Effects of Extracellular Vesicles on Kidney Repair: Perspective for Clinical Applications

Extracellular vesicles (EVs) are membranous vesicles containing active proteins, lipids and different types of genetic material. They are involved into the communication over long distances, modulating the gene expression profile and fate of target cells. It has been demonstrated that they play an important role in kidney pathophysiology. EVs are released by almost all cell types, in particular stem cell-derived EVs, especially mesenchymal stem cell-derived EVs (MSC-EVs) are thought to be a new promising therapeutic option in acute and chronic renal injury as wells as for kidney preconditioning. This thesis will analyse three different aspects relevant for therapeutic application of MSC-EVs for kidney disease: EV biodistribution, EV application in graft preconditioning and EV large-scale production. A new method to label EVs (the DPA-SCP tracker) has been recelty proposed in a renal ischemia-reperfusion (I/R) injured model, exhibiting a higher tracking ability compared to the commercially available EV tracker PKH26. Further analysis identified the regulatory mechanism contributing to the protective and regenerative actions on mitochondria via activating the Keap1-Nrf2 signalling pathway. Among the different therapeutic options to cure renal disease, kidney transplantation currently is the only strategy in case of end-stage kidney, but its use is limited by the low availability of organs. MSC-EVs have been administrated during the hypothermic oxygenated perfusion, showing that EVs can be considered a new organ preservation strategy for increasing the donor pool and improving transplant outcomes. The robustness of these data in favour of EV application should be an encouragement to the transition to clinical trials, unfortunately, due to their lack of self-replication activity, one of the biggest problems is linked to scaled production. Polyethylene glycol-based precipitation protocol has been tested to obtain a higher concentration of EVs from small volumes of fluids. For large volumes, the tangential flow filtration (TFF) was fine-tuned and showed greater efficiency and higher batch-to-batch reproducibility compared to a classic ultracentrifugation protocol.