Exp Dermatol. 2012 Dec;21(12):956-8. doi: 10.1111/exd.12033.

Extracellular histones inhibit hair shaft elongation in cultured human hair follicles and promote regression of hair follicles in mice.

Shin SH, Joo HW, Kim MK, Kim JC, Sung YK.

Abstract

Release of histone H4 in rat vibrissa dermal papilla (DP) cells exposed to sub-toxic dose of colchicines has been recently reported. In addition, exposure to histone H4 has been reported to result in inhibited proliferation and reduced alkaline phosphatase (ALP) activity of cultured vibrissa DP cells. These findings prompted us to investigate the role of extracellular histones in hair growth using cultured human hair follicles and hair cycling using back skin of mice. We report here that exposure of cultured hair follicles to histone H4 and H2A resulted in significant inhibition of elongation of hair shafts, decreased expression of IGF-1 and decreased expression and activity of ALP. Injection of histones into hypodermis of mice during anagen resulted in premature onset of catagen. Findings of the current study provide strong evidence suggesting the inhibitory role of extracellular histones in hair growth.

© 2012 John Wiley & Sons A/S.

Int J Mol Sci. 2015 Feb 5;16(2):3579-98. doi: 10.3390/ijms16023579.

Analysis of dermal papilla cell interactome using STRING database to profile the ex vivo hair growth inhibition effect of a vinca alkaloid drug, colchicine.

Hsia CW1, Ho MY2, Shui HA3, Tsai CB4,5, Tseng MJ6.

Author information

Abstract

Dermal papillae (DPs) control the formation of hair shafts. In clinical settings, colchicine (CLC) induces patients' hair shedding. Compared to the control, the ex vivo hair fiber elongation of organ cultured vibrissa hair follicles (HFs) declined significantly after seven days of CLC treatment. The cultured DP cells (DPCs) were used as the experimental model to study the influence of CLC on the protein dynamics of DPs. CLC could alter the morphology and down-regulate the expression of alkaline phosphatase (ALP), the marker of DPC activity, and induce IκBα phosphorylation of DPCs. The proteomic results showed that CLC modulated the expression patterns (fold>2) of 24 identified proteins, seven down-regulated and 17 up-regulated. Most of these proteins were presumably associated with protein turnover, metabolism, structure and signal transduction. Protein-protein interactions (PPI) among these proteins, established by Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database, revealed that they participate in protein metabolic process, translation, and energy production. Furthermore, ubiquitin C (UbC) was predicted to be the controlling hub, suggesting the involvement of ubiquitin-proteasome system in modulating the pathogenic effect of CLC on DPC.

PMID:

 

25664862

 

[PubMed - in process] 

Free full text

J Tissue Eng Regen Med. 2015 Feb 17. doi: 10.1002/term.1997. [Epub ahead of print]

Enhanced restoration of in situ-damaged hairs by intradermal transplantation of trichogenous dermal cells.

Yamao M1, Inamatsu M, Okada T, Ogawa Y, Tateno C, Yoshizato K.

Author information

Abstract

We developed a nude rat model for determining the capacity of trichogenous cells to restore in vivo-damaged hair follicles (HFs). A surgical scalpel was inserted into the rat's dermis to generate the in vivo-damaged pelage HFs, the HFs whose lower parts were lost, but the upper parts containing sebaceous and bulge regions remained intact. Dermal papilla cells (DPCs) and dermal sheath cells (DSCs) from EGFP transgenic rat vibrissae were propagated in culture, and each alone (DPC or DSC) or a mixture (DPC/DSC) was transplanted into the intradermal path made by a scalpel. It was found that the in vivo-damaged HFs had hair self-restoration ability, and the transplanted trichogenic dermal cells prominently enhanced this ability, DPC/DSC transplants being more effective in enhancement than DPC or DSC alone. The restored bulbs contained EGFP-positive cells, shed their original straight shafts, generated new shafts, and further developed into hairs with a sebaceous gland and bulge structures by ~6 weeks post-transplantation. Compared to the preceding animal models, this model is less invasive, requires fewer donor cells and allows repeated operations with higher reproducibility and accuracy. The present study suggests that conditions causing in situ-damaged HFs, such as androgenic alopecia, in which HFs are damaged and miniaturized, can be restored by functional trichogenous dermal cell transplantation therapy. Copyright © 2015 John Wiley & Sons, Ltd.

