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

DNA Microarray and Bioinformatic Analysis Reveals the Potential of Whale Oil in Enhancing Hair Growth in a C57BL/6 Mice Dorsal Skin Model

Much research has been conducted to determine how hair regeneration is regulated, as this could provide therapeutic, cosmetic, and even psychological interventions for hair loss. The current study focused on the hair growth effect and effective utilization of fatty oil obtained from Bryde's whales through a high-throughput DNA microarray approach in conjunction with immunohistochemical observations. The research also examined the mechanisms and factors involved in hair growth. In an experiment using female C57BL/6J mice, the vehicle control group (VC: propylene glycol: ethanol: water), the positive control group (MXD: 3% minoxidil), and the experimental group (WO: 20% whale oil) were topically applied to the dorsal skin of the mouse. The results showed that 3% MXD and 20% WO were more effective than VC in promoting hair growth, especially 20% WO. Furthermore, in hematoxylin and eosin-stained dorsal skin tissue, an increase in the number of hair follicles and subcutaneous tissue thickness was observed with 20% WO. Whole-genome transcriptome analysis also confirmed increases for 20% WO in filaggrin (Flg), a gene related to skin barrier function; fibroblast growth factor 21 (Fgf21), which is involved in hair follicle development; and cysteine-rich secretory protein 1 (Crisp1), a candidate gene for alopecia areata. Furthermore, the results of KEGG pathway analysis indicated that 20% WO may have lower stress and inflammatory responses than 3% MXD. Therefore, WO is expected to be a safe hair growth agent.

Kir6.1 and SUR2B in Cantú syndrome

Kir6.1 and SUR2 are subunits of ATP-sensitive potassium (KATP) channels expressed in a wide range of tissues. Extensive study has implicated roles of these channel subunits in diverse physiological functions. Together they generate the predominant KATP conductance in vascular smooth muscle and are the target of vasodilatory drugs. Roles for Kir6.1/SUR2 dysfunction in disease have been suggested based on studies of animal models and human genetic discoveries. In recent years, it has become clear that gain-of-function (GoF) mutations in both genes result in Cantú syndrome (CS)-a complex, multisystem disorder. There is currently no targeted therapy for CS, but studies of mouse models of the disease reveal that pharmacological reversibility of cardiovascular and gastrointestinal pathologies can be achieved by administration of the KATP channel inhibitor, glibenclamide. Here we review the function, structure, and physiological and pathological roles of Kir6.1/SUR2B channels, with a focus on CS. Recent studies have led to much improved understanding of the underlying pathologies and the potential for treatment, but important questions remain: Can the study of genetically defined CS reveal new insights into Kir6.1/SUR2 function? Do these reveal new pathophysiological mechanisms that may be important in more common diseases? And is our pharmacological armory adequately stocked?

Pharmacological Management of Pattern Hair Loss

Pattern hair loss (PHL) is a condition that worsens with time and the only way it can be slowed down is with pharmacological intervention. Pharmacological treatments for PHL, from an evidenced-based perspective with respect to safety and efficacy, are limited to only two drugs, minoxidil and finasteride. However, there are a host of drugs being used, off-label with limited evidence. This article attempts to review the literature on this topic, and the authors add to this, with their experience of over two decades on incorporating pharmacologic treatments along with hair transplantation in their management of PHL.

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

Background and Purpose

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

Experimental Approach

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

Key Results

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

Conclusion and Implications

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

KATP Channel Openers Inhibit Lymphatic Contractions and Lymph Flow as a Possible Mechanism of Peripheral Edema

