The biology of hair follicles.

Department of Dermatology, University Hospital Eppendorf, University of Hamburg, Germany.
New England Journal of Medicine (Impact Factor: 54.42). 09/1999; 341(7):491-7. DOI: 10.1056/NEJM199908123410706
Source: PubMed


Available from: Ralf Paus, Apr 17, 2015
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    ABSTRACT: Alopecia is an exceedingly prevalent problem effecting men and women of all ages. The standard of care for alopecia involves either transplanting existing hair follicles to bald areas or attempting to stimulate existing follicles with topical and/or oral medication. Yet, these treatment options are fraught with problems of cost, side effects, and, most importantly, inadequate long-term hair coverage. Innovative cell-based therapies have focused on the dermal papilla cell as a way to grow new hair in previously bald areas. However, despite this attention, many obstacles exist, including retention of dermal papilla inducing ability and maintenance of dermal papilla productivity after several passages of culture. The use of adipocyte lineage cells, including adipose-derived stem cells, has shown promise as a cell-based solution to regulate hair regeneration and may help in maintaining or increasing dermal papilla cells inducing hair ability. In this review, we highlight recent advances in the understanding of the cellular contribution and regulation of dermal papilla cells and summarize adipocyte lineage cells in hair regeneration.
    01/2014; 5:2041731414556850. DOI:10.1177/2041731414556850
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    ABSTRACT: BP201, porcine lung tissue-derived phospholipids, consists of phosphatidylcholine as a major phospholipid species. BP201 promoted hair growth after application onto the shaved backs of BALB/c and C3H mice. Its effect was enhanced when applied together with minoxidil (MNX) in C3H mice. When the tissue specimens prepared from the shaved skins of BP201-treated and control mice were microscopically examined, the total numbers of hair follicles in both anagen and telogen phases of BP201-treated mice were significantly higher than those of control mice. The numbers of hair follicles in the anagen phase of BP201-treated mice were also higher than those of control mice. In combination with MNX, BP201 further increased the total number of hair follicles, but did not alter the percentage of hair follicles in the anagenic phase. BP201 also increased the proliferation of human hair follicle dermal papilla cells. Collectively, BP201 possesses hair growth promoting potential, which would suggest its use singly or in combination for hair growth products.
    Biomolecules and Therapeutics 03/2015; 23(2):174-179. DOI:10.4062/biomolther.2014.108 · 0.84 Impact Factor
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    ABSTRACT: The hair follicle (HF) represents a prototypic ectodermal–mesodermal interaction system in which central questions of modern biology can be studied. A unique feature of these stem-cell-rich mini-organs is that they undergo life-long, cyclic transformations between stages of active regeneration (anagen), apoptotic involution (catagen), and relative proliferative quiescence (telogen). Due to the low proliferation rate and small size of the HF during telogen, this stage was conventionally thought of as a stage of dormancy. However, multiple lines of newly emerging evidence show that HFs during telogen are anything but dormant. Here, we emphasize that telogen is a highly energy-efficient default state of the mammalian coat, whose function centres around maintenance of the hair fibre and prompt responses to its loss. While actively retaining hair fibres with minimal energy expenditure, telogen HFs can launch a new regeneration cycle in response to a variety of stimuli originating in their autonomous micro-environment (including its stem cell niche) as well as in their external tissue macro-environment. Regenerative responses of telogen HFs change as a function of time and can be divided into two sub-stages: early ‘refractory’ and late ‘competent’ telogen. These changing activities are reflected in hundreds of dynamically regulated genes in telogen skin, possibly aimed at establishing a fast response-signalling environment to trauma and other disturbances of skin homeostasis. Furthermore, telogen is an interpreter of circadian output in the timing of anagen initiation and the key stage during which the subsequent organ regeneration (anagen) is actively prepared by suppressing molecular brakes on hair growth while activating pro-regenerative signals. Thus, telogen may serve as an excellent model system for dissecting signalling and cellular interactions that precede the active ‘regenerative mode’ of tissue remodeling. This revised understanding of telogen biology also points to intriguing new therapeutic avenues in the management of common human hair growth disorders.
    Biological Reviews 11/2014; DOI:10.1111/brv.12151 · 9.79 Impact Factor