Therapeutic strategies for treating hair loss

Discovery of petroleum ether extract of eclipta targeting p53/Fas pathway for the treatment of chemotherapy-induced alopecia: Network pharmacology and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Ecliptea herba, a traditional Chinese herbal medicine for hair loss, was first recorded in the Tang Dynasty's 'Qian Jin Yue Ling', of which the active ingredients and mechanisms of action in the treatment of chemotherapy-induced hair loss remain poorly investigated.

AIM OF THE STUDY

To investigate the effects of the petroleum ether extract of Eclipta (PEE) on alopecia and follicle damage and elucidate its potential therapeutic mechanisms using the integration of network pharmacology, bioinformatics, and experimental validation.

MATERIALS AND METHODS

UPLC-MS was used to analyse the chemical composition of PEE. A network pharmacology approach was employed to establish the 'components-targets-pathways' network of PEE to explore potential therapeutic pathways and targets. Molecular docking was used for validation, and the mechanism of PEE in treating chemotherapy-induced alopecia (CIA) was elucidated using in vitro and in vivo on CIA models.

RESULTS

UPLC-MS analysis of PEE revealed 185 components, while network pharmacology and molecular docking analyses revealed potential active compounds and their target molecules, suggesting the involvement of core genes, such as TP53, ESR1, AKT1, IL6, TNF, and EGFR. The key components included wedelolactone, dimethyl-wedelolactone, luteoloside, linarin, and hispidulin. In vivo, PEE promoted hair growth, restored the number of hair follicles, and reduced follicle apoptosis. Conversely, in vitro, PEE enhanced cell viability, reduced apoptosis, and protected HaCaT cells from damage induced by 4-hydroperoxycyclophosphamide (4-HC).

CONCLUSIONS

PEE alleviated hair follicle damage in CIA mice by inhibiting the P53/Fas pathway, which may be associated with inhibiting hair follicle cell apoptosis. This study provides a novel therapeutic strategy for treating cyclophosphamide-induced hair loss.

Delivery Strategies of siRNA Therapeutics for Hair Loss Therapy

Therapeutic needs for hair loss are intended to find small interfering ribonucleic acid (siRNA) therapeutics for breakthrough. Since naked siRNA is restricted to meet a druggable target in clinic,, delivery systems are indispensable to overcome intrinsic and pathophysiological barriers, enhancing targetability and persistency to ensure safety, efficacy, and effectiveness. Diverse carriers repurposed from small molecules to siRNA can be systematically or locally employed in hair loss therapy, followed by the adoption of new compositions associated with structural and environmental modification. The siRNA delivery systems have been extensively studied via conjugation or nanoparticle formulation to improve their fate in vitro and in vivo. In this review, we introduce clinically tunable siRNA delivery systems for hair loss based on design principles, after analyzing clinical trials in hair loss and currently approved siRNA therapeutics. We further discuss a strategic research framework for optimized siRNA delivery in hair loss from the scientific perspective of clinical translation.

Effect of topical naringenin and its combination with minoxidil on enhancing hair growth in a mouse model

This study aimed to investigate the efficacy of naringenin (NAR) in reducing hair loss. Twenty-four adult Wistar Albino mice, weighing between 25-35 g and aged 6-7 weeks, were used in this research. The dorsal hair of these mice was meticulously clipped and stained subsequently. The mice were randomly divided into four groups (n=6 for each group): (1) negative control group, treated with absolute ethanol alcohol as the vehicle (2) minoxidil (5%) treated group; (3) 0.5% naringenin treated group, and (4) naringenin plus minoxidil treated group. The treatment groups had significantly higher total antioxidant capacity in tissue levels and increased serum levels of vascular endothelial growth factor compared to the control group. No significant differences were observed in keratinocyte growth factor tissue levels between the treatment and control groups. However, the medication significantly increased hair growth, hair follicle diameter expansion, and hair follicle quantity compared to the control group. The finding suggests that the antioxidant and anti-inflammatory properties of NAR significantly reduced hair loss in adult male mice.

Efficacy and predictive factors of cyclosporine A in alopecia areata: a systematic review with meta-analysis

INTRODUCTION

Drugs for alopecia areata (AA) can induce hair regrowth, but do not change the disease course. Dual properties of cyclosporine A (CsA) as hypetrichotic and immunosuppressive agent have encouraged use in AA. We aimed to determine the most meaningful efficacy of CsA and reveal features helping enhance its efficacy and reduce relapses.

METHOD

Efficacy of CsA and predictive factors were investigated. Cochrane, MEDLINE, Pubmed and Embase databases were searched.

