Merkel cells are long-lived cells whose production is stimulated by skin injury

Area of Science:

• Neurobiology
• Dermatology
• Cell Biology

Background:

• Mechanosensitive Merkel cells are crucial for touch sensation.
• The lifespan and origin of Merkel cells remain debated, impacting understanding of skin homeostasis and disease.

Purpose of the Study:

• To determine the lifespan and turnover rate of Merkel cells.
• To identify the precursor cells responsible for maintaining the Merkel cell population.
• To investigate the impact of mechanical stimuli on Merkel cell production.

Main Methods:

• Embryonic EdU (5-ethynyl-2'-deoxyuridine) labeling to track cell division and survival.
• Live imaging of Merkel cell dynamics in adult mice.
• Genetic cell ablation and fate-mapping experiments.
• Analysis of Merkel cell numbers during normal and induced hair cycles and after skin shaving.

Main Results:

• Merkel cells undergo terminal division during embryogenesis and persist into adulthood.
• Merkel cell production is infrequent during normal skin homeostasis and unaffected by hair cycles.
• Mild mechanical injury, like skin shaving, significantly enhances Merkel cell production.
• New Merkel cells in adult mice originate from surrounding touch dome keratinocytes.

Conclusions:

• Adult mouse Merkel cells are long-lived with rare replacement under normal conditions.
• Mechanical stimuli, such as repeated shaving, can induce Merkel cell proliferation.
• Keratinocytes are the source of new Merkel cells in adult mice, with implications for sensory neurobiology and Merkel cell carcinoma research.