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Special Issue "Mechanisms of Hair Morphology"

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Biochemistry".

Deadline for manuscript submissions: closed (15 December 2020).

Special Issue Editor

Prof. Dr. Kazumasa Wakamatsu
Website
Guest Editor
Department of Chemistry, Fujita Health University School of Medical Sciences, Toyoake, Aichi 470-1192, Japan
Interests: UV damage; biosynthesis of melanin pathway; internal and external melanin; melanoma; fossil melanin; pro-oxidant activity

Special Issue Information

Dear Colleagues,

Hair on mammals has a unique character and several functions, from protection of skin to sexual and social communication. The psychological impact on quality of life caused by hair disorders, such as hirsutism, hair loss, etc., can be quite significant. A significantly higher prevalence of personality disorders in subjects with androgenetic alopecia compared with the prevalence of such diagnoses in the general population has been discovered. Mammalian skin produces hair almost all over the body surface, except for a few areas of the body, i.e., the soles of the feet, palms of the hands, buccal surface of the lip, and portions of external genitalia, whereas hair in other areas, such as the scalp, eyelashes, and eyebrows, is longer, thicker, and heavily pigmented. Differences are also related to the hair’s form, which can be straight, helical, or wavy. The color is dependent on the balance of quality and quantity of melanin (brown to black—indolic eumelanin and yellow to reddish brown—sulfur-containing pheomelanin). Human hair is usually classified according to three conventional ethnic human subgroups, i.e., African, Asian, and European. Nevertheless, a recent study showed that it is possible to classify the various hairs found worldwide into eight main coherent hair types by the measurement of three easily accessible parameters: curve diameter, curl index, and number of waves. Several studies on human hair have been conducted within many fields of science, including biology, dermatology, cosmetics, forensic sciences, and medicine. For this Special Issue of IJMS, we are looking for articles that can deliver a profound insight into the mechanism of hair morphology with respect to the principal anatomical and physiological aspects of the different types of mammalian hair; the molecular structure of hair; the immunology of hair follicles; the classification of hair; clinical observations of human hair, including aging; hormonal effects on hair follicles; and diagnostic use to consider the clinical and basic significance of the different structures and distribution of hair in the mammalian body.

Prof. Kazumasa Wakamatsu
Guest Editor

Manuscript Submission Information

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Keywords

  • eumelanin
  • pheomelanin
  • anatomical structure
  • aging
  • cosmetics
  • forensic science
  • hair follicles
  • classification of hair
  • molecular structure of hair
  • immunology of follicles

Published Papers (5 papers)