Copyright © 2015 John Wiley & Sons, Ltd.

Exp Dermatol. 2015 Feb 24. doi: 10.1111/exd.12672. [Epub ahead of print]

PDGF signalling in the dermis and in dermal condensates is dispensable for hair follicle induction and formation.

Rezza A1, Sennett R, Tanguy M, Clavel C, Rendl M.

Author information

Abstract

Embryonic hair follicle (HF) induction and formation is dependent on signalling crosstalk between the dermis and specialized dermal condensates on the mesenchymal side and epidermal cells and incipient placodes on the epithelial side, but the precise nature and succession of signals remain unclear. Platelet-derived growth factor (PDGF) signalling is involved in the development of several organs and the maintenance of adult tissues, including HF regeneration in the hair cycle. As both PDGF receptors, PDGFRα and PDGFRβ, are expressed in embryonic dermis and dermalcondensates, we explored in this study the role of PDGF signalling in HF induction and formation in the developing skin mesenchyme. We conditionally ablated both PDGF receptors with Tbx18Cre in early dermal condensates before follicle formation, and with Prx1-Cre broadly in the ventral dermis prior to HF induction. In both PDGFR double mutants, HF induction and formation ensued normally, and the pattern of HF formation and HF numbers were unaffected. These data demonstrate that mesenchymal PDGF signalling, either in the specialized niche or broadly in the dermis, is dispensable for HF induction and formation.

Mapping the expression of epithelial hair follicle stem and progenitor cell-related transcription factors LHX2 and SOX9 in the human hair follicle. Purba TS1, Haslam IS, Shahma

Exp Dermatol. 2015 Mar 23. doi: 10.1111/exd.12700. [Epub ahead of print]

Mapping the expression of epithelial hair follicle stem and progenitor cell-related transcription factors LHX2 and SOX9 in the human hair follicle.

Purba TS1, Haslam IS, Shahmalak A, Bhogal RK, Paus R.

Author information

Abstract

In the murine hair follicle (HF) the transcription factors LHX2 and SOX9 are involved with epithelial hair follicle stem cell (eHFSC) self-renewal and the maintenance of eHFSC niche characteristics. However, the exact expression patterns of LHX2 and SOX9 in human HF are unclear. We have quantitatively mapped the localisation of known human eHFSC markers keratin 15 (K15) and keratin 19 (K19) in the ORS of male occipital scalp anagen HFs, and related this to the localisation of LHX2 and SOX9 protein expression. As expected, K15+ and K19+ cells represented two distinct progenitor cell populations in the bulge and in the proximal bulb ORS (pbORS). Interestingly, cell fluorescence for K19 was significantly stronger within the pbORS versus the bulge, and vice versa for K15, describing a hitherto unrecognised differential expression pattern. LHX2 and SOX9 expressing cells were distributed throughout the ORS, including the bulge, but were not restricted to it. SOX9 expression was most prominent in the ORS immediately below the human bulge whereas LHX2+ cells were similarly distributed between the sub-bulge and pbORS, i.e. compartments not enriched with quiescent eHFSCs. During catagen development, the intensity of LHX2 and SOX9 protein expression increased in the proximal HF epithelium. Double-immunostaining showed that SOX9+ cells in human anagen HF epithelium generally do not express K15, K19 or Lhx2. This data suggests that LHX2 and SOX9 may highlight distinct epithelial progenitor cell populations, in addition to K15+ or K19+ cells, that could play an important role in the maintenance of human HF epithelium. This article is protected by copyright. All rights reserved.

