Validation of a Light Source for Phototoxicity in in vitro Conditions

Abstract

Phototoxicity is a chemically induced skin irritation in the presence of sunlight. Phototoxic substances after irradiation with sunlight absorb and convert light energy into chemical energy, leading to the formation of highly reactive oxygen species with toxic effects. Recently LED technologies made possible their application for novel effective solar simulators, to be used in biology and medicine. We study the possibilities of application of LED sunlight simulator (Helios-iO, model LE-9ND55-H – 5500K) for in vitro testing of synthetic and natural products for phototoxicity. Cytotoxicity/phototoxicity was assessed by validated BALB/3T3 clone A31 Neutral Red Uptake Assay. The morphological alterations in BALB/3T3 cells induced by the Radachlorin® and irradiated with dose 2.4 J, were analyzed by fluorescent microscopy. The physical characteristics of the lamp were determined and the intensity distribution of the LED light over a model of a 96-well plate at a distance of 25 cm from the lamp diode matrix center was estimated. The obtained results show that the light emitted by the solar simulator used is similar to the natural sun light. The biological testing results reveal the high efficiency of the solar simulator in an in vitro experimental system for phototoxicity testing.