Pharmacological openers of ATP-sensitive potassium (KATP) channels are effective antihypertensive agents, but off-target effects, including severe peripheral edema, limit their clinical usefulness. It is presumed that the arterial dilation induced by KATP channel openers (KCOs) increases capillary pressure to promote filtration edema. However, KATP channels also are expressed by lymphatic muscle cells (LMCs), raising the possibility that KCOs also attenuate lymph flow to increase interstitial fluid. The present study explored the effect of KCOs on lymphatic contractile function and lymph flow. In isolated rat mesenteric lymph vessels (LVs), the prototypic KATP channel opener cromakalim (0.01-3 µmol/l) progressively inhibited rhythmic contractions and calculated intraluminal flow. Minoxidil sulfate and diazoxide (0.01-100 µmol/l) had similar effects at clinically relevant plasma concentrations. High-speed in vivo imaging of the rat mesenteric lymphatic circulation revealed that superfusion of LVs with cromakalim and minoxidil sulfate (0.01-10 µmol/l) maximally decreased lymph flow in vivo by 38.4% and 27.4%, respectively. Real-time polymerase chain reaction and flow cytometry identified the abundant KATP channel subunits in LMCs as the pore-forming Kir6.1/6.2 and regulatory sulfonylurea receptor 2 subunits. Patch-clamp studies detected cromakalim-elicited unitary K+ currents in cell-attached patches of LMCs with a single-channel conductance of 46.4 pS, which is a property consistent with Kir6.1/6.2 tetrameric channels. Addition of minoxidil sulfate and diazoxide elicited unitary currents of similar amplitude. Collectively, our findings indicate that KCOs attenuate lymph flow at clinically relevant plasma concentrations as a potential contributing mechanism to peripheral edema. SIGNIFICANCE STATEMENT: ATP-sensitive potassium (KATP) channel openers (KCOs) are potent antihypertensive medications, but off-target effects, including severe peripheral edema, limit their clinical use. Here, we demonstrate that KCOs impair the rhythmic contractions of lymph vessels and attenuate lymph flow, which may promote edema formation. Our finding that the KATP channels in lymphatic muscle cells may be unique from their counterparts in arterial muscle implies that designing arterial-selective KCOs may avoid activation of lymphatic KATP channels and peripheral edema.

Skin and hair abnormalities of Cantu syndrome: A congenital hypertrichosis due to a genetic alteration mimicking the pharmacological effect of minoxidil

Cantu syndrome is an autosomal dominant disorder, first described by Cantu in 1982, that is characterized by congenital hypertrichosis, characteristic facial anomalies and cardiomegaly. Recent investigations have revealed that this syndrome is caused by mutations of ABCC9, which encodes a regulatory subunit of SUR2, an adenosine triphosphate-mediated potassium channel opener, expressed not only in smooth muscle but also in hair follicles. However, the abnormalities of skin and hair in patients with Cantu syndrome have not been well explored. We herein report three Japanese patients with Cantu syndrome and describe their specific skin manifestations and alterations in the histopathology of their hair follicles and sebaceous glands. Similar alterations were shared among those three patients and may be related to the function of SUR2, namely the regulation of hair follicle growth, because SUR2 is a known pharmacological target of minoxidil.

Possible New Strategies for the Treatment of Congenital Hyperinsulinism

OBJECTIVE

Congenital hyperinsulinism (CHI) is a rare disease characterized by persistent hypoglycemia as a result of inappropriate insulin secretion, which can lead to irreversible neurological defects in infants. Poor efficacy and strong adverse effects of the current medications impede successful treatment. The aim of the study was to investigate new approaches to silence β-cells and thus attenuate insulin secretion.

RESEARCH DESIGN AND METHODS

In the scope of our research, we tested substances more selective and more potent than the gold standard diazoxide that also interact with neuroendocrine ATP-sensitive K⁺ (K_ATP) channels. Additionally, K_ATP channel-independent targets as Ca²⁺-activated K⁺ channels of intermediate conductance (K_Ca3.1) and L-type Ca²⁺ channels were investigated. Experiments were performed using human islet cell clusters isolated from tissue of CHI patients (histologically classified as pathological) and islet cell clusters obtained from C57BL/6N (WT) or SUR1 knockout (SUR1^-/-) mice. The cytosolic Ca²⁺ concentration ([Ca²⁺]_c) was used as a parameter for the pathway regulated by electrical activity and was determined by fura-2 fluorescence. The mitochondrial membrane potential (ΔΨ) was determined by rhodamine 123 fluorescence and single channel currents were measured by the patch-clamp technique.