This article is protected by copyright. All rights reserved.

J Dermatol. 2015 Mar 26. doi: 10.1111/1346-8138.12857. [Epub ahead of print]

Trichoscopic findings of androgenetic alopecia and their association with disease severity.

Hu R1, Xu F, Han Y, Sheng Y, Qi S, Miao Y, Yang Q.

Author information

Abstract

Trichoscopy is a novel tool for the diagnosis of hair loss disorders such as androgenetic alopecia (AGA), but there are still few reports on the association between trichoscopic findings and disease severity, especially in the Chinese population. A case-control observational study was conducted to observe the trichoscopic findings of AGA and to evaluate their relationship with disease severity. Trichoscopic examination was performed with a handheld dermoscope on 750 Chinese male AGA (MAGA) and 200 female AGA (FAGA) patients, along with 100 male and 50 female normal controls. Trichoscopically, AGA was featured by hair shaft thickness heterogeneity (HSTH), brown peripilar sign (BPPS), white peripilar sign (WPPS), yellow dots, pinpoint white dots, focal atrichia and scalp pigmentation. No significant difference in the occipital area was found between AGA and controls (P > 0.05). HSTH of more than 20% was demonstrated in all MAGA patients, and HSTH of more than 10% was seen in all FAGA patients. WPPS, yellow dots, pinpoint white dots, focal atrichia and scalp pigmentation were positively related to severity of disease (P < 0.05), while BPPS was the contrary (P < 0.05). HSTH is an essential criterion for diagnosing AGA. BPPS was more common in early AGA. However, WPPS, yellow dots, pinpoint white dots, focal atrichia and scalp pigmentation are positively correlated with advanced AGA.

© 2015 Japanese Dermatological Association.

Clin Exp Dermatol. 2015 Mar 26. doi: 10.1111/ced.12650. [Epub ahead of print]

Effect of mycophenolic acid on proliferation of dermal papilla cells and induction of anagenhair follicles.

Jeong KH1, Joo HJ, Kim JE, Park YM, Kang H.

Author information

Abstract

BACKGROUND:

Mycophenolic acid (MPA), the active metabolite of mycophenolate mofetil, has anti-inflammatory effects, and is widely used as an immunomodulatory agent. However, the beneficial effect of MPA in hair-loss disorders is not fully understood.

AIM:

To investigate the direct effect of MPA on dermal papilla cells (DPCs), and to examine the hair growth-stimulating effects of MPA topically applied to mouse skin.

METHODS:

Cultured DPCs were treated with various concentrations of MPA and analysed by MTT assay. Expressions ofhair growth-related genes, including Wnt/β-catenin pathway-related genes and cellular apoptosis-regulating genes, such as Bcl-2, Bax and caspase-9, were examined using reverse transcription (RT)-PCR and western blotting. The Wnt/extracellular signal-regulated kinase (ERK) pathway was analysed by western blotting. The effect of topically applied MPA on anagenhair follicle induction after microneedle (MN) treatment with or without minoxidil (MXD) was evaluated by histopathological examination and RT-PCR.

RESULTS:

MPA showed a promoting effect on DPC proliferation, which was associated with increased Axin2 transcription levels. In addition, phospho-ERK protein was detected in the MPA-treated DPCs. An increased Bcl-2/Bax transcript ratio contributed to cellular proliferation, and this was maintained in the MPA-treated environment. Topically applied MPA promoted anagen hair follicle induction in mice. The effect of MPA on hair follicles was compatible with that of MXD, and this effect was accelerated by MN treatment.

CONCLUSIONS:

MPA promotes proliferation of DPCs and induction of anagen hair follicles in mice. This finding raises the possibility that MPA could be used as a treatment option for hair-loss disorders.

© 2015 British Association of Dermatologists.

