Whole hair follicle culture

Discovery of a novel and highly selective JAK3 inhibitor as a potent hair growth promoter

JAK-STAT signalling pathway inhibitors have emerged as promising therapeutic agents for the treatment of hair loss. Among different JAK isoforms, JAK3 has become an ideal target for drug discovery because it only regulates a narrow spectrum of γc cytokines. Here, we report the discovery of MJ04, a novel and highly selective 3-pyrimidinylazaindole based JAK3 inhibitor, as a potential hair growth promoter with an IC50 of 2.03 nM. During in vivo efficacy assays, topical application of MJ04 on DHT-challenged AGA and athymic nude mice resulted in early onset of hair regrowth. Furthermore, MJ04 significantly promoted the growth of human hair follicles under ex-vivo conditions. MJ04 exhibited a reasonably good pharmacokinetic profile and demonstrated a favourable safety profile under in vivo and in vitro conditions. Taken together, we report MJ04 as a highly potent and selective JAK3 inhibitor that exhibits overall properties suitable for topical drug development and advancement to human clinical trials.

Impact of Thyroid Dysfunction on Hair Disorders

Hair loss is a problem for everyone, regardless of their age or sex. The three most prevalent types of hair loss, telogen effluvium, alopecia areata, and androgenetic alopecia, have been associated with a variety of risk factors. Strong evidence links thyroid hormones (THs) to hair loss. THs control the growth, differentiation, metabolism, and thermogenesis of body cells. The skin is a significant target organ for THs; however, the cellular and molecular causes of thyroid dysfunction-related skin diseases remain unknown. Hyperthyroidism, hypothyroidism, and drug-induced hypothyroidism can induce widespread hair shedding. Little information is available regarding the incidence and effects of thyroid dysfunction on hair problems. This study aimed to review the impact and prevalence of thyroid disorders on hair loss. The conclusions drawn from this study highlight the underestimated prevalence and impact of thyroid disorders on hair loss. The review of scientific articles, including original research, review articles, and a case report, provides a comprehensive understanding of the topic. This research adds to the existing literature by enhancing our understanding of the relationship between thyroid dysfunction and hair disorders. It contributes to the body of evidence by reviewing relevant studies and summarizing the impact of thyroid disorders on hair loss. The study also highlights the gaps in knowledge and the need for more research in this area to improve the diagnosis and management of hair disorders associated with thyroid dysfunction.

Effect of Platelet-Rich Plasma and other Key Factors on Hair Follicle Preservation

Background

Hair graft preservation is an important factor that influences graft survival in hair transplantation.

Objective

To investigate the benefits of adding platelet-rich plasma (PRP), and the effect of different storage solutions and temperatures on hair follicle preservation.

Materials and Methods

This randomized-controlled study included 10 androgenetic alopecia patients who underwent hair transplantation. Forty-five hair grafts were collected from each patient and then randomized to 8 different culture conditions for 7 days. Hair grafts were cultured in Williams' Medium E or Ringer's lactate solution (RLS) at either 4°C or 37°C, and with or without 10% PRP supplementation.

Results

In vitro hair growth in Williams' Medium E was significantly greater than in RLS. The 37°C temperature condition was found to be significantly better than the 4°C condition. The growth of hair grafts cultured with PRP was not significance difference from those without PRP. However, immunofluorescence staining for cytokeratin 15 showed greater expression in hair graft cultured with PRP.

Conclusion

PRP may have a beneficial effect for preserving the viability of hair grafts. Williams' Medium E and 37°C temperature were found to be superior to RLS and 4°C relative to hair follicle growth in organ culture.

Minoxidil-loaded hyaluronic acid dissolving microneedles to alleviate hair loss in an alopecia animal model

Alopecia is defined as hair loss in a part of the head due to various causes, such as drugs, stress and autoimmune disorders. Various therapeutic agents have been suggested depending on the cause of the condition and patient sex, and age. Minoxidil (MXD) is commonly used topically to treat alopecia, but its low absorption rate limits widespread use. To overcome the low absorption, we suggest microneedles (MNs) as controlled drug delivery systems that release MXD. We used hyaluronic acid (HA) to construct MN, as it is biocompatible and safe. We examined the effect of HA on the hair dermal papilla (HDP) cells that control the development of hair follicles. HA enhanced proliferation, migration, and aggregation of HDP cell by increasing cell-cell adhesion and decreasing cell substratum. These effects were mediated by the cluster of differentiation (CD)-44 and phosphorylation of serine‑threonine kinase (Akt). In chemotherapy-induced alopecia mice, topical application of HA tended to decrease chemotherapy-induced hair loss. Although the amount of MXD administered by HA-MNs was 10% of topical treatment, the MXD-containing HA-MNs (MXD-HA-MNs) showed better effects on the growth of hair than topical application of MXD. In summary, our results demonstrated that HA reduces hair loss in alopecia mice, and that delivery of MXD and HA using MXD-HA-MNs maximizes therapeutic effects and minimize the side effects of MXD for the treatment of alopecia. STATEMENT OF SIGNIFICANCE: (1) Significance, This work reports a new approach for treatment of alopecia using a dissolving microneedle (MN) prepared with hyaluronic acid (HA). The HA provided a better environment for cellular functions in the hair dermal papilla cells. The HA-MNs containing minoxidil (MXD) exhibited a significant reduction of hair loss, although amount of MXD contained in them was only 10% of topically applied MXD., (2) Scientific impact, This is the first report demonstrating the direct anti-alopecia effects of HA administrated in a transdermal route and the feasibility of novel therapeutics using MXD-containing HA-MNs. We believe that our work will excite interdisciplinary readers of Acta Biomaterialia, those who are interested in the natural polymers, drug delivery, and alopecia.

