Immunostaining study of cytokeratins in human hair follicle development

Abstract Background: The hair follicle is a unique structure, one of the most dynamic structures in mammalians, which can reproduce in every new cycle all the mechanism involved in its fetal development. Although a lot of research has been made about the human hair follicle much less has been discovered about the importance of the cytokeratins (CKs) in its development. Objective: Study the immunohistochemical pattern of epithelial CKs during human hair follicle development. Methods: We performed an immunohistochemical study using fresh post-mortem skin biopsies of human fetuses between 4 and 25 weeks of gestational age to study the expression of cytokeratins (CKs): CK1, CK10, CK13, CK14, CK16 and CK20 during human hair follicle fetal development. Study limitations: Restrospective study with a good number of makers but with a small population. Results/conclusion: We found that, the CKs were expressed in an intermediate time during follicular development. The epithelial CKs (CK1, CK14, CK10, CK13) and the epithelial CKs with a proliferative character such as CK16 were expressed first, as markers of cellular maturation and follicular keratinization. At a later phase, CK20 was expressed in more developed primitive hair follicles as previously discussed in literature.

Discovery and molecular analysis of conserved circRNAs from cashmere goat reveal their integrated regulatory network and potential roles in secondary hair follicle

Background: Circular RNAs, a novel class in the eukaryotic transcriptome, are characterized by the 3' and 5' ends that are covalently joined in a covalently closed loop without free ends. Circular RNAs are considerably stable molecules and act as microRNA sponges with regulatory potential to the protein-coding genes. Results: Eight circular RNAs were found to be significantly upregulated at anagen skin tissue of cashmere goat compared with their counterparts at telogen. Rich and complex regulatory patterns were revealed among the eight upregulated circular RNAs at anagen and related miRNAs with their potential regulatory genes. The potential regulatory genes of eight upregulated circular RNAs at anagen were involved in several pathways related to the main physiological process of hair follicle, such as histone acetylation and axon. For chi_circ_1926, chi_circ_3541, chi_circ_0483, chi_circ_3196, and chi_circ_2092, overall, the relative expression in secondary hair follicle exhibited highly similar trends with their corresponding host genes during the different stages of the hair follicle cycle. However, the expression trends of chi_circ_0100, chi_circ_2829, and chi_circ_1967 were found to diverge from their corresponding host genes during the different stages of the hair follicle cycle. Conclusions: A total of eighteen circular RNAs were identified and characterized from skin tissue of cashmere goat. The eight upregulated circular RNAs at anagen might have significant roles in the secondary hair follicle of cashmere goat. Our results would provide a novel regulatory layer to elucidate the molecular mechanisms underlying the development of secondary hair follicle and the growth of cashmere fiber in cashmere goat.

Effects of all-trans retinoic acid on goat dermal papilla cells cultured in vitro

Background: All-trans retinoic acid (ATRA), a vitamin A-derived active metabolite, exerts important functions in hair biology. Previous studies indicated that excess ATRA hampered hair follicle morphogenesis and cyclic regeneration in adulthood, but other studies stated that ATRA promoted hair growth. Dermal papilla (DP), a cluster of specialized fibroblasts, plays pivotal roles in controlling development and regeneration of hair follicle. Several lines of evidence indicated that DP might be the target cells of ATRA in the hair follicle. To confirm this hypothesis, the present study was performed to explore the biological effects of ATRA on goat dermal papilla cells (DPCs) and clarify the roles of ATRA in hair biology. Results: Our experimental results indicated that key signaling transducers of ATRA were dynamically expressed in distinct stages of goat cashmere growth cycle, and high-dose ATRA treatment (10-5 M) significantly impaired the viability of goat DPCs and lowered the ratio of proliferating cells. Otherwise, goat DPCs were stimulated to enter apoptosis and their cell cycle progression was severely blocked by ATRA. Moreover, the expression of fibroblast growth factor 7 (Fgf7), one of the potent hair growth stimulators secreted by DPCs, was transcriptionally repressed following ATRA treatment. Conclusion: DPCs are the targets of ATRA in the hair follicle, and ATRA negatively regulates hair growth by the targeted suppression of cell viability and growth factor expression of goat DPCs. Through these observations, we offer a new mechanistic insight into the roles of ATRA in hair biology.

