Power of Blue Light: Reducing Organ Damage During Surgeries

Issue Date: 
May 16, 2016

A 24-hour exposure to bright blue light before surgery reduces inflammation and organ damage at the cellular level in a mouse model, according to research from the University of Pittsburgh School of Medicine.

The finding suggests that a potential pre-treatment light therapy could improve outcomes in patients undergoing procedures characterized by a period of blood restriction, such as liver resection or organ transplantation. The research, which was reported in a recent issue of the Proceedings of the National Academy of Sciences, was funded by the National Institutes of Health.

Matthew Rosengart“We were incredibly surprised by our results,” said senior author Matthew R. Rosengart, an associate professor in the Pitt School of Medicine’s Departments of Surgery and Critical Care Medicine. “There’s long been evidence suggesting that light and circadian rhythms profoundly influence our biology, and specifically the physiological response to stress. So while we were expecting to find some correlation with light spectrum and the immune response, we were not expecting results quite so striking.”

Circadian rhythms are physical, mental, and behavioral changes that occur over a 24-hour cycle, responding primarily to light and darkness.

Light is complex and consists of intensity, duration of exposure, and wavelength. This study is one of the first that accounts for this complexity and produces results that could guide future clinical trials in humans.

Rosengart and his team compared what happened when mice were exposed to red light, ambient white fluorescent light similar to that in hospitals, and high-intensity blue light. The exposures of all three types were done 24 hours before kidney or liver surgery involving periods of blood restriction and restoration.

The high-intensity blue light outperformed the red and white lights, attenuating cellular and organ injury through at least two cellular mechanisms. The blue light spurred a reduction in the influx of neutrophils, a type of white blood cell involved in inflammation, which can lead to organ damage and other problems. Additionally, blue light inhibited dying cells from releasing a protein called HMGB1 that triggers organ-damaging inflammation.

The team then tested whether the blue light was acting through the optic pathway or some other mechanism, like the skin. Blind mice had the same healing response regardless of whether they were exposed to blue or red light, indicating that the protective impact of blue light does, indeed, act through the optic pathway.

Rosengart stressed that mice are nocturnal animals with visual, circadian, and immune biology that is distinct from humans. Thus, the results of his study should not be broadly extended to patients or hospital settings until robust clinical trials have been performed. 

Additional Pitt School of Medicine researchers on this project are Du Yuan, Richard D. Collage, Hai Huang, Xianghong Zhang, Ben C. Kautza, Anthony J. Lewis, Brian S. Zuckerbraun, Allan Tsung, and Derek C. Angus.