RESULTS

2,189 papers were retrieved. Based on 344 patients, mean proportion of responders was 73%. CsA monotherapy showed proportion of hair regrowth of 66%, whereas CsA combined with systemic corticosteroids yielded 78%. Overall efficacy in studies with duration of CsA treatment <6 months was: 74% (53-88%), while in those with duration ≥6 months was: 73% (47-89%). Recurrence with CsA monotherapy was 55% (6-96%) whereas when CsA was combined with systemic corticosteroids it was 28% (6-72%).

CONCLUSION

CsA confers a favorable therapeutic effect and concomitant use of steroids slightly enhances efficacy, but it dramatically decreases relapses. Longer treatments seem to lead to less relapse likelihood, but daily dose does not influence recurrence. Optimal CsA dosage is 5 mg/kg/day in single therapy regimen, whereas it is 3 mg/kg/day in the steroid-associated regimen. KEY POINTSWhat is already known about this subject? Most treatments for alopecia areata have not been critically evaluated. Current outcomes about the efficacy and relapse rate of cyclosporine A (CsA) are inconsistent and predictive factors about the clinical response are lacking.What this study adds? CsA confers a favorable therapeutic hair regrowth. Longer treatment seems to lead to less likelihood of relapse of AA, but the daily dose does not exert any effect on the recurrence of the disease. The concomitant use of corticosteroids broadly decreases relapses, and it also enhances efficacy.Impact on clinical practice The combination with corticosteroids is the most predictive feature to prevent relapse of AA, followed by the duration of CsA therapy. The daily dose of CsA is the feature with the least or null impact on the clinical course of AA.

KY19382, a novel activator of Wnt/β-catenin signalling, promotes hair regrowth and hair follicle neogenesis

Background and Purpose

The promotion of hair regeneration and growth heavily depends on the activation of Wnt/β‐catenin signalling in the hair follicle, including dermal papilla (DP). KY19382, one of the newly synthesized analogues of indirubin‐3′‐monoxime (I3O), was identified as a Wnt/β‐catenin signalling activator via inhibition of the interaction between CXXC‐type zinc finger protein 5 (CXXC5) and dishevelled (Dvl). Given the close relationship between the Wnt/β‐catenin signalling and hair regeneration, we investigated the effect of KY19382 on hair regrowth and hair follicle neogenesis.

Experimental Approach

In vitro hair induction effects of KY19382 were performed in human DP cells. The hair elongation effects of KY19382 were confirmed through the human hair follicle and vibrissa culture system. In vivo hair regeneration abilities of KY19382 were identified in three models: hair regrowth, wound‐induced hair follicle neogenesis (WIHN) and hair patch assays using C57BL/6 mice. The hair regeneration abilities were analysed by immunoblotting, alkaline phosphatase (ALP) and immunohistochemical staining.

Key Results

KY19382 activated Wnt/β‐catenin signalling and elevated expression of ALP and the proliferation marker PCNA in DP cells. KY19382 also increased hair length in ex vivo‐cultured mouse vibrissa and human hair follicles and induced hair regrowth in mice. Moreover, KY19382 significantly promoted the generation of de novo hair follicles as shown by WIHN and hair patch assays.

Conclusion and Implications

These results indicate that KY19382 is a potential therapeutic drug that exhibits effective hair regeneration ability via activation of the Wnt/β‐catenin signalling for alopecia treatments.

Topical odorant application of the specific olfactory receptor OR2AT4 agonist, Sandalore® , improves telogen effluvium-associated parameters

BACKGROUND

Human hair follicles (HFs) express the olfactory receptor (OR)2AT4, which is selectively stimulated by the synthetic sandalwood-like odorant, Sandalore^® . In organ-cultured, human scalp HFs, Sandalore^® prolongs anagen and suppresses apoptosis by up-regulating intrafollicular IGF-1 mediated signaling.

AIMS

The objective of this study is to demonstrate whether effects of Sandalore^® observed ex vivo translate into a clinically relevant effect in patients with telogen effluvium.

PATIENTS/METHODS

In a randomized, double-blinded, placebo-controlled, clinical trial, 60 female volunteers (18-65 years) affected by telogen effluvium received over a period of 24 weeks treatment with either 1% Sandalore^® solution (n = 30) or placebo (identically smelling, but non-OR2AT4 activating sandalwood oil n = 30). The study read-out parameters were the degree of hair shedding, hair volume, terminal/vellus hair ratio, anagen/catagen-telogen ratio, and patient self-assessment.