Hydra and the hair follicle - An unconventional comparative biology approach to exploring the human holobiont

The microbiome of human hair follicles (HFs) has emerged as an important player in different HF and skin pathologies, yet awaits in-depth exploration. This raises questions regarding the tightly linked interactions between host environment, nutrient dependency of host-associated microbes, microbial metabolism, microbe-microbe interactions and host immunity. The use of simple model systems facilitates addressing generally important questions and testing overarching, therapeutically relevant principles that likely transcend obvious interspecies differences. Here, we evaluate the potential of the freshwater polyp Hydra, to dissect fundamental principles of microbiome regulation by the host, that is the human HF. In particular, we focus on therapeutically targetable host-microbiome interactions, such as nutrient dependency, microbial interactions and host defence. Offering a new lens into the study of HF - microbiota interactions, we argue that general principles of how Hydra manages its microbiota can inform the development of novel, microbiome-targeting therapeutic interventions in human skin disease.

The Glypican-1/HGF/C-Met and Glypican-1/VEGF/VEGFR2 Ternary Complexes Regulate Hair Follicle Angiogenesis

The hair renewal involves changes in the morphology of the hair follicle and its micro-vascularization. In alopecia, the hair cycle is accelerated, resulting in the formation of thinner and shorter hair. In addition, alopecia is associated with a decrease in the micro-vascularization of the hair follicles. In this study, the role of glypicans (GPCs) was analyzed in the regulation of the angiogenesis of human dermal microvascular endothelial cells (HDMEC). The analysis of glypican gene expression showed that GPC1 is the major glypican expressed by human keratinocytes of outer root sheath (KORS), human hair follicle dermal papilla cells (HHFDPC) and HDMEC. KORS were demonstrated to secrete VEGF and HGF. The HDMEC pseudotube formation was induced by KORS conditioned media (KORS_CM). It was totally abrogated after GPC1 siRNA transfection of HDMEC. Moreover, when cleaved by phospholipase C (PLC), GPC1 promotes the proliferation of HDMEC. Finally, GPC1 was shown to interact directly with VEGFR2 or c-Met to regulate angiogenesis induced by the activation of these receptors. Altogether, these results showed that GPC1 is a key regulator of microvascular endothelial cell angiogenesis induced by VEGF and HGF secreted by KORS. Thus, GPC1 might constitute an interesting target to tackle alopecia in dermatology research.

Hair Histology and Glycosaminoglycans Distribution Probed by Infrared Spectral Imaging: Focus on Heparan Sulfate Proteoglycan and Glypican-1 during Hair Growth Cycle

The expression of glypicans in different hair follicle (HF) compartments and their potential roles during hair shaft growth are still poorly understood. Heparan sulfate proteoglycan (HSPG) distribution in HFs is classically investigated by conventional histology, biochemical analysis, and immunohistochemistry. In this report, a novel approach is proposed to assess hair histology and HSPG distribution changes in HFs at different phases of the hair growth cycle using infrared spectral imaging (IRSI). The distribution of HSPGs in HFs was probed by IRSI using the absorption region relevant to sulfation as a spectral marker. The findings were supported by Western immunoblotting and immunohistochemistry assays focusing on the glypican-1 expression and distribution in HFs. This study demonstrates the capacity of IRSI to identify the different HF tissue structures and to highlight protein, proteoglycan (PG), glycosaminoglycan (GAG), and sulfated GAG distribution in these structures. The comparison between anagen, catagen, and telogen phases shows the qualitative and/or quantitative evolution of GAGs as supported by Western immunoblotting. Thus, IRSI can simultaneously reveal the location of proteins, PGs, GAGs, and sulfated GAGs in HFs in a reagent- and label-free manner. From a dermatological point of view, IRSI shows its potential as a promising technique to study alopecia.

"Two-Cell Assemblage" Assay: A Simple in vitro Method for Screening Hair Growth-Promoting Compounds

Alopecia arises due to inadequate hair follicle (HF) stem cell activation or proliferation, resulting in prolongation of the telogen phase of the hair cycle. Increasing therapeutic and cosmetic demand for alleviating alopecia has driven research toward the discovery or synthesis of novel compounds that can promote hair growth by inducing HF stem cell activation or proliferation and initiating the anagen phase. Although several methods for evaluating the hair growth-promoting effects of candidate compounds are being used, most of these methods are difficult to use for large scale simultaneous screening of various compounds. Herein, we introduce a simple and reliable in vitro assay for the simultaneous screening of the hair growth-promoting effects of candidate compounds on a large scale. In this study, we first established a 3D co-culture system of human dermal papilla (hDP) cells and human outer root sheath (hORS) cells in an ultra-low attachment 96-well plate, where the two cell types constituted a polar elongated structure, named "two-cell assemblage (TCA)." We observed that the long axis length of the TCA gradually increased for 5 days, maintaining biological functional integrity as reflected by the increased expression levels of hair growth-associated genes after treatment with hair growth-promoting molecules. Interestingly, the elongation of the TCA was more prominent following treatment with the hair growth-promoting molecules (which occurred in a dose-dependent manner), compared to the control group (p < 0.05). Accordingly, we set the long axis length of the TCA as an endpoint of this assay, using a micro confocal high-content imaging system to measure the length, which can provide reproducible and reliable results in an adequate timescale. The advantages of this assay are: (i) it is physiologically and practically advantageous as it uses 3D cultured two-type human cells which are easily available; (ii) it is simple as it uses length as the only endpoint; and (iii) it is a high throughput system, which screens various compounds simultaneously. In conclusion, the "TCA" assay could serve as an easy and reliable method to validate the hair growth-promoting effect of a large volume of library molecules.

