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How do skin stem cells help replace the outer layers of skin?

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Diagram showing the locations of neural stem cells in brain regions such as the hippocampus and ventricles, and hematopoietic stem cells in the bone marrow and blood, with labeled illustrations of the brain, spinal cord, circulatory system, and skeleton. — stem cell Stem cells of neural and hematopoietic origin have tremendous potential in the development of therapies for certain diseases, such as diabetes and Parkinson disease. Neural stem cells occur in the spinal cord and in specific regions of the brain, and hematopoietic stem cells occur in the blood and bone marrow.

In the human epidermis, skin stem cells play a critical role in the continuous renewal of the skin's outer layers. This process occurs through the following mechanism:1

Location and Division: The epidermis contains keratinocytes, which are organized into layers. Stem cells are located specifically in the basal layer, which sits adjacent to the dermis. These stem cells undergo cell division to produce new cells.213
Maturation and Migration: As new keratinocytes are formed, they do not remain in the basal layer. Instead, they slowly migrate outward through the epidermis. During this migration, the cells mature and differentiate.2
Replacement and Shedding: As these mature cells reach the surface of the skin, they eventually die and are sloughed off (desquamated). This constant cycle ensures that the population of skin cells is maintained, balancing the loss of surface cells with the production of new ones from the basal stem cells.213

This highly regulated process of proliferation and migration is essential for maintaining the integrity and thickness of the skin.13