RESULTS

Sandalore^® 1% ameliorated clinical signs of telogen effluvium, namely it reduced hair shedding, and increased hair volume and the percentage of anagen HFs, the latter two parameters significantly more than placebo when changes were calculated to baseline. Sandalore^® also increased the ratio of terminal/vellus hairs at week 8. Most of the anti-hair shedding effects were seen after 8 weeks and maintained at week 24. Patient questionnaire showed that verum group patients were more satisfied than the placebo group in regard to the overall results.

CONCLUSION

This clinical trial supports previous findings of anagen-prolonging effects of Sandalore^® ex vivo with similar results now reproduced in clinical practice. It also provides proof-of-principle that a topically applied cosmetic odorant acting through HF olfactory receptors can be a therapeutic alternative to treat hair loss disorders characterized by excessive hair shedding such as telogen effluvium.

Cyclosporin A-loaded poly(d,l-lactide) nanoparticles: a promising tool for treating alopecia

Background: Alopecia treatments are scarce and lack efficacy. Cyclosporin A (CsA) has hair growth-inducing properties but its poor cutaneous absorption undermines its use in topical treatments. Aim: Development of a new potential topical treatment of alopecia with CsA. Materials & methods: CsA-loaded poly(d,l-lactide) (PLA) nanoparticles were obtained and characterized. Skin permeation was evaluated in ex vivo porcine skin. Results: Nanoparticles with good physicochemical stability increased CsA skin permeation/hair follicles accumulation, compared with a noncolloidal formulation. CsA biocompatibility in NCTC2455 keratinocytes (reference skin cell line) was clearly improved when encapsulated in PLA nanoparticles. Conclusion: This work fosters further in vivo investigation of CsA-loaded PLA nanoparticles as a promising new strategy to treat alopecia, a very traumatic, possibly autoimmune, disease.

Hair Growth Promoting Effect of Dicerocaryum senecioides Phytochemicals

Phytochemicals from Dicerocaryum senecioides were studied for hair rejuvenation activity using BalB/c mice. Solvent extractions and thin layer chromatography (TLC) were used to extract and isolate the phytochemicals respectively. Phytochemicals were identified by spraying with target-specific revealing reagents. In vivo hair growth stimulating activity for each extract was tested on denuded dorsal skin of 5-week old BalB/c mice against the controls and the standard drug minoxidil. The parameters used to evaluate hair growth were hair growth completion time, hair length, hair weight, hair follicle length, and relative hair follicle area. The identified phytochemicals from the active ethanol extract were steroidal glycosides, triterpenoid glycosides, and flavonoid glycosides. Flavonoid glycosides treatment had the uppermost hair rejuvenation capacity as measured by the shortest hair growth completion time (19 days) versus control (29 days) and longest hair length (11.04 mm and 11.86 mm for male and female mice respectively while the control group had 5.15 mm for male mice and 5.33 mm for female mice). Hair growth stimulation by flavonoid glycosides was also dependent on dose concentration. It can be concluded from this study that flavonoid glycosides extracted from the leaves of Dicerocaryum senecioides have remarkable hair rejuvenation capacity in BalB/c mice. The present results provides insights on the use of Dicerocaryum senecioides for hair rejuvenation in traditional practices and on the potential of the plant as a source of novel compounds that can be used as hair growth promoters.

Understanding and Addressing Hair Disorders in Transgender Individuals

In the United States, an increasing number of individuals are identifying as transgender. Males at birth who identify as females are called male-to-female (MTF) transgender individuals or trans women, and females at birth who identify as males are called female-to-male (FTM) transgender individuals or trans men. The transgender patient population possess unique health concerns disparate from those of the general populace. Exogenous hormone therapy for transgender patients leads to changes in the distribution and pattern of hair growth. Exogenous testosterone can lead to male pattern hair loss and hirsutism, while estrogen therapy usually results in decreased facial and body hair growth and density. A thorough understanding of the hormonal treatments that may be used in transgender individuals as well the unique and complex biologic characteristics of the hair follicle is required for appropriate diagnosis, counseling and treatment of patients. The aim of this article is to provide a framework for understanding hair disorders in transgender individuals and effective treatment options.

