Distinct types of stem cell divisions determine organ regeneration and aging in hair follicles.

Hair follicles, mammalian mini-organs that grow hair, miniaturize during aging, leading to hair thinning and loss. Here we report that hair follicle stem cells (HFSCs) lose their regenerative capabilities during aging owing to the adoption of an atypical cell division program. Cell fate tracing and cell division axis analyses revealed that while HFSCs in young mice undergo typical symmetric and asymmetric cell divisions to regenerate hair follicles, upon aging or stress, they adopt an atypical 'stress-responsive' type of asymmetric cell division.

Precision Medicine and the Practice of Trichiatry: Adapting the Concept.

Evidence-based medicine (EBM) aims for the ideal that healthcare professionals make conscientious, explicit, and judicious use of the best available evidence gained from the scientific method to clinical decision-making. It seeks to assess the strength of the evidence for benefits of diagnostic tests and treatments, using techniques from science, engineering, and statistics, such as the systematic review of medical literature, meta-analysis, risk-benefit analysis, and randomized controlled trials. The limited success rate of EBM therapies suggests that the complex nature of hair loss may be inadequately served by the present levels of evidence, and that physicians treating hair loss may have fallen short of adequately researching a robust evidence to underpin their practices.

Trichologist, Dermatotrichologist, or Trichiatrist? A Global Perspective on a Strictly Medical Discipline.

Few dermatologic problems carry as much emotional overtones as the complaint of hair loss. The best way to alleviate the distress related to hair loss is to effectively treat it. In fact, one of the oldest medical professions is the Egyptian physician who specialized on diseases of the head.

Guidelines for the diagnosis and treatment of male-pattern and female-pattern hair loss, 2017 version.

Male-pattern hair loss (MPHL, androgenetic alopecia) is a slowly progressive form of alopecia which begins after puberty. In 2010, we published the first Japanese edition of guidelines for the diagnosis and treatment of MPHL. It achieved the original goal of providing physicians and patients in Japan with evidence-based information for choosing efficacious and safe therapy for MPHL.

Hair follicle aging is driven by transepidermal elimination of stem cells via COL17A1 proteolysis.

Hair thinning and loss are prominent aging phenotypes but have an unknown mechanism. We show that hair follicle stem cell (HFSC) aging causes the stepwise miniaturization of hair follicles and eventual hair loss in wild-type mice and in humans. In vivo fate analysis of HFSCs revealed that the DNA damage response in HFSCs causes proteolysis of type XVII collagen (COL17A1/BP180), a critical molecule for HFSC maintenance, to trigger HFSC aging, characterized by the loss of stemness signatures and by epidermal commitment.

HSL Attenuates the Follicular Oxidative Stress and Enhances the Hair Growth in ob/ob Mice.

We demonstrated enhanced hair regeneration following topical administration of N-(3-oxododecanoyl)-l-homoserine lactone (HSL) in ob/ob mice. The ob/ob mice showed delayed hair regeneration (more than 6 wk) after depilation, which rapidly induced transition to anagen in the hair cycle in wild-type mice. Vehicle and HSL solutions were applied to the depilated dorsal skin of ob/ob mice.

Polymorphic CAG repeat numbers in the androgen receptor gene of female pattern hair loss patients.

Female pattern hair loss (FPHL) is frequently referred to as female androgenetic alopecia (FAGA). However, the role of androgen in this type of hair loss remains uncertain. We previously reported greater therapeutic efficacy of finasteride in Japanese male androgenetic alopecia (MAGA) patients in cases where the CAG repeats of the androgen receptor (AR) gene were short.

Androgen receptor co-activator Hic-5/ARA55 as a molecular regulator of androgen sensitivity in dermal papilla cells of human hair follicles.

Androgen site-specifically affects human hair growth after puberty through androgen receptors in the dermal papilla, which transactivate target genes acting in conjunction with co-activators. To examine the regulation of androgen sensitivity in hair follicles, we focused on androgen receptor co-activator Hic-5/ARA55. Its interaction with transfected androgen receptor in beard dermal papilla cells was confirmed with mammalian two-hybrid assays.