Human Skin Stem Cells and the Aging Process

The document discussed how skin integrity in healthy individuals is maintained by epidermal stem cells, which self-renew and generate differentiated cells. Despite the presence of senescence markers in aged skin, the number of epidermal stem cells remains normal throughout life. Skin aging is attributed to impaired stem cell mobilization or a reduced number of responsive stem cells. Various distinct stem cell populations exist in the skin, including multipotent stem cells in the hair follicle bulge, which support hair follicle regeneration and epidermal repair. Bulge cells can form hair follicles, interfollicular epidermis, and sebaceous glands, and in murine models, they can also become non-epithelial cells. Dermal stem cells, representing 0.3% of human dermal foreskin fibroblasts, and progenitor cells in the sebaceous gland, which can differentiate into sebocytes and interfollicular epidermis, were also identified. The self-renewal and multi-lineage differentiation capabilities of skin stem cells make them valuable for studying the aging process and for applications in regenerative medicine, tissue repair, gene therapy, and cell-based therapies.