Ultraviolet-C-induced apoptosis protected by 635-nm laser irradiation in human gingival fibroblasts.

OBJECTIVE

The purpose of this study was to examine the protection afforded by 635-nm irradiation against ultraviolet (UV)-C-induced apoptosis in primary human gingival fibroblasts (hGFs).

BACKGROUND DATA

UV irradiation is known to cause photoaging and cellular apoptosis of skin cells and is considered to be one of the leading causes of skin carcinogenesis.

MATERIALS AND METHODS

To induce apoptosis, UV-C (100 mJ/cm2) was used to irradiate hGFs. To protect them from apoptosis, pretreatment with 635-nm irradiation was performed for 1 h immediately after cell plating 36 or 48 h before UV-C irradiation. The light source used for irradiation was a continuous-wave 635-nm LED laser emitting at 1 mW/cm2. Experimental samples were selected 24 h after UV-C irradiation. To measure the numbers of apoptotic cells, MTT assay and flow cytometric analyses were performed. For histomorphologic findings, Diff-Quick staining was carried out. Also, the activities and mRNA expression of caspase-3, caspase-8, and caspase-9 were measured.

RESULTS

In the present study, the number of apoptotic cells declined in the cells that were pretreated with 635-nm light irradiation in a time-dependent manner. In addition, the activities and mRNA expression of caspase-3, caspase-8, and caspase-9 were significantly recovered by pretreatment with 635-nm irradiation.

CONCLUSION

These results suggest that 635-nm visible light irradiation may be used as a protective tool to prevent UV-C-induced apoptosis.