Identifying novel strategies for treating human hair loss disorders: Cyclosporine A suppresses the Wnt inhibitor, SFRP1, in the dermal papilla of human scalp hair follicles

Hair growth disorders often carry a major psychological burden. Therefore, more effective human hair growth–modulatory agents urgently need to be developed. Here, we used the hypertrichosis-inducing immunosuppressant, Cyclosporine A (CsA), as a lead compound to identify new hair growth–promoting molecular targets. Through microarray analysis we identified the Wnt inhibitor, secreted frizzled related protein 1 (SFRP1), as being down-regulated in the dermal papilla (DP) of CsA-treated human scalp hair follicles (HFs) ex vivo. Therefore, we further investigated the function of SFRP1 using a pharmacological approach and found that SFRP1 regulates intrafollicular canonical Wnt/β-catenin activity through inhibition of Wnt ligands in the human hair bulb. Conversely, inhibiting SFRP1 activity through the SFRP1 antagonist, WAY-316606, enhanced hair shaft production, hair shaft keratin expression, and inhibited spontaneous HF regression (catagen) ex vivo. Collectively, these data (a) identify Wnt signalling as a novel, non–immune-inhibitory CsA target; (b) introduce SFRP1 as a physiologically important regulator of canonical β-catenin activity in a human (mini-)organ; and (c) demonstrate WAY-316606 to be a promising new promoter of human hair growth. Since inhibiting SFRP1 only facilitates Wnt signalling through ligands that are already present, this ‘ligand-limited’ therapeutic strategy for promoting human hair growth may circumvent potential oncological risks associated with chronic Wnt over-activation.

Hair loss is a common disorder and can lead to psychological distress. Cyclosporine A, a fungal metabolite commonly used as an immunosuppressant, can potently induce hair growth in humans. However, it cannot be effectively used to restore hair growth because of its toxic profile. In this study, we used Cyclosporine A as a lead compound to identify novel therapeutic targets that can aid the development of new hair growth–promoting agents. Through microarray analysis, we found that the level of the secreted Wnt inhibitor, SFRP1, was significantly reduced by Cyclosporine A. This inspired us to design a new pharmacological approach that uses WAY-316606, a reportedly well-tolerated and specific antagonist of SFRP1, to prolong the growth phase of the hair cycle. We show that WAY-316606 enhances human hair growth ex vivo, suggesting that it is a more targeted hair growth promoter with the potential to treat human hair loss disorders.

A Clinical and Biological Guide for Understanding Chemotherapy-Induced Alopecia and Its Prevention

Chemotherapy-induced alopecia (CIA) is the most visibly distressing side effect of commonly administered chemotherapeutic agents. Because psychological health has huge relevance to lifestyle, diet, and self-esteem, it is important for clinicians to fully appreciate the psychological burden that CIA can place on patients. Here, for the first time to our knowledge, we provide a comprehensive review encompassing the molecular characteristics of the human hair follicle (HF), how different anticancer agents damage the HF to cause CIA, and subsequent HF pathophysiology, and we assess known and emerging prevention modalities that have aimed to reduce or prevent CIA. We argue that, at present, scalp cooling is the only safe and U.S. Food and Drug Administration-cleared modality available, and we highlight the extensive available clinical and experimental (biological) evidence for its efficacy. The likelihood of a patient that uses scalp cooling during chemotherapy maintaining enough hair to not require a wig is approximately 50%. This is despite different types of chemotherapy regimens, patient-specific differences, and possible lack of staff experience in effectively delivering scalp cooling. The increased use of scalp cooling and an understanding of how to deliver it most effectively to patients has enormous potential to ease the psychological burden of CIA, until other, more efficacious, equally safe treatments become available.

IMPLICATIONS FOR PRACTICE

Chemotherapy-induced alopecia (CIA) represents perhaps the most distressing side effect of chemotherapeutic agents and is of huge concern to the majority of patients. Scalp cooling is currently the only safe option to combat CIA. Clinical and biological evidence suggests improvements can be made, including efficacy in delivering adequately low temperature to the scalp and patient-specific cap design. The increased use of scalp cooling, an understanding of how to deliver it most effectively, and biological evidence-based approaches to improve its efficacy have enormous potential to ease the psychological burden of CIA, as this could lead to improvements in treatment and patient quality-of-life.

Comparison of Saccharina japonica-Undaria pinnatifida Mixture and Minoxidil on Hair Growth Promoting Effect in Mice

BACKGROUND

Algae have traditionally been used for promotion of hair growth. Use of hair regrowth drugs, such as minoxidil, is limited due to side effects. The aim of this study was to examine a mixture of Saccharina japonica and Undaria pinnatifida (L-U mixture) on hair growth and to compare the promoting effect of hair growth by a 3% minoxidil and a L-U mixture.

METHODS

To evaluate the hair growth-promoting activity, saline, 50% ethanol, 3% minoxidil, and the L-U mixture were applied 2 times a day for a total of 14 days on the dorsal skin of C57BL/6 mice after depilation. Analysis was determined by using a high-resolution hair analysis system, real-time polymerase chain reaction, and H&E staining.