RESULTS

The selective K_ATP channel opener NN414 (5 µM) diminished [Ca²⁺]_c in isolated human CHI islet cell clusters and WT mouse islet cell clusters stimulated with 10 mM glucose. In islet cell clusters lacking functional K_ATP channels (SUR1^-/-) the drug was without effect. VU0071063 (30 µM), another K_ATP channel opener considered to be selective, lowered [Ca²⁺]_c in human CHI islet cell clusters. The compound was also effective in islet cell clusters from SUR1^-/- mice, showing that [Ca²⁺]_c is influenced by additional effects besides K_ATP channels. Contrasting to NN414, the drug depolarized ΔΨ in murine islet cell clusters pointing to severe interference with mitochondrial metabolism. An opener of K_Ca3.1 channels, DCEBIO (100 µM), significantly decreased [Ca²⁺]_c in SUR1^-/- and human CHI islet cell clusters. To target L-type Ca²⁺ channels we tested two already approved drugs, dextromethorphan (DXM) and simvastatin. DXM (100 µM) efficiently diminished [Ca²⁺]_c in stimulated human CHI islet cell clusters as well as in stimulated SUR1^-/- islet cell clusters. Similar effects on [Ca²⁺]_c were observed in experiments with simvastatin (7.2 µM).

CONCLUSIONS

NN414 seems to provide a good alternative to the currently used K_ATP channel opener diazoxide. Targeting K_Ca3.1 channels by channel openers or L-type Ca²⁺ channels by DXM or simvastatin might be valuable approaches for treatment of CHI caused by mutations of K_ATP channels not sensitive to K_ATP channel openers.

Exploiting the Diversity of Ion Channels: Modulation of Ion Channels for Therapeutic Indications

Ion channels are macromolecular proteins that form water-filled pores in cell membranes and they are critical for a variety of physiological and pharmacological functions. Dysfunctional ion channels can cause diseases known as channelopathies. Ion channels are encoded by approximately 400 genes, representing the second largest class of proven drug targets for therapeutic areas including neuropsychiatric disorders, cardiovascular and metabolic diseases, immunological diseases, nephrological diseases, gastrointestinal diseases, pulmonary/respiratory diseases, and many cancers. With more ion channel structures are being solved and functional robust assays are being developed, there are tremendous opportunities for identifying specific modulators targeting ion channels for new therapy.

Minoxidil Downregulates Interleukin-1 Alpha Gene Expression in HaCaT Cells

Introduction:

Minoxidil has been used topically to stimulate hair growth for male androgenetic alopecia (AGA) for more than 3 decades. It is currently being used for female AGA and alopecia areata (AA) as well. Although much time has passed since its first use, our understanding of its mechanism of action is highly limited. Therefore, we examined the inflammatory properties of AGA and AA, two entities in which minoxidil is being used as a therapeutic agent. We investigated the in vitro expression levels of cytokine interleukin-1 alpha (IL-1α), a potent inhibitor of hair growth, in minoxidil-treated human keratinocyte (HaCaT) cells to determine whether this molecule exerts anti-inflammatory effects.

Materials and Methods:

Cellular proliferation was examined using the Cell Proliferation Kit II (XTT) reagent. After determining a noncytotoxic concentration, HaCaT cells were treated with minoxidil. RNA was isolated from both untreated and treated cells with TRI Reagent^®. Expression of the IL-1α gene was determined by reverse transcription quantitative polymerase chain reaction analysis and is reported relative to glyceraldehyde-3-phosphate dehydrogenase (GAPDH), which served as a control.

Results:

Results are presented as IL-1α/GAPDH fold change. Minoxidil treatment downregulated IL-1α expression by 0.3433-fold compared with untreated cells (P = 0.001).

Conclusion:

This anti-inflammatory effect of minoxidil, as evidenced by significant downregulation of IL-1α gene expression in HaCaT cells, may represent one of its mechanisms of action in alopecia.

The KATP channel in migraine pathophysiology: a novel therapeutic target for migraine

BACKGROUND

To review the distribution and function of KATP channels, describe the use of KATP channels openers in clinical trials and make the case that these channels may play a role in headache and migraine.

DISCUSSION

KATP channels are widely present in the trigeminovascular system and play an important role in the regulation of tone in cerebral and meningeal arteries. Clinical trials using synthetic KATP channel openers report headache as a prevalent-side effect in non-migraine sufferers, indicating that KATP channel opening may cause headache, possibly due to vascular mechanisms. Whether KATP channel openers can provoke migraine in migraine sufferers is not known.

CONCLUSION

We suggest that KATP channels may play an important role in migraine pathogenesis and could be a potential novel therapeutic anti-migraine target.