The Androgenic Alopecia Protective Effects of Forsythiaside-A and the Molecular Regulation in a Mouse Model.

Shin HS1, Park SY, Song HG, Hwang E, Lee DG, Yi TH.

Author information

Abstract

This study examined the inhibitory effect of forsythiaside-A, a natural substance derived from Forsythia suspensa (F. suspensa), on entry into catagen induced by dihydrotestosterone (DHT) in an androgenic alopecia mouse model. In vitro experiment comparing finasteride with forsythiaside-A showed that forsythiaside-A treatment resulted in a 30% greater inhibition of DHT-induced apoptosis in human hair dermal papilla cell (HHDPCs) and human keratinocytes (HaCaTs). In vivo experiment showed that mouse hair density and thickness were increased by 50% and 30%, respectively, in the forsythiaside-A-treated group when compared to a DHT group. Tissue histological results revealed that the forsythiaside-A-treated group had an increase in size and shape of the hair follicles and a 1.5 times increase in the follicle anagen/telogen ratio when compared to the finasteride group. Western blot examination of TGF-β2 expression related to apoptosis signaling in mouse skin verified that forsythiaside-A reduced the expression of TGF-β2 by 75% and suppressed apoptosis by reducing the expression of caspase-9 by 40%, and caspase-3 by 53%, which play an roles up-regulator in the apoptosis signal. The forsythiaside-A group also showed a 60% increase in the Bcl-2/Bax ratio, which is a factor related to mitochondrial apoptosis. Our results indicated that forsythiaside-A prevents apoptosis by similar mechanism with finasteride, but forsythiaside-A is more effective than finasteride. In summary, forsythiaside-A controlled the apoptosis ofhair cells and retarded the entry into the catagen phase and therefore represents a natural product with much potential for use as a treatment for androgenic alopecia. Copyright © 2015 John Wiley & Sons, Ltd.

Copyright © 2015 John Wiley & Sons, Ltd.

KEYWORDS:

TGF-β2; androgenic alopecia; apoptosis; dihydrotestosterone; forsythiaside-A

Androgens, hair loss and eugenics: a tale of discovery and American social history.

Ayob SM1, Messenger AG.

Author information

Abstract

According to Hippocrates 'eunuchs are not subject to gout nor do they become bald' (Aphorisms VI, 28). The explanation for this insight into male balding eventually emerged over two millennia later from the work of the American anatomist James B Hamilton (Fig.1), published in the American Journal of Anatomy in 1942 (1). (The full text is freely available via http://onlinelibrary.wiley.com/doi/10.1002/aja.1000710306/pdf). Prior to this it was well known that balding is an inherited trait and that it is more common in men than women (2, 3). It was also known that scalp hair loss occurs in women with androgen-secreting tumours. But it was Hamilton who made the key connection that male balding requires both a genetic predisposition and testosterone. This article is protected by copyright. All rights reserved.

This article is protected by copyright. All rights reserved.

Exp Dermatol. 2014 Mar;23(3):216-8. doi: 10.1111/exd.12339.

Insulin-like growth factor-1: roles in androgenetic alopecia.

Panchaprateep R1, Asawanonda P.

Author information

• 1Division of Dermatology, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.

Abstract

Of all the cytokines or growth factors that have been postulated to play a role in hair follicle, insulin-like growth factor-1 (IGF-1) is known to be regulated by androgens. However, how IGF-1 is altered in the balding scalp has not yet been investigated. In this study, expressions of IGF-1 and its binding proteins by dermal papilla (DP) cells obtained from balding versus non-balding hair follicles were quantified using growth factor array. DP cells from balding scalp follicles were found to secrete significantly less IGF-1, IGFBP-2 and IGFBP-4 (P < 0.05) than their non-balding counterparts. Our data confirmed that the downregulation of IGF-1 may be one of the important mechanisms contributing to male pattern baldness.

© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Prev Nutr Food Sci. 2014 Sep;19(3):136-44. doi: 10.3746/pnf.2014.19.3.136.

