Protective actions of administered mesenchymal stem cells in acute kidney injury: relevance to clinical trials

Current therapies for acute kidney injury remain primarily supportive and have failed to reduce morbidity, mortality (>50%), and associated costs. This prompted our studies in which rats with bilateral ischemia/reperfusion-induced acute kidney injury were treated with bone marrow-derived, culture-expanded allogeneic mesenchymal stem cells. Their administration into the suprarenal aorta after reflow significantly protected renal function and hastened repair, mediated by complex antiapoptotic, mitogenic, anti-inflammatory, and immune modulating actions that were not elicited by isogeneic fibroblasts. Infused mesenchymal stem cells, recruited to renal sites of injury, did not significantly differentiate into target cells but rather disappeared from kidneys and other organs within 72 h. Furthermore, at 3 months, compared with vehicle-treated controls, renal function was well preserved and interstitial fibrosis was absent. These preclinical data served as the scientific basis for a recently completed Phase I Clinical Trial (http://www.clinicaltrials.gov; # NCT00733876), in which patients at high risk for cardiac surgery-associated AKI were treated with allogeneic mesenchymal stem cells. Until now, MSC therapy in the study subjects has been safe, and none of the patients has developed postoperative AKI or subsequent loss of renal function, suggesting that this novel form of therapy may have promise in this group of high-risk patients, which will be further investigated in a Phase II Trial.