Anagen Phase Research Articles

The Hairless Phenotype of the Hirosaki Hairless Rat Is Due to the Deletion of an 80-kb Genomic DNA Containing Five Basic Keratin Genes

Most models of hereditary hypotrichosis are due to alterations in growth factors and transcription factors, and the examples of causative mutations in hair keratin genes are limited. The Hirosaki hairless rat (HHR) is a mutant strain spontaneously derived from Sprague-Dawley rats (SDRs). In this study, the locus of the responsible gene was examined by linkage analysis and mapped on chromosome 7q36. Because many basic keratin genes are clustered on 7q36, their expression was examined. Reverse transcription-PCR and genomic PCR indicated that the Kb21 (Krt81), -23 (Krt83), and -26 (Krt86) genes encoding basic hair keratins were not expressed and were deleted. Furthermore, 80-kb genomic DNA ranging from exon 9 of Kb25 (Krt85) to exon 9 of Krt2-25 was deleted. The breakpoints of these genes were within a 95-bp portion shared by the two genes, suggesting that deletion due to non-allelic homologous recombination occurred. Proteins identified as Kb21, Kb23, and Krt2-25 in SDR hairs by mass spectrometry were not detected in HHR. Instead, the product of a fusion gene became dominant in HHR. Because fusion occurred between the exons of the two genes with the same sequences, the product was identical to the wild-type Kb25 protein. By using immunohistochemistry, Kb21 was not detected in HHR hair follicles. Kb25 was expressed in the cortex in HHRs, whereas it was in the medulla in SDRs. This study clearly illustrates the importance of hair keratin genes in hair growth.

Hair growth promoting activity of Eclipta alba in male albino rats

Alopecia is a dermatological disorder with psychosocial implications on patients with hair loss. Eclipta alba Hassk. is a well-known Ayurvedic herb with purported claims of hair growth promotion. In the reported work attempts were undertaken to evaluate petroleum ether and ethanol extract of E. alba Hassk. for their effect on promoting hair growth in albino rats. The extracts were incorporated into oleaginous cream (water in oil cream base) and applied topically on shaved denuded skin of albino rats. The time (in days) required for hair growth initiation as well as completion of hair growth cycle was recorded. Minoxidil 2% solution was applied topically and served as positive control for comparison. Hair growth initiation time was significantly reduced to half on treatment with the extracts, as compared to control animals. The time required for complete hair growth was also significantly reduced. Quantitative analysis of hair growth after treatment with petroleum ether extract (5%) exhibited greater number of hair follicles in anagenic phase (69 +/- 4) which were higher as compared to control (47 +/- 13). The result of treatment with 2 and 5% petroleum ether extracts were better than the positive control minoxidil 2% treatment.

Cycling in Synchrony

Hair follicles cycle through growth, involution, and resting phases, with entry into the anagen (or growth) phase depending on activation of hair stem cells. Following anagen, there is a refractory period that has been postulated to depend on an inhibitory substance called "chalone." Whereas cycling in individual follicles depends on periodic activation of the Wnt effector β-catenin, hair regeneration in various mammalian species occurs in coordinated waves, and the mechanism whereby cycling in populations of follicles is coordinated has been unclear. Plikus et al . analyzed cycling of hair follicle domains (in which cycling is coordinated) and found that there was a minimum 28-day telogen (resting) phase, which they defined as "early telogen," followed by a "late telogen" phase of 0 to 60 days. Entry into anagen after hair plucking was faster for hairs in late telogen than for hairs in early telogen, indicating that early telogen correlated with the refractory period. Experiments with lacZ reporter mice revealed that interfollicular expression of bone morphogenetic protein 2 ( Bmp2 ) and Bmp4 fluctuated with hair cycles, such that BMP signaling was out of phase with Wnt signaling. Bmp expression, which was not apparent in early anagen, rose during anagen and remained active during early (refractory) telogen but disappeared in late telogen. Similarly, Smad 1/5/8 is active (phosphorylated) in refractory follicles but not during late telogen. Overexpression of the BMP antagonist noggin shortened the refractory phase, whereas administration of BMP4 ahead of an anagen wave caused local follicles to become refractory, and experiments involving skin grafts from Nog -overexpressing to wild-type mice revealed mutual effects of host and donor on follicle cycling. Thus the authors conclude that BMP signaling regulates and coordinates regional hair follicle cycling and may constitute the long-postulated inhibitory "chalone." M. V. Plikus, J. A. Mayer, D. de la Cruz, R. E. Baker, P. K. Maini, R. Maxson, C.-M. Chuong, Cyclic dermal BMP signalling regulates stem cell activation during hair regeneration. Nature 451 , 340-344 (2008). [PubMed]