Platycarya strobilacea S. et Z. Extract Has a High Antioxidant Capacity and Exhibits HairGrowth-promoting Effects in Male C57BL/6 Mice.

Kim EJ1, Choi JY1, Park BC2, Lee BH3.

Author information

Abstract

This study was conducted to evaluate the effects of Platycarya strobilacea S. et Z. (PSE) extract on mouse hair growth and to determine the mechanism of action of PSE. PSE was purchased and its antioxidant activities, such as electron donating ability, total polyphenol content, and flavonoid content were tested. Toxicity during topical treatment was determined by the CCK-8 assay, a cell viability test. Fifteen 4-week-old male C57BL/6 mice were assigned to receive one of three treatments: dimethyl sulfoxide (negative control), minoxidil (positive control) or PSE. Test materials were topically applied to the shaved dorsal skin of each mouse daily for 3 weeks. After 21 days, we observed skin tissue hair follicle morphology and length, mast cell number, and stem cell factor (SCF) expression using hematoxylin and eosin (H&E), toluidine blue, and immunohistochemical staining, respectively. Furthermore, the expression of cytokines involved in hair growth [i.e., insulin-like growth factor (IGF)-1, keratinocyte growth factor (KGF), and transforming growth factor (TGF)-β1] was determined by PCR. PSE was found to have very high antioxidant activity. The cell viability rate of PSE-treated mice was markedly higher than that of mice in the control group. We also observed an increase in hair follicle length, strong SCF staining, and a decrease in mast cell number in the PSE group. In addition, PSE-treated mice had higher IGF-1 and KGF expression and lower TGF-β1 expression than mice in the minoxidil-treated group. These results suggest that topical application of PSE promotes hair growth by intensifying SCF, suppressing mast cell production, and increasing hair growth-promoting cytokine expression.

KEYWORDS:

C57BL/6 mouse; Platycarya strobilacea S. et Z.; antioxidant activity; hair growth; hair growth factors

PMID:

 

25320710

 

[PubMed] 

PMCID:

 

PMC4195618

 

Free PMC Article

Br J Dermatol. 2014 Nov;171(5):1031-43. doi: 10.1111/bjd.13114. Epub 2014 Oct 30.

Differential effects of caffeine on hair shaft elongation, matrix and outer root sheath keratinocyte proliferation, and transforming growth factor-β2/insulin-like growth factor-1-mediated regulation of the hair cycle in male and female human hair follicles in vitro.

Fischer TW1, Herczeg-Lisztes E, Funk W, Zillikens D, Bíró T, Paus R.

Author information

Abstract

BACKGROUND:

Caffeine reportedly counteracts the suppression of hair shaft production by testosterone in organ-cultured male human hair follicles (HFs).

OBJECTIVES:

We aimed to investigate the impact of caffeine (i) on additional key hair growth parameters, (ii) on major hairgrowth regulatory factors and (iii) on male vs. female HFs in the presence of testosterone.

METHODS:

Microdissected male and female human scalp HFs were treated in serum-free organ culture for 120 h with testosterone alone (0·5 μg mL(-1)) or in combination with caffeine (0·005-0·0005%). The following effects on hair shaft elongation were evaluated by quantitative (immuno)histomorphometry: HF cycling (anagen-catagen transition); hair matrix keratinocyte proliferation; expression of a key catagen inducer, transforming growth factor (TGF)-β2; and expression of the anagen-prolonging insulin-like growth factor (IGF)-1. Caffeine effects were further investigated in human outer root sheath keratinocytes (ORSKs).