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Research

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Open AccessArticle
Selective Elimination of NG2-Expressing Hair Follicle Stem Cells Exacerbates the Sensitization Phase of Contact Dermatitis in a Transgenic Rat Model
Int. J. Mol. Sci. 2020, 21(18), 6922; https://doi.org/10.3390/ijms21186922 - 21 Sep 2020
Abstract
The hair cycle consists of three different phases: anagen (growth), catagen (regression), and telogen (resting). During the anagen phase, hair follicle stem cells (HFSCs) in the bulge and the secondary hair germ proliferate and generate the outer and inner root sheath cells and [...] Read more.
The hair cycle consists of three different phases: anagen (growth), catagen (regression), and telogen (resting). During the anagen phase, hair follicle stem cells (HFSCs) in the bulge and the secondary hair germ proliferate and generate the outer and inner root sheath cells and the hair shafts. We previously identified NG2-immunoreactive (NG2+) cells as HFSCs in both regions of the hair follicles. Recently, the interaction between the hair cycle and the cutaneous immune system has been re-examined under physiological and pathological conditions. However, the roles of NG2+ HFSCs in the skin’s immune system remain completely elucidated. In the present study, we investigated whether the elimination of NG2+ HFSCs affects the induction of allergic contact dermatitis, using a herpes simplex virus thymidine kinase (HSVtk)/ganciclovir (GCV) suicide gene system. When the GCV solution was applied to the skin of NG2-HSVtk transgenic (Tg) rats during the depilation-induced anagen phase, NG2+ HFSCs in the Tg rat skin induced apoptotic cell death. Under exposure of a hapten, the selective ablation of NG2+ HFSCs during the anagen phase aggravated the sensitization phase of allergic contact dermatitis. These findings suggest that NG2+ HFSCs and their progeny have immunosuppressive abilities during the anagen phase. Full article
(This article belongs to the Special Issue Mechanisms of Hair Morphology)
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Open AccessArticle
Thymosin β4 Identified by Transcriptomic Analysis from HF Anagen to Telogen Promotes Proliferation of SHF-DPCs in Albas Cashmere Goat
Int. J. Mol. Sci. 2020, 21(7), 2268; https://doi.org/10.3390/ijms21072268 - 25 Mar 2020
Cited by 1
Abstract
Increasing cashmere yield is one of the important goals of cashmere goat breeding. To achieve this goal, we screened the key genes that can improve cashmere performance. In this study, we used the RNA raw datasets of the skin and dermal papilla cells [...] Read more.
Increasing cashmere yield is one of the important goals of cashmere goat breeding. To achieve this goal, we screened the key genes that can improve cashmere performance. In this study, we used the RNA raw datasets of the skin and dermal papilla cells of secondary hair follicle (SHF-DPCs) samples of hair follicle (HF) anagen and telogen of Albas cashmere goats and identified a set of significant differentially expressed genes (DEGs). To explore potential associations between gene sets and SHF growth features and to identify candidate genes, we detected functional enrichment and constructed protein-protein interaction (PPI) networks. Through comprehensive analysis, we selected Thymosin β4 (Tβ4), Rho GTPase activating protein 6 (ARHGAP6), ADAM metallopeptidase with thrombospondin type 1 motif 15, (ADAMTS15), Chordin (CHRD), and SPARC (Osteonectin), cwcv and kazal-like domains proteoglycan 1 (SPOCK1) as candidate genes. Gene set enrichment analysis (GSEA) for these genes revealed Tβ4 and ARHGAP6 have a close association with the growth and development of SHF-DPCs. However, the expression of Tβ4 in the anagen was higher than that in the telogen, so we finally chose Tβ4 as the ultimate research object. Overexpressing Tβ4 promoted and silencing Tβ4 inhibited the proliferation of SHF-DPCs. These findings suggest that Tβ4 can promote the growth and development of SHF-DPCs and indicate that this molecule may be a valuable target for increasing cashmere production. Full article
(This article belongs to the Special Issue Mechanisms of Hair Morphology)
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Review