RESULTS

On day 14, the hair growth effect of the L-U mixture was the same as that of the 3% minoxidil treatment. The L-U mixture significantly (P<0.05) stimulated hair growth-promoting genes, as vascular endothelial growth factor (VEGF) and insulin-like growth factor -1. Increase of VEGF was observed in the L-U mixture group compared with minoxidil and the negative control. In contrast, the L-U mixture suppressed the expression of transforming growth factor-β1, which is the hair loss-related gene. In histological examination in the L-U mixture and minoxidil groups, the induction of an anagen stage of hair follicles was faster than that of control groups.

CONCLUSIONS

This study provides evidence that the L-U mixture can promote hair growth in mice, similar to the effect from minoxidil, and suggests that there is potential application for hair loss treatments.

Human Hair Reconstruction: Close, But Yet So Far

Billions of dollars are annually invested in pharmaceutical industry and cosmetic sector with intent to develop new drugs and treatment strategies for alopecia. Because the hair looks an important characteristic of humans-an effective appendage in perception, expression of beauty, and preservation of self-esteem-the global market for hair loss treatment products is exponentially increasing. However, current methods to treat hair loss endure yet multiple challenges, such as unfavorable outcomes, nonpermanent and patient-dependent results, as well as unpredictable impacts, which limit their application. Over recent years, remarkable advances in the fields of regenerative medicine and hair tissue engineering have raised new hopes for introducing novel cell-based approaches to treat hair loss. Through cell-based approaches, it is possible to produce hair-like structures in the laboratory setting or manipulate cells in their native niche (in vivo lineage reprogramming) to reconstruct the hair follicle. However, challenging issues still exist with the functionality of cultured human hair cells, the proper selection of nonhair cell sources in cases of shortage of donor hair, and the development of defined culture conditions. Moreover, in the case of in vivo lineage reprogramming, selecting appropriate induction factors and their efficient delivery to guide resident cells into a hair fate-with the aim of reconstructing functional hair-still needs further explorations. In this study, we highlight recent advances and current challenges in hair loss treatment using cell-based approaches and provide novel insights for crucial steps, which must be taken into account to develop reproducible, safe, and efficient cell-based treatment.

Topical Products for Human Hair Regeneration: A Comparative Study on an Animal Model

Background

Hair loss and hair growth is the subject of tremendous amount of research.

Objective

This study investigated the efficacy of three chemical treatments used in humans for hair loss, using a rat model of hair regrowth. The products tested were 2% minoxidil, Hairgrow (Dar-Al-Dawa Pharma), Aminexil, Dercos (Vichy Laboratoires), and Kerium, Anti-chute (La Roche-Posay).

Methods

Thirty-two adult female Wistar-Bratislava rats were assigned to 4 groups. Two rectangular areas (2×4 cm) were shaved on either sides of the mid dorsal line (left side - control; right side - test area). Group I was treated topically with 2% minoxidil, group II with Aminexil, and group III with Kerium. Each rat received 0.3 ml of substance applied topically to the shaved dorsal skin every day for 28 days. Rats in group IV served as sham controls receiving no treatment. Hair regrowth was evaluated by trichoscopy (with a dermatoscope), grown hair weight (from a surface area of 1 cm²), and histopathological examination for skin thickness, follicle count, and percentage of anagen induction (morphometric assessment).

Results

Treatment with 2% minoxidil significantly induced hair regrowth as assessed by trichoscopy, hair weight examination, and morphometric evaluation. Hair weight examination and morphometric assessment demonstrated the lowest hair growth effect with Aminexil among the tested products. Treatment with Kerium was found to significantly induce hair regrowth (p<0.05 as compared to the control group).

Conclusion

Our study demonstrates that hair regrowth efficacy of products recommended for human use is not similar when tested on an animal model.

Drug discovery for alopecia: gone today, hair tomorrow

INTRODUCTION

Hair loss or alopecia affects the majority of the population at some time in their life, and increasingly, sufferers are demanding treatment. Three main types of alopecia (androgenic [AGA], areata [AA] and chemotherapy-induced [CIA]) are very different, and have their own laboratory models and separate drug-discovery efforts.

AREAS COVERED

In this article, the authors review the biology of hair, hair follicle (HF) cycling, stem cells and signaling pathways. AGA, due to dihydrotesterone, is treated by 5-α reductase inhibitors, androgen receptor blockers and ATP-sensitive potassium channel-openers. AA, which involves attack by CD8(+)NK group 2D-positive (NKG2D(+)) T cells, is treated with immunosuppressives, biologics and JAK inhibitors. Meanwhile, CIA is treated by apoptosis inhibitors, cytokines and topical immunotherapy.

