The use of extended criteria donor grafts is a promising strategy to increase the number of organ transplantations and reduce waitlist mortality. However, these organs are often compromised and/or damaged, are more susceptible to preservation injury, and are at risk for developing post‐transplant complications. Ex vivo organ perfusion is a novel technology to preserve donor organs while providing oxygen and nutrients at distinct perfusion temperatures. This preservation method allows to resuscitate grafts and optimize function with therapeutic interventions prior to solid organ transplantation. Stem cell‐based therapies are increasingly explored for their ability to promote regeneration and reduce the inflammatory response associated with in vivo reperfusion. The aim of this review is to describe the current state of stem cell‐based therapies during ex vivo organ perfusion for the kidney, liver, lung, and heart. We discuss different strategies, including type of cells, route of administration, mechanisms of action, efficacy, and safety. The progress made within lung transplantation justifies the initiation of clinical trials, whereas more research is likely required for the kidney, liver, and heart to progress into clinical application. We emphasize the need for standardization of methodology to increase comparability between future (clinical) studies.

Mesenchymal stromal cells (MSC) have been shown to mitigate IRI through their anti-inflammatory and immune-modulating capacities. This study aims to demonstrate the feasibility, safety, and effectiveness of hepatic administration of bone marrow-derived (BM)-MSCs in a large pig model relevant to human anatomy. After complete vascular exclusion for 45 min, 3 × 10⁶ human BM-MSCs/kg body weight were infused via the portal vein or hepatic artery. BM-MSC infusion did not cause obstruction of hepatic or pulmonary blood flow within 6 h after infusion. Cells were effectively retained in the liver, being undetectable in peripheral blood, lung, and spleen samples. Human B2M expression, as a marker for BM-MSC presence, was significantly higher for the left liver lobe in arterial infusion compared to portal infusion. In liver samples with high BM-MSC levels, we identified the prevention of up- or downregulation of some genes related to inflammation and energy metabolism that was present in non-treated control samples, indicating biological effects within 6 h of infusion. We conclude that hepatic BM-MSC infusion is feasible and safe, with the hepatic artery serving as the optimal administration route for homogenous distribution. These findings pave the way for clinical studies on MSC infusion in IRI, either in situ in liver conditions or ex situ during machine perfusion.