Human hair growth in vitro: a model for the study of hair follicle biology

Anti-hair loss effect of a shampoo containing caffeine and adenosine

BACKGROUND

Hair loss is a widespread health problem that affects numerous individuals and is associated with age, lack of sleep, stress, endocrine problems, and other problems. Caffeine exerts various pharmacological effects, particularly after ingestion. The caffeine-induced inhibition of phosphodiesterases can increase intracellular cAMP concentrations, ultimately resulting in stimulatory effects on cell metabolism and proliferation. Hence, caffeine has been confirmed to inhibit hair loss caused by premature termination of the hair growth phase. Adenosine also improves hair loss by stimulating hair growth and thickening hair shafts. However, further empirical evidence is required to comprehensively assess the efficacy of hair loss treatment and prevention using a formulation of caffeine and adenosine in specific proportions in shampoos.

OBJECTIVES

This study aimed to evaluate a shampoo with caffeine and adenosine as a daily scalp care product for hair loss in 77 subjects aged 18-60 years.

METHODS

The overall and local hair densities were assessed using professional cameras and dermoscopes at different magnifications and distances. Five hairs that came off the participant's head were randomly selected to measure hair diameter. The self-assessment questionnaires were filled on third month of product use.

RESULTS

The combination of caffeine and adenosine in the shampoo significantly enhanced hair density compared to that of the baseline. The results revealed a significant reduction in hair loss. The hair diameters of the subjects did not change significantly. Most of the participants (71.05%) were satisfied with their hair after using the product.

CONCLUSIONS

Shampoos containing caffeine and adenosine have been demonstrated to exert therapeutic benefits for reducing hair loss.

Quantification of Squalene and Lactic Acid in Hair Bulbs with Damaged Sheaths: Are They Metabolic Wastes in Alopecia?

Alopecia is a pathological and multifactorial condition characterised by an altered hair growth cycle and ascribed to different pathogenic causes. Cell energetic imbalances in hair follicles occurring in this disorder could lead to the production of some "metabolic wastes", including squalene and lactic acid, which could be involved in the clinically observed sheath damage. The aim of this work was the extraction and analytical quantification of squalene and lactic acid from hair bulbs of subjects with clinical alopecia in comparison with controls, using HPLC-DAD and HPLC-MS techniques. The analytical quantification was performed after a preliminary observation through a polarised optical microscope to assess sheath damage and morphological alterations in the cases group. A significantly larger amount of squalene was quantified only in subjects affected by alopecia (n = 31) and with evident damage to hair sheaths. For lactic acid, no statistically significant differences were found between cases (n = 21) and controls (n = 21) under the experimental conditions used. Therefore, the obtained results suggest that squalene can represent a metabolic and a pathogenic marker for some alopecia conditions.

DNA Methylation Mediates lncRNA2919 Regulation of Hair Follicle Regeneration

Hair follicles (HFs) are organs that periodically regenerate during the growth and development of mammals. Long non-coding RNAs (lncRNAs) are non-coding RNAs with crucial roles in many biological processes. Our previous study identified that lncRNA2919 is highly expressed in catagen during the HF cycle. In this study, the in vivo rabbit model was established using intradermal injection of adenovirus-mediated lncRNA2919. The results showed that lncRNA2919 decreased HF depth and density and contributed to HF regrowth, thereby indicating that lncRNA2919 plays a negative role in HF regeneration. Moreover, methylation levels of the lncRNA2919 promoter at different HF cycle stages were detected through bisulfite sequencing. The key CpG site that negatively correlates with lncRNA2919 expression during the HF cycle was identified. 5-Aza-dc-induced demethylation upregulated lncRNA2919 expression, and the core promoter region of lncRNA2919 was verified on the basis of luciferase activity. Furthermore, we found that DNA methylation could prevent the binding of EGR1 to the lncRNA2919 promoter region, thereby affecting the transcriptional expression of lncRNA2919. Collectively, DNA methylation inhibits the transcriptional expression of lncRNA2919, which plays a vital role in the HF cycle and HF regrowth. These findings contribute to the basic theory of epigenetics in HF biology and provide references for further research in HF disease treatment and animal wool production.

Dexamethasone, a synthetic glucocorticoid, induces the activity of androgen receptor in human dermal papilla cells

Psychosocial stress stimulates the secretion of glucocorticoids (GCs), which are stress-related neurohormones. GCs are secreted from hair follicles and promote hair follicle regression by inducing cellular apoptosis. Moreover, the androgen receptor (AR) is abundant in the balding scalp and androgens suppress hair growth by binding to androgen receptor (AR) in androgenetic alopecia (AGA). First, by using immunofluorescence, we investigated whether the treatment of dermal papilla (DP) cells with dexamethasone (DEX), a synthetic GC, causes the translocation of the glucocorticoid receptor (GR) into the nucleus. DEX treatment causes the translocation of the GR into the nucleus. Next, we investigated whether stress-induced GCs affect the AR, a key factor in male pattern baldness. In this study, we first assessed that DEX increases the expression of AR mRNA in non-balding DP cells, which rarely express AR without androgen. RU486, a GR antagonist, attenuated DEX-inducible AR mRNA expression and AR activation in human non-balding DP cells. In addition, AR translocated into the nucleus after DEX treatment. Furthermore, we indeed showed that the expression of AR was induced in the nucleus by DEX in DP cells of human and mouse hair follicles. Our results first suggest that stress-associated hair loss may be due to increased AR expression and activity induced by DEX. These results demonstrate that hair loss occurs in non-balding scalps with low AR expression

An extract of Leontopodium alpinum inhibits catagen development ex vivo and increases hair density in vivo

Objectives

Hair loss and reduction in hair volume are hallmarks of hair disorders, such as telogen effluvium, or male or female pattern hair loss, and hair ageing, which can cause severe distress in both men and women. Common anti‐hair loss drugs carry some side effects; therefore, novel, safer approaches targeting milder phenotypes are highly advocated. In this context, we investigated an extract of the alpine plant Edelweiss, Leontopodium alpinum var. Helvetia, for its ability to modulate hair follicle (HF) growth ex vivo and inhibit hair loss while increasing hair regeneration in vivo.

Methods

Human amputated HFs were microdissected from three donors, two women and one man, and cultured ex vivo for 6 days. After treatment with 0.001% Edelweiss extract (EWDE), we investigated hair shaft production and anagen/catagen conversion, and measured known parameters associated with hair growth, that is hair matrix keratinocyte proliferation and apoptosis, dermal papilla inductivity, and growth factors, by quantitative (immuno)histomorphometry. To assess the anti‐hair loss potential of the alpine plant compound, we performed a randomized, placebo‐controlled human study enrolling Caucasian women and men, aged 18 to 65 years, with normal hair loss. After 5 months’ daily use of an extract containing leave‐on serum, we analysed hair density and anagen‐to‐catagen/telogen ratio by the Trichogram analysis.

Results

Our results revealed a significant prolongation in the anagen phase in HFs treated with 0.001% Edelweiss, as indicated by an increase in HFs remaining in anagen and a significant decrease in hair cycle score. In line with this effect, EWDE significantly stimulated hair matrix (HM) keratinocyte proliferation, and dermal papilla inductivity, as shown by a significant up‐regulation of versican expression and alkaline phosphatase activity, and a tendential increase in FGF7 immunoreactivity in the dermal papilla of all HFs or only anagen VI HFs. Corroborating the ex vivo results, we observed a significant increase in growing hair shaft numbers (hair density) after treatment with Edelweiss extract formulation, and a tendential up‐regulation in the anagen‐to‐catagen/telogen ratio.

Conclusions

We show here, through several lines of evidence, that the selected extract of the alpine plant Leontopodium alpinum var Helvetia (Edelweiss) inhibits premature catagen induction, possibly by stimulating dermal papilla inductivity. It is therefore worth exploiting this extract clinically as an anti‐hair loss agent, both for preventing ageing‐associated hair shedding and as an adjuvant therapy for hair loss disorders.

