In vitro effects of Red LED Light on human epidermal keratinocytes: a skin regeneration strategy.

The Red LED (light-emitting diode) light is a promising approach for skin regeneration. Even if its mechanism of action is not clearly understood, its regenerative properties have been investigated since about ten years ago. Keratinocytes represent the first and primary target of this technology because of they are involved in epidermal reconstitution. In these experiments, a new treatment, named “Dermodinamica” (Elisor, Milan), with a wavelength of 630nm, has been used. Different factors produced by keratinocytes have a key role in skin regenerative process: transforming growth factor-b1 (TGF-b1) with a crucial role in maintaining skin homeostasis and in re-epithelialization but also the modulation of metalloproteinases (MMP), in particular 1 and 8, during extracellular matrix production. Moreover, ROS-detoxifying enzymes, such as superoxide dismutase 1 (SOD-1) and heme-oxygenase 1 (HO-1), have an important role in cutaneous wound repair. The aim of the present in vitro study was to evaluate the effect of Red LED light (Dermodinamica, Elisor, Milan) on normal human epidermal keratinocytes (NHEK) after 1 day and 3 days of exposition monitoring: cell viability using MTT assay; TGF-1 production using ELISA kit; expression of collagen type I, MMP-1, MMP-8, SOD-1 and HO-1, using immunohistochemical technique; morphological evaluation analyzing semi-fine sections. Moreover, short (15 min exposition) and prolonged (30 min exposition) treatments were investigated. The results showed an increase of cell viability with the short treatment (15 min of exposition) and a modulation of TGF-b1, ROS-detoxifying enzymes, metalloproteinases. Morphological data confirm the induction of cell cycle physiological progression of keratinocytes. These data indicate a positive role of Red LED light in promoting keratinocytes renewal.