Background/Objectives: The growing shortage of organs for transplantation requires optimized preservation techniques. Normothermic (NMP) and Subnormothermic Machine Perfusion (SMP) allow for the assessment of organ viability prior to transplantation and enable targeted therapeutic interventions while maintaining a metabolically active state in contrast to hypothermic settings. Methods: In this study, the synthetic perfusion solution “Omnisol” was used in a 6 h ex vivo setting with porcine kidneys (n = 6 NMP; n = 6 SMP). Perfusion parameters (arterial flow, intrarenal resistance and urinary flow), renal function (excretory and filtration performance), renal injury (cellular and circulating biomarkers) and tissue and perfusate oxygenation were assessed. Results: NMP resulted in better arterial flow and lower intrarenal resistance during the first 3 h of perfusion, while SMP surpassed NMP from 3 to 6 h. Renal injury biomarkers increased in the NMP group after 3 h, while no increase was detectable in the SMP group. Omnisol fully met the oxygen requirements of the kidneys in both groups, despite being fully synthetic. Conclusions: Both NMP and SMP offer distinct advantages for kidney preservation, and the synthetic perfusate Omnisol appears to be feasible for both methods. In this experimental setting, the data indicate that NMP of porcine kidneys was associated with favorable functional parameters during the early phase of perfusion, whereas SMP showed comparatively stable parameters at later time points. These findings should primarily be considered exploratory observations and require validation in future studies, especially for the translation into a clinical scenario using human kidneys.

Static cold storage remains the most widely used method for organ preservation in transplantation. Over time, preservation solutions have undergone continuous optimization. Ecosol is a novel extracellular-type, colloid-based preservation solution. In this study, we evaluated the safety and efficacy of Ecosol in comparison to the gold standard University of Wisconsin (UW) solution using both allogeneic and syngeneic rat orthotopic liver transplantation models. Liver function parameters were assessed and compared to baseline values of the respective rat strains. In the syngeneic setting, alanine transaminase (ALT) levels were significantly higher in the UW group than in the Ecosol group on day 1 post-transplantation (p < 0.05). Lactate dehydrogenase (LDH) levels were significantly elevated in the UW group compared to Ecosol in both allogeneic and syngeneic models on day 1 (p < 0.001). Gamma-glutamyl transferase (GGT) and total bilirubin were also significantly higher in the UW syngeneic group on day 1 (p < 0.05). In the allogeneic setting, aspartate aminotransferase (AST) and ALT levels were significantly elevated in both the UW (p < 0.0001) and Ecosol (p < 0.0001 and p < 0.001, respectively) groups on day 1 compared to the baseline values of Brown Norway (BN) rats. On day 7, these elevations persisted in the UW group, whereas no significant differences were observed in the Ecosol group compared to the baseline BN values (UW vs. Ecosol: p < 0.0001). In syngeneic transplants, AST and ALT levels were significantly elevated in both groups on day 1 compared to the baseline values of Lewis rats (p < 0.0001). By day 7, AST levels remained significantly elevated in the UW group, while Ecosol showed no significant difference from baseline (p < 0.0001). Organ viability, assessed via non-invasive imaging after 8 h of cold storage, was improved with Ecosol. Overall, Ecosol demonstrated biological safety and non-inferiority to the UW solution for liver preservation in a rat orthotopic liver transplantation model.