Single-cell transcriptomic reconstruction of the human hair cycle: Capturing the temporal dynamics of skin tissue remodeling

To investigate dynamic molecular and cellular changes associated with skin tissue remodeling during the human hair cycle, we aimed to obtain single-cell RNA sequencing (scRNA-seq) data from different hair cycle phases. We obtained scRNA-seq from randomly dissected human skin samples containing a single hair. Nineteen small skin pieces with a single hair were dissected from three female donors (single-hair samples). For comparison, we also collected three small skin pieces with no hairs from the same donors (non-hair samples). We enzymatically removed the interfollicular epidermis to focus our analysis on hair follicles and their surrounding dermis, which are the main areas of hair cycle-dependent tissue remodeling. Overall design: We obtained human abdominal skin tissues from three healthy female donors who underwent a cosmetic surgery: donor A (40 years old), donor B (37 years old), and donor C (36 years old). After dissecting 19 single-hair samples (seven samples from each of donors A and B, and five samples from donor C) as well as three non-hair samples (one sample from each of the three donors), each sample was initially treated with dispase to remove the interfollicular epidermis and then treated with a collagenase and hyaluronidase mixture to make a single-cell suspension. Each sample was subjected to scRNA-seq using the 10X Genomics Chromium system (v3 chemistry). Cell quality control was performed for all 22 scRNA-seq data, and a total of 44,601 cells that passed our quality standards were integrated and used for subsequent analysis.