Viability of Cultured Human Keratinocyte and Melanocyte after UVB Exposure

Cho, Yang Hoon; Lee, Mu Hyoung

Abstract

BACKGROUND
Each kind of human cell has its own characteristic morphological and functional property. In the skin, epidermal cells, including keratinocyte and melanocyte, also have their own functional characteristics. Thus, it is expected that there are some different responses to external stimuli, such as ionizing radiatio,, free radicals, and cytokines between these cells.
OBJECTIVE
AND METHODS: To im estigate whether there are different effects of UV light on the viability of cultured human ker tinocytes and rnelanocytes. Cultured human keratinocytes and melanocytes are irradiated by UVB at 5, 25, 50, and 100mJ/cm, and examined by Methylthiazole tetrazollium assay at 0, 1, 3, 6, 24, 48, and 72 hours after UVB exposure.
RESULTS
1. The effects on viability according to the doses of UVB are as follows: 1) In the keratinocytes, the viability was increased in most of the UVB exposure groups within 24 hours after UVB exposure, and was significantly increased at 25, 50, and 100mJ/cm of UVB at 3 hours after UVB exposur.(p<0.05). However, the viability was significantly decreased at relatively high doses of UVB (50, 100mJ/cm) from 48 hours after UVB exposure (p<0.05). 2) In the melanocytes, the viability was decreased in all of the UVB exposure groups within 3 hours, and was significantly decreased in all of the UVB exposure groups at, 1 hour after UVB exposure (p<0.05). The viability was increased from 6 to 24 hours, which was significantly decreased at 100mJ/cm of UVB from 48 hours after UVB exposure (p<0.05). 2. The effects on viability according to the time after UVB exposure at the same dose of UUB In both cells, the viability was increased as time went by. The slopes of the viability curve gradually decreased according to the increment of UVB doses.
CONCLUSION
The viability of keratinocyte was decreased at 50mJ/cm of UVB which melanocyte did not show decrease. Melanocyte was more easily damaged than keratinocyte in relatively earlier time period after UVB exposure. These results suggest that the change of viability in cultured keratinocyte and melanocyte after UVB exposure at the dose of less than 100mJ/cm is related to the time course after UVB exposure as well as to the UVB dose.