Effect of miR-125b on dermal papilla cells of goat secondary hair follicle

Background: MicroRNAs (miRNAs) are endogenous noncoding RNAs that regulate various biological processes. miR-125b is a miRNA that has been reported to be critical for hair follicle (HF) morphogenesis and development. We identified that the expression of miR-125b varies during an individual hair cycle (anagen, catagen, and telogen) in the skin of cashmere goats. We constructed a gain model (by overexpressing miR-125b) and a loss model (by inhibiting endogenous miR-125b) based on dermal papilla cells (DPCs) to further investigate the role of miR-125b in HF cycle. In addition, we used a dual-luciferase system to highlight the predicated target genes of miR-125b. Results: We found that miR-125b affects the expression of FGF5, IGF-1, SHH, TNF-α, MSX2, LEF-1, FGF7, NOGGIN, BMP2, BMP4, TGF-ß1, and ß-catenin. The dual-luciferase assay further validated a direct interaction between miR-125b and FGF5 and TNF-α. Conclusion: miR-125b affects the expression levels of genes related to hair cycle and may also play a critical role in regulating the periodic development of HF.

Transplante capilar de unidades foliculares: experiência de 15 casos / Hair transplant of follicular units: a 15-case experience

Introdução: O transplante capilar de unidades foliculares (UFs) é a técnica que permite a obtenção dos resultados mais naturais. A implantação de 20 a 25 UF/cm2 possui baixo risco de dano aos folículos e tem resultado satisfatório com duas sessões. Densidade superior a 30-35 UF/cm2 permite resultado com uma única sessão, mas aumenta os riscos de dano ao folículo e perda de crescimento dos fios. O objetivo do estudo foi relatar a experiência de 15 casos de transplante capilar com implantação de 30 ou mais UF/cm2, com incisões previamente realizadas e utilizando um instrumento cirúrgico modificado para facilitar a implantação. Método: Foi realizado estudo retrospectivo de 15 pacientes submetidos em sequência a um total de 17 cirurgias, no período de julho de 2008 a junho de 2012, com tempo de seguimento de 1 ano. Resultados: Foi implantada uma quantidade média de 1433,3 UF e 3019,8 fios por cirurgia. O tempo médio de duração das cirurgias foi de 10 horas e 23 minutos. Ocorreu crescimento satisfatório dos fios com resultado visível a partir de 6 meses, com poucas complicações. Dos 15 pacientes, dois necessitaram de uma segunda sessão. Conclusões: A técnica empregada possibilitou manipulação delicada das UFs e permitiu implantação com alta densidade, obtendo bom resultado com uma sessão, mas requer tempo de execução acima da média, devendo ter uso restrito a áreas pequenas com necessidade de maior densidade.

Introduction: The transplant of follicular units (FUs) for hair restoration yields the most natural results. The implantation of 20-25 FU/cm2 has a low risk of follicular damage and yields satisfactory results within two sessions. A density greater than 30-35 FU/cm2 yields the same results within a single session but increases the risk of follicular damage and hair growth loss. We report our experience with 15 cases of hair transplantation, with an implantation density of ≥ 30 FU/cm2 and with incisions made previously using a surgical instrument modified to facilitate implantation. Method: A retrospective study of 15 patients who consecutively underwent 17 surgeries between July 2008 and June 2012 and were followed up for 1 year. Results: A mean of 1433.3 FUs and 3019.8 hairs were implanted per surgery. The mean surgical duration was 10 hours and 23 minutes. Satisfactory hair growth occurred, and results were visible at 6 months onward with few complications. Of the 15 patients, two required a second session. Conclusions: The technique used here enabled delicate manipulation of the FUs and high-density implantation that achieved good results within one session but required an above-average execution time and should be restricted to small areas requiring greater density.

Productos capilares alternativos para alopecia: mecanismos de acción y evidencia científica / Alternative hair products for alopecia: mechanisms of action and scientific evidence

La pérdida excesiva y falta de crecimiento capilar son un motivo frecuente de consulta dermatológica. En las últimas décadas, la investigación constante en la biología folicular ha permitido desarrollar numerosos productos farmacológicos que serían capaces de modificar la biología folicular y capilar, con resultados prometedores. No obstante, su indicación así como también las expectativas de éxito terapéutico deben ser tomadas con prudencia, ya que muchos de estos productos carecen de evidencia científica clínica en enfermedades capilares. En la siguiente revisión, se analizarán los mecanismos de acción y evidencia científica clínica de los principales productos capilares comercializados.

Insufficient growth and excessive hair loss are a common complaint in dermatologic consultation. In the past decades, a sustained research in hair follicle biology has prompted the development of many drugs that modify hair shaft and follicle biology, with promising results. However, their use as well as positive expectations have to be taken with caution, since many of them lack clinical evidence in hair diseases. In this paper, the mechanism of action and clinical evidence of the most common hair products available will be analyzed.

