Distinct lineages of human dermal fibroblasts play complementary roles in skin rejuvenation and wound healing, which
makes them a target of phototherapy. However, knowledge about differential responses of specific cell lineages to
different light parameters and moreover the actual molecular targets remain to be unravelled.
The goal of this study was to investigate the impact of a range of parameters of light on the metabolic activity, collagen
production, and cell migration of distinct lineages of human dermal fibroblasts. A rational approach was used to identify
parameters with high therapeutic potential.
Fibroblasts exhibited both inhibitory and cytotoxic change when exposed to a high dose of blue and cyan light in tissue
culture medium containing photo-reactive species, but were stimulated by high dose red and near infrared light.
Cytotoxic effects were eliminated by refreshing the medium after light exposure by removing potential ROS formed by
extracellular photo-reactive species.
Importantly, distinct lineages of fibroblasts demonstrated opposite responses to low dose blue light treatment when
refreshing the medium after exposure. Low dose blue light treatment also significantly increased collagen production by
papillary fibroblasts; high dose significantly retarded closure of the scratch wound without signs of cytotoxicity, and this
is likely to have involved effects on both cell migration and proliferation.
We recommend careful selection of fibroblast subpopulations and their culture conditions, a systematic approach in
choosing and translating treatment parameters, and pursuit of fundamental research on identification of photoreceptors
and triggered molecular pathways, while seeking effective parameters to address different stages of skin rejuvenation and