Symbiotic Photosynthetic Oxygenation within 3D-Bioprinted Vascularized Tissues

In this study, we present the photosynthetic oxygen (O₂) supply to mammalian cells within a volumetric extracellular matrix-like construct, whereby a three-dimensional (3D)-bioprinted fugitive pattern encapsulating unicellular green algae, Chlamydomonas reinhardtii, served as a natural photosynthetic O₂ generator. The presence of bioprinted C. reinhardtii enhanced the viability and functionality of mammalian cells while reducing the hypoxic conditions within the tissues. We were able to subsequently endothelialize the hollow perfusable microchannels formed after enzymatic removal of the bioprinted C. reinhardtii-laden patterns from the matrices following the initial oxygenation period to obtain biologically relevant vascularized mammalian tissue constructs. The feasibility of co-culture of C. reinhardtii with human cells, the printability and the enzymatic degradability of the fugitive bioink, and the exploration of C. reinhardtii as a natural, eco-friendly, cost-effective, and sustainable source of O₂ would likely promote the development of engineered tissues, tissue models, and food for various applications.