Toxidermie folliculaire à la ciclosporine

Cyclosporine is one of the immunosuppressant agents most widely used in the prevention and treatment of organ transplant rejection and also in autoimmune diseases. Many cutaneous side effects have been described with oral cyclosporine, mainly in transplant recipients, for example, hypertrichosis, gingival hyperplasia and viral skin infections. Here, we report an unusual follicular eruption induced by this drug. A 22-year-old man presenting cystic fibrosis received a double-lung graft in January 2005. Six weeks later, he developed a subacute eruption of follicular papules, not highly pruritic, located mainly on the trunk, the extensor surfaces of the limbs and the face. Diagnosis of cyclosporine-induced follicular eruption was adopted on the basis of the histological and microbiological findings. Complete regression was obtained after switching to tacrolimus. Three similar cases were previously reported characterized by typical follicular changes different from those observed in hypertrichosis or pilar keratosis. This rare cutaneous side effect may be explained by the direct action of cyclosporine on the pilosebaceous unit: this drug is known to extend the anagen phase of the follicular cycle and to induce toxic follicular dystrophy at higher tissue concentrations. This particular toxicity is usually seen after many months of treatment. In our patient, the time to onset was shorter, probably due to occasionally excessive plasma concentrations.

NG2 Proteoglycan Expression in Mouse Skin: Altered Postnatal Skin Development in the NG2 Null Mouse

In early postnatal mouse skin, the NG2 proteoglycan is expressed in the subcutis, the dermis, the outer root sheath of hair follicles, and the basal keratinocyte layer of the epidermis. With further development, NG2 is most prominently expressed by stem cells in the hair follicle bulge region, as also observed in adult human skin. During telogen and anagen phases of the adult hair cycle, NG2 is also found in stem cell populations that reside in dermal papillae and the outer root sheaths of hair follicles. Ablation of NG2 produces alterations in both the epidermis and subcutis layers of neonatal skin. Compared with wild type, the NG2 null epidermis does not achieve its full thickness due to reduced proliferation of basal keratinocytes that serve as the stem cell population in this layer. Thickening of the subcutis is also delayed in NG2 null skin due to deficiencies in the adipocyte population.

Repigmentación del pelo canoso tras tratamiento con hormona tiroidea

Background and objectives Darkening of gray and white hairs occurred in 2 patients with increased exogenous triiodothyronine (T3) due to treatment of myxedema coma in one case and iatrogenic hyperthyroidism in the other. We hypothesized that thyroid hormone may affect the homeostasis of hair follicles. To test our hypothesis and investigate the influence of thyroid hormone on the hair cycle, we used an in vivo murine model and an in vitro model based on culture of follicular units. Methods We used the standard C57BL/6 murine model of the hair cycle. T3 (0.5 μg) dissolved in ethanol was applied topically once daily for 10 days to a depilated area in the telogen phase on the backs of the mice. Follicular units, obtained from hair transplant interventions, were cultured in vitro with different concentrations of T3. Results On day 5, all T3-treated mice entered the anagen phase, whereas the anagen phase started spontaneously in control mice on day 9, and not until day 15 had all controls entered this phase. In the in vitro experiment, follicular units treated with 100 nmol/L T3 grew significantly larger compared to the control group. Conclusions These data suggest that follicles in the telogen phase can be induced to enter the anagen phase by the topical application of T3. This thyroid hormone may reverse graying of the terminal hair. In the in vitro experiments, T3 stimulated hair shaft growth. Follicular melanocytes may be the target cell for these actions.