Topical sulfonylurea as a novel therapy for hypertrichosis secondary to diazoxide, and potentially for other conditions with excess hair growth

It is hypothesized that a topical application of a sulfonylurea drug, which can inhibit the ATP-sensitive potassium-gated channels (Kir6.X/SUR) present in human hair bulb tissues, will inhibit hair growth in a targeted manner. Diazoxide is used to treat severe hypoglycemia due to hyperinsulinism of infancy. However, this often results in hypertrichosis that can be severe enough to prevent its use. Diazoxide blocks insulin release from the pancreas by opening the SUR1/Kir6.2 channels in ß-cells. Diazoxide can also act on two potassium-gated channels in the skin that affect hair growth, namely SUR1/Kir6.2 and SUR2B/Kir6.1, thus causing hypertrichosis. It is proposed that a topical sulfonylurea will inhibit the excessive hair growth due to diazoxide, but will not impact the beneficial effects of diazoxide on beta cells. This approach can also be applied to rare cases of Cantú syndrome, caused by mutations in ABCC9 (coding for SUR2) or in KCNJ8 (coding for Kir6.1) that is characterized by congenital hypertrichosis. More importantly, this approach may also be effective in treating other forms of hypertrichosis or hirsutism, that are quite common, yet very distressing to patients worldwide.

Regenerative medicine and hair loss: how hair follicle culture has advanced our understanding of treatment options for androgenetic alopecia

Many of the current drug therapies for androgenetic alopecia were discovered serendipitously, with hair growth observed as an off-target effect when drugs were used to treat a different disorder. Subsequently, several studies using cultured cells have enabled identification of hair growth modulators with similar properties to the currently available drugs, which may also provide clinical benefit. In situations where the current therapeutics do not work, follicular unit transplantation is an alternative surgical option. More recently, the concept of follicular cell implantation, or hair follicle neogenesis, has been attempted, exploiting the inherent properties of cultured hair follicle cells to induce de novo hair growth in balding scalp. In this review, we discuss both the advances in cell culture techniques that have led to a wider range of potential therapeutics to promote hair growth, in addition to detailing current knowledge on follicular cell implantation, and the challenges in making this approach a reality.

Influence of the alkylsulfonylamino substituent located at the 6-position of 2,2-dimethylchromans structurally related to cromakalim: from potassium channel openers to calcium entry blockers?

The present study described the synthesis of original R/S-6-alkylsulfonylamino-3,4-dihydro-2,2-dimethyl-2H-1-benzopyrans bearing a 3- or 4-substituted phenylthiourea or phenylurea moiety at the 4-position. Their biological effects were evaluated both on insulin-secreting and smooth muscle cells and were compared to those of reference KATP channel activators such as (±)-cromakalim, diazoxide and previously synthesized cromakalim analogues. The study aimed at exploring the influence of the introduction of an alkylsulfonylamino substituent at the 6-position of 2,2-dimethylchromans in order to improve biological activity, tissue selectivity but also hydrophilicity of dihydrobenzopyran derivatives. Several compounds were found to be equipotent or even more potent than (±)-cromakalim and diazoxide at inhibiting the insulin releasing process. Most of the newly synthesized and more hydrophilic dihydrobenzopyrans also exhibited a marked vasorelaxant activity although they were less potent than (±)-cromakalim. Additional pharmacological and radioisotopic investigations suggested that R/S-N-3-chlorophenyl-N'-(3,4-dihydro-6-methylsulfonylamino-2,2-dimethyl-2H-1-benzopyran-4-yl)thiourea (21) did not act as a potassium channel opener but rather as a Ca(2+) entry blocker.

New investigational drugs for androgenetic alopecia

INTRODUCTION

Androgenetic alopecia (AGA) is the most common form of hair loss, however current treatment options are limited and moderately effective. In the past few years, there has been an increased interest in deciphering the molecular mechanisms responsible for this disorder, which has opened the possibility of novel treatments that promise to not only stimulate hair growth, but also to induce formation of new hair follicles.

AREAS COVERED

The future holds more effective topical treatments with less systemic side effects (such as topical 5-alfa-reductase inhibitors), prostaglandin analogs and antagonists, medications which act through the Wnt signaling pathway, stem cells for hair regeneration, platelet-rich plasma (PRP) and more effective ways of transplanting hair. A comprehensive search was made using PubMed, GoogleScholar and Clinicaltrial.gov using different combination of key words, which included AGA treatment, new treatments for AGA, Wnt pathway, prostaglandins, PRP and stem cells for hair regrowth.

