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In vitro effects of 635 nm photobiomodulation under hypoxia/reoxygenationculture conditions

Photobiomodulation (PBM), especially in the red wavelength range, has been demonstrated to be an effective

treatment option for superficial and chronic wounds. However, ischemia and subsequent reperfusion can further

challenge wound healing. Therefore, we investigated the effect of pulsed red LED light at 635 nm on cellular

function in an in-vitro model of hypoxia/reoxygenation (H/R) challenge.

Mouse myoblasts and fibroblasts were incubated in oxygen-deprived starvation medium (hypoxia) for 3 h

after which the media was changed to oxygenated, fully supplemented media to simulate reperfusion. Cells were

then treated with pulsed red LED light at a wavelength of 635 nm at 40 mW/cm2

. Mitochondrial respiratory

activity, ATP production and ROS levels were analysed immediately post-illumination. The effects on cellular

metabolic activity and proliferation were measured at 6 h and 24 h and apoptosis/necrosis was measured at 24 h


Our results show that both cell types reacted differently to H/R challenge and PBM. PBM of H/R-challenged

cells enhanced mitochondrial activity and rescued decreased ATP levels, with significant effects in fibroblasts.

This was associated with increased cell proliferation rates in both cell types. The increase was again more

pronounced in fibroblasts.

Our study concluded that PBM with red LED light significantly restored ATP levels during H/R and effectively

promoted cell growth under both normoxic and H/R conditions. In clinical applications, PBM has been re-

peatedly reported to resolve difficult clinical situations in which ischemia/reperfusion injuries are a major issue.

Our study confirms the beneficial effects of PBM especially in H/R-challenged cells.


Chaudary et al
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