First Demonstration of New Hair Follicle Generation
May 17, 2007 - 8:25:51 AM
, Reviewed by: Dr. Ankush Vidyarthi
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A better understanding of this process could lead to novel treatments for hair loss, other skin and hair disorders, and wounds.
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Level of Evidence
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2c - Outcomes Research
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Key Points of this article
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Researchers at the University of Pennsylvania School of Medicine have found that hair follicles in adult mice regenerate by re-awakening genes once active only in developing embryos.
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These findings provide unequivocal evidence for the first time that, like other animals such as newts and salamanders, mammals have the power to regenerate.
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Main results
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In this study, researchers found that wound healing in a mouse model created an âembryonic windowâ of opportunity. Dormant embryonic molecular pathways were awakened, sending stem cells to the area of injury. Unexpectedly, the regenerated hair follicles originated from non-hair-follicle stem cells.
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WNT Signaling Pathway
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The wnt signaling pathway describes a complex network of proteins most well known for their roles in embryogenesis and cancer, but also involved in normal physiological processes in adult animals.
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Epidemiology
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The average human head has about 100,000 hair follicles. Each follicle can grow about 20 individual hairs in a person's lifetime. Average hair loss is about 100 strands a day. Incidence of pattern baldness varies from population to population based on genetic background. Environmental factors do not seem to affect this type of baldness greatly. One large scale study in Maryborough, in central Victoria (Australia) showed the prevalence of mid-frontal hair loss increases with age and affects 57% of women and 73.5% of men aged 80 and over.
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By University of Pennsylvania School of Medicine,
[RxPG] Researchers at the University of Pennsylvania School of Medicine have found that hair follicles in adult mice regenerate by re-awakening genes once active only in developing embryos. These findings provide unequivocal evidence for the first time that, like other animals such as newts and salamanders, mammals have the power to regenerate.
âWe showed that wound healing triggered an embryonic state in the skin which made it receptive to receiving instructions from wnt proteins,â says senior author George Cotsarelis, MD, Associate Professor of Dermatology. âThe wnts are a network of proteins implicated in hair-follicle development.â
Researchers previously believed that adult mammal skin could not regenerate hair follicles. In fact, investigators generally believe that mammals had essentially no true regenerative qualities. The liver can regenerate large portions, but it is not de novo regeneration; some of the original liver has to remain so that it can regenerate.
In this study, researchers found that wound healing in a mouse model created an âembryonic windowâ of opportunity. Dormant embryonic molecular pathways were awakened, sending stem cells to the area of injury. Unexpectedly, the regenerated hair follicles originated from non-hair-follicle stem cells.
âWeâve found that we can influence wound healing with wnts or other proteins that allow the skin to heal in a way that has less scarring and includes all the normal structures of the skin, such as hair follicles and oil glands, rather than just a scar,â explains Cotsarelis.
By introducing more wnt proteins to the wound, the researchers found that they could take advantage of the embryonic genes to promote hair-follicle growth, thus making skin regenerate instead of just repair. Conversely by blocking wnt proteins, they also found that they could stop the production of hair follicles in healed skin.
Increased wnt signaling doubled the number of new hair follicles. This suggests that the embryonic window created by the wound-healing process can be used to manipulate hair-follicle regeneration, leading to novel ways to treat hair loss and hair overgrowth.
These findings go beyond just a possible treatment for male-pattern baldness. If researchers can effectively control hair growth, then they could potentially find cures for people with hair and scalp disorders, such as scarring alopecia where the skin scars, and hair overgrowth.
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Growth of regenerated hair follicles over 45 days. Arrows indicate hair shaft. The bulge is the area from which new hair shafts arise. The regenerated follicles possess normal stem cells and function normally by producing a hair shaft and cycling through growth phases. Image Credit: George Cotsarelis, MD, University of Pennsylvania School of Medicine; Nature |
| Funding information and declaration of competing interests:
This research was funded in part by the National Institute of Arthritis, Musculoskelatal and Skin Diseases and the Pennsylvania Department of Health. Other co-authors in addition to Cotsarelis are Mayumi Ito, Zaixin Yang, Thomas Andl, Chunhua Cui, Noori Kim, and Sarah E. Millar, all from Penn.
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About Dr. Ankush Vidyarthi
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This news story has been reviewed by Dr. Ankush Vidyarthi before its publication on RxPG News website. Dr. Ankush Vidyarthi, MBBS is a senior editor of RxPG News. He is also managing the marketing and public relations for the website. In his capacity as the senior editor, he is responsible for content related to mental health and psychiatry. His areas of special interest are mass-media and psychopathology.
RxPG News is committed to promotion and implementation of Evidence Based Medical Journalism in all channels of mass media including internet.
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Additional information about the news article
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Cotsarelis and Ito are listed as inventors on a patent application related to hair-follicle neogenesis and owned by the University of Pennsylvania. Cotsarelis also serves on the scientific advisory board and has equity in Follica, a start-up company that has licensed the patent from the University of Pennsylvania. Cotsarelis was also a co-founder of Follica.
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