EXPERT OPINION

The desire to treat alopecia with an easy topical preparation is expected to grow with time, particularly with an increasing aging population. The discovery of epidermal stem cells in the HF has given new life to the search for a cure for baldness. Drug discovery efforts are being increasingly centered on these stem cells, boosting the hair cycle and reversing miniaturization of HF. Better understanding of the molecular mechanisms underlying the immune attack in AA will yield new drugs. New discoveries in HF neogenesis and low-level light therapy will undoubtedly have a role to play.

Follicular dermal papilla structures by organization of epithelial and mesenchymal cells in interfacial polyelectrolyte complex fibers

The hair follicle is a regenerating organ that produces a new hair shaft during each growth cycle. Development and cycling of the hair follicle is governed by interactions between the epithelial and mesenchymal components. Therefore, development of an engineered 3D hair follicle would be useful for studying these interactions to identify strategies for treatment of hair loss. We have developed a technique suitable for assembly of different cell types in close proximity in fibrous hydrogel scaffolds with resolutions of ∼50 μm. By assembly of dermal papilla (DP) and keratinocytes, structures similar to the native hair bulb arrangement are formed. Gene expression of these constructs showed up-regulation of molecules involved in epithelial-mesenchymal interactions of the hair follicle. Implantation of the follicular structures in SCID mice led to the formation of hair follicle-like structures, thus demonstrating their hair inductive ability. The transparency of the fiber matrix and the small dimensions of the follicular structures allowed the direct quantitation of DP cell proliferation by confocal microscopy, clearly illustrating the promoting or inhibitory effects of hair growth regulating agents. Collectively, our results suggested a promising application of these 3D engineered follicular structures for in vitro screening and testing of drugs for hair growth therapy.

Techniques for the discovery and evaluation of drugs against alopecia

INTRODUCTION

Hair care, color and style play an important role in physical appearance and self-perception. Hair loss or alopecia is a common dermatological and affective disorder. Factors contributing to alopecia include genetic predisposition, hormonal factors, disease status, side effects of chemotherapeutic agents and stress. To keep pace with the demand for drugs for alopecia, attempts are being made to explore drugs with hair-growth-promotion activity. To explore and evaluate these, it is necessary to be familiar with the basics and the availability and suitability of techniques and experimental models of hair growth activity assessment.

AREAS COVERED

Basic and advanced techniques and models for assessing hair growth activity. A variety of pharmacological models of hair growth are reviewed. This review will help in selecting a suitable, relevant, inexpensive, easy and reliable model for hair growth assessment.

EXPERT OPINION

There is a need to identify the genes involved in hair follicle growth for the production of more effective animal models of the disorder. Standardization of pharmacological models will also be essential for better comparison and validation of results. Recently developed hair follicle organ culture models are a suitable, relevant and inexpensive alternative to traditional whole-animal pharmacological models and will, largely, replace whole-animal systems in the future.

Role of genetics and sex steroid hormones in male androgenetic alopecia and female pattern hair loss: an update of what we now know

The role of genetic predisposition and the influence of sex steroid hormones are indisputable to the pathogenesis of male androgenetic alopecia (MAGA). The role of sex steroid hormones in female pattern hair loss (FPHL) is less known. A good knowledge of the pathophysiology underlying MAGA and FPHL empowers the clinician to confidently counsel patients and make informed therapeutic decisions. Vigorous research in recent years has provided greater insight into the role of genetics and sex steroids in physiological hair growth and cycling, as well as in hair follicle miniaturization, the histological hallmark of MAGA and FPHL. In the present review article directed towards clinicians, we discuss the current understanding of the role of androgens and oestrogens, as well as genetic associations with MAGA and FPHL. We also briefly discuss the interpretation of direct-to-consumer genetic testing for baldness to help clinicians understand the limitations of such tests.

Hair growth and rejuvenation: an overview

Hair has psychological and sociological importance throughout the ages in framing the personality and general appearance of an individual. Significant progress is being made on discovering an effective and safe drug for hair growth. Angiogenesis, androgen antagonism, vasodilation, potassium channel opening and 5-alpha reductase inhibition are the major non-surgical therapeutic strategies of hair growth promotion. In spite of a flood of drugs claiming to be useful as hair growth promoters, more rational strategies, which can target the problem areas or stages of the hair growth cycle effectively, are still awaited. This article highlights the developments in hair rejuvenation strategies and reviews the potential of herbal drugs as safer and effective alternatives.

