Red (660 nm) or near-infrared (810 nm) photobiomodulation stimulates, while blue (415 nm), green (540 nm) light inhibits proliferation in human adipose-derived stem cells

Abstract

We previously showed that blue (415 nm) and green (540 nm) wavelengths were more effective in stimulating osteoblast differentiation of human adipose-derived stem cells (hASC), compared to red (660 nm) and near-infrared (NIR, 810 nm). Intracellular calcium was higher after blue/green, and could be inhibited by the ion channel blocker, capsazepine. In the present study we asked what was the effect of these four wavelengths on proliferation of the hASC? When cultured in proliferation medium there was a clear difference between blue/green which inhibited proliferation and red/NIR which stimulated proliferation, all at 3 J/cm2. Blue/green reduced cellular ATP, while red/NIR increased ATP in a biphasic manner. Blue/green produced a bigger increase in intracellular calcium and reactive oxygen species (ROS). Blue/green reduced mitochondrial membrane potential (MMP) and lowered intracellular pH, while red/NIR had the opposite effect. Transient receptor potential vanilloid 1 (TRPV1) ion channel was expressed in hADSC, and the TRPV1 ligand capsaicin (5uM) stimulated proliferation, which could be abrogated by capsazepine. The inhibition of proliferation caused by blue/green could also be abrogated by capsazepine, and by the antioxidant, N-acetylcysteine. The data suggest that blue/green light inhibits proliferation by activating TRPV1, and increasing calcium and ROS.

Differential response of human dermal fibroblast subpopulations to visible and near‐infrared light: Potential of photobiomodulation for addressing cutaneous conditions

“…Therefore, the observation of photorejuvenation, wound healing or hair regrowth effects cannot yet be associated with a stimulation/inhibition of a particular cell type, for example, dermal fibroblasts. Some of our results concurred with previous research studies . In particular, it was clear that three consecutive exposures to short visible wavelengths (⇐530 nm), exerted inhibitory effects on DFs while long visible and NIR wavelengths (>=530 nm) had a neutral impact at standard environmental oxygen concentration.…”

“…The results of our study also agrees with previously published data on the involvement of ROS as part of the immediate effect of light on cells [16,18,[21][22][23][24]50]. It has been demonstrated that exposure to short visible wavelength light induced ROS in various models [22,50] and could result in DNA damage in human epithelial cells for example [22].…”

“…The downstream impact of the molecular reactions, triggered by reception of light, is mediated by many molecular players, including ROS (reactive oxygen species) [13][14][15][16], adenosine triphosphate (ATP) [1,4] and iongated channels [4,10,16,17].…”

“…High quantities of ROS have been shown to be generated by short visible wavelength light acting on flavoproteins and nitrosated proteins [13][14][15][16] and this has been proposed to be the first point of light interaction with cells. We now know that ROS are involved in the molecular reactions generated by visible light, both at short but also at long wavelengths, in range of different cell types including but not limited to HeLa cells [18], adipose-derived stem cells [16], human skin fibroblasts and keratinocytes [19,20], and others [18,[21][22][23][24].…”

Non‐mammalian Hosts and Photobiomodulation: Do All Life‐forms Respond to Light?

“…The most important alternative chromophore appears to be transient receptor potential (TRP) ion channels that can be activated by light or heat . An example is TRPV1 that can be activated by blue or green light and by longer wavelength NIR light (980 nm) that targets water in the form of nanostructured exclusion zone water clusters . Regardless of whether CCO is activated by red/NIR light, or TRP ion channels are activated by blue/green/980 nm light, the cellular results have some aspects in common, but also display some differences.…”