Follicular Unit Extraction (FUE) Hair Transplant: Curves Ahead

The hair transplant has become widely popular aesthetic procedure. Follicular unit transplantation (FUT) and follicular unit extraction (FUE) are two commonly used and accepted techniques. FUT requires excision of strip of tissue from occipital donor area leading to linear scar. To overcome scarring and other complications of FUT, FUE technique has been attempted which involves harvesting of small individual follicular units. Hair transplantation has been successfully used in correction of alopecia, cleft lip scars, post-burn or surgical scars, vitiligo and as an adjuvant to other maxillofacial procedures. FUE demands greater skills and orientation but can yield excellent results in experienced hands. Several maxillofacial surgeons have incorporated hair transplantation procedure in their aesthetic practice successfully. Sound knowledge of surgical technique, armamentarium and proper surgical planning are essential for desired results. The aim of this article is to explain FUE technique, risk and complications, holding solutions and other associated factors in detail. A simple protocol has been put forth for reference and for better understanding of the technique.

Next generation human skin constructs as advanced tools for drug development

Many diseases, as well as side effects of drugs, manifest themselves through skin symptoms. Skin is a complex tissue that hosts various specialized cell types and performs many roles including physical barrier, immune and sensory functions. Therefore, modeling skin in vitro presents technical challenges for tissue engineering. Since the first attempts at engineering human epidermis in 1970s, there has been a growing interest in generating full-thickness skin constructs mimicking physiological functions by incorporating various skin components, such as vasculature and melanocytes for pigmentation. Development of biomimetic in vitro human skin models with these physiological functions provides a new tool for drug discovery, disease modeling, regenerative medicine and basic research for skin biology. This goal, however, has long been delayed by the limited availability of different cell types, the challenges in establishing co-culture conditions, and the ability to recapitulate the 3D anatomy of the skin. Recent breakthroughs in induced pluripotent stem cell (iPSC) technology and microfabrication techniques such as 3D-printing have allowed for building more reliable and complex in vitro skin models for pharmaceutical screening. In this review, we focus on the current developments and prevailing challenges in generating skin constructs with vasculature, skin appendages such as hair follicles, pigmentation, immune response, innervation, and hypodermis. Furthermore, we discuss the promising advances that iPSC technology offers in order to generate in vitro models of genetic skin diseases, such as epidermolysis bullosa and psoriasis. We also discuss how future integration of the next generation human skin constructs onto microfluidic platforms along with other tissues could revolutionize the early stages of drug development by creating reliable evaluation of patient-specific effects of pharmaceutical agents. Impact statement Skin is a complex tissue that hosts various specialized cell types and performs many roles including barrier, immune, and sensory functions. For human-relevant drug testing, there has been a growing interest in building more physiological skin constructs by incorporating different skin components, such as vasculature, appendages, pigment, innervation, and adipose tissue. This paper provides an overview of the strategies to build complex human skin constructs that can faithfully recapitulate human skin and thus can be used in drug development targeting skin diseases. In particular, we discuss recent developments and remaining challenges in incorporating various skin components, availability of iPSC-derived skin cell types and in vitro skin disease models. In addition, we provide insights on the future integration of these complex skin models with other organs on microfluidic platforms as well as potential readout technologies for high-throughput drug screening.

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.

In vitro skin models to study epithelial regeneration from the hair follicle

The development of dermal equivalents (DEs) for the treatment of burns has contributed toward efficient wound closure. A collagen-glycosaminoglycan DE (C-GAG) grafted with hair follicles converted a full-thickness wound to partial-thickness resulting in complete wound closure and restored hair. In this study we compared the ability of both intact pilosebaceous units (PSU) or truncated hair follicles (THF) to regenerate a multilayered epidermis in vitro when implanted into de-epidermalized dermis (DED) or C-GAG with the epidermis generated in vivo using C-CAG. Keratinocytes explanted from the outer root sheath of PSU and THF in both DED and C-GAG but only formed a multilayered epidermis with PSU in DED. PSU were more effective at forming multilayered epidermis in DED than THF. Both DED and C-GAG skin expressed proliferation (PCNA), differentiation (K1, K10), hyperproliferation (K6, K16), basal (K14), putative stem cell (p63), extracellular matrix protein (Collagen IV), mesenchymal (vimentin) and adherens junction (β-catenin) markers. These data suggest DEs supported initial maintenance of the implanted hair follicles, in particular PSU, and provide an excellent model with which to investigate the regulation of hair follicle progenitor epithelial cells during epidermal regeneration. Although neither PSU nor THF formed multilayered epidermis in C-CAG in vitro, hair follicles implanted into engrafted C-GAG on a burns patient resulted in epithelial regeneration and expression of proliferation and differentiation markers in a similar manner to that seen in vitro. However, the failure of C-GAG to support epidermal regeneration in vitro suggests in vivo factors are essential for full epidermal regeneration using C-GAG.

Hair loss and regeneration performed on animal models

Research in the field of reversal hair loss remains a challenging subject. As Minoxidil 2% or 5% and Finasteride are so far the only FDA approved topical treatments for inducing hair regrowth, research is necessary in order to improve therapeutical approach in alopecia. In vitro studies have focused on cultures of a cell type - dermal papilla or organ culture of isolated cell follicles. In vivo research on this topic was performed on mice, rats, hamsters, rabbits, sheep and monkeys, taking into consideration the advantages and disadvantages of each animal model and the depilation options. Further studies are required not only to compare the efficiency of different therapies but more importantly to establish their long term safety.

The cycling hair follicle as an ideal systems biology research model

In the postgenomic era, systems biology has rapidly emerged as an exciting field predicted to enhance the molecular understanding of complex biological systems by the use of quantitative experimental and mathematical approaches. Systems biology studies how the components of a biological system (e.g. genes, transcripts, proteins, metabolites) interact to bring about defined biological function or dysfunction. Living systems may be divided into five dimensions of complexity: (i) molecular; (ii) structural; (iii) temporal; (iv) abstraction and emergence; and (v) algorithmic. Understanding the details of these dimensions in living systems is the challenge that systems biology aims to address. Here, we argue that the hair follicle (HF), one of the signature features of mammals, is a perfect and clinically relevant model for systems biology research. The HF represents a stem cell-rich, essentially autonomous mini-organ, whose cyclic transformations follow a hypothetical intrafollicular "hair cycle clock" (HCC). This prototypic neuroectodermal-mesodermal interaction system, at the cross-roads of systems and chronobiology, encompasses various levels of complexity as it is subject to both intrafollicular and extrafollicular inputs (e.g. intracutaneous timing mechanisms with neural and systemic stimuli). Exploring how the cycling HF addresses the five dimensions of living systems, we argue that a systems biology approach to the study of hair growth and cycling, in man and mice, has great translational medicine potential. Namely, the easily accessible human HF invites preclinical and clinical testing of novel hypotheses generated with this approach.

