About this Research Topic
Tissues and organs undergo structural and functional declines in the aging process, with a gradual decrease in regenerative ability. The hair follicle is a complex mini-organ that undergoes cyclic self-renewal during postnatal life, as the follicle contains stem cells that can be activated and silenced cyclically. Thus, it serves as an excellent model for studying regeneration. However, follicles gradually lose hairs and stem cells enter quiescence or differentiate into other skin epithelial lineages during aging. This process is largely influenced by intrinsic epigenetic status and extrinsic environmental factors which affect the hair follicle stem cell behavior during hair cycling. In aged mice, the expression of the activators is decreased and the expression of inhibitors is increased, leading to decreased or failed hair regeneration which may cause alopecia.
Today, 50 million men and 30 million women in the United States experience complete or partial hair loss. To advance our understanding of alopecia during aging process, we need to know:
1.) How stem cells are regulated at the intrinsic and extrinsic level including:
• The epigenetic regulation such as DNA methylation, chromatin and histone modification,
• Intra- and extra-follicular niches such as bulge, dermal papilla, and intradermal adipose,
• Systemic factors such as sex hormone, immune, nerve, blood and lymphatic vessels,
• External environment such as circadian rhythm and seasonal changes, etc.
2) How adult somatic cells can be motivated and trans-differentiate into a neonatal state to regenerate hair follicles during wound healing, namely wound-induced hair neogenesis.
3) How the stem or progenitor cells are regulated to form skin with appendages and to apply those principles toward medical use.
The aim of this Research Topic is to cover recent, promising and novel research trends in the skin aging, alopecia and stem cells. Areas to be covered in this Research Topic may include, but are not limited to:
• Aging of skin and appendages
• Physiological development and regeneration of skin and hair follicle
• Intrinsic and extrinsic regulation of hair follicle stem cells
• Wound-induced hair follicle neogenesis in the adult
• Tissue engineering-based hair follicle neogenesis
Keywords: Alopecia, Aging, Hair Follicle Stem Cell, Regeneration, Tissue Engineering
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