The Small RNA Repertoire of Small Extracellular Vesicles Isolated From Donor Kidney Preservation Fluid Provides a Source for Biomarker Discovery for Organ Quality and Posttransplantation Graft Function.

Delayed graft function (DGF) after kidney transplantation is negatively associated with long-term graft function and survival. Kidney function after transplantation depends on multiple factors, both donor- and recipient-associated. Prediction of posttransplantation graft function would allow timely intervention to optimize patient care and survival. Currently, graft-based predictions can be made based on histological and molecular analyses of 0-hour biopsy samples. However, such analyses are currently not implemented, as biopsy samples represent only a very small portion of the entire graft and are not routinely analyzed in all transplantation centers. Alternatives are thus required. METHODS: We analyzed whether donor organ preservation fluid contain small extracellular vesicles (sEV) and whether the RNA content of these vesicles could be used as a source for potential biomarkers for posttransplantation kidney function. RESULTS: We provide proof of principle that sEVs are present in preservation fluid, which contain RNAs associated with donor origin. Furthermore, sEV micro RNA profiles could be associated with graft function during the first 7 days posttransplantation, but no significant correlation with DGF could be established based on the current dataset. CONCLUSIONS: Overall, the predictive potential of sEV RNA biomarkers together with relatively easy and noninvasive sample collection and analysis methods could pave the way towards universal screening of donor kidney-associated risk for DGF, optimized patient treatment, and subsequently improved short- and long-term graft function and survival.