Circadian rhythm affects wound healing speed

Within each of our cells, an intrinsic biochemical “clock” orchestrates gene and protein expression over an approximately 24-hour cycle. To better understand how this circadian rhythm influences cell function, researchers led by John S. O’Neill of the MRC Laboratory of Molecular Biology turned to a type of connective tissue cell that has a well-studied cellular clock. These cells, called fibroblasts, migrate to wounds and promote healing. The scientists found that many of the rhythmically expressed proteins in fibroblasts regulated polymerization of actin, a structural protein important for migration. In experiments with cell cultures, tissue samples, and mice, fibroblasts migrated more quickly to a wound received during the active phase of the circadian cycle than to a wound received in the dormant phase (Sci. Transl. Med. 2017, DOI: 10.1126/scitranslmed.aal2774). The researchers analyzed data from burn clinics around the U.K. and found a similar phenomenon in humans, with burns sustained during daylight hours healing about 60% faster than burns sustained at night. With further study, these findings could influence clinical decisions on treatment, the researchers note, or provide an avenue to use a drug to pharmacologically reset cellular clocks to aid in wound healing. “Theoretically this will allow us to trick the cells into ‘thinking’ it’s daytime during the night,” says lead author Nathaniel P. Hoyle. “It’s just a case of selecting the right compound.”