Emerging Role of Dermal White Adipose Tissue in Modulating Hair Follicle Development During Aging

Hair follicle stem cells are extensively reprogrammed by the aging process, manifesting as diminished self-renewal and delayed responsiveness to activating cues, orchestrated by both intrinsic microenvironmental and extrinsic macroenvironmental regulators. Dermal white adipose tissue (dWAT) is one of the peripheral tissues directly adjacent to hair follicles (HFs) and acts as a critical macroenvironmental niche of HF. dWAT directly contributes to HF aging by paracrine signal secretion. However, the altered interrelationship between dWAT and HF with aging has not been thoroughly understood. Here, through microdissection, we separated dWAT from the skin of aged mice (18 months) and young mice (2 months) in telogen and depilation-induced anagen for transcriptome comparing. Notably, compared with young dWAT, aberrant inflammatory regulators were recapitulated in aging dWAT in telogen, including substantial overexpressed inflammatory cytokines, matrix metalloproteinases, and prostaglandin members. Nonetheless, with anagen initiation, inflammation programs were mostly abolished in aging dWAT, and instead of which, impaired collagen biosynthesis, angiogenesis, and melanin synthesis were identified. Furthermore, we confirmed the inhibitory effect on hair growth of CXCL1, one of the most significantly upregulated inflammation cytokines in aging dWAT. Besides this, we also identified the under-expressed genes related to Wnt signaling fibroblast growth factor family members and increased BMP signaling in aging dWAT, further unraveling the emerging role of dWAT in aging HFs malfunction. Finally, we proved that relieving inflammation of aging dWAT by injecting high-level veratric acid stimulated HF regenerative behavior in aged mice. Concomitantly, significantly decreased TNF-a, CCL2, IL-5, CSF2, and increased IL10 in dWAT was identified. Overall, the results elaborated on the complex physiological cycling changes of dWAT during aging, providing a basis for the potential regulatory effect of dWAT on aging HFs.

Morus alba Root Extract Induces the Anagen Phase in the Human Hair Follicle Dermal Papilla Cells

Restoring hair follicles by inducing the anagen phase is a promising approach to prevent hair loss. Hair follicle dermal papilla cells (HFDPCs) play a major role in hair growth via the telogen-to-anagen transition. The therapeutic effect of Morus alba activates β-catenin in HFDPCs, thereby inducing the anagen phase. The HFDPCs were treated with M. alba root extract (MARE) to promote hair growth. It contains chlorogenic acid and umbelliferone and is not cytotoxic to HFDPCs at a concentration of 20%. It was demonstrated that a small amount of MARE enhances growth factor secretion (related to the telogen-to-anagen transition). Activation of β-catenin was observed in MARE-treated HFDPCs, which is crucial for inducing the anagen phase. The effect of conditioned medium derived from MARE-treated HFDPCs on keratinocytes and endothelial cells was also investigated. The findings of this study demonstrate the potency of MARE in eliciting the telogen-to-anagen transition.

UDP-GlcNAc-1-Phosphotransferase Is a Clinically Important Regulator of Human and Mouse Hair Pigmentation

UDP-GlcNAc-1-phosphotransferase, a product of two separate genes (GNPTAB, GNPTG), is essential for the sorting and transportation of lysosomal enzymes to lysosomes. GNPTAB gene defects cause extracellular missorting of lysosomal enzymes resulting in lysosomal storage diseases, namely mucolipidosis type II and mucolipidosis type III alpha/beta, which is associated with hair discoloration. Yet, the physiological functions of GNPTAB in the control of hair follicle (HF) pigmentation remain unknown. To elucidate these, we have silenced GNPTAB in organ-cultured human HFs as a human ex vivo model for mucolipidosis type II. GNPTAB silencing profoundly inhibited intrafollicular melanin production, the correct sorting of melanosomes, tyrosinase activity, and HMB45 expression in the HF pigmentary unit and altered HF melanocyte morphology in situ. In isolated primary human HF melanocytes, GNPTAB knockdown significantly reduced melanogenesis, tyrosinase activity, and correct tyrosinase protein sorting as well as POMC expression and caused the expected lysosomal enzyme missorting in vitro. Moreover, transgenic mice overexpressing an inserted missense mutation corresponding to that seen in human mucolipidosis type II and mucolipidosis type III alpha/beta showed significantly reduced HF pigmentation, thus corroborating the in vivo relevance of our ex vivo and in vitro findings in the human system. This identifies GNPTAB as a clinically important enzymatic control of human HF pigmentation, likely by directly controlling tyrosinase sorting and POMC transcription in HF melanocytes.

New effects of caffeine on corticotropin-releasing hormone (CRH)-induced stress along the intrafollicular classical hypothalamic-pituitary-adrenal (HPA) axis (CRH-R1/2, IP3 -R, ACTH, MC-R2) and the neurogenic non-HPA axis (substance P, p75NTR and TrkA) in ex vivo human male androgenetic scalp hair follicles

BACKGROUND

Human hair is highly responsive to stress, and human scalp hair follicles (HFs) contain a peripheral neuroendocrine equivalent of the systemic hypothalamic-pituitary-adrenal (HPA) stress axis. Androgenetic alopecia (AGA) is supposed to be aggravated by stress. We used corticotropin-releasing hormone (CRH), which triggers the HPA axis, to induce a stress response in human ex vivo male AGA HFs. Caffeine is known to reverse testosterone-mediated hair growth inhibition in the same hair organ culture model.

OBJECTIVES

To investigate whether caffeine would antagonize CRH-mediated stress in these HFs.

METHODS

HFs from balding vertex area scalp biopsies of men affected by AGA were incubated with CRH (10-7 mol L-1 ) with or without caffeine (0·001% or 0·005%).

RESULTS

Compared to controls, CRH significantly enhanced the expression of catagen-inducing transforming growth factor-β2 (TGF-β2) (P < 0·001), CRH receptors 1 and 2 (CRH-R1/2) (P < 0·01), adrenocorticotropic hormone (ACTH) (P < 0·001) and melanocortin receptor 2 (MC-R2) (P < 0·001), and additional stress-associated parameters, substance P and p75 neurotrophin receptor (p75NTR ). CRH inhibited matrix keratinocyte proliferation and expression of anagen-promoting insulin-like growth factor-1 (IGF-1) and the pro-proliferative nerve growth factor receptor NGF-tyrosine kinase receptor A (TrkA). Caffeine significantly counteracted all described stress effects and additionally enhanced inositol trisphosphate receptor (IP3 -R), for the first time detected in human HFs.

CONCLUSIONS

These findings provide the first evidence in ex vivo human AGA HFs that the stress mediator CRH induces not only a complex intrafollicular HPA response, but also a non-HPA-related stress response. Moreover, we show that these effects can be effectively antagonized by caffeine. Thus, these data strongly support the hypothesis that stress can impair human hair physiology and induce hair loss, and that caffeine may effectively counteract stress-induced hair damage and possibly prevent stress-induced hair loss.

Impairment of autophagy may be associated with follicular miniaturization in androgenetic alopecia by inducing premature catagen

Androgenetic alopecia is the most common form of hair loss disorder. The features of this process are shortening of the anagen phase in hair cycling and progressive miniaturization of the hair follicle. However, the mechanisms in androgenetic alopecia are still unclear, and the treatment methods are also limited. Therefore, further study on the pathogenesis and new therapies for androgenetic alopecia are urgently needed. In this study, we found that endogenous autophagy was severely impaired, accompanied by increased apoptosis in early catagen-like miniaturized hair follicles from the balding scalps of androgenetic alopecia patients. Moreover, inhibition of autophagy using 3-methyladenine could induce apoptosis, premature hair follicle regression and slow down the hair growth in organ-cultured hair follicles. Taken together, these results suggest that impairment of autophagy could be a potential mechanism in androgenetic alopecia.

