Cell Lines and Cell Culture

Human foreskin fibroblasts (HFF-1) and Human umbilical vein endothelial cells (HUVECs) were obtained from Hunan Engineering Research Center of Skin Health and Disease (Changsha, China). HFF-1, HUVECs, and PKFs (Primary keloid fibroblasts) were cultured in Dulbecco’s Modified Eagle Medium (DMEM, BasalMedia, L110KJ) supplemented with 10% Fetal Bovine Serum (FBS, ExCell, FCS500) and 1% penicillin streptomycin solution (BI, 03–031-1B), which was also referred to as complete medium later, in a humidified incubator at 37°C with 5% CO₂. Cells were subcultured via trypsinization once reaching a confluency of ~90% . Passages of 2 to 6 cells were used for experiment.