Thp 1

Human primary epidermal keratinocytes (HEKn; ATCC, Manassas, VA, USA) and a human monocyte cell line (THP-1; ATCC) were used. The HEKn were cultivated with a growth cell medium (ATCC) and a keratinocyte growth kit (ATCC). The THP-1 were cultivated with high-glucose Dulbecco’s Modified Eagle Medium (Welgene, Gyeongsan-si, Korea) with 10% fetal bovine serum (Millipore, Burlington, MA, USA) and 1% penicillin/streptomycin (Welgene). All cells were maintained at 37 °C under 5% CO₂. For the in vitro model, the cells were exposed to UVB for 5 min, were RF irradiated (2 MHz, 10 W, 100 ms), and were cultured for 24 h.

Periodontal ligament stem cells (PDLSCs) and THP-1 were obtained from Cell Engineering for Origin (Seoul, Korea, http://www.cefobio.com/index.php?hCode=products_02_01_04) and American Type Culture Collection (Manassa, VA, USA), respectively. PDLSC was cultured in α-Minimum Essential Medium (MEM, Gibco, Grand Island, NY, USA) with 10% fetal bovine serum (FBS, Hyclone, Logan, UT, USA) and 1% antibiotics (Lonza, Allendale, NJ, USA). THP-1 cells were cultured in RPMI-1640 medium (Welgene, Seoul, Korea) supplemented with 10% FBS, 0.05 mM of 2-mercaptoethanol, and 1% antibiotics. The cells were maintained in a humidified atmosphere of 5% CO₂ at 37 °C. LPS from E. coli O111:B4 was purchased from Sigma-Aldrich (Gillingham, UK). Recombinant human IL-4 and IFN-γ was obtained from Cusabio technology (Houston, TX, USA). Recombinant human IL-13 was purchased from PEPRO tech (Rocky Hill, NJ, USA). FBS in all experiments was depleted EVs by ultracentrifugation at 100,000 g for 16 h.