Hair Physiology and Its Disorders

May 2008 in “ Drug Discovery Today: Disease Mechanisms ”

Kevin J. McElwee, Rodney Sinclair

From the encyclopedia

autoimmune disorder causing patchy hair loss

Hair transplantation moves DHT-resistant follicles from a donor area (back and sides of the scalp) into thinning or bald areas. The transplanted hair is generally permanent, though surrounding native hair can keep thinning.

Studysummary This review discusses the physiology of hair follicles, their disorders, and the principles behind developing treatments, reporting no new results.

Our plain-language summary. Not medical advice or a treatment recommendation. Consult a qualified healthcare professional before changing treatment. Full disclaimer

The 2008 document reviews the complex structure and growth cycles of hair follicles, including the anagen, catagen, telogen, and exogen phases, and how deviations in these cycles and follicle characteristics can lead to hair disorders. It discusses congenital disorders like atrichia and Marie Unna hypotrichosis, which are genetic and prevent hair follicles from entering new growth cycles, as well as acquired disorders such as telogen effluvium, cicatricial alopecia, androgenetic alopecia, and alopecia areata, which involve changes in hair growth cycle parameters, hair follicle density, and immune system interference. Treatments focus on modulating hair follicle density, size, and growth cycle, with potential strategies including drug therapies, hair follicle replication, transplantation, and emerging cell-based therapies and genetic manipulation. Despite the significant commercial potential, the pharmaceutical industry has not heavily invested in this area due to the complexity of hair follicle biology, but biotech companies led by academic scientists are exploring new treatments. Research in this field is supported by various foundations and research councils.

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Research cited in this study

17 / 17 results

research Hair Loss in Women

129 citations , October 2007 in “The New England Journal of Medicine”

This article discusses the evaluation and management of a 45-year-old woman with diffuse scalp-hair loss and reports no new clinical findings.

research Androgenetic Alopecia: Clinical Features, Classification, and Treatments

103 citations , June 2007 in “Endocrinology and Metabolism Clinics of North America”

This article discusses treatment options for androgenetic alopecia, noting that medical interventions like finasteride and minoxidil can halt and partially reverse hair loss in mild to moderate cases, especially when combined with surgery.

research Wnt-Dependent De Novo Hair Follicle Regeneration in Adult Mouse Skin After Wounding

829 citations , May 2007 in “Nature”

Hair follicles can regrow in wounded adult mouse skin using a process like embryo development.

research Hair Follicles and Their Role in Skin Health

16 citations , December 2006 in “Expert Review of Dermatology”

This review discusses the multifaceted roles of hair follicles in skin health, including potential contributions to skin neoplasias, and reports no new results.

research Modulation of Hair Growth with Small Molecule Agonists of the Hedgehog Signaling Pathway

113 citations , September 2005 in “Journal of Investigative Dermatology”

This study found that a topical hedgehog agonist can stimulate hair growth by promoting the transition from the resting to growth phase of the hair cycle in adult mouse skin.

research Molecular Principles of Hair Follicle Induction and Morphogenesis

479 citations , January 2005 in “BioEssays”

This review introduces the morphological and molecular principles of hair follicle development but reports no new experimental results, focusing on recent insights and forming a working hypothesis.

research Transient Activation of Beta-Catenin Signaling in Adult Mouse Epidermis Induces New Hair Follicles, Continuous Activation Maintains Tumors

335 citations , March 2004 in “Development”

This study found that continuous β-catenin signaling in adult mouse epidermis can reprogram hair follicles to form benign tumors, which regress after the signaling is discontinued.

Hair Growth Induction by the Tellurium Immunomodulator AS101: Association with Delayed Terminal Differentiation of Follicular Keratinocytes and Ras-Dependent Up-Regulation of KGF Expression

research Hair Growth Induction by the Tellurium Immunomodulator AS101: Association with Delayed Terminal Differentiation of Follicular Keratinocytes and Ras-Dependent Up-Regulation of KGF Expression

51 citations , December 2003 in “The FASEB Journal”

This study reports that AS101 induced hair growth in mice and suggests potential for treating chemotherapy-induced alopecia in humans, which was observed in case report studies with three adolescents.

Cultured Peribulbar Dermal Sheath Cells Can Induce Hair Follicle Development and Contribute to the Dermal Sheath and Dermal Papilla

research Cultured Peribulbar Dermal Sheath Cells Can Induce Hair Follicle Development and Contribute to the Dermal Sheath and Dermal Papilla

208 citations , December 2003 in “Journal of Investigative Dermatology”

This study found that dermal papilla and peribulbar dermal sheath cup cells in mice can both induce hair follicle formation, suggesting they may have similar functional roles in hair growth.

research Molecular Mechanisms Regulating Hair Follicle Development

854 citations , February 2002 in “The journal of investigative dermatology/Journal of investigative dermatology”

This review summarizes recent advances in understanding the molecular mechanisms of hair follicle formation and discusses potential future clinical applications for treating hair loss and skin tumors, but it reports no new clinical results.

research Kenogen

90 citations , January 2002 in “Dermatology”

This study describes the kenogen phase, where hair follicles rest after shedding, and finds its duration and frequency are greater in individuals with androgenetic alopecia, potentially contributing to baldness.

research Induction of the Hair Growth Phase in Postnatal Mice by Localized Transient Expression of Sonic Hedgehog

231 citations , October 1999 in “Journal of Clinical Investigation”

This study found that administering an adenovirus vector to increase Sonic hedgehog gene expression in mouse skin accelerated the transition of hair follicles into the growth phase, promoting hair growth.

research The Psychosocial Consequences of Androgenetic Alopecia: A Review of the Research Literature

180 citations , September 1999 in “British Journal of Dermatology”

This review discusses the psychological and social impacts of androgenetic alopecia and suggests that medical treatments can have some positive psychological effects, highlighting the condition's moderate stress and impact on body image.

research Splitting Hairs: Molecular Mechanisms of Hair and Feather Development

158 citations , November 1998 in “Cell”

β-catenin affects hair growth and can lead to tumors, needing more research for better understanding.

research Fortnightly Review: Male Pattern Androgenetic Alopecia

179 citations , September 1998 in “BMJ”

This article reviews the pathogenesis, genetic basis, and recent treatment breakthroughs for androgenetic alopecia but reports no new clinical findings.

research Hair Regrowth

118 citations , April 1998 in “Dermatologic Clinics”

This review discusses the advancements in understanding and treating androgenetic alopecia and alopecia areata but reports no clinical findings; the authors emphasize the need for further research on molecular control mechanisms.

research The Secret Life of the Hair Follicle

745 citations , February 1992 in “Trends in genetics”

This article describes the potential role of various growth factors and molecules in regulating mammalian hair follicle development but does not present new experimental results.