In Vitro UVB induced cellular damage assessment using primary human skin derived fibroblasts

Abstract

Nowadays there is a great deal of concern resulting from the impact of UV light on human skin especially when skin damage levels are predicted to rise due to ozone layer depletion. The skin acts as an important biological barrier, and plays an important physiological and immunological role. This study reports the UVB-induced effect on skin derived primary fibroblasts one of the most abundant cells in the dermis. Two time points, immediately and 24 hour post UVB exposure were used to measure the magnitude of UVB-induced cytotoxicity. The induced cell membrane damage was assessed by neutral red (NR) dye uptake while cellular metabolic activity was assessed by the 5-(3-carboxy-methoxyphenyl)-2-(4.5-dimethylthiazolyl)-3-(4-sulphonyl) (MTS) cytotoxicity assay. A correlation was found between the MTS and neutral red (NR) assay in measuring UVB-induced cellular damage in exposed skin fibroblasts cultures immediately post exposure. These findings indicated that doses higher than 2.2 J/cm2 were needed for the immediate expression of measurable cell membrane damage by the assays systems used. This should not indicate that no damage is triggered by lower irradiation levels, since our observations 24h post UVB-irradiation of the same cells showed cellular membrane damage for lower doses (0.7J/cm2) by comparison to immediately post exposure. The assessment of cellular metabolic activity indicated that MTS displayed a higher sensitivity in detecting early cell damage by comparison to the NR assay. The UVB induction follows a dose dependent response, and the cellular damage induced by exposure is best-measured 24h following exposure.