EXPERT OPINION

In the near future, treatments with topical 5-alfa-reductase inhibitors and prostaglandin agonists or antagonists are expected. More evidence is needed to verify the efficacy of PRP. Although hair follicle bioengineering and multiplication is a fascinating and promising field, it is still a long way from being available to clinicians.

Therapeutic strategy for hair regeneration: hair cycle activation, niche environment modulation, wound-induced follicle neogenesis, and stem cell engineering

INTRODUCTION

There are major new advancements in the fields of stem cell biology, developmental biology, regenerative hair cycling, and tissue engineering. The time is ripe to integrate, translate, and apply these findings to tissue engineering and regenerative medicine. Readers will learn about new progress in cellular and molecular aspects of hair follicle development, regeneration, and potential therapeutic opportunities these advances may offer.

AREAS COVERED

Here, we use hair follicle formation to illustrate this progress and to identify targets for potential strategies in therapeutics. Hair regeneration is discussed in four different categories: i) Intra-follicle regeneration (or renewal) is the basic production of hair fibers from hair stem cells and dermal papillae in existing follicles. ii) Chimeric follicles via epithelial-mesenchymal recombination to identify stem cells and signaling centers. iii) Extra-follicular factors including local dermal and systemic factors can modulate the regenerative behavior of hair follicles, and may be relatively easy therapeutic targets. iv) Follicular neogenesis means the de novo formation of new follicles. In addition, scientists are working to engineer hair follicles, which require hair-forming competent epidermal cells and hair-inducing dermal cells.

EXPERT OPINION

Ideally self-organizing processes similar to those occurring during embryonic development should be elicited with some help from biomaterials.

Biology of human hair: know your hair to control it

Hair can be engineered at different levels--its structure and surface--through modification of its constituent molecules, in particular proteins, but also the hair follicle (HF) can be genetically altered, in particular with the advent of siRNA-based applications. General aspects of hair biology are reviewed, as well as the most recent contributions to understanding hair pigmentation and the regulation of hair development. Focus will also be placed on the techniques developed specifically for delivering compounds of varying chemical nature to the HF, indicating methods for genetic/biochemical modulation of HF components for the treatment of hair diseases. Finally, hair fiber structure and chemical characteristics will be discussed as targets for keratin surface functionalization.

New R/S-3,4-dihydro-2,2-dimethyl-2H-1-benzopyrans as K(ATP) channel openers: modulation of the 4-position

The present work aimed at exploring a series of diversely 4-arylthiourea-substituted R/S-3,4-dihydro-2,2-dimethyl-6-halo-2H-1-benzopyrans structurally related to (+/-)-cromakalim. These new compounds were examined in vitro as putative potassium channel openers (PCOs) on rat pancreatic islets (inhibition of insulin release) as well as on rat aorta rings (relaxation of aorta ring) and their activity was compared to that of the reference K(ATP) channel activators (+/-)-cromakalim, (+/-)-pinacidil, diazoxide and of previously reported cromakalim analogues. Structure-activity relationships indicated that the most pronounced inhibitory activity on the insulin secretory process was obtained with molecules bearing a strong meta- or para-electron-withdrawing group (CN or NO(2)) on the phenyl ring of the arylthiourea moiety at the 4-position of the benzopyran nucleus (compounds 12-23). Among those, R/S-6-chloro-4-(4-cyanophenylaminothiocarbonylamino)-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran (16) was found to be the most potent benzopyran-type inhibitor of insulin release ever described. Most of these original benzopyran derivatives show increased selectivity for pancreatic versus vascular tissue. Radioisotopic investigations indicated that these new compounds activated pancreatic K(ATP) channels.