Influence of TRPV3 mutation on hair growth cycle in mice

We recently reported that Gly573Ser substitution of the transient receptor potential cation channel, subfamily V member 3 (TRPV3) caused hair loss in DS- Nh mice. To further elucidate the effects of this mutation on the development of the spontaneous hairless phenotype, we examined the temperature–response to epidermal sheets from DS- Nh and DS mice. It was indicated that the mutation was gain-of-function. We also performed genetic and histological analyses with both strain skins. DNA microarray data revealed that the levels of keratin-associated protein 16-1, 16-3, and 16-9 genes related to the anagen phase were decreased in the skins of DS- Nh mice compared with those of three days old DS mice. Histological analysis revealed that the anagen phase persisted in DS- Nh mice, and that the telogen phase was seen in DS but not DS- Nh mice at 21 days of age. Regulation of TRPV3 appears to be important for appropriate hair development in rodents.

The TFIID subunit TAF4 regulates keratinocyte proliferation and has cell-autonomous and non-cell-autonomous tumour suppressor activity in mouse epidermis

The TAF4 subunit of transcription factor TFIID was inactivated in the basal keratinocytes of foetal and adult mouse epidermis. Loss of TAF4 in the foetal epidermis results in reduced expression of the genes required for skin barrier function, leading to early neonatal death. By contrast, TAF4 inactivation in adult epidermis leads to extensive fur loss and an aberrant hair cycle characterised by a defective anagen phase. Although the mutant epidermis contains few normal anagen-phase hair follicles, many genes expressed at this stage are strongly upregulated indicating desynchronized and inappropriate gene expression. The TAF4 mutant adult epidermis also displays interfollicular hyperplasia associated with a potent upregulation of several members of the EGF family of mitogens. Moreover, loss of TAF4 leads to malignant transformation of chemically induced papillomas and the appearance of invasive melanocytic tumours. Together, our results show that TAF4 is an important regulator of keratinocyte proliferation and has cell-autonomous and non-cell-autonomous tumour suppressor activity.

A new Gsdma3 mutation affecting anagen phase of first hair cycle

Recombination-induced mutation 3 ( Rim3) is a spontaneous mouse mutation that exhibits dominant phenotype of hyperkeratosis and hair loss. Fine linkage analysis of Rim3 and sequencing revealed a novel single point mutation, G1124A leading to Ala348Thr, in Gsdma3 in chromosome 11. Transgenesis with BAC DNA harboring the Rim3-type Gsdma3 recaptured the Rim3 phenotype, providing direct evidence that Gsdma3 is the causative gene of Rim3. We examined the spatial expression of Gsdma3 and characterized the Rim3 phenotype in detail. Gsdma3 is expressed in differentiated epidermal cells in the skin, but not in the proliferating epidermal cells. Histological analysis of Rim3 mutant showed hyperplasia of the epidermal cells in the upper hair follicles and abnormal anagen phase at the first hair cycle. Furthermore, immunohistochemical analysis revealed hyperproliferation and misdifferentiation of the upper follicular epidermis in Rim3 mutant. These results suggest that Gsdma3 is involved in the proliferation and differentiation of epidermal stem cells.

Development and evaluation of polyherbal formulation for hair growth–promoting activity

Cuscuta reflexa (Roxb.), Citrullus colocynthis (Schrad.), and Eclipta alba (Hassk.) are traditionally acclaimed herbs for their hair growth-promoting potential. Aim In the present study, it was envisaged to prepare herbal formulations containing petroleum ether extracts of the three herbs in varying ratio and evaluating the formulations for the hair growth-promoting activity. The formulations as well as minoxidil (2%) solution (positive control) were applied topically on shaved skin of rats, and the time required for initiation and completion of hair growth cycle was recorded. Hair growth initiation time was markedly reduced to one third on treatment with the prepared formulation compared with control animals. The time required for complete hair growth was also reduced by 32%. Quantitative analysis of hair growth cycle after treatment with formulations and minoxidil (2%) exhibited greater number of hair follicles in anagenic phase compared with control. The results thus corroborate with the traditionally acclaimed hair growth-promoting capabilities of the plants. The prepared formulation also holds potential for treatment of alopecia.