Hair growth promoting effect of Zizyphus jujuba essential oil

This study was undertaken to examine the efficacy of essential oil from seeds of Zizyphus jujuba for its potential role on hair growth by in vivo method. Essential oil was applied at different concentrations (0.1%, 1% and 10%) over the shaved skin onto the backs of BALB/c mice and monitored for 21 days. After 21 days, mice treated with 1% and 10% of oil produced a greater effect on the length of hair which were measured to be 9.96 and 10.02 mm, respectively, as compared to the control (8.94 mm). We measured the weight of hair/cm(2) area of dorsal skin and also evaluated hair thickness and hair follicles microscopically after plucking the hair immediately from the shaved area of mice and found the best results for 1% of essential oil-treated mice. From this study, it is concluded that Z. jujuba essential oil possesses hair growth promoting activity.

Characterization of rat hair follicle stem cells selected by vario magnetic activated cell sorting system

Hair follicle stem cells (HfSCs) play crucial roles in hair follicle morphogenesis and hair cycling. These stem cells are self-renewable and have the multi-lineage potential to generate epidermis, sebaceous glands, and hair follicle. The separation and identification of hair follicle stem cells are important for further research in stem cell biology. In this study, we report on the successful enrichment of rat hair follicle stem cells through vario magnetic activated cell sorting (Vario MACS) and the biological characteristics of the stem cells. We chose the HfSCs positive surface markers CD34, α6-integrin and the negative marker CD71 to design four isolation strategies: positive selection with single marker of CD34, positive selection with single marker of α6-integrin, CD71 depletion followed by CD34 positive selection, and CD71 depletion followed by α6-integrin positive selection. The results of flow cytometry analysis showed that all four strategies had ideal effects. Specifically, we conducted a series of researches on HfSCs characterized by their high level of CD34, termed CD34^bri cells, and low to undetectable expression of CD34, termed CD34^dim cells. CD34^bri cells had greater proliferative potential and higher colony-forming ability than CD34^dim cells. Furthermore, CD34^bri cells had some typical characteristics as progenitor cells, such as large nucleus, obvious nucleolus, large nuclear:cytoplasmic ratio and few cytoplasmic organelles. Our findings clearly demonstrated that HfSCs with high purity and viability could be successfully enriched with Vario MACS.

A human folliculoid microsphere assay for exploring epithelial- mesenchymal interactions in the human hair follicle

The search for more effective drugs for the management of common hair growth disorders remains a top priority, both for clinical dermatology and industry. In this pilot study, we report a pragmatic organotypic assay for basic and applied hair research. The patented technique produces microdroplets, which generate human folliculoid microspheres (HFMs), consisting of human dermal papilla fibroblasts and outer root sheath keratinocytes within an extracellular matrix that simulates elements of the hair follicle mesenchyme. Studying a number of different markers (for example, proliferation, apoptosis, cytokeratin-6, versican), we show that these HFMs, cultured under well-defined conditions, retain several essential epithelial-mesenchymal interactions characteristic for human scalp hair follicle. Selected, recognized hair growth-modulatory agents modulate these parameters in a manner that suggests that HFMs allow the standardized preclinical assessment of test agents on relevant human hair growth markers under substantially simplified in vitro conditions that approximate the in vivo situation. Furthermore, we show by immunohistochemistry, reverse transcriptase-PCR, and DNA microarray techniques that HFMs also offer a useful discovery tool for the identification of target genes and their products for candidate hair drugs. HFM thus represent an instructive modern experimental and screening tool for basic and applied hair research in the human system.

Management of primary cicatricial alopecias: options for treatment

Primary cicatricial alopecias (PCAs) are a poorly understood group of disorders that result in permanent hair loss. Clinically, they are characterized not only by permanent loss of hair shafts but also of visible follicular ostia along with other visible changes in skin surface morphology, while their histopathological hallmark usually (although not always) is the replacement of follicular structures with scar-like fibrous tissue. As hair follicle neogenesis in adult human scalp skin is not yet a readily available treatment option for patients with cicatricial alopecias, the aim of treatment, currently, remains to reduce symptoms and to slow or stop PCA progression, namely the scarring process. Early treatment is the key to minimizing the extent of permanent alopecia. However, inconsistent terminology, poorly defined clinical end-points and a lack of good quality clinical trials have long made management of these conditions very challenging. As one important step towards improving the management of this under-investigated and under-serviced group of dermatoses, the current review presents evidence-based guidance for treatment, with identification of the strength of evidence, and a brief overview of clinical features of each condition. Wherever only insufficient evidence-based advice on PCA management can be given at present, this is indicated so as to highlight important gaps in our clinical knowledge that call for concerted efforts to close these in the near future.

