Photobiomodulation of human dermal fibroblasts in vitro: decisive role of cell culture conditions and treatment protocols on experimental outcome

Photobiomodulation of human dermal fibroblasts in vitro: decisive role of cell culture conditions and treatment protocols on experimental outcome

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Abstract Photobiomodulation-based (LLLT) therapies show tantalizing promise for treatment of skin diseases.Confidence in this approach is medline remedy phytoplex protectant z-guard paste blighted however by lamentable inconsistency in published experimental designs, and so complicates interpretation.Here we interrogate the appropriateness of a range of previously-reported treatment parameters, including light wavelength, irradiance and radiant exposure, as well as cell culture conditions (e.g., serum concentration, cell confluency, medium refreshment, direct/indirect treatment, oxygen concentration, etc.

), in primary cultures of normal human dermal fibroblasts exposed to visible and near infra-red (NIR) light.Apart from irradiance, all study parameters impacted significantly on fibroblast metabolic activity.Moreover, when cells were grown at atmospheric O2 levels (i.e.20%) short wavelength light inhibited cell metabolism, while negligible effects were seen with long visible and NIR wavelength.

By contrast, NIR stimulated cells when exposed to dermal tissue oxygen levels (approx.2%).The impact of culture conditions was further seen when inhibitory effects of short wavelength light were reduced with increasing serum concentration and cell confluency.We conclude that a significant source of problematic interpretations in photobiomodulation reports derives from poor optimization of study design.Further development of this field using in vitro/ex vivo models should embrace significant skeleton yard stakes standardization of study design, ideally within a design-of-experiment setting.