Intermediate hair follicles: a new more clinically relevant model for hair growth investigations

BACKGROUND

Alopecia causes widespread psychological distress, but is relatively poorly controlled. The development of new treatments is hampered by the lack of suitable human hair follicle models. Although intermediate and vellus hair follicles are the main clinical targets for pharmacological therapy, terminal hair follicles are more frequently studied as smaller hair follicles are more difficult to obtain.

OBJECTIVES

This investigation was designed to quantify in vivo morphological and in vitro behavioural differences in organ culture between matched intermediate and terminal hair follicles, in order to develop a new clinically relevant model system.

METHODS

Microdissected terminal and intermediate hair follicles, from the same individuals, were analysed morphometrically (250 follicles; five individuals), or observed and measured over 9 days of organ culture (210 follicles; six individuals).

RESULTS

Intermediate hair follicles were less pigmented and smaller, penetrating less below the skin surface (mean +/- SEM) (2.59 +/- 0.07 vs. 3.52 +/- 0.10 mm; P = 0.02), with smaller fibre (0.03 +/- 0.002 vs. 0.07 +/- 0.002 mm), connective tissue sheath (0.24 +/- 0.01 mm vs. 0.33 +/- 0.01 mm), bulb (0.19 +/- 0.01 vs. 0.31 +/- 0.01 mm) and dermal papilla (0.06 +/- 0.002 vs. 0.12 +/- 0.01 mm) diameters (P < 0.001). Intermediate hair follicle bulbs appeared 'tubular', unlike their 'bulbous' terminal follicle counterparts. In organ culture they also grew more slowly (0.044 +/- 0.002 vs. 0.067 +/- 0.003 mm per day; P < 0.001), remained in anagen longer (84 +/- 0.03% vs. 74 +/- 0.03% at day 9; P = 0.012) and produced less hair fibre (0.36 +/- 0.02 vs. 0.50 +/- 0.03 mm; P < 0.001) than terminal follicles.

CONCLUSIONS

Smaller intermediate hair follicles showed major morphological differences from terminal follicles in vivo and retained significant, biologically relevant differences in vitro in organ culture. Therefore, intermediate hair follicles offer a novel, exciting, more clinically relevant, albeit technically difficult, model for future investigations into hair growth. This should be particularly important for developing new therapies.

Expression patterns of keratin intermediate filament and keratin associated protein genes in wool follicles

The catalogue of hair keratin intermediate filaments (KIFs) and keratin-associated proteins (KAPs) present in wool follicles is incomplete. The full coding sequences for three novel sheep KIFs (KRT27, KRT35 and KRT38) and one KAP (KRTAP4-3) were established in this study. Spatial expression patterns of these and other genes (KRT31, KRT85, KRTAP6-1 and trichohyalin) were determined by in situ hybridisation in wool follicles at synchronised stages of growth. Transcription proceeded in the order: trichohyalin, KRT27, KRT85, KRT35, KRT31, KRT38, KRTAP6-1 and KRTAP4-3, as determined by increasing distance of their expression zones from the germinal matrix in anagen follicles. Expression became gradually more restricted to the lower follicle during follicle regression (catagen), and ceased during dormancy (telogen). Some genes (KRT27, KRT31, KRT85 and KRTAP6-1), but not others, were expressed in cortical cells forming the brush-end, indicating specific requirements for the formation of this anchoring structure. The resumption of keratin expression was observed only in later stages of follicle reactivation (proanagen). KIF expression patterns in primary wool follicles showed general resemblance to their human homologues but with some unique features. Consistent differences in localisation between primary and secondary wool follicles were observed. Asymmetrical expression of KRT27, KRT31, KRT35, KRT85 and trichohyalin genes in secondary follicles were associated with bulb deflection and follicle curvature, suggesting a role in the determination of follicle and fibre morphology.

Hair morphogenesis in vitro: formation of hair structures suitable for implantation

AIM

To develop a construct through which implanted follicular cells will efficiently cause hair regeneration for the treatment of androgenetic alopecia.

MATERIALS & METHODS

Follicular dermal and epidermal cells isolated from embryonic mouse skin were formed into aggregates. The aggregates were incubated in culture for 5-7 days and then implanted intradermally into athymic mice.

RESULTS

During culture, mixed cell aggregates developed into hair-like structures, termed 'proto-hairs'. Proto-hairs contained structures that resembled normal hair components, such as dermal papillae, hair matrix and rudimentary hair shafts. When implanted into mouse skin, they developed further into mature hair follicles capable of prolonged growth.

CONCLUSION

Mixed aggregates of murine follicular cells have the ability to develop in culture into proto-hairs that retain the ability to fully develop into hair follicles after implantation. Proto-hairs from human cells could provide a convenient and practical means by which follicular cells could be implanted for efficient hair regeneration to treat hair loss.

Degree of hyperinsulinemia, independent of androgen levels, is an important determinant of the severity of hirsutism in PCOS

OBJECTIVE

To determine whether the severity in hyperandrogenemia determines, to a significant degree, the severity of hirsutism in patients with polycystic ovary syndrome (PCOS).

DESIGN

Cross-sectional study.

SETTING

Tertiary care academic referral center.

PATIENT(S)

A total of 749 patients with PCOS.

INTERVENTION(S)

History and physical examination, blood sampling.