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Open AccessReview
Hormonal Effects on Hair Follicles
Int. J. Mol. Sci. 2020, 21(15), 5342; https://doi.org/10.3390/ijms21155342 - 28 Jul 2020
Cited by 3
Abstract
The hair cycle and hair follicle structure are highly affected by various hormones. Androgens—such as testosterone (T); dihydrotestosterone (DHT); and their prohormones, dehydroepiandrosterone sulfate (DHEAS) and androstendione (A)—are the key factors in terminal hair growth. They act on sex-specific areas of the body, [...] Read more.
The hair cycle and hair follicle structure are highly affected by various hormones. Androgens—such as testosterone (T); dihydrotestosterone (DHT); and their prohormones, dehydroepiandrosterone sulfate (DHEAS) and androstendione (A)—are the key factors in terminal hair growth. They act on sex-specific areas of the body, converting small, straight, fair vellus hairs into larger darker terminal hairs. They bind to intracellular androgen receptors in the dermal papilla cells of the hair follicle. The majority of hair follicles also require the intracellular enzyme 5-alpha reductase to convert testosterone into DHT. Apart from androgens, the role of other hormones is also currently being researched—e.g., estradiol can significantly alter the hair follicle growth and cycle by binding to estrogen receptors and influencing aromatase activity, which is responsible for converting androgen into estrogen (E2). Progesterone, at the level of the hair follicle, decreases the conversion of testosterone into DHT. The influence of prolactin (PRL) on hair growth has also been intensively investigated, and PRL and PRL receptors were detected in human scalp skin. Our review includes results from many analyses and provides a comprehensive up-to-date understanding of the subject of the effects of hormonal changes on the hair follicle. Full article
(This article belongs to the Special Issue Mechanisms of Hair Morphology)
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Open AccessReview
Systematic Review of Platelet-Rich Plasma Use in Androgenetic Alopecia Compared with Minoxidil®, Finasteride®, and Adult Stem Cell-Based Therapy
Int. J. Mol. Sci. 2020, 21(8), 2702; https://doi.org/10.3390/ijms21082702 - 13 Apr 2020
Cited by 12
Abstract
The number of articles evaluating platelet-rich plasma (PRP) efficacy in androgenic alopecia (AGA) have exponentially increased during the last decade. A systematic review on this field was performed by assessing in the selected studies the local injections of PRP compared to any control [...] Read more.
The number of articles evaluating platelet-rich plasma (PRP) efficacy in androgenic alopecia (AGA) have exponentially increased during the last decade. A systematic review on this field was performed by assessing in the selected studies the local injections of PRP compared to any control for AGA. The protocol was developed in accordance with the Preferred Reporting for Items for Systematic Reviews and Meta-Analyses-Protocols (PRISMA-P) guidelines. A multistep search of the PubMed, MEDLINE, Embase, PreMEDLINE, Ebase, CINAHL, PsycINFO, Clinicaltrials.gov, Scopus database, and Cochrane databases was performed to identify studies on hair loss treatment with platelet-rich plasma. Of the 163 articles initially identified, 123 articles focusing on AGA were selected and, consequently, only 12 clinical trials were analyzed. The studies included had to match predetermined criteria according to the PICOS (patients, intervention, comparator, outcomes, and study design) approach. In total, 84% of the studies reported a positive effect of PRP for AGA treatment. Among them, 50% of the studies demonstrated a statistically significant improvement using objective measures and 34% of the studies showed hair density and hair thickness improvement, although no p values or statistical analysis was described. In total, 17% of the studies reported greater improvement in lower-grade AGA, while 8% noted increased improvement in higher-grade AGA. Only 17% of the studies reported that PRP was not effective in treating AGA. The information analyzed highlights the positive effects of PRP on AGA, without major side effects and thus it be may considered as a safe and effective alternative procedure to treat hair loss compared with Minoxidil® and Finasteride®. Full article
(This article belongs to the Special Issue Mechanisms of Hair Morphology)
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Open AccessReview
Protective Role of Nutritional Plants Containing Flavonoids in Hair Follicle Disruption: A Review
Int. J. Mol. Sci. 2020, 21(2), 523; https://doi.org/10.3390/ijms21020523 - 14 Jan 2020
Cited by 2
Abstract
Hair loss is a disorder in which the hair falls out from skin areas such as the scalp and the body. Several studies suggest the use of herbal medicine to treat related disorders, including alopecia. Dermal microcirculation is essential for hair maintenance, and [...] Read more.
Hair loss is a disorder in which the hair falls out from skin areas such as the scalp and the body. Several studies suggest the use of herbal medicine to treat related disorders, including alopecia. Dermal microcirculation is essential for hair maintenance, and an insufficient blood supply can lead to hair follicles (HF) diseases. This work aims to provide an insight into the ethnohistorical records of some nutritional compounds containing flavonoids for their potential beneficial features in repairing or recovering from hair follicle disruption. We started from a query for “alopecia” OR “hair loss” AND “Panax ginseng C.A. Mey.“ (or other six botanicals) terms included in Pubmed and Web of Sciences articles. The activities of seven common botanicals introduced with diet (Panax ginseng C.A. Mey., Malus pumila Mill cultivar Annurca, Coffea arabica, Allium sativum L., Camellia sinensis (L.) Kuntze, Rosmarinum officinalis L., Capsicum annum L.) are discussed, which are believed to reduce the rate of hair loss or stimulate new hair growth. In this review, we pay our attention on the molecular mechanisms underlying the bioactivity of the aforementioned nutritional compounds in vivo, ex vivo and in vitro studies. There is a need for systematic evaluation of the most commonly used plants to confirm their anti-hair loss power, identify possible mechanisms of action, and recommend their best adoption. Full article
(This article belongs to the Special Issue Mechanisms of Hair Morphology)
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