Dpc growth medium

Primary human follicle DPCs (55-year-old, Caucasian, females) isolated from the human dermis of the scalp were purchased from PromoCell (Heidelberg, Germany) and grown in DPC growth medium with supplement mix (PromoCell) and 1% penicillin-streptomycin (10,000 U/mL; Gibco; Grand Island, NE, USA) at 37 °C in a 5% CO₂ humidified atmosphere. At 70% confluency, the cells were sub-cultured according to the PromoCell subcultivation protocol using the DetachKit (2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid (HEPES) buffer, trypsin/ethylenediaminetetraacetic acid (EDTA), and trypsin neutralization solution; PromoCell). Passages 3–5 of DPCs were used in this study.

Individual HFs were generously provided by Dr. Jino Kim (New Hair Institute, Seoul, Republic of Korea). All biopsies were performed with full written consent from the patients. Furthermore, the ethical and scientific committees of the participating institution confirmed that the current study adhered to the ethical standards outlined in the 1964 Declaration of Helsinki.
Human DPCs were microdissected from the HFs under a stereomicroscope. The lower part of the bulb was inverted using forceps and needles, and any remaining epithelium-derived tissue was removed to expose the DP. The DP was then attached to a 35 mm culture dish (CellBIND^®, Corning, New York, NY, USA) and cultured without disturbance for ten days. DPCs were cultured in DPC growth medium (PromoCell, Heidelberg, Germany) with 1% antibiotic-antimycotic (Thermo Fisher Scientific, Waltham, MA, USA).
Human DFs were cultured in Dulbecco’s modified Eagle’s medium (DMEM; Gibco, Grand Island, NY, USA) with 10% fetal bovine serum (FBS; Hyclone, Logan, UT, USA) and maintained in a humidified incubator at 37 °C with 5% CO₂.