Knockdown of FOXA2 Impairs Hair-Inductive Activity of Cultured Human Follicular Keratinocytes

Reciprocal interactions between hair-inductive dermal cells and epidermal cells are essential for de novo genesis of hair follicles. Recent studies have shown that outer root sheath (ORS) follicular keratinocytes can be expanded in vitro, but the cultured cells often lose receptivity to hair-inducing dermal signals. In this study, we first investigated whether the hair-inductive activity (trichogenicity) of cultured human ORS follicular keratinocytes was correlated with the cultivation period. ORS follicular keratinocytes from the scalp were cultured for 3, 4, 5, or 6 weeks and were then implanted into nude mice along with freshly isolated neonatal mouse dermal cells. We observed that the trichogenicity of the implanted ORS cells was inversely correlated with their cultivation period. These initial findings prompted us to investigate the differentially expressed genes between the short-term (20 days) and long-term (42 days) cultured ORS cells, trichogenic and non-trichogenic, respectively, by microarray analysis. We found that forkhead box protein A2 (FOXA2) was the most up-regulated transcription factor in the trichogenic ORS cells. Thus, we investigated whether the trichogenicity of the cells was affected by FOXA2 expression. We found a significant decrease in the number of induced hair follicles when the ORS cells were transfected with a FOXA2 small interfering RNA versus control small interfering RNA. Taken together, our data strongly suggest that FOXA2 significantly influences the trichogenicity of human ORS cells.

Effect of Chrysanthemum zawadskii Extract on Dermal Papilla Cell Proliferation and Hair Growth

Background

Chrysanthemum zawadskii (CZ) belongs to the genus Chrysanthemum, also known as ‘Gu-Jeol-Cho’ in Korea. CZ has been used as herbal remedy to manage cough, hypertensive disorders, pharyngitis, bronchitis, gastroenteritis, pneumonia, bladder diseases and common cold. However, its effect on hair growth has not been documented.

Objective

The aim of present study was to elucidate the beneficial effects of CZ on hair growth.

Methods

Proliferation of follicular dermal papilla (DP) cells from human scalp skin was evaluated by MTT assay. The expression of various molecules in DP cells was checked by western blot assay. Effect of CZ extract on the hair growth was evaluated by hair organ culture and C57BL/6 mice model.

Results

Cultivation of DP cells with CZ extract increased cellular proliferation, increased expression of phosphorylated protein kinase B (p-Akt), p-ERK, B-cell lymphoma 2, and decreased expression of Bax. Treatment of human hair follicles with CZ extract significantly enhanced hair growth. Additionally, CZ markedly shortened telogen period, increased anagen transformation and stimulated hair growth in the animal study.

Conclusion

These results suggest that CZ extract has an effect of promoting hair growth and may therefore be a useful a therapeutic remedy for preventing hair loss.

Hair growth control by innate immunocytes: Perifollicular macrophages revisited

The role of innate immunocytes such as mast cells, γδ T cells, NK cells and macrophages (MACs) in hair growth control under physiological and pathological conditions has recently begun to be re-explored. Here, we revisit the role of resident perifollicular macrophages (pfMACs) located in the hair follicle (HF) mesenchyme (CTS). Substantial, stringently timed fluctuations in the number and localization of pfMACs were first observed long ago during murine HF morphogenesis and cycling. This already suggested some involvement of these innate immunocytes, with a recognized role in tissue remodelling and in hair growth control. The relatively recent demonstration of a Wnt signalling-driven crosstalk between these immunocytes and HF epithelial stem cells in telogen HFs, which promotes anagen induction, has reinvigorated interest in the role that pfMAC plays in hair biology. Besides the apoptosis-associated secretion of stem cell-activating Wnts and the differential secretion of HF-targeting growth factors such as FGF-5 and FGF5s from pfMACs, we also explore how MAC polarization, and thus function, may be influenced by the local metabolic and immune environment. Moreover, we examine how pfMACs may contribute to hair cycle-associated angiogenesis, vascular remodelling, HF immune privilege and immunopathology. On this basis, we discuss why targeting pfMACs may be relevant in the management of hair growth disorders. Finally, we argue that studying pfMACs offers an excellent, clinically relevant model system for characterizing and experimentally manipulating MAC interactions with an easily accessible mammalian, continuously remodelled (mini-)organ under both physiological and pathological conditions.

Caffeine and Its Pharmacological Benefits in the Management of Androgenetic Alopecia: A Review

Caffeine, particularly after ingestion, is well known to exert various pharmacological effects. A growing body of evidence implicates the ingestion of caffeine with beneficial effects on several diseases. The easy penetration of caffeine across the skin barrier and into human skin makes caffeine an ideal compound for topical application. Hair loss is known to negatively affect the quality of life and predispose to depression and anxiety. Androgenetic alopecia (AGA) is the most common type of hair loss in both men and women. To date, only few approved drug-based treatments for AGA exist, and these are inevitably associated with side effects. Therefore, the development of topical treatments based on well-tolerated natural ingredients such as caffeine to alleviate hair loss may provide a much-needed alternative to drug-based approaches.

Vascular Endothelial Growth Factor Blockade Induces Dermal Endothelial Cell Apoptosis in a Clinically Relevant Skin Organ Culture Model

BACKGROUND/AIMS

Vascular endothelial growth factor (VEGF), a key mediator of angiogenesis, plays a key role in physiological processes and is a major contributor to several diseases including cancer and psoriasis. Anti-VEGF therapies are widely used as cancer and ophthalmological treatments. There is some evidence that VEGF blockade may have utility in the management of psoriasis, although their potential has been largely unexplored. We hypothesized that a human skin organ culture could provide a stable ex vivo model in which the cutaneous microvascular network could be studied and experimentally manipulated.

METHODS

Punch biopsies (3 mm) of skin, donated by healthy individuals (39-72 years old, n = 5), were incubated with monoclonal antibody (mAb) to human VEGF (bevacizumab) at doses based on data from animal and clinical studies. After 3-day culture, cell death and proliferation as well as vascular endothelial cell changes were assessed using quantitative immunohistomorphometry.

RESULTS

Anti-VEGF mAb at 0.8 mg/mL induced a significant increase in cleaved caspase-3 expression in CD31+ cells (p < 0.05). None of the doses tested increased TUNEL or decreased Ki-67 expression in the basal layer of the epidermis, confirming the model's viability. In addition, the lactate dehydrogenase (LDH) assay showed no increase in LDH activity in treated samples compared to untreated control. The highest anti-VEGF mAb dose (0.8 mg/mL) induced an increase in TUNEL expression in the upper epidermis, which did not correlate with caspase-3 immunoreactivity. Further investigation revealed that anti-VEGF mAb did not change the expression of markers of terminal differentiation such as keratin 10, filaggrin, and involucrin, suggesting that VEGF depletion does not affect keratinocyte terminal differentiation. In contrast to the control group, levels of VEGF protein were undetectable in the culture supernatant of samples treated with 0.8 mg/mL of anti-VEGF mAb, suggesting sufficient dose.

CONCLUSION

Our pilot study provides the first evidence that anti-VEGF therapy promotes endothelial cell apoptosis in human skin ex vivo. Our pragmatic human skin organ culture assay offers a valuable tool for future preclinical endothelial cell and translational microvascular network/anti-angiogenesis research in human skin.

Plasmacytoid dendritic cells as a possible key player to initiate alopecia areata in the C3H/HeJ mouse

BACKGROUND

Alopecia areata (AA) is a tissue-specific autoimmune disease, and interferon (IFN)-γ has been regarded as the key cytokine in the pathogenesis of AA. The clinical observation that AA can occur after viral infection or IFN-α administration implies that IFN-α-producing plasmacytoid dendritic cells (pDCs) may be involved in the AA pathogenesis.