MAIN OUTCOME MEASURE(S)

Hirsutism defined by a value of >or=6 using the modified Ferriman-Gallwey (mFG) score, age, body mass index (BMI), calculated homeostatic assessment for insulin resistance (HOMA-IR) value, and levels of total (TT) and free (FT) testosterone, dehydroepiandrosterone sulfate (DHEAS) 17-hydroxyprogesterone (17OH-P), and fasting insulin (INS) and glucose (GLC).

RESULT(S)

Univariate correlations revealed associations between the mFG score and INS, 17OH-P, HOMA-IR, and BMI. Multivariate classification and regression tree analysis indicated that INS had the most significant association with mFG score and that at higher INS levels T played an additional role whereas at lower INS levels 17OH-P had an effect; however, this model accounted for only 8.2% of total variation in mFG score.

CONCLUSION(S)

Insulin appears to have a direct effect on the severity of hirsutism in PCOS and appears to have a synergistic interaction with TT. Notably, over 90% of the variation in the mFG score was not related to the factors studied and likely reflects intrinsic factors related to pilosebaceous unit function or sensitivity and to other factors not yet assessed.

Human hair follicles contain two forms of ATP-sensitive potassium channels, only one of which is sensitive to minoxidil

Hair disorders cause psychological distress but are generally poorly controlled; more effective treatments are required. Despite the long-standing use of minoxidil for balding, its mechanism is unclear; suggestions include action on vasculature or follicle cells. Similar drugs also stimulate hair, implicating ATP-sensitive potassium (K(ATP)) channels. To investigate whether K(ATP) channels are present in human follicles, we used organ culture, molecular biological, and immunohistological approaches. Minoxidil and tolbutamide, a K(ATP) channel blocker, opposed each other's effects on the growing phase (anagen) of scalp follicles cultured in media with and without insulin. Reverse transcriptase-polymerase chain reaction identified K(ATP) channel component gene expression including regulatory sulfonylurea receptors (SUR) SUR1 and SUR2B but not SUR2A and pore-forming subunits (Kir) Kir6.1 and Kir6.2. When hair bulb tissues were examined separately, epithelial matrix expressed SUR1 and Kir6.2, whereas both dermal papilla and sheath exhibited SUR2B and Kir6.1. Immunohistochemistry demonstrated similar protein distributions. Thus, human follicles respond biologically to K(ATP) channel regulators in culture and express genes and proteins for two K(ATP) channels, Kir6.2/SUR1 and Kir6.1/SUR2B; minoxidil only stimulates SUR2 channels. These findings indicate that human follicular dermal papillae contain K(ATP) channels that can respond to minoxidil and that tolbutamide may suppress hair growth clinically; novel drugs designed specifically for these channels could treat hair disorders.

The effect of tripeptide-copper complex on human hair growth in vitro

The tripeptide-copper complex, described as a growth factor for various kinds of differentiated cells, stimulates the proliferation of dermal fibroblasts and elevates the production of vascular endothelial growth factor, but decreased the secretion of transforming growth factor-beta1 by dermal fibroblasts. Dermal papilla cells (DPCs) are specialized fibroblasts, which are important in the morphogenesis and growth of hair follicles. In the present study, the effects of L-alanyl-L-histidyl-L-lysine-Cu2+ (AHK-Cu) on human hair growth ex vivo and cultured dermal papilla cells were evaluated. AHK-Cu (10(-12) - 10(-9) M) stimulated the elongation of human hair follicles ex vivo and the proliferation of DPCs in vitro. Annexin V-fluorescein isothiocyanate/propidium iodide labeling and flow cytometric analysis showed that 10(-9) M AHK-Cu reduced the number of apoptotic DPCs, but this decrease was not statistically significant. The ratio of Bcl-2/Bax was elevated, and the levels of the cleaved forms of caspase-3 and PARP were reduced by treatment with 10(-9) M AHK-Cu. The present study proposed that AHK-Cu promotes the growth of human hair follicles, and this stimulatory effect may occur due to stimulation of the proliferation and the preclusion of the apoptosis of DPCs.

How Long Can Hair Follicle Units Be Preserved at 0 and 4°C for Delayed Transplant?

BACKGROUND

Preservation of hair follicle units for the purpose of delayed transplant will help us graft thousands of hair grafts at one session, even in a clinic with fewer assistants and less equipment.

OBJECTIVE

This study was undertaken to evaluate and compare the viability of hair follicle units preserved at 0 and 4 degrees C for various periods.

MATERIALS AND METHODS

Cell cultures and transplant of hair follicle units into athymic mice were performed.

RESULTS

Outer root sheath cells could be cultivated in 96% (0 degrees C group) and 92% (4 degrees C group) of the hair follicles after 24 hours of preservation, whereas 85% (0 degrees C group) and 79% (4 degrees C group) of the follicles implanted into the mice regrew well after the same period of preservation. Then, in both the 0 degrees C and the 4 degrees C group, these rates decreased significantly with length of preservation in cell cultures and mice transplant; however, 0 degrees C seems better than 4 degrees C for preservation of grafts (p<.05).

CONCLUSION

Grafts are better preserved at 0 degrees C instead of 4 degrees C. When delayed transplant is an option, it should be completed within 24 hours and no later than 48 hours.

Phenotypic spectrum of polycystic ovary syndrome: clinical and biochemical characterization of the three major clinical subgroups

OBJECTIVE

We tested the hypothesis that the three clinical phenotypes of polycystic ovary syndrome (PCOS) represent forms of the same metabolic disorder.

DESIGN

Prospective cohort analysis.

SETTING

University-based tertiary care.

PATIENT(S)

Three-hundred sixteen untreated consecutive women diagnosed as having PCOS.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Each subject underwent an evaluation of ovulatory function, body habitus, acne, and hirsutism; serum free and total testosterone (T), 17-hydroxyprogesterone (17-HP), and DHEAS; and fasting plasma glucose and insulin levels. Insulin resistance and beta-cell function were assessed using the homeostatic assessment model equation (HOMA-IR and HOMA-beta-cell, respectively).