RESULTS:

Caffeine enhanced hair shaft elongation, prolonged anagen duration and stimulated hair matrix keratinocyte proliferation. Female HFs showed higher sensitivity to caffeine than male HFs. Caffeine counteracted testosterone-enhanced TGF-β2 protein expression in male HFs. In female HFs, testosterone failed to induce TGF-β2 expression, while caffeine reduced it. In male and female HFs, caffeine enhanced IGF-1 protein expression. In ORSKs, caffeine stimulated cell proliferation, inhibited apoptosis/necrosis, and upregulated IGF-1 gene expression and protein secretion, while TGF-β2 protein secretion was downregulated.

CONCLUSIONS:

This study reveals new growth-promoting effects of caffeine on human hair follicles in subjects of both sexes at different levels (molecular, cellular and organ).

© 2014 British Association of Dermatologists.

Toxicol Res. 2014 Dec;30(4):297-304. doi: 10.5487/TR.2014.30.4.297.

Peppermint Oil Promotes Hair Growth without Toxic Signs.

Oh JY1, Park MA2, Kim YC2.

Author information

Abstract

Peppermint (Mentha piperita) is a plant native to Europe and has been widely used as a carminative and gastric stimulant worldwide. This plant also has been used in cosmetic formulations as a fragrance component and skin conditioning agent. This study investigated the effect of peppermint oil on hair growth in C57BL/6 mice. The animals were randomized into 4 groups based on different topical applications: saline (SA), jojoba oil (JO), 3% minoxidil (MXD), and 3% peppermint oil (PEO). The hair growth effects of the 4-week topical applications were evaluated in terms of hair growth, histological analysis, enzymatic activity of alkaline phosphatase (ALP), and gene expression of insulin-like growth factor-1 (IGF-1), known bio-markers for the enhanced hair growth. Of the 4 experimental groups, PEO group showed the most prominent hairgrowth effects; a significant increase in dermal thickness, follicle number, and follicle depth. ALP activity and IGF-1expression also significantly increased in PEO group. Body weight gain and food efficiency were not significantly different between groups. These results suggest that PEO induces a rapid anagen stage and could be used for a practical agent forhair growth without change of body weight gain and food efficiency.

KEYWORDS:

Alkaline phosphatase; Hair follicle; Hair growth; Insulin-like growth factor-1; Peppermint oil

PMID:

 

25584150

 

[PubMed] 

PMCID:

 

PMC4289931

 

Free PMC Article

Naunyn Schmiedebergs Arch Pharmacol. 2014 Dec 2. [Epub ahead of print]

Baicalin, a flavonoid, affects the activity of human dermal papilla cells and promotes anagen induction in mice.

Shin SH1, Bak SS, Kim MK, Sung YK, Kim JC.

Author information

Abstract

Baicalin, a flavonoid isolated from Scutellaria baicalensis, is known to have multiple biological functions. Recent studies have demonstrated that baicalin treatment increases alkaline phosphatase activity (ALP) and osteoprotegerin secretion by osteoblasts. Furthermore, baicalin induces the differentiation of cultured osteoblasts via the activation of the Wnt/β-catenin signaling pathway. In this study, we evaluated the hair growth-promoting effects of baicalin in human follicular dermal papilla (DP) cells. A reporter assay and Western blotting were used to assess the effect of baicalin on β-catenin signaling in DP cells. ALP activity and messenger RNA (mRNA) expression were examined by ALP staining and real-time polymerase chain reaction (PCR), respectively. Growth factor expression levels were also evaluated using real-time PCR. Finally, the effect of baicalin on hair growth in vivo was examined by topical application of baicalin on the shaved dorsal skin of C57BL/6 mice. Our results indicate that baicalin activates Wnt/β-catenin signaling in a dose-dependent manner in human DP cells. ALP mRNA expression and activity were significantly induced in the presence of baicalin. In addition, treatment with baicalin induced the mRNA expression of growth factors, such as insulin-like growth factor-1 (IGF-1) and vascular endothelial growth factor (VEGF). Moreover, compared to vehicle treatment, baicalin treatment induced an earlier conversion from telogen to anagen. Our results strongly suggest that baicalin promotes hair growth by regulating the activity of DP cells.

http://www.ncbi.nlm.nih.gov/pubmed/25434532

Acta Otolaryngol. 2015 Mar 5:1-5. [Epub ahead of print]

The minimum peptides of IGF-1 and substance P protect vestibular hair cells against neomycin ototoxicity.