METHODS

We generated AA in C3H/HeJ mice by intradermal injection of T cells derived from lymph nodes of AA-bearing syngeneic mice and stimulated IL-2, IL-7, and IL-15. Distribution of IFN-γ producing pDCs were immunohistochemically analyzed. Realtime PCR were also demonstrated to detect the expression of IFN-γ mRNA. Hair follicles were cultured with IFN-α in order to calculate the hair elongation. Imiquimod was employed to induce catagen stage. PDCs were injected into C3H/HeJ mice to initiate AA.

RESULTS

In this mouse, IFN-α-producing pDCs densely infiltrated around HFs in not only AA lesional but also vicinity of AA lesion. Importantly, intradermal injection of pDCs induced AA lesions. Finally, IFN-α inhibited hair elongation of murine vibrissae and upregulated MHC class I and CXCL10 levels in vitro.

CONCLUSIONS

These findings suggest that IFN-α-producing pDCs initiate AA by inducing apoptosis and increasing Th1/Tc1 chemokine production such as CXCL10, that accumulates Th1/Tc1 cells and result in autoimmune reactions against hair follicles.

CDK4/6 inhibition mitigates stem cell damage in a novel model for taxane-induced alopecia

Taxanes are a leading cause of severe and often permanent chemotherapy‐induced alopecia. As the underlying pathobiology of taxane chemotherapy‐induced alopecia remains poorly understood, we investigated how paclitaxel and docetaxel damage human scalp hair follicles in a clinically relevant ex vivo organ culture model. Paclitaxel and docetaxel induced massive mitotic defects and apoptosis in transit amplifying hair matrix keratinocytes and within epithelial stem/progenitor cell‐rich outer root sheath compartments, including within Keratin 15+ cell populations, thus implicating direct damage to stem/progenitor cells as an explanation for the severity and permanence of taxane chemotherapy‐induced alopecia. Moreover, by administering the CDK4/6 inhibitor palbociclib, we show that transit amplifying and stem/progenitor cells can be protected from paclitaxel cytotoxicity through G1 arrest, without premature catagen induction and additional hair follicle damage. Thus, the current study elucidates the pathobiology of taxane chemotherapy‐induced alopecia, highlights the paramount importance of epithelial stem/progenitor cell‐protective therapy in taxane‐based oncotherapy, and provides preclinical proof‐of‐principle in a healthy human (mini‐) organ that G1 arrest therapy can limit taxane‐induced tissue damage.

An important role of cutaneous lymphatic vessels in coordinating and promoting anagen hair follicle growth

The lymphatic vascular system plays important roles in the control of tissue fluid homeostasis and immune responses. While VEGF-A-induced angiogenesis promotes hair follicle (HF) growth, the potential role of lymphatic vessels (LVs) in HF cycling has remained unknown. In this study, we found that LVs are localized in close proximity to the HF bulge area throughout the postnatal and depilation-induced hair cycle in mice and that a network of LVs directly connects the individual HFs. Increased LV density in the skin of K14-VEGF-C transgenic mice was associated with prolongation of anagen HF growth. Conversely, HF entry into the catagen phase was accelerated in K14-sVEGFR3 transgenic mice that lack cutaneous LVs. Importantly, repeated intradermal injections of VEGF-C promoted hair growth in mice. Conditioned media from lymphatic endothelial cells promoted human dermal papilla cell (DPC) growth and expression of IGF-1 and alkaline phosphatase, both activators of DPCs. Our results reveal an unexpected role of LVs in coordinating and promoting HF growth and identify potential new therapeutic strategies for hair loss-associated conditions.

Radon emanation from human hair

Bio-indicator of long time exposure to pollutants, human hair is studied in contaminated areas. The number of studies on background environments remains small, and factors impacting human hair radioactivity in contaminated and background areas remain poorly known. Radon-222, a radioactive noble gas of half-life 3.8 days, is the alpha decay daughter of radium-226 in the uranium-238 chain. Radon emission depends on radium concentration (C_Ra) and probability of decaying radium to liberate radon (i.e., the emanation coefficient E). The radon-222 emanating power (i.e., radon emanation or effective radium-226 concentration, EC_Ra) is measured in the laboratory from human hair of a cohort of 93 individuals living in uranium non-contaminated areas using a high-sensitivity method based on 371 long accumulation sessions. E of human hair is also determined. EC_Ra values from human hair are heterogeneous, ranging from 0.059 ± 0.008 to 3.7 ± 0.1 Bq kg^-1 (mean: 0.484 ± 0.006 Bq kg^-1). We find 2.6 ± 0.1 and 2.5 ± 0.1 times larger values for females than males and for color-treated than natural hair, respectively. By contrast, E is homogeneous (mean: 0.33 ± 0.11; n = 9). Our data suggest a different behavior of accumulation/elimination processes of heavy elements in females and non-negligible radium concentration in hair dye products. Our results demonstrate ²²⁶Ra-²³⁸U disequilibrium in human hair, indicating secondary radium intake, and that EC_Ra mainly depends on C_Ra. Other factors such as age and sampling time are also studied. The impact of factors on EC_Ra from human hair in uranium non-contaminated areas is ordered as follows: (body site?) > sex > hair dyeing > dietary/drinking habits > natural color > time period > geographical location > age. Any human hair-based study should take into consideration these factors. Our method, cost-effective and easy to implement, may be applied to large numbers of samples for large-scale epidemiological studies, and may also be useful for criminal investigations.

Dose-response of human follicles during laser-based hair removal: Ex vivo photoepilation model with classification system embracing morphological and histological features

OBJECTIVES

Photoepilation is a commonly used technology in home-use devices (HUDs) and in professional systems to remove unwanted body hair using pulses of laser or intense pulsed light (IPL). Albeit HUDs and professional systems operate at different fluences and treatment regimes, both demonstrate high hair reduction. The underlying mechanisms, however, remain unknown partly due to high divergence of the existing literature data. The objective of this study was to develop an ex vivo photoepilation model with a set of criteria evaluating response to light pulses; and to investigate dose-response behavior of hair follicles (HFs) subjected to a range of fluences.

METHODS

After ex vivo treatment (single pulse, 810 nm, 1.7-26.4 J/cm² , 4-64 ms pulse) human anagen HFs were isolated and maintained in culture for 7-10 days. Response to light was evaluated based on gross-morphology and histological examination (H&E and TUNEL stainings).

RESULTS

HFs treated ex vivo demonstrated a dose-dependent response to light with five distinct classes defined by macroscopic and microscopic criteria. Fluences below 13.2 J/cm² provoked catagen-like transition, higher fluences resulted in coagulation in HF compartments.

CONCLUSION

Observed changes in the HF organ culture model were reflected by clinical efficacy. The developed photoepilation model provides an easy and fast method to predict clinical efficacy and permanency of light-based hair removal devices. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Light-based home-use devices for hair removal: Why do they work and how effective they are?

OBJECTIVES

This review has the following objectives: Firstly, it provides an explanation of the evolution of laser/intense pulsed light (IPL) hair reduction modalities from high fluence professional devices to low fluence home-use appliances. Secondly, it summarises published literature reviews on home-use devices (HUDs) as evidence of their growing credibility. Thirdly, it proposes mechanistic differences in light delivery regimes and the resulting divergences in mode of action.

MATERIALS AND METHODS

An extensive literature search was performed to review the progress of laser/IPL-induced hair reduction and determine what evidence is available to explain the mode of action of professional and HUDs for hair removal. Establishing the likely biological mode of action of professional high-fluence systems versus home-use low-fluence appliances was performed by combining data obtained using ex vivo hair follicle (HF) organ culture and the clinical results involving human participants.

