Selective inhibition of melanoma and basal cell carcinoma cells by short-lived species, long-lived species, and electric fields generated from cold plasma

This study investigated the effects of atmospheric-pressure cold plasma-generated short-lived species, long-lived species, and electric fields on skin melanoma and basal cell carcinoma cells (A2058 cells, BCC cells) and normal cells (BJ cells, Detroit 551 cells). Previous studies showed that either plasma-generated species or electric fields can cause cell apoptosis, but the effects of plasma-generated short-lived species, long-lived species, and electric fields on skin cancer cells have not been fully investigated yet. In this research, we adjusted the distance between the cells and plasma-medium interface to treat the cells with different concentrations of short-lived species such as •OH. A phosphate-buffered saline (PBS)-agarose gel was used to cover the PBS solution surface to prevent the plasma-generated species entering the liquid, ensuring the cells were treated with the electric field only. We compared cell viability and apoptosis to determine which factor had a greater impact on the cells. The results showed that the penetration depth of •OH in PBS reached ∼0.6 mm. With our experimental setup, long-lived species and electric field generated by the plasma did not have significant effects on either the normal or cancer skin cells. By contrast, the short-lived species significantly inhibited the viability and induced apoptosis of skin cancer cells but not the normal skin cells. By comparing the effects of plasma-generated short-lived species, long-lived species, and electric field on skin cancer cells (A2058, BCC) and normal cells (BJ, Detroit 551), this study verified that short-lived species in plasma inhibit skin cancer cells more than normal skin cells.