RESULT(S)

The Oligo+HA+Hirsutism phenotype was present in 48% of subjects, Oligo+HA in 29%, and Oligo+Hirsutism in 23%. The three phenotypes did not differ in mean body mass index, waist-to-hip ratio, racial composition, degree of oligo-ovulation, prevalence of acne, or family history of hyperandrogenic symptomatology. However, subjects demonstrating the Oligo+HA+Hirsutism phenotype were the youngest and had the greatest degrees of hyperandrogenemia, hyperinsulinemia, and beta-cell function; patients with the Oligo+Hirsutism phenotype where the oldest and had the mildest degrees of hyperandrogenemia, hyperinsulinemia, and beta-cell function. Subjects with the Oligo+HA phenotype demonstrated intermediate degrees of hyperandrogenemia and metabolic dysfunction.

CONCLUSION(S)

We conclude that the three clinical phenotypes of PCOS do not represent forms of the same metabolic disorder and may be the result of varying degrees of metabolic dysfunction; greater degrees of beta-cell function and circulating insulin levels favored the development of hirsutism and frank hyperandrogenemia.

A hot new twist to hair biology: involvement of vanilloid receptor-1 (VR1/TRPV1) signaling in human hair growth control

The vanilloid receptor-1 (VR1, or transient receptor potential vanilloid-1 receptor, TRPV1) is activated by capsaicin, the key ingredient of hot peppers. TRPV1 was originally described on sensory neurons as a central integrator of various nociceptive stimuli. However, several human skin cell populations are also now recognized to express TRPV1, but with unknown function. Exploiting the human hair follicle (HF) as a prototypic epithelial-mesenchymal interaction system, we have characterized the HF expression of TRPV1 in situ and have examined TRPV1 signaling in organ-cultured human scalp HF and outer root sheath (ORS) keratinocytes in vitro. TRPV1 immunoreactivity was confined to distinct epithelial compartments of the human HF, mainly to the ORS and hair matrix. In organ culture, TRPV1 activation by capsaicin resulted in a dose-dependent and TRPV1-specific inhibition of hair shaft elongation, suppression of proliferation, induction of apoptosis, premature HF regression (catagen), and up-regulation of intrafollicular transforming growth factor-beta(2). Cultured human ORS keratinocytes also expressed functional TRPV1, whose stimulation inhibited proliferation, induced apoptosis, elevated intracellular calcium concentration, up-regulated known endogenous hair growth inhibitors (interleukin-1beta, transforming growth factor-beta(2)), and down-regulated known hair growth promoters (hepatocyte growth factor, insulin-like growth factor-I, stem cell factor). These findings strongly support TRPV1 as a significant novel player in human hair growth control, underscore the physiological importance of TRPV1 in human skin beyond nociception, and identify TRPV1 as a promising, novel target for pharmacological manipulations of epithelial growth disorders.

Novel and Established Potassium Channel Openers Stimulate Hair Growth In Vitro: Implications for their Modes of Action in Hair Follicles

Although ATP-sensitive potassium (K(ATP)) channel openers, e.g., minoxidil and diazoxide, can induce hair growth, their mechanisms require clarification. Improved drugs are needed clinically. but the absence of a good bioassay hampers research. K(ATP) channels from various tissues contain subtypes of the regulatory sulfonylurea receptor, SUR, and pore-forming, K(+) inward rectifier subunits, Kir6.X, giving differing sensitivities to regulators. Therefore, the in vitro effects of established potassium channel openers and inhibitors (tolbutamide and glibenclamide), plus a novel, selective Kir6.2/SUR1 opener, NNC 55-0118, were assessed on deer hair follicle growth in serum-free median without streptomycin. Minoxidil (0.1-100 microM, p<0.001), NNC 55-0118 (1 mM, p<0.01; 0.1, 10, 100 microM, p<0.001), and diazoxide (10 microM, p<0.01) increased growth. Tolbutamide (1 mM) inhibited growth (p<0.001) and abolished the effect of 10 microM minoxidil, diazoxide and NNC 55-0118; glibenclamide (10 microM) had no effect, but prevented stimulation by 10 microM minoxidil. Phenol red stimulated growth (p<0.001), but channel modulator responses remained unaltered. Thus, deer follicles offer a practical, ethically advantageous in vitro bioassay that reflects clinical responses in vivo. The results indicate direct actions of K(ATP) channel modulators within hair follicles via two types of channels, with SUR 1 and SUR 2, probably SUR2B, sulfonylurea receptors.

Topical minoxidil counteracts stress-induced hair growth inhibition in mice

Stress has long been suspected as a possible cause of hair loss in various species, even though convincing experimental evidence has not been available. Recently, we have shown in a murine model that sonic stress alters hair growth and cycling in vivo, and have postulated the existence of a 'brain-hair follicle axis' (BHA). In order to study whether a clinically available and widely used topically active hair growth stimulator mitigates stress-triggered hair growth inhibition in this stress model, we have applied a 5% minoxidil solution. Female CBA/J mice were depilated and randomized in to two groups: control (n = 20) and sonic stress (n = 20). These groups were further divided and either treated daily with 5% minoxidil solution or vehicle alone. The stress group was exposed to sonic stress for 24 h starting 14 days after anagen induction by depilation. All mice were sacrificed 16 days after the depilation and assessed by quantitative histomorphometry. Sonic stress significantly increased the number of hair follicles with apoptotic cells and inhibited intrafollicular keratinocyte proliferation. In addition, the number of clusters of perifollicular MHC class II+ cells and degranulated perifollicular mast cells was significantly enhanced in the stressed mice. In accordance with previous findings, all stressed mice showed an advanced hair cycle progression towards catagen. All of these stress-induced hair growth inhibitory changes along the BHA were down-regulated by topical minoxidil application. This encourages one to explore clinically whether topical minoxidil is a safe and effective pharmacologic tool for the management of stress-associated telogen effluvium in humans.

