Association of blood mitochondrial DNA copy number with risk of acute kidney injury after cardiac surgery

Acute kidney injury (AKI) is a common complication of cardiac surgery and its occurrence is associated with increased risk of all-cause mortality, adverse cardiovascular outcomes, and chronic kidney disease (CKD). Mitochondria are essential for healthy function of the kidneys due to their roles in oxidative phosphorylation, reactive oxygen species generation, and programmed cell death. Experimental evidence suggests that mitochondrial dysfunction is a key contributor to the pathophysiology of acute kidney injury (AKI) and that replenishment of mitochondrial stores is necessary for recovery from AKI, but limited data exist in humans. Mitochondrial DNA copy number (mtDNA-CN) is an indirect marker of mitochondrial abundance that quantifies the number of mitochondrial genomes per cell. Recent studies have reported that higher blood mtDNA-CN is associated with reduced risks of chronic kidney disease (CKD), cardiovascular disease (CVD), and mortality, but no prior study has investigated associations with AKI. We hypothesized that mitochondrial quantity, assessed by mtDNA-CN, might indicate resilience from acute ischemic stress.