Analysis of haemolysis-based injury in immortalised proximal tubule epithelial cells is impaired by haemoglobin interference with bioluminescence assays.

Acute kidney injury (AKI) is a significant complication that frequently affects patients undergoing cardiac and aortic/vascular surgery. While the causes of AKI following cardiac surgery are multifactorial, one increasingly recognized contributor is haemolysis, which occurs due to the use of cardiopulmonary bypass machines. Haemolysis, the destruction of red blood cells, releases free haemoglobin (fHb) into the bloodstream, which has been shown to cause kidney injury. The exact mechanisms underlying haemolysis-induced kidney injury are not yet fully understood.

In a recent study, researchers examined the impact of fHb on human-derived conditionally immortalised proximal tubule epithelial cells (ciPTECs). The findings revealed that fHb interference leads to a reduction in bioluminescence signal output. However, this effect was significantly reduced when fHb solutions and haemolysed plasma were removed before starting the assay.

The researchers also discovered that the effect of fHb on ciPTECs varied between haemolysed plasma and fHb solutions, suggesting the presence of additional factors in the plasma that contribute to the injury response.

Contrary to expectations, haemolysed plasma only resulted in a slight increase in NF-B activity and had a minimal effect on mitochondrial function. These results imply that care should be taken when conducting bioluminescent assays with fHb, whether it is in solution or present in haemolysed plasma. The study also suggests that fHb may not cause severe injury to ciPTECs.