RESULTS

Significant basic science and clinical evidence has been published to confirm the clinical efficacy and technical safety of many laser and IPL home-use devices for hair removal. Clearly, HUDs are different compared to professional systems both in terms of fluence per pulse and in terms of biological mechanisms underlying hair removal. Here we presented data showing that a single low fluence pulse of both 810 nm laser (6.6 J/cm² , 16 ms) and IPL (9 J/cm² , 15 ms and 6.8 J/cm² , 1.9 ms) leads to induction of catagen transition. Catagen transition was characterized by morphological changes similar to what occurs in vivo with occasional detection of apoptosis in the dermal papilla and outer root sheath cells. This suggests that high hair reduction can be expected in vivo and longer-term treatment might result in HF miniaturization due to a cumulative effect on the dermal papilla and outer root sheath cells. In line with this hypothesis, in this review we demonstrate that long-term application of a commercially-available home-use IPL appliance resulted in persistent hair reduction (80%) one year after last treatment. These data are in line with what was previously reported in the literature, where clinical studies with home-use IPL appliances demonstrated high efficacy of hair reduction on female legs, armpits and bikini zones, with full hair regrowth after four treatments following cessation of IPL administration. Limitations of HUDs include lack of hair clearance for very dark skin types and low speed of treatment compared with professional devices. Numerous uncontrolled and controlled clinical efficacy studies and technical safety investigations on consumer-use appliances support many of the leading manufacturers' claims.

ANALYSIS & CONCLUSIONS

Manufacturers make consumer appliances safe and easy to use by considering "human factors," needs and capabilities of a variety of users. Safety is of primary concern to manufacturers, regulators and standards bodies as these appliances may be accessible to children or their use attempted on unsuitable skin types without full awareness of potential side effects. Consumer cosmetic appliances are provided with warnings and obvious safety notices describing the nature of any ocular or dermal hazard and precautions for reducing risk of accidental injury, infection, etc. HUDs employing optical energy are provided with design and engineering controls such as safety switches, alarms and sensors to prevent their incorrect operation or eye exposure. In-vivo studies demonstrated that low fluence home-use hair removal devices can result in high hair reduction efficacy after a short treatment regime, while prolonged and less frequent (once in six weeks) maintenance treatment over a year can lead to high and sustained hair reduction even one year after cessation of treatment. Home-use hair removal devices can be a useful adjunct to professional in-office treatments with high professional awareness. There are sufficient positive arguments for practitioners to make the case to patients for HUDs as "companion" products to professional treatments. In addition, devices for hair removal can be used effectively as stand-alone products by the consumer if they are willing to adopt a regime of regular or frequent use. Further clinical studies involving dynamic observation of HF cycle stage and type (terminal vs. vellus) over the total duration of treatment, for example, using biopsies or non-invasive imaging are necessary to confirm the proposed mode of action of low fluence pulses in a combination with treatment and maintenance regimes. Lasers Surg. Med. 51:481-490, 2019. © 2019 Wiley Periodicals, Inc.

Changes in the hair growth cycle in women with non-scarring alopecia

One of the key elements in the pathophysiological process of androgenetic alopecia and telogen hair loss is the change of hair cycle. Growth factors controlling the development and cycle of the hair follicle have thus far been established. However, the role of growth factors in the pathogenesis of alopecia remains to be revealed.Objective. This study was aimed at investigating the expression of the VEGF, KGF, EGF and TGF-01 growth factors in women with androgenetic alopecia and telogen hair loss, as well as their role in the development of alopecia.Materials and methods. 60 female patients diagnosed with telogen hair loss (30 women) and androgenetic alopecia (30 women) were observed. In order to investigate the expression of the VEGF, KGF, EGF and TGF-01 growth factors, we conducted an immunofluorescent analysis of skin samples obtained by punch biopsy (4 mm) from the frontoparietal scalp area of patients with androgenetic alopecia and telogen hair loss. 15 samples obtained from healthy people were used as a reference group.Results. A change in the expression of the VEGF, KGF and TGF-01 growth factors in women with androgenetic alopecia and telogen hair loss was established in comparison with healthy individuals. A correlation was found between the expression of the growth factors under study, age (p ≤ 0.05), as well as the character and duration of the disease (p ≤ 0.05) in women with non-scarring alopecia. The expression of the growth factors is found to be dependent on the clinical form of alopecia (p 0.001).Conclusion. The VEGF growth factor is established to have the most significant effect on the development of androgenetic alopecia in women, with the KGF, TGF-01 and EGF factors being less significant as the predictors of this disorder. The VEGF growth factor is shown to affect telogen hair loss to a greater extent compared to the EGF factor. Our study confirms differences in the pathogenesis of androgenetic alopecia and telogen hair loss in women. The findings suggest that the VEGF and KGF growth factors, as well as TGF-01 inhibitors may be used as potential pharmacological agents for treating patients suffering from androgenetic alopecia and telogen hair loss.

Restoration of hair-inductive activity of cultured human follicular keratinocytes by co-culturing with dermal papilla cells

Hair follicle outer root sheath (ORS) cells can be expanded in vitro, but often lose receptivity to hair-inducing dermal signals. Recent studies have shown hair-inductive activity (trichogenicity) can be restored in rat ORS cells expanded with a fibroblast feeder by co-culturing with rat vibrissae dermal papilla (DP) cells. In this study, we investigated whether the trichogenicity of human ORS cells can be restored by co-culturing with human DP cells. ORS cells from human scalp hair follicles were cultured independently or with DP cells for 5 days and implanted into nude mice alongside freshly isolated neonatal mouse dermal cells. Although there was no hair induction when monocultured ORS cells were implanted, it was observed in co-cultured ORS cells. We also observed differential regulation of a number of genes in ORS cells co-cultured with DP cells compared to monocultured ORS cells as examined by microarray. Taken together, our data strongly suggest that human DP cells restore the trichogenicity of co-cultured ORS cells by influencing ORS gene expression through paracrine factors.

SOCS3 treatment prevents the development of alopecia areata by inhibiting CD8+ T cell-mediated autoimmune destruction

Alopecia areata is one of the most common autoimmune diseases resulting from T cell-mediated damage of hair follicles. CD8+ T cells infiltrate hair follicles and are responsible for destruction of hair follicles. However the underlying mechanisms for hair loss remain still obscure. In the present study, we identified that suppressor of cytokine signaling-3 (SOCS3), a classical inhibitor of cytokine signaling, significantly inhibits CD8+T cell maturation, interferon-γ (IFN-γ) production and alopecia areata. SOCS3 is downregulated in the skin of alopecia areata patients and murine autoimmune alopecia model. Furthermore, SOCS3 treatment prevents the development of alopecia areata in the graft model. SOCS3 decreases the CD44^high CD62L^low effector memory CD8+ T cells, resulting in the decrease of IFN-γ production. The expression of Fas and major histocompatibility complex-1 (MHC I) is upregulated in skin from C3H/HeJ alopecia areata mice, and this increase is suppressed by SOCS3. The SOCS3 level is negative correlation with the Fas and MHC I level in patients with alopecia areata. These results suggest that SOCS3 treatment may be an effective strategy to treat autoimmune alopecia as well as to more generally prevent cytokine-dependent tissue destruction in inflammatory diseases.

An Asian traditional herbal complex containing Houttuynia cordata Thunb, Perilla frutescens Var. acuta and green tea stimulates hair growth in mice

BACKGROUND

Houttuynia cordata Thunb (HC) is a traditional herbal medicine widely used in Asia for the treatment of patients with alopecia, usually in combination with other two herbal medicines (Perilla frutescens var. acuta (PFVA) and green tea (GT)). However, the effect of this herbal complex has not been clearly demonstrated. We sought to determine the hair growth-promoting effect of this herbal complex (HC, PFVA, and GT) in the animal model.

METHODS

Six-week-old male C57BL/6 mice were randomly divided into four groups (negative control, finasteride (1 mg/kg) as a positive control, and two (200 and 400 mg/kg) concentrations of the herbal complex as experimental groups) and were fed its corresponding medications orally for 25 days. Hair growth was evaluated visually and microscopically. Western blot analysis for insulin-like growth factor (IGF)-1 and transforming growth factor (TGF)-β1 was performed.