An unusual terminal hair growth on the nose tip associated with gefitinib therapy

Conflicts of interest: none declared. Sir, The epidermal growth factor receptor (EGFR) pathway, a key driver in regulating normal epithelial cell growth and differentiation, also plays a role in promoting proliferation of malignant epithelial cells1 by increasing proliferation, adhesion and invasive capacity, and also by blocking apoptosis.1–4 For this reason, EGFR expression is associated with metastasis, late‐stage disease, resistance to therapy and poor prognosis. Therapies targeting EGFR are now under development, such as antibodies to EGFR or EGFR‐specific tyrosine kinase inhibitors. Gefitinib, also known as ZD 1839 or Iressa®, is a low‐molecular‐weight compound that inhibits the activation of EGFR tyrosine kinase through competitive binding of the receptor.1–4 A 65‐year‐old woman presented with a 2‐month history of asymptomatic, brown to black hairs on the nose tip that had been gradually thickening and lengthening (Fig. 1). Six months before, she had been diagnosed with metastatic lung adenocarcinoma and had undergone treatment with radiotherapy (whole brain and femur, 3000 cGy × 2 cycles) and chemotherapy (docetaxel 100 mg daily every 3 weeks for 2 months). Two months before, she began treatment with gefitinib 250 mg daily. One week after starting treatment, she noticed tiny brown to black spots on her nose tip. Ever since, hairs have been growing at these sites. When she presented to our department, the hairs were 1–3 mm in length, localized to the nose tip. There were no vellus hairs, which normally there should be. There was no abnormality of hair density or length at other body sites. She denied a personal history of other cutaneous problems, trauma or administration of any drugs such as might induce hair growth. Skin biopsy revealed multiple hair follicles in anagen phase that were located in the superficial dermis (Fig. 2). The hair shaft was 0·054 mm in diameter and was myelinated, indicative of terminal hair. There was also solar elastosis and a mild inflammatory infiltrate in the papillary dermis. On the basis of these findings, the patient was diagnosed with terminal hair growth associated with gefitinib and was recommended to discontinue gefitinib. However, as the patient's lung adenocarcinoma had had a poor response to radiochemotherapy, gefitinib could not be discontinued and the hairs have continued to grow.

Development and Evaluation of Herbal Formulations for Hair Growth

Hair formulation of Emblica officinalis (Euphorbiaceae), Bacopa, monnieri (Scrophulariaceae), Trigonella foenumgraecum (Leguminosae), Murraya koenigii (Rutaceae) in various concentrations in the form of herbal oil were studied for their hair growth activity. Each drug was tested for their hair growth activity in a concentration range for 1‐10% separately. Based on these results mixture of crude drugs Murraya koeniigi, leaf (Rutaceae), Bacopa monnieri, leaf (Scrophulariaceae), Trigonella foenumgraecum (Leguminosae), Murraya koenigii (Rutaceae) were prepared in varying concentration in the form of herbal hair oil by three different oils preparation techniques and were tested for hair growth activity. The result revealed that the hair growth activity of each drug was found proportional to the concentration range tested. Similarly higher concentrations of drug in the formulation were found to have higher hair growth activities. But looking towards the formulation viscosity the maximum concentration of combined drug was found to be 30% at their maximum level. The formulation containing 7.5% of each drug used for the study and showed excellent hair growth activity with standard (2% minoxidil ethanolic solution) by an enlargement of follicular size and prolongation of the anagen phase. It holds the promise of potent herbal alternative for minoxidil. Excellent results of hair growth were seen in formulation prepared by cloth pouch decoction method of oils preparation technique.

