypoxia/reoxygenation (H/R)‐treated HUVECs in the proliferation, intracellular ROS and cellular migratory ability. In addition, the Algae‐gel could downregulate the expression of hypoxia‐inducible factors 1α (HIF‐1α) and vascular endothelial growth factor (VEGF) of hypoxia and H/R‐injured HUVECs due to the improvement of hypoxia and H/R injury. This photosynthetic co‐culture system could offer a promising approach for repairing hypoxia and H/R‐injured cells or tissue by providing safe and stable O2.