RESULTS

The herbal complex exhibited hair growth-promoting activity in C57BL/6 mice. Grossly, the area of hair regrowth was 55.1 (±3.8) %, 70.2 (±6.3) % and 83.5 (±5.7) % in negative control, herbal complex 200 mg/kg and 400 mg/kg group, respectively. In histologic examination, the hair follicle count in deep subcutis was 2.6 (±0.7), 5.8 (±0.7) and 8.6 (±1.2) and the diameter of hair follicles was 11.9 (±5.0) μm, 17.4 (±3.9) μm and 22.8 (±5.2) μm in negative control, herbal complex 200 and 400 mg/kg group, respectively. The expression of IGF-1 was 0.14 (±0.01), 0.23 (±0.02) and 0.24 (±0.01) and the expression of TGF-β1 was 0.26 (±0.01), 0.19 (±0.02) and 0.15 (±0.01) in negative control, the 200 and 400 mg/kg group, respectively.

CONCLUSIONS

This data provides adequate preliminary experimental evidence to support the hair regeneration effect of this herbal complex.

Wnt/β-catenin and ERK pathway activation: A possible mechanism of photobiomodulation therapy with light-emitting diodes that regulate the proliferation of human outer root sheath cells

BACKGROUND

Outer root sheath cells (ORSCs) play important roles in maintaining hair follicle structure and provide support for the bulge area. The hair growth promoting effects of photobiomodulation therapy (PBMT) have been reported, but the mechanisms for this in human ORCs (hORSCs) have rarely been studied.

OBJECTIVE

The aim of this study was to investigate the effect of various wavelengths of light-emitting diode (LED) irradiation on human ORSCs (hORSCs).

METHODS

LED irradiation effects on hORSC proliferation and migration were examined with MTT assay, BrdU incorporation assay and migration assays. hORSCs were irradiated using four LED wavelengths (415, 525, 660, and 830 nm) with different low energy levels. LED irradiation effects on the expression of molecules associated with the Wnt/β-catenin signaling and ERK pathway, hair stem cell markers, and various growth factors and cytokines in hORSCs were examined with real-time PCR and Western blot assay. The effect of the LED-irradiated hORSCs on cell proliferation of human dermal papilla cells (hDPCs) was examined with co-culture and MTT assay.

RESULTS

PBMT with LED light variably promoted hORSC proliferation and suppressed cell apoptosis depending on energy level. LED irradiation induced Wnt5a, Axin2, and Lef1 mRNA expression and β-catenin protein expression in hORSCs. Phosphorylation of ERK, c-Jun, and p38 in hORSCs was observed after LED light irradiation, and ERK inhibitor treatment before irradiation reduced ERK and c-Jun phosphorylation. Red light-treated hORSCs showed substantial increase in IL-6, IL-8, TNF-a, IGF-1, TGF-β1, and VEGF mRNA. Light irradiation at 660 and 830 nm projected onto hORSCs accelerated in vitro migration. LED-irradiated hORSCs increased hDPCs proliferation when they were co-cultured. The conditioned medium from LED-irradiated hORSCs was sufficient to stimulate hDPCs proliferation.

CONCLUSION

These results demonstrate that LED light irradiation induced hORSC proliferation and migration and inhibited apoptosis in vitro. The growth-promoting effects of LEDs on hORSCs appear to be associated with direct stimulation of the Wnt5a/β-catenin and ERK signaling pathway. Lasers Surg. Med. 49:940-947, 2017. © 2017 Wiley Periodicals, Inc.

Panax ginseng extract antagonizes the effect of DKK‑1-induced catagen-like changes of hair follicles

It is well known that Panax ginseng (PG) has various pharmacological effects such as anti-aging and anti-inflammation. In a previous study, the authors identified that PG extract induced hair growth by means of a mechanism similar to that of minoxidil. In the present study, the inhibitory effect of PG extract on Dickkopf-1 (DKK-1)-induced catagen-like changes in hair follicles (HFs) was investigated in addition to the underlying mechanism of action. The effects of PG extract on cell proliferation, anti-apoptotic effect, and hair growth were observed using cultured outer root sheath (ORS) keratinocytes and human HFs with or without DKK-1 treatment. The PG extract significantly stimulated proliferation and inhibited apoptosis, respectively, in ORS keratinocytes. PG extract treatment affected the expression of apoptosis-related genes Bcl-2 and Bax. DKK-1 inhibited hair growth, and PG extract dramatically reversed the effect of DKK-1 on ex vivo human hair organ culture. PG extract antagonizes DKK-1-induced catagen-like changes, in part, through the regulation of apoptosis-related gene expression in HFs. These findings suggested that PG extract may reduce hair loss despite the presence of DKK-1, a strong catagen inducer via apoptosis.

β-Catenin is involved in oleanolic acid-dependent promotion of proliferation in human hair matrix cells in an in vitro organ culture model

Oleanolic acid (OA), a pentacyclic triterpenoid compound which can be found in >1600 plants, has been shown to promote hair growth. To study the mechanisms of OA on hair growth, we investigated hair follicle (HF) growth on four different concentration OA using human hair follicle organ culture model. We found that HFs treated with 1 or 10μg/mL OA showed statistically enhanced elongation of the hair shaft and anagen-like stage. Moreover, higher positive rate of Ki-67, a matrix cellular marker of proliferation, was detected in the same groups treated with 1 or 10μg/mL than those treated with vehicle. We further demonstrated that β-catenin, a key Wnt signaling transducer, was highly expressed in the OA treated groups using immunofluorescence stain assay. These results suggest that OA may promote human hair growth by stimulating hair matrix cell proliferation through the Wnt/β-catenin pathway.

Compartmentation of Mitochondrial and Oxidative Metabolism in Growing Hair Follicles: A Ring of Fire

Little is known about the energetics of growing hair follicles, particularly in the mitochondrially abundant bulb. Here, mitochondrial and oxidative metabolism was visualized by multiphoton and light sheet microscopy in cultured bovine hair follicles and plucked human hairs. Mitochondrial membrane potential (ΔΨ), cell viability, reactive oxygen species (ROS), and secretory granules were assessed with parameter-indicating fluorophores. In growing follicles, lower bulb epithelial cells had high viability, and mitochondria were polarized. Most epithelially generated ROS co-localized with polarized mitochondria. As the imaging plane captured more central and distal cells, ΔΨ disappeared abruptly at a transition to a nonfluorescent core continuous with the hair shaft. Approaching the transition, ΔΨ and ROS increased, and secretory granules disappeared. ROS and ΔΨ were strongest in a circumferential paraxial ring at putative sites for formation of the outer cortex/cuticle of the hair shaft. By contrast, polarized mitochondria in dermal papillar fibroblasts produced minimal ROS. Plucked hairs showed a similar abrupt transition of degranulation/depolarization near sites of keratin deposition, as well as an ROS-generating paraxial ring of fire. Hair movement out of the follicle appeared to occur independently of follicular bulb bioenergetics by a tractor mechanism involving the inner and outer root sheaths.

Preclinical and Clinical Studies Demonstrate That the Proprietary Herbal Extract DA-5512 Effectively Stimulates Hair Growth and Promotes Hair Health

The proprietary DA-5512 formulation comprises six herbal extracts from traditional oriental plants historically associated with therapeutic and other applications related to hair. Here, we investigated the effects of DA-5512 on the proliferation of human dermal papilla cells (hDPCs) in vitro and on hair growth in C57BL/6 mice and conducted a clinical study to evaluate the efficacy and safety of DA-5512. DA-5512 significantly enhanced the viability of hDPCs in a dose-dependent manner (p < 0.05), and 100 ppm of DA-5512 and 1 μM minoxidil (MXD) significantly increased the number of Ki-67-positive cells, compared with the control group (p < 0.05). MXD (3%) and DA-5512 (1%, 5%) significantly stimulated hair growth and increased the number and length of hair follicles (HFs) versus the controls (each p < 0.05). The groups treated with DA-5512 exhibited hair growth comparable to that induced by MXD. In clinical study, we detected a statistically significant increase in the efficacy of DA-5512 after 16 weeks compared with the groups treated with placebo or 3% MXD (p < 0.05). In conclusion, DA-5512 might promote hair growth and enhance hair health and can therefore be considered an effective option for treating hair loss.