Melanocytic Matricoma: A Distinctive Clinicopathological Entity

Melanocytic matricoma is a rare recently reported entity. It usually presents as pigmented, dark-papular, crusted lesion on sun-damaged skin of adult patients. Histopathologically, these lesions consist of well-circumscribed nodules with groups of “shadow cells” or “ghost cells” (matrical/supramatrical cells) and prominent pigmented dendritic melanocytes. It differs from matricomas and pilomatricomas by its lack of calcification, cyst formation, granulomas, and connections to the epidermis and other adnexal structures. The clinical differential diagnosis includes hemangioma, pigmented basal cell carcinoma, and melanoma. Melanocytic matricoma presumably is the representation of an epithelial-melanocytic interaction in the anagen phase of the hair cycle, and the melanization is due to normal melanocytes colonizing a neoplastic proliferation. A extensive search of the medical literature revealed 5 reports of benign melanocytic matricomas and 2 malignant counterparts. We present 2 additional cases of melanocytic matricoma with clinicopathologic correlation. The first case is from the dorsum of the hand of a 70-year-old white male and the second from the preauricular area of an 82-year-old white male, both with prior history of skin cancer. The small size, well-circumscribed appearance, and the symptom-free nature signifies benignity. However, if cytologic atypia is present, it is indicative of malignant behavior. Correct interpretation of melanocytic matricoma is extremely important due to its clinical and histopathologic overlap with other more ominous lesions.

Gene angora as a modifier of the hairless gene in mouse

The interaction between mouse angora-Y (Fgf5 go-Y) and hairless (hr) genes have been studied. Homozygous mutant gene Fgf5 go-Y increases length of all hair types, while homozygotes for the h gene lose hair completely starting on day 14 after birth. We obtained mice with genotypes +/+ hr/hr F2, +/Fgf5 go-Y hr/hr and Fgf5 go-Y/Fgf5 go-Y hr/hr. Both +/Fgf5 go-Y hr/hr and +/+ hr/hr mice began to loose hair from their heads on day 14. This further extended on the whole body. On day 21 the mice were completely deprived of hair. Therefore a single dose of gene Fgf5 go-Y does not modify alopecia in mice homozygous for hr. However in double homozygotes Fgf5 go-Y/Fgf5 go-Y hr/hr alopecia started 4 days later, namely on day 18. It usually finished 10–12 days after detection of first bald patches. On days 28–30 double homozygotes lose coat completely. Hair loss in double homozygous mice was 1.5-fold slower than in +/+ hr/hr mice. This resulted from a significant extension of anagen phase induced by a mutant homozygous gene Fgf5 go-Y in morphogenesis of the hair follicle. The hr gene was expressed at the transmission phase from anagen to catagen. Our data shows that the angora gene is a modifier of the hairless gene and this results in a strong repression of alopecia progression in double homozygous mice compared to +/+ hr/hr animals.

Repigmentation of Gray Hair After Thyroid Hormone Treatment

Introduction and objectives Darkening of gray and white hairs occurred in 2 patients with increased exogenous triiodothyronine (T3) due to treatment of myxedema coma in one case and iatrogenic hyperthyroidism in the other. We hypothesized that thyroid hormone may affect the homeostasis of hair follicles. To test our hypothesis and investigate the influence of thyroid hormone on the hair cycle, we used an in vivo murine model and an in vitro model based on culture of follicular units. Methods We used the standard C57BL/6 murine model of the hair cycle. T3 (0.5 #mg) dissolved in ethanol was applied topically once daily for 10 days to a depilated area in the telogen phase on the backs of the mice. Follicular units, obtained from hair transplant interventions, were cultured in vitro with different concentrations of T3. Results On day 5, all T3-treated mice entered the anagen phase, whereas the anagen phase started spontaneously in control mice on day 9, and not until day 15 had all controls entered this phase. In the in vitro experiment, follicular units treated with 100 nmol/L T3 grew significantly larger compared to the control group. Conclusions These data suggest that follicles in the telogen phase can be induced to enter the anagen phase by the topical application of T3. In the in vitro experiments, T3 stimulated hair shaft growth. Follicular melanocytes may be the target cell for these actions.

Promotive Effect of Minoxidil Combined with All-trans Retinoic Acid (tretinoin) on Human Hair Growth in Vitro

