Adult Stem Cells and Extracellular Vesicles in Acute and Chronic Kidney Injury

Acute and chronic kidney diseases represent an emerging problem in management and costs of healthcare. Understanding the mechanisms responsible for injury and repair is the mainstay to a more precise classification and staging thus envisioning potential strategies of intervention. Experimental models of acute kidney disease and chronic kidney disease are important even if necessarily artefactual to having a deep insight into the mechanisms of acute lesions and functional deterioration. The evidence that even a single episode of acute kidney disease predisposes the kidney to initiate a complex series of events leading to scarring and reduction of functional parenchyma emphasizes the need to prevent acute kidney disease or to reduce its impact in the later development of chronic kidney disease. In the past years, innovative cell therapies with stem cells have been proposed and tested in pre-clinical development and in pilot clinical studies, leading to the strong hope that these novel approaches might be of relevance. However, not all these studies have led to a unanimous agreement mainly due to lack of standardization, batch-to-batch variability, lack of potency tests, and difficulty in patient stratification. More recently, extracellular vesicles, nanoparticles released physiologically from all cells, and capable of transferring genetic information to target cells, have attracted major interest in regenerative medicine. In this review, we intend to describe the main mechanisms of acute kidney disease and chronic kidney disease, the experimental models that may allow insight into the mechanisms and the potential therapeutic targets using stem cells and their derived extracellular vesicles. A compilation of the main patents relative to stem cells and extracellular vesicles in acute kidney disease and chronic kidney disease will follow.