Nhems

Human HaCaT cells, HDFs, NHEKs, NHEMs and murine B16F10 cells were purchased from Thermo Fisher Scientific (Waltham, MA, USA). HaCaT cells, HDFs and B16F10 cells were cultured in Dulbecco’s modified Eagle’s medium (HyClone, GE Healthcare Life Sciences, Logan, UT, USA) with 10% fetal bovine serum (HyClone) and 1% penicillin–streptomycin (LS202-02, Welgene, Daegu, Korea). NHEKs and NHEMs were cultured in keratinocyte media (MEP1500CA, Gibco, Life Technologies, Carlsbad, CA, USA) and Medium 254 (M254500, Gibco) supplemented with human keratinocyte and melanocyte growth supplement (S0015, S0025, Gibco) and 1% penicillin-streptomycin at 37 °C in a humidified mixture of air (95% (v/v)) and 5% CO₂. For LTAP exposure, 5 × 10⁵ cells were seeded in 35 mm dishes and incubated for 24 h. Before LTAP exposure, the medium was exchanged for 2 mL of new growth medium. The lid was opened, and the dish was placed 1 cm below the part where argon gas was ejected from the LTAP generator, and exposed for 1, 3, or 5 min. After exposure for the indicated time, the dishes were placed in a CO₂ incubator at 37 °C.