Photosynthetic Solutions for Organ Perfusion Based on Microalgae and Cyanobacteria Display Differential In Vitro and In Vivo Features for Intravascular Oxygenation.

The delivery of photosynthetic microorganisms has emerged as a strategy for tissue oxygenation, offering a promising approach to treat several hypoxic conditions. Among these, intravascular photosynthesis has been proposed for ex vivo organ preservation; however, the most suitable photosynthetic microorganisms and their behavior during intravascular perfusion remain to be fully elucidated. Therefore, this study evaluates key properties of photosynthetic solutions for organ perfusion, based on the microalgaeChlamydomonas reinhardtii and the cyanobacterium Synechococcus elongatus. In vitro characterization showed that both microorganisms maintained viability, morphology, and oxygen production capacity in a Ringer's lactate-based medium for at least 24 h, with both photosynthetic solutions exhibiting rheological properties compatible with organ perfusion. In vivo perfusion of rat kidneys demonstrates sustained hemodynamic stability, with S. elongatus showing lower variability in vascular resistance. Histological analysis revealed significant retention of both microorganisms within renal structures, with S. elongatus inducing less tubular damage. Additionally, biocompatibility assays with human endothelial cells and zebrafish larvae showed no significant cytotoxic effects of the photosynthetic solutions. These findings support the feasibility of using photosynthetic microorganisms for intravascular photosynthesis, highlighting S. elongatus as particularly promising due to its lower oxygen consumption in darkness and reduced tissue damage after perfusion. This work provides significant insights toward the development of biologically active perfusion systems for innovative preservation strategies for organ transplantation.