Minoxidil induces hair growth in male pattern baldness and prolongs the anagen phase. All-trans retinoic acid (ATRA) has been reported to act synergistically with minoxidil in vivo: they can enhance more dense hair regrowth than either compound alone. We evaluated the effect of minoxidil combined with ATRA on hair growth in vitro. The effect of co-treatment of minoxidil and ATRA on hair growth was studied in hair follicle organ culture. In cultured human dermal papilla cells (DPCs) and normal human epidermal keratinocytes, the expressions of Erk, Akt, Bcl-2, Bax, P53 and P21 were evaluated by immunoblot analysis. Minoxidil plus ATRA additively promoted hair growth in vitro, compared with minoxidil alone. In addition, minoxidil plus ATRA elevated phosphorylated Erk, phosphorylated Akt and the ratio of Bcl-2/Bax, but decreased the expressions of P53 and P21 more effectively than by minoxidil alone. Our results suggest that minoxidil plus ATRA would additively enhance hair growth by mediating dual functions: 1) the prolongation of cell survival by activating the Erk and Akt signaling pathways, and 2) the prevention of apoptosis of DPCs and epithelial cells by increasing the ratio of Bcl-2/Bax and downregulating the expressions of P53 and P21.

Viewpoint 7

Viewpoint 7

The Additive Effects of Minoxidil and Retinol on Human Hair Growth in Vitro

Minoxidil enhances hair growth by prolonging the anagen phase and induces new hair growth in androgenetic alopecia (AGA), whereas retinol significantly improves scalp skin condition and promotes hair growth. We investigated the combined effects of minoxidil and retinol on human hair growth in vitro and on cultured human dermal papilla cells (DPCs) and epidermal keratinocytes (HaCaT). The combination of minoxidil and retinol additively promoted hair growth in hair follicle organ cultures. In addition, minoxidil plus retinol more effectively elevated phosphorylated Erk, phosphorylated Akt levels, and the Bcl-2/Bax ratio than minoxidil alone in DPCs and HaCaT. We found that the significant hair shaft elongation demonstrated after minoxidil plus retinol treatment would depend on the dual kinetics associated with the activations of Erk- and Akt-dependent pathways and the prevention of apoptosis by increasing the Bcl-2/Bax ratio.

Effect of Citrullus colocynthis. on Hair Growth in Albino Rats

Citrullus colocynthis. Schrad (Cucurbitaceae) is a traditionally acclaimed hair tonic in Ayurveda (the traditional Indian system of medicine). Studies were therefore undertaken to evaluate petroleum ether and ethanol extracts of C. colocynthis. for their effect on hair growth in albino rats. The extracts incorporated into oleaginous ointment base were applied topically on shaved denuded skin of albino rats. The time required for initiation of hair growth as well as completion of hair growth cycle was recorded. Minoxidil 2% solution was applied topically and served as the standard. Hair growth initiation time was significantly reduced to half on treatment with the petroleum ether extracts compared with untreated control animals. The time required for complete hair growth was also considerably reduced. The treatment was successful in bringing a greater number of hair follicles (>70%) to anagenic phase than standard minoxidil (67%). The result of treatment with 2 and 5% petroleum ether extracts were comparable with the standard minoxidil.

Bone Morphogenetic Protein Signaling Inhibits Hair Follicle Anagen Induction by Restricting Epithelial Stem/Progenitor Cell Activation and Expansion

Epithelial stem cells (EP-SCs) located in the bulge region of a hair follicle (HF) have the potential to give rise to hair follicle stem/progenitor cells that migrate down to regenerate HFs. Bone morphogenetic protein (BMP) signaling has been shown to regulate the HF cycle by inhibiting anagen induction. Here we show that active BMP signaling functions to prevent EP-SC activation and expansion. Dynamic expression of Noggin, a BMP antagonist, releases EP-SCs from BMP-mediated restriction, leading to EP-SC activation and initiation of the anagen phase. Experimentally induced conditional inactivation of the BMP type IA receptor (Bmpr1a) in EP-SCs leads to overproduction of HF stem/progenitor cells and the eventual formation of matricomas. This genetic manipulation of the BMP signaling pathway also reveals unexpected activation of beta-catenin, a major mediator of Wnt signaling. We propose that BMP activity controls the HF cycle by antagonizing Wnt/beta-catenin activity. This is at least partially achieved by BMP-mediated enhancement of transforming growth factor-beta-regulated epithelial cell-specific phosphatase (PTEN) function. Subsequently, PTEN, through phosphatidyl inositol 3-kinase-Akt, inhibits the activity of beta-catenin, the convergence point of the BMP and Wnt signaling pathways.