Regulation of PDGF and PDGF receptor in cultured dermal papilla cells and follicular keratinocytes of the human hair follicle

Platelet-derived growth factor (PDGF) is a potent mitogenic factor for many cell types and has been shown to be important in follicular development and vasculogenesis. In this study, we examined the expression pattern of both PDGF factors and their corresponding receptors in mesenchyme-derived dermal papilla cells (DPCs) and epithelial follicular keratinocytes (FKs). Both types of PDGF receptors are expressed in FKs, whereas DPCs only express PDGF receptor beta on the protein level, a finding also seen in whole organ cultures. By examining the expression of PDGF ligands, we were able to show that cultured FKs synthesize both PDGF-A and PDGF-B, whereas, DPCs only express PDGF-A. As immunomodulatory cytokines were shown to affect hair growth, we investigated the effects of IL-1beta, IL-4, TNF-alpha, TGF-beta and IFN-gamma on the expression levels of PDGF factors in cultured DPCs and FKs. Interestingly, we could show a significant down-regulatory effect by catagen-inducing cytokines like IL-1beta or IFN-gamma, suggesting a possible involvement of PDGF signaling in the induction of catagen. The question concerning the latter hypothesis remains to be elucidated in further studies on whole organ cultures.

Adrenomedullin: expression and possible role in human skin and hair growth

BACKGROUND

Adrenomedullin (AM) is a regulatory peptide that is synthesized and secreted by a wide number of cells and tissues. AM is a potent vasodilator, but also exerts other functions, such as regulating cell growth and antimicrobial defence. Two receptors, L1 and calcitonin receptor-like receptor (CRLR), which are able to bind AM, have been cloned and characterized.

OBJECTIVES

To investigate expression of AM protein and its receptors in human skin and during different stages of the human hair cycle and, moreover, because of the suggested antimicrobial function of AM in skin, to investigate AM immunoreactivity (IR) in inflammatory acne lesions compared with healthy pilosebaceous follicles.

METHODS

We used immunohistochemistry to determine the distribution of AM and its receptors in human skin and during different stages of the human hair cycle. AM IR in inflammatory acne lesions was investigated to evaluate the antimicrobial function of the protein, and hair follicle cultures were performed to examine the role of AM in differentiation and proliferation of hair follicle keratinocytes.

RESULTS

Strong IR for AM and its receptors was present in the suprabasal epidermis, in the melanocytes of the epidermis, and in sweat and sebaceous glands. In the hair follicle, AM protein was strongly expressed in the basal and suprabasal layers of the hair bulb and the proximal outer root sheath (ORS). In the distal ORS, AM expression was increasingly suprabasal, especially in proximity to the bulge region where the basal cell layer was free of IR. IR for the CRLR revealed a similar expression pattern to that seen for AM. In contrast, L1 IR showed a suprabasal pattern of IR throughout the ORS. Similar expression of AM and its receptors was observed in catagen and early anagen follicles. AM expression was not markedly upregulated in acne lesions, suggesting a minor role for this antimicrobial peptide in acne. Despite its well-documented mitogenic effects, particularly in oral and skin keratinocytes, AM had no significant effect on hair follicle growth in vitro.

CONCLUSIONS

AM and its receptors are expressed in human hair follicles, and both AM and its receptors are colocalized in the same compartments and cell types of the skin. This finding is consistent with the proposed autocrine/paracrine mechanism in the physiology of AM.

Genetic mosaic analysis indicates that the bulb region of coat hair follicles contains a resident population of several active multipotent epithelial lineage progenitors

The hair follicle represents an excellent model system for exploring the properties of lineage-forming units in a dynamic epithelium containing multiple cell types. During its growth (anagen) phase, the proximal-distal axis of the mouse coat hair (pelage) follicle provides a historical record of all epithelial lineages generated from its resident stem cell population. An unresolved question in the field is whether the bulb region of anagen pelage follicles contains multipotential progenitors and whether their individual contribution to cellular census fluctuates over time. To address this issue, chimeric follicles were harvested in midanagen from three types of genetic mosaic mouse models. Analysis of the distribution of genotypic markers, including digital three-dimensional reconstruction of serially sectioned chimeric follicles, revealed that on average the bulb contains four or fewer active progenitors, each capable of giving rise to all six follicular epithelial fates. Moreover, analysis of mosaic pelage, as well as cultured whisker follicles provided evidence that bulb-associated progenitors can give rise to expanding descendant clones during midanagen, leading to the conclusion that the bulb contains dormant or symmetrically dividing stem cells. This latter feature resembles the behavior of hematopoietic stem cells after bone marrow transplantation, and raises the question of whether this property may be shared by stem cells in other self-renewing epithelia.

Prevention of temporal alopecia following rhytidectomy: the prophylactic use of minoxidil. A study of 60 patients

BACKGROUND

Temporal hair loss that results from traumatized hair follicles following rhytidectomy is an unsightly complication that can distress both the patient and the operating surgeon. Topical minoxidil is a proven therapy for androgenic alopecia and female senile alopecia. It has also been found to be useful in preventing the hair loss that commonly follows hair transplantation.

OBJECTIVE

To analyze through a retrospective study the effect of topical minoxidil on the incidence of temporal hair loss following facelift procedures. To our knowledge this is the first study to investigate the role of minoxidil in preventing post-rhytidectomy temporal alopecia.

METHODS

The charts of 60 women with a mean age of 58 years who underwent primary cervicofacial rhytidectomy were studied. Either a standard SMAS/flap technique or pliation was done in all cases. Each patient received either 2% or 5% topical minoxidil for 2 weeks before surgery and for 4 weeks after surgery, with a 5-day break period beginning on the day of surgery. Patients were monitored for complications immediately postoperatively and in 3-6 months of follow-up.

