Clinical Trial of Mesenchymal Stem Cells in the Treatment of Severe Acute Kidney Injury

Inclusion Criteria: * Have severe AKI defined as more than two-fold increase serum creatinine level compared with baseline within 48 hours and/or urinary output consistently\<0.5 ml/kg/h over 12 hours * Age between 18 and 65 years * Willing or having a legally acceptable representative to give a written informed consent * Able to comply with visit schedule and study procedures including post-hospitalization discharge follow-up Exclusion Criteria: * AKI due to post-renal outflow obstruction,glomerulonephritis,lupus nephritis, antineutrophil cytoplasmic antibody (ANCA) related nephritis, antiglomerular basement membrane disease, cryoglobulinemia, thrombotic microangiopathy, and AKI caused by purpura nephritis * Pregnant or lactating woman * Allergic person * Organ transplant or hematopoietic stem cell transplant * Patients with malignant tumors or those with a history of cancer * Life expectancy is less than 3 months * Known end-stage liver disease * Uncontrollable infection * Patients younger than 65 years old ,whose estimated glomerular filtration rate (eGFR) were less than 60 * Severe pulmonary dysfunction * Severe cardiac dysfunction,left ventricular ejection fraction is less than 40%, or severe arrhythmia patients * Hemodynamically unstable patients * Organ failure affecting more than 2 non-renal organs * Acute or chronic vasculitis of any cause * History of chronic systemic infection of any cause * The investigators believe that subjects may need to gradually increase the dose of vasopressor to achieve and / or maintain hemodynamic stability * Systemic immunosuppressive therapy that has not been stabilized for greater than 4 months, or in the case of chronic corticosteroid therapy, a dose of \>15 mg/day of prednisone or the equivalent within the past 30 days * Platelet count \<25,000/uL or other severe hematologic abnormalities, causing the subject to be at risk of death * Patients need mechanical ventilation * Participate in other clinical trials