Acute kidney injury (AKI) is a frequent and serious complication of sepsis in ICU patients and is associated with a very high mortality. Despite the advent of sophisticated renal replacement therapies (RRT) employing high-dose hemofiltration and high-flux membranes, mortality and morbidity from sepsis-induced AKI remained high. Moreover, these dialytic modalities could not substitute for the important functions of renal tubular cells in decreasing sepsis-induced AKI biological dysregulations. The results from the in vitro and preclinical animal model studies were very intriguing and led to the development of a bioartificial kidney consisting of a renal tubule assist device containing human proximal tubular cells (RAD) added in tandem to a continuous venovenous hemofiltration circuit. The results from the phase I safety trial and the recent phase II clinical trial showed that the RAD not only can replace many of the indispensable biological kidney functions, but also modify the natural history of sepsis-induced AKI by ameliorating patient survival.