RESULTS

Almost 80% of the patients underwent SMAS/flap procedures. Transient temporal alopecia was noted in only one patient, 6 weeks after discontinuing minoxidil. This resolved within 4 weeks of its reintroduction. The only other complications noted included minor hematomas (3.3%), skin slough/infection (1.7%), minor transient and localized edema (8.3%), minor ecchymosis (1.7%), a unilateral neuropraxia of the buccal nerve lasting 3 months (1.7%), and a minor temporary unilateral skin depression (1.7%). Side effects of minoxidil were not observed.

CONCLUSION

On comparing our findings to results of larger rhytidectomy series in which minoxidil was not used prophylactically, and our experience before using minoxidil, we conclude that minoxidil plays a role in effectively preventing the temporal hair loss that occurs following primary cervicofacial rhytidectomies. We also found that minoxidil did not negatively impact on the risk of hematoma formation, skin necrosis, edema, or ecchymosis. Side effects of minoxidil did not present a problem.

Controls of hair follicle cycling

Nearly 50 years ago, Chase published a review of hair cycling in which he detailed hair growth in the mouse and integrated hair biology with the biology of his day. In this review we have used Chase as our model and tried to put the adult hair follicle growth cycle in perspective. We have tried to sketch the adult hair follicle cycle, as we know it today and what needs to be known. Above all, we hope that this work will serve as an introduction to basic biologists who are looking for a defined biological system that illustrates many of the challenges of modern biology: cell differentiation, epithelial-mesenchymal interactions, stem cell biology, pattern formation, apoptosis, cell and organ growth cycles, and pigmentation. The most important theme in studying the cycling hair follicle is that the follicle is a regenerating system. By traversing the phases of the cycle (growth, regression, resting, shedding, then growth again), the follicle demonstrates the unusual ability to completely regenerate itself. The basis for this regeneration rests in the unique follicular epithelial and mesenchymal components and their interactions. Recently, some of the molecular signals making up these interactions have been defined. They involve gene families also found in other regenerating systems such as fibroblast growth factor, transforming growth factor-beta, Wnt pathway, Sonic hedgehog, neurotrophins, and homeobox. For the immediate future, our challenge is to define the molecular basis for hair follicle growth control, to regenerate a mature hair follicle in vitro from defined populations, and to offer real solutions to our patients' problems.

Human stratified squamous epithelia differ in cellular fatty acid composition

The phospholipid component of the cellular membrane is crucial to the structure and function of cells. Basal cells from three epithelial tissues, adult human skin epidermis, oral mucosa, and hair follicles, grow rapidly in serum- and lipid-free medium. Analysis of phospholipid extracts from the above three types of stratified squamous epithelium in both in vivo and in vitro was done to relate fatty acid cell composition to cell function. The fatty acid composition of hair follicles in vivo was analyzed in plucked scalp hairs, and those of skin epidermis and oral mucosa in vivo were analyzed after separating the tissue into suprabasal and basal layers. The fatty acid composition of the in vivo cells from hair follicles shows a partial essential fatty acid (EFA)-deficient state. There was no significant difference between the skin epidermis and the oral mucosa in the fatty acid composition of the in vivo cells from each basal layer. However, in the suprabasal layers, the percent of linoleic acid (18:2) from the skin epidermis was higher than that from the oral mucosa. This study shows that total fatty acid composition in cell membranes of stratified squamous epithelium varies with their keratinization pattern. When cultured, the three types of rapidly growing keratinocytes showed the same essential fatty acid deficient pattern in the membrane phospholipids.

Role of hormones in pilosebaceous unit development

Androgens are required for sexual hair and sebaceous gland development. However, pilosebaceous unit (PSU) growth and differentiation require the interaction of androgen with numerous other biological factors. The pattern of PSU responsiveness to androgen is determined in the embryo. Hair follicle growth involves close reciprocal epithelial-stromal interactions that recapitulate ontogeny; these interactions are necessary for optimal hair growth in culture. Peroxisome proliferator-activated receptors (PPARs) and retinoids have recently been found to specifically affect sebaceous cell growth and differentiation. Many other hormones such as GH, insulin-like growth factors, insulin, glucocorticoids, estrogen, and thyroid hormone play important roles in PSU growth and development. The biological and endocrinological basis of PSU development and the hormonal treatment of the PSU disorders hirsutism, acne vulgaris, and pattern alopecia are reviewed. Improved understanding of the multiplicity of factors involved in normal PSU growth and differentiation will be necessary to provide optimal treatment approaches for these disorders.

Management of androgenetic alopecia

Androgenetic alopecia is by far the most common cause of hair loss. It affects approximately 50% of men by the age of 50 and 20 to 53% of women by the age 50. Although it is a medically benign condition, it is a significant psychosocial issue for many patients. Various different treatment options are now available for androgenetic alopecia. The best treatment option for women with androgenetic alopecia Ludwig stage I and II is minoxidil 5% solution. If it is not effective after 1 year, antiandrogens can be tried, but there are no large studies showing their efficacy and they have considerable adverse effects. Also, for patients with alopecia that is unresponsive to treatment or with Ludwig stage III, hair transplantation can be offered if the occipital donor area is sufficient. For men, we always offer minoxidil or finasteride therapy and leave the choice of therapy to the patient. Some patients may prefer a systemic agent, whereas others may favor a topical agent. If the condition is not stabilized after 1 year or if the patient wants greater hair density, hair transplantation can be discussed. There have been tremendous advances in the treatment of hair loss in recent years and the future is very encouraging. As our knowledge of androgenetic alopecia pathophysiology increases, novel targeted treatments will potentially be developed.

Hair regrowth. Therapeutic agents

Today there are new classes of hair growth promotors with proven efficacy. This article reviews the current state of the art agents for treatment of two of the most common forms of hair loss encountered in clinical practice, androgenetic alopecia and alopecia areata. Current therapeutic strategies are based on recent advances in the understanding of disordered hair growth. Practical treatment protocols are presented.