Androgens and hair growth

Hair's importance in human communication means that abnormalities like excess hair in hirsutism or hair loss in alopecia cause psychological distress. Androgens are the main regulator of human hair follicles, changing small vellus follicles producing tiny, virtually invisible hairs into larger intermediate and terminal follicles making bigger, pigmented hairs. The response to androgens varies with the body site as it is specific to the hair follicle itself. Normally around puberty, androgens stimulate axillary and pubic hair in both sexes, plus the beard, etc. in men, while later they may also inhibit scalp hair growth causing androgenetic alopecia. Androgens act within the follicle to alter the mesenchyme-epithelial cell interactions, changing the length of time the hair is growing, the dermal papilla size and dermal papilla cell, keratinocyte and melanocyte activity. Greater understanding of the mechanisms of androgen action in follicles should improve therapies for poorly controlled hair disorders like hirsutism and alopecia.

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.

Differences in Expression of Specific Biomarkers Distinguish Human Beard from Scalp Dermal Papilla Cells

Androgen exposure stimulates the growth of beard hair follicles. The follicle dermal papilla appears to be the site of androgen action; however, the molecular mechanisms that regulate this process are not well understood. In an attempt to identify genes that contribute to the androgen-responsive phenotype, we compared gene expression patterns in unstimulated and androgen-treated cultured human dermal papilla cells isolated from beard (androgen-sensitive) and occipital scalp (androgen-insensitive) hair follicles. Through this analysis, we identified three genes that are expressed at significantly higher levels in beard dermal papilla cells. One of these genes, sfrp-2 has been identified as a dermal papilla signature gene in mouse pelage follicles. Two of these genes, mn1 and atp1beta1, have not been studied in the hair follicle. A fourth, fibulin-1d, was slightly upregulated in beard dermal papilla cells. The differences in the expression of these genes in cultured beard and scalp dermal papilla cells reflected similar differences in microdissected dermal papilla isolated from intact beard and scalp follicles. Our findings introduce potentially novel signaling pathways in dermal papilla cells. In addition, this study supports that cultured dermal papilla cells provide a cell-based model system that is reflective of the biology of in vivo hair follicle cells.

Binding studies and GRIND/ALMOND-based 3D QSAR analysis of benzothiazine type K(ATP)-channel openers

For seventeen 1,4-benzothiazine potassium channel openers, we performed binding studies in rat aortic smooth muscle cells and cardiomyocytes, compared their binding affinities with published relaxation data, and derived 3D-QSAR models using GRIND/ALMOND descriptors. Binding affinities in smooth muscle cells range from a pK(D) of 4.76 for compound 3e to 9.10 for compound 4c. Comparison of data for smooth muscle relaxation and binding shows preferentially higher pEC(50)s for the former. In cardiomyocytes, pK(D) values range from 4.21 for 3e to 8.16 for 4c. 3D-QSAR analysis resulted in PLS models of two latent variables for all three activities with determination coefficients of 0.97 (smooth muscle relaxation) and 0.94 (smooth muscle cells- and cardiomyocytes-binding). Internal validation yielded q(2) values of 0.69, 0.66, and 0.64. The carbonyl on the N-4 substituent, the hydrogen bond acceptor at C-6, the five-membered ring at N-4, and the gem-dimethyls mainly guide strong binding and strong smooth muscle relaxation.

Human hair growth ex vivo is correlated with in vivo hair growth: selective categorization of hair follicles for more reliable hair follicle organ culture

Of the numerous assays used to assess hair growth, hair follicle organ culture model is one of the most popular and powerful in vitro systems. Changes in hair growth are commonly employed as a measurement of follicular activity. Hair cycle stage of mouse vibrissa follicles in vivo is known to determine subsequent hair growth and follicle behavior in vitro and it is recommended that follicles be taken at precisely the same cyclic stage. This study was performed to evaluate whether categorization of human hair follicles by the growth in vivo could be used to select follicles of the defined anagen stage for more consistent culture. Occipital scalp samples were obtained from three subjects, 2 weeks later after hair bleaching. Hair growth and follicle length of isolated anagen VI follicles were measured under a videomicroscope. Follicles were categorized into four groups according to hair growth and some were cultured ex vivo for 6 days. Follicles showed considerable variations with respect to hair growth and follicle length; however, these two variables were relatively well correlated. Hair growth in culture was closely related with hair growth rate in vivo. Moreover, minoxidil uniquely demonstrated a significant increase of hair growth in categorized hair follicles assumed at a similar early anagen VI stage of hair cycle. Selection of follicles at a defined stage based on hair-growth rate would permit a more reliable outcome in human hair follicle organ culture.