Acute kidney injury (AKI) is a common complication of cardiac surgery involving cardiopulmonary bypass. There are nearly 2 million cardiac surgeries annually worldwide, with AKI incidence rates between 5% and 42%.1 AKI in the setting of cardiac surgery has been associated with longer hospital stays and increased mortality risk. The relationship between cardiac surgery and AKI in humans has served as a natural experiment; cardiac surgery is common and often used for biomarker discovery, yet our understanding of the mechanism of AKI following it has been evolving.