A new path in defining light parameters for hair growth: Discovery and modulation of photoreceptors in human hair follicle

BACKGROUND AND OBJECTIVE

Though devices for hair growth based on low levels of light have shown encouraging results, further improvements of their efficacy is impeded by a lack of knowledge on the exact molecular targets that mediate physiological response in skin and hair follicle. The aim of this study was to investigate the expression of selected light-sensitive receptors in the human hair follicle and to study the impact of UV-free blue light on hair growth ex vivo.

MATERIAL AND METHODS

The expression of Opsin receptors in human skin and hair follicles has been characterized using RT-qPCR and immunofluorescence approaches. The functional significance of Opsin 3 was assessed by silencing its expression in the hair follicle cells followed by a transcriptomic profiling. Proprietary LED-based devices emitting two discrete visible wavelengths were used to access the effects of selected optical parameters on hair growth ex vivo and outer root sheath cells in vitro.

RESULTS

The expression of OPN2 (Rhodopsin) and OPN3 (Panopsin, Encephalopsin) was detected in the distinct compartments of skin and anagen hair follicle. Treatment with 3.2 J/cm² of blue light with 453 nm central wavelength significantly prolonged anagen phase in hair follicles ex vivo that was correlated with sustained proliferation in the light-treated samples. In contrast, hair follicle treatment with 3.2 J/cm² of 689 nm light (red light) did not significantly affect hair growth ex vivo. Silencing of OPN3 in the hair follicle outer root sheath cells resulted in the altered expression of genes involved in the control of proliferation and apoptosis, and abrogated stimulatory effects of blue light (3.2 J/cm² ; 453 nm) on proliferation in the outer root sheath cells.

CONCLUSIONS

We provide the first evidence that (i) OPN2 and OPN3 are expressed in human hair follicle, and (ii) A 453 nm blue light at low radiant exposure exerts a positive effect on hair growth ex vivo, potentially via interaction with OPN3. Lasers Surg. Med. 49:705-718, 2017. © 2017 Wiley Periodicals, Inc.

A primer for studying cell cycle dynamics of the human hair follicle

The cell cycle is of major importance to human hair follicle (HF) biology. Not only is continuously active cell cycling required to facilitate healthy hair growth in anagen VI HFs, but perturbations in the cell cycle are likely to be of significance in HF pathology (i.e. in scarring, non-scarring, chemotherapy-induced and androgenic alopecias). However, cell cycle dynamics of the human hair follicle (HF) are poorly understood in contrast to what is known in mouse. The current Methods Review aims at helping to close this gap by presenting a primer that introduces immunohistological/immunofluorescent techniques to study the cell cycle in the human HF. Moreover, this primer encourages the exploitation of the human HF as a powerful and clinically relevant tool to investigate mammalian cell cycle biology in situ. To achieve this, we describe methods to study markers of general 'proliferation' (nuclei count, Ki-67 expression), apoptosis (terminal deoxynucleotidyl transferase dUTP nick-end labelling, cleaved caspase 3), mitosis (phospho-histone H3, 'pS780'), DNA synthesis (5-ethynyl-2'-deoxyuridine) and cell cycle regulation (cyclins) in the human HF. In addition, we provide specific examples of dual immunolabelling for instructive cell cycle analyses and for investigating the cell cycle behaviour of specific HF keratinocyte subpopulations, such as keratin 15+ stem/progenitor cells.

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

In the murine hair follicle (HF), the transcription factors LHX2 and SOX9 are implicated in 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 the human HF are unclear. Therefore, we have quantitatively mapped the localisation of known human eHFSC markers keratin 15 (K15) and keratin 19 (K19) in the outer root sheath (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, that is 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 the majority of SOX9(+) cells in the human anagen HF epithelium did not co-express K15, K19 or LHX2. This expression profile suggests that LHX2 and SOX9 highlight distinct epithelial progenitor cell populations, in addition to K15(+) or K19(+) cells, that could play an important role in the maintenance of the human HF epithelium.

Hot water extract of oriental melon leaf promotes hair growth and prolongs anagen hair cycle: In vivo and in vitro evaluation

Effects of hot water extracts of oriental melon leaves (OML) on promotion of hair growth were investigated. Topical OML extract administration for hair regeneration was investigated using an in vivo model with C57BL/6 mice. Effects of OML extracts on the human hair growth were investigated using a hair follicle organ culture. OML extracts induced a shortened telogen to anagen conversion and promoted hair growth in the C57BL/6 mouse model. Culture of human hair follicles in the presence of OML extracts for 8 days promoted hair growth and prolonged the anagen duration due to induction of hair follicle cell proliferation in the bulb region. OML extracts exert a hair growth promotion effect and, therefore, can be used as a therapeutic agent for prevention of hair loss.

Differential Expression between Human Dermal Papilla Cells from Balding and Non-Balding Scalps Reveals New Candidate Genes for Androgenetic Alopecia

Androgenetic alopecia (AGA) is a common heritable and androgen-dependent hair loss condition in men. Twelve genetic risk loci are known to date, but it is unclear which genes at these loci are relevant for AGA. Dermal papilla cells (DPCs) located in the hair bulb are the main site of androgen activity in the hair follicle. Widely used monolayer-cultured primary DPCs in hair-related studies often lack dermal papilla characteristics. In contrast, immortalized DPCs have high resemblance to intact dermal papilla. We derived immortalized human DPC lines from balding (BAB) and non-balding (BAN) scalp. Both BAB and BAN retained high proportions of dermal papilla signature gene and versican protein expression. We performed expression analysis of BAB and BAN and annotated AGA risk loci with differentially expressed genes. We found evidence for AR but not EDA2R as the candidate gene at the AGA risk locus on chromosome X. Further, our data suggest TWIST1 (twist family basic helix-loop-helix transcription factor 1) and SSPN (sarcospan) to be the functionally relevant AGA genes at the 7p21.1 and 12p12.1 risk loci, respectively. Down-regulated genes in BAB compared to BAN were highly enriched for vasculature-related genes, suggesting that deficiency of DPC from balding scalps in fostering vascularization around the hair follicle may contribute to the development of AGA.

Protective effect of Korean Red Ginseng against chemotherapeutic drug-induced premature catagen development assessed with human hair follicle organ culture model

Background

Chemotherapy-induced alopecia (CIA) is one of the most distressing side effects for patients undergoing chemotherapy. This study evaluated the protective effect of Korean Red Ginseng (KRG) on CIA in a well-established in vitro human hair follicle organ culture model as it occurs in vivo.

Methods

We examined whether KRG can prevent premature hair follicle dystrophy in a human hair follicle organ culture model during treatment with a key cyclophosphamide metabolite, 4-hydroperoxycyclophosphamide (4-HC).

Results

4-HC inhibited human hair growth, induced premature catagen development, and inhibited proliferation and stimulated apoptosis of hair matrix keratinocytes. In addition, 4-HC increased p53 and Bax protein expression and decreased Bcl2 protein expression. Pretreatment with KRG protected against 4-HC-induced hair growth inhibition and premature catagen development. KRG also suppressed 4-HC-induced inhibition of matrix keratinocyte proliferation and stimulation of matrix keratinocyte apoptosis. Moreover, KRG restored 4-HC-induced p53 and Bax/Bcl2 expression.

Conclusion

Overall, our results indicate that KRG may protect against 4-HC-induced premature catagen development through modulation of p53 and Bax/Bcl2 expression.

Role of peptide growth factors in the rhythm of change hair

The article presents current data on the role growth factors play in hair physiology. Based on a review of literature, the authors described the role growth factors play for initiating, suppressing the growth and differentiating hair follicles. According to them, each morphologic development stage of hair follicles is characterized by its own factor expression pattern. Referring to experimental and clinical studies, the authors describe the role some growth factors play for mechanisms promoting the development of androgynous and focal alopecia.

