Single-Cell RNA Sequencing Reveals Age-Related Changes in Epidermal Cell Populations and Interactions

Utilizing single-cell RNA sequencing, we analyzed epidermal cells from young (20-30 years old) and elderly (60+ years old) subjects. Our findings reveal that aged epidermis exhibits increased expression of inflammation-related genes and pathways associated with nonsense-mediated decay, oxidative phosphorylation, and apoptotic signaling, predominantly in keratinocytes. Furthermore, we observed a reduction in cell-to-cell interactions from the proliferative basal and granular layers to other epidermal cells. This study underscores how epidermal aging primarily impacts keratinocytes and diminishes intercellular interactions, unveiling a novel mechanism of skin aging. Excess upper eyelid skin was obtained from three young (age range: 20-30 years) and three older (age range: 60-80 years) patients undergoing double eyelid surgery or elective blepharoplasty for ptosis at Kyoto University Hospital and an affiliated plastic surgery clinic. Patients receiving systemic immunotherapy or anticancer agents and those with skin diseases were excluded. For the skin samples, the epidermis was separated using dispase, and epidermal suspension was prepared using 0.25% trypsin/EDTA. The cells were used to prepare a library using the 10X Chromium Next GEM Single Cell 3' Kit, and scRNA-seq was performed. *************************************************************** Raw files for human/patient samples were not submitted to GEO due to concerns about submitting personally identifiable sequence data for open access. ***************************************************************