Yoshida S1, Sugahara K, Hashimoto M, Hirose Y, Shimogori H, Yamashita H.

Author information

Abstract

Abstract Conclusions: Our data indicate that SSSR and SSSR + FGLM-NH2 protect sensory hair cells against neomycin-induced death in the vestibular epithelium. In addition, the results show that SSSR and FGLM-NH2 can be used as protective molecules against aminoglycoside ototoxicity. Objectives: This study investigated the role of the peptides SSSR and SSSR + FGLM-NH2 in mammalian vestibular hair cell death induced by aminoglycoside. Methods: Cultured utricles from mature CBA/N mice were used in this study. The cultured utricles were assigned to five groups (control group, neomycin group, neomycin + SSSR group, neomycin + FGLM-NH2 group, and neomycin + SSSR + FGLM-NH2 group). Aat 24 h after exposure to neomycin, the hair cells were labeled immunohistochemically, and the rate of survival of vestibular hair cells was evaluated using a fluorescence microscope. Results: The rate of survival of vestibular hair cells was significantly higher in the neomycin + SSSR and neomycin + SSSR + FGLM-NH2 groups than in the neomycin group. The results suggest that SSSR could protect hair cells against aminoglycoside ototoxicity.

KEYWORDS:

FGLM-NH2; SSSR; aminoglycoside; hair cell degeneration

Appl Ergon. 2015 May;48:177-85. doi: 10.1016/j.apergo.2014.11.007. Epub 2014 Dec 25.

The effect of hair density on the coupling between the tactor and the skin of the human head.

Myles K1, Kalb JT2, Lowery J3, Kattel BP4.

Author information

Abstract

The purpose of this study was to determine the effect of hair density on vibration detection thresholds associated with the perception of low frequency vibration stimuli applied to the head. A host of tactile sensitivity information exists for other parts of the body, however the same information is lacking for the head. Thirty-three college students, age 18-35, were recruited for the study. A mixed design was used to evaluate the effect of hair density, head location, and frequency on vibration detection thresholds. Results suggest that hair density might slightly impede vibration signals from reaching the scalp and reduce vibration sensitivity, for the least sensitive locations on the head. This research provides design recommendations for head-mounted tactile displays for women and those with hair that can be used to convey directional cues for navigation and as alerts to critical events in the environment.

Published by Elsevier Ltd.

Dev Cell. 2014 Dec 8;31(5):543-58. doi: 10.1016/j.devcel.2014.10.022. Epub 2014 Nov 26.

Hair follicle dermal stem cells regenerate the dermal sheath, repopulate the dermal papilla, and modulate hair type.

Rahmani W1, Abbasi S1, Hagner A1, Raharjo E1, Kumar R2, Hotta A3, Magness S4, Metzger D5, Biernaskie J6.

Author information

Abstract

The dermal papilla (DP) provide instructive signals required to activate epithelial progenitors and initiate hair follicle regeneration. DP cell numbers fluctuate over the hair cycle, and hair loss is associated with gradual depletion/atrophy of DP cells. How DP cell numbers are maintained in healthy follicles remains unclear. We performed in vivo fate mapping of adult hair follicle dermal sheath (DS) cells to determine their lineage relationship with DP and found that a subset of DS cells are retained following each hair cycle, exhibit self-renewal, and repopulate the DS and the DP with new cells. Ablating these hair follicle dermal stem cells and their progeny retarded hair regrowth and altered hair type specification, suggesting that they function to modulate normal DP function. This work identifies a bipotent stem cell within the adult hair follicle mesenchyme and has important implications toward restoration of hair growth after injury, disease, and aging.