(Neuro-)endocrinology of epithelial hair follicle stem cells

The hair follicle is a repository of different types of somatic stem cells. However, even though the hair follicle is both a prominent target organ and a potent, non-classical site of production and/or metabolism of numerous polypetide- and steroid hormones, neuropeptides, neurotransmitters and neurotrophins, the (neuro-)endocrine controls of hair follicle epithelial stem cell (HFeSC) biology remain to be systematically explored. Focussing on HFeSCs, we attempt here to offer a "roadmap through terra incognita" by listing key open questions, by exploring endocrinologically relevant HFeSC gene profiling and mouse genomics data, and by sketching several clinically relevant pathways via which systemic and/or locally generated (neuro-)endocrine signals might impact on HFeSC. Exemplarily, we discuss, e.g. the potential roles of glucocorticoid and vitamin D receptors, the hairless gene product, thymic hormones, bone morphogenic proteins (BMPs) and their antagonists, and Skg-3 in HFeSC biology. Furthermore, we elaborate on the potential role of nerve growth factor (NGF) and substance P-dependent neurogenic inflammation in HFeSC damage, and explore how neuroendocrine signals may influence the balance between maintenance and destruction of hair follicle immune privilege, which protects these stem cells and their progeny. These considerations call for a concerted research effort to dissect the (neuro-)endocrinology of HFeSCs much more systematically than before.

Melatonin and the hair follicle

Melatonin, the chief secretory product of the pineal gland, has long been known to modulate hair growth, pigmentation and/or molting in many species, presumably as a key neuroendocrine regulator that couples coat phenotype and function to photoperiod-dependent environmental and reproductive changes. However, the detailed effects and mechanisms of this surprisingly pleiotropic indole on the hair follicle (HF) regarding growth control and pigmentation have not yet been completely understood. While unspecific melatonin binding sites have long been identified (e.g., in goat and mouse HFs), specific melatonin membrane MT2 receptor transcripts and both protein and mRNA expression for a specific nuclear melatonin binding site [retinoid-related orphan receptor alpha (RORalpha)] have only recently been identified in murine HFs. MT1, known to be expressed in human skin cells, is not transcribed in mouse skin. After initial enzymologic data from hamster skin related to potential intracutaneous melatonin synthesis, it has recently been demonstrated that murine and human skin, namely human scalp HFs in anagen, are important sites of extrapineal melatonin synthesis. Moreover, HF melatonin production is enhanced by catecholamines (as it classically occurs in the pineal gland). Melatonin may also functionally play a role in hair-cycle control, as it down-regulates both apoptosis and estrogen receptor-alpha expression, and modulates MT2 and RORalpha expression in murine skin in a hair-cycle-dependent manner. Because of melatonin's additional potency as a free radical scavenger and DNA repair inducer, the metabolically and proliferatively highly active anagen hair bulb may also exploit melatonin synthesis in loco as a self-cytoprotective strategy.

Dissecting the impact of chemotherapy on the human hair follicle: a pragmatic in vitro assay for studying the pathogenesis and potential management of hair follicle dystrophy

Chemotherapy-induced alopecia represents one of the major unresolved problems of clinical oncology. The underlying molecular pathogenesis in humans is virtually unknown because of the lack of adequate research models. Therefore, we have explored whether microdissected, organ-cultured, human scalp hair follicles (HFs) in anagen VI can be exploited for dissecting and manipulating the impact of chemotherapy on human HFs. Here, we show that these organ-cultured HFs respond to a key cyclophosphamide metabolite, 4-hydroperoxycyclophosphamide (4-HC), in a manner that resembles chemotherapy-induced HF dystrophy as it occurs in vivo: namely, 4-HC induced melanin clumping and melanin incontinence, down-regulated keratinocyte proliferation, massively up-regulated apoptosis of hair matrix keratinocytes, prematurely induced catagen, and up-regulated p53. In addition, 4-HC induced DNA oxidation and the mitochondrial DNA common deletion. The organ culture system facilitated the identification of new molecular targets for chemotherapy-induced HF damage by microarray technology (eg, interleukin-8, fibroblast growth factor-18, and glypican 6). It was also used to explore candidate chemotherapy protectants, for which we used the cytoprotective cytokine keratinocyte growth factor as exemplary pilot agent. Thus, this novel system serves as a powerful yet pragmatic tool for dissecting and manipulating the impact of chemotherapy on the human HF.