Mechanisms underlying skin disorders induced by EGFR inhibitors

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is frequently mutated or overexpressed in a large number of tumors such as carcinomas or glioblastoma. Inhibitors of EGFR activation have been successfully established for the therapy of some cancers and are more and more frequently being used as first or later line therapies. Although the side effects induced by inhibitors of EGFR are less severe than those observed with classic cytotoxic chemotherapy and can usually be handled by out-patient care, they may still be a cause for dose reduction or discontinuation of treatment that can reduce the effectiveness of antitumor therapy. The mechanisms underlying these cutaneous side effects are only partly understood. Important questions, such as the reasons for the correlation between the intensity of the side effects and the efficiency of treatment with EGFR inhibitors, remain to be answered. Optimized adjuvant strategies to accompany anti-EGFR therapy need to be found for optimal therapeutic application and improved quality of life of patients. Here, we summarize current literature on the molecular and cellular mechanisms underlying the cutaneous side effects induced by EGFR inhibitors and provide evidence that keratinocytes are probably the optimal targets for adjuvant therapy aimed at alleviating skin toxicities.

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

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 hair growth 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).

Mycophenolate antagonizes IFN-γ-induced catagen-like changes via β-catenin activation in human dermal papilla cells and hair follicles

Recently, various immunosuppressant drugs have been shown to induce hair growth in normal hair as well as in alopecia areata and androgenic alopecia; however, the responsible mechanism has not yet been fully elucidated. In this study, we investigate the influence of mycophenolate (MPA), an immunosuppressant, on the proliferation of human dermal papilla cells (hDPCs) and on the growth of human hair follicles following catagen induction with interferon (IFN)-γ. IFN-γ was found to reduce β-catenin, an activator of hair follicle growth, and activate glycogen synthase kinase (GSK)-3β, and enhance expression of the Wnt inhibitor DKK-1 and catagen inducer transforming growth factor (TGF)-β2. IFN-γ inhibited expression of ALP and other dermal papillar cells (DPCs) markers such as Axin2, IGF-1, and FGF 7 and 10. MPA increased β-catenin in IFN-γ-treated hDPCs leading to its nuclear accumulation via inhibition of GSK3β and reduction of DKK-1. Furthermore, MPA significantly increased expression of ALP and other DPC marker genes but inhibited expression of TGF-β2. Therefore, we demonstrate for the first time that IFN-γ induces catagen-like changes in hDPCs and in hair follicles via inhibition of Wnt/β-catenin signaling, and that MPA stabilizes β-catenin by inhibiting GSK3β leading to increased β-catenin target gene and DP signature gene expression, which may, in part, counteract IFN-γ-induced catagen in hDPCs.

DNA Polymorphism of Insulin-like Growth Factor-binding Protein-3 Gene and Its Association with Cashmere Traits in Cashmere Goats

Insulin-like growth factor binding protein-3 (IGFBP-3) gene is important for regulation of growth and development in mammals. The present investigation was carried out to study DNA polymorphism by PCR-RFLP of IGFBP-3 gene and its effect on fibre traits of Chinese Inner Mongolian cashmere goats. The fibre traits data investigated were cashmere fibre diameter, combed cashmere weight, cashmere fibre length and guard hair length. Four hundred and forty-four animals were used to detect polymorphisms in the hircine IGFBP-3 gene. A 316-bp fragment of the IGFBP-3 gene in exon 2 was amplified and digested with HaeIII restriction enzyme. Three patterns of restriction fragments were observed in the populations. The frequency of AA, AB and BB genotypes was 0.58, 0.33 and 0.09 respectively. The allelic frequency of the A and B allele was 0.75 and 0.25 respectively. Nucleotide sequencing revealed a C>G transition in the exon 2 region of the IGFBP-3 gene resulting in R158G change which caused the polymorphism. Least squares analysis revealed a significant effect of genotypes on cashmere weight (p<0.0001), cashmere fibre length (p<0.001) and hair length (p<0.05) of the animals. The effect of genotypes on cashmere fibre diameter was not statistically significant (p>0.05). The animals of AB and BB genotypes showed higher cashmere weight, cashmere fibre length and hair length than the animals possessing AA genotype. These results suggested that polymorphisms in the hircine IGFBP-3 gene might be a potential molecular marker for cashmere weight in cashmere goats.

Complex changes in the apoptotic and cell differentiation programs during initiation of the hair follicle response to chemotherapy

Chemotherapy has severe side-effects for normal rapidly proliferating organs, such as hair follicle, and causes massive apoptosis in hair matrix keratinocytes followed by hair loss. To define the molecular signature of hair follicle response to chemotherapy, human scalp hair follicles cultured ex vivo were treated with doxorubicin and global microarray analysis was performed 3 hours after treatment. Microarray data revealed changes in expression of 504 genes in doxorubicin-treated hair follicles versus the controls. Among these genes, upregulations of several tumor necrosis factor family of apoptotic receptors (FAS, TRAIL receptors 1/2), as well as of a large number of the keratin-associated protein genes were seen after doxorubicin treatment. Hair follicle apoptosis induced by doxorubicin was significantly inhibited by either TRAIL neutralizing antibody or caspase 8 inhibitor, thus suggesting a novel role for TRAIL receptor signaling in mediating doxorubicin-induced hair loss. These data demonstrate that the early phase of the hair follicle response to doxorubicin includes upregulation of apoptosis-associated markers, as well as substantial re-organization of the terminal differentiation programs in hair follicle keratinocytes. These data provide an important platform for further studies towards the design of novel approaches for management of chemotherapy-induced hair loss.

Exogenous IGF-1 promotes hair growth by stimulating cell proliferation and down regulating TGF-β1 in C57BL/6 mice in vivo

OBJECTIVE

Insulin-like growth factor 1 (IGF-1) increases the growth of cultured hair follicles and plays a role in regulating hair migration during the development of hair follicles in transgenic mice. However, the exogenous effect of IGF-1 on hair growth in wild-type mice has not been reported. In the present study, we examined whether IGF-1 was an important regulator of hair follicle growth in wide-type mice in vivo.

DESIGN

C57BL/6 mice were injected with different concentrations of IGF-1 on dorsal skin. The treated tissues were analyzed by immunoassay methods for TGF-β1 and BrdU.

RESULTS

Local injection of IGF-1 increased hair follicle number and prolonged the growing phase during the transition from anagen to telogen. Meanwhile, immunology analyses revealed that IGF-1 also stimulated the proliferation of follicle cells in anagen of the matrix and down regulated TGF-β1 expression in hair follicles.

CONCLUSIONS

These observations suggest that IGF-1 is an effective stimulator of hair follicle development in wide-type mice in vivo and may be a promising drug candidate for baldness therapy.

A meeting of two chronobiological systems: circadian proteins Period1 and BMAL1 modulate the human hair cycle clock

The hair follicle (HF) is a continuously remodeled mini organ that cycles between growth (anagen), regression (catagen), and relative quiescence (telogen). As the anagen-to-catagen transformation of microdissected human scalp HFs can be observed in organ culture, it permits the study of the unknown controls of autonomous, rhythmic tissue remodeling of the HF, which intersects developmental, chronobiological, and growth-regulatory mechanisms. The hypothesis that the peripheral clock system is involved in hair cycle control, i.e., the anagen-to-catagen transformation, was tested. Here we show that in the absence of central clock influences, isolated, organ-cultured human HFs show circadian changes in the gene and protein expression of core clock genes (CLOCK, BMAL1, and Period1) and clock-controlled genes (c-Myc, NR1D1, and CDKN1A), with Period1 expression being hair cycle dependent. Knockdown of either BMAL1 or Period1 in human anagen HFs significantly prolonged anagen. This provides evidence that peripheral core clock genes modulate human HF cycling and are an integral component of the human hair cycle clock. Specifically, our study identifies BMAL1 and Period1 as potential therapeutic targets for modulating human hair growth.