Variación estacional del tricograma en residentes chilenos / Seasonal variation of trichogram in Chilean subjects

Background: Human hair follicle experiments cyclical transformations throughout its life. These are rest (telogen phase), growth (anagen phase) and regression mediated by apoptosis (catagen). During summer the percentage of telogen increases and the percentage of anagen decreases. Aim: To determine the seasonal changes of scalp hair follicle phases among Chilean subjects. Material and methods: Retrospective analysis of 514 differential trichograms of normal scalps from subjects aged 36±14 years, obtained between 1998 and 2008. Results: During summer and winter, the mean percentage of telogen was 20 percent±10 percent and 16 percent±10 percent, respectively (p <0.01). The figures for anagen in the same periods were 80 percent±10 percent and 83 percent±10 percent, respectively. Conclusions: This study confirms the presence of seasonal variations in normal trichogram.

Hair transplantation: standard guidelines of care.

Hair transplantation is a surgical method of hair restoration. PHYSICIAN QUALIFICATION: The physician performing hair transplantation should have completed post graduation training in dermatology; he should have adequate background training in dermatosurgery at a centre that provides education training in cutaneous surgery. In addition, he should obtain specific hair transplantation training or experience at the surgical table(hands on) under the supervision of an appropriately trained and experienced hair transplant surgeon. In addition to the surgical technique, training should include instruction in local anesthesia and emergency resuscitation and care. FACILITY: Hair transplantation can be performed safely in an outpatient day case dermatosurgical facility. The day case theatre should be equipped with facilities for monitoring and handling emergencies. A plan for handling emergencies should be in place and all nursing staff should be familiar with the emergency plan. It is preferable, but not mandatory to have a standby anesthetist. Indication for hair transplantation is pattern hair loss in males and also in females. In female pattern hair loss, investigations to rule out any underlying cause for hair loss such as anemia and thyroid deficiency should be carried out. Hair transplantation can also be performed in selected cases of scarring alopecia, eyebrows and eye lashes, by experienced surgeons. PREOPERATIVE COUNSELING AND INFORMED CONSENT: Detailed consent form listing details about the procedure and possible complications should be signed by the patient. The consent form should specifically state the limitations of the procedure and if more procedures are needed for proper results, it should be clearly mentioned. Patient should be provided with adequate opportunity to seek information through brochures, computer presentations, and personal discussions. Need for concomitant medical therapy should be emphasized. Patients should understand that proper hair growth can be expected after about 9 months after transplantation. Preoperative laboratory studies to be performed include Hb%, blood counts including platelet count, bleeding and clotting time (or prothrombin time and activated partial thromboplastin time), blood chemistry profile including sugar. METHODS: Follicular unit hair transplantation is the gold standard method of hair transplantation; it preserves the natural architecture of the hair units and gives natural results. Mini-micro-grafting is a method hair transplantation involving randomly assorted groups of hairs, with out consideration of their natural configuration of follicular units, under loupe or naked eye examination. Mini-grafts consist of 4-5-6 hairs while micro-grafts consist of 1-3 hairs. Punch gives ugly cosmetically unacceptable results and should no longer be used. PATIENT SELECTION: Hair transplantation can be performed in any person with pattern hair loss, with good donor area, in good general health and reasonable expectations. Caution should be exercised in, very young patients whose early alopecia is still evolving, patients with Norwood grade VI or VII with poor density, patients with unrealistic expectations, and patients with significant systemic health problems. MEDICAL THERAPY: Most patients will need concurrent medical treatment since the process of pattern hair loss is progressive and may affect the remaining hairs. MANPOWER: Hair transplantation is a team effort. Particularly, performing large sessions, needs a well trained team of trained assistants. ANESTHESIA: 2% lignocaine with adrenaline is generally used for anesthesia; tumescent technique is preferred. Bupivacaine has been used by some authors in view of its prolonged duration of action. DONOR DISSECTION: Strip dissection by single blade is recommended for donor area. Steromicroscopic dissection is recommended for dissection of hair units in follicular unit transplantation; mini-micro-grafting does not need microscopic dissection. RECIPIENT INSERTION: Different techniques and different instruments have been used for recipient site creation ;these depend on the choice of the operating surgeon and have been described in the guidelines. Graft preservation is important to ensure survival. DENSITY: Minimum density of 35-45 units per sq cm is recommended. Results depend on donor characteristics, technique used and individual skills of the surgeon.

Histomorphometric study of skin in the sheep fetus

Histogenesis and histomorphometric studies of skin from regions of the face, neck, shoulder and fore-limb were carried out on 75 healthy sheep fetuses, which were collected from Urmia slaughter-house. After measurement of the crown-rump [CR] for determining the age of fetuses, tissue specimens were collected and fixed in 10% buffer formal saline, processed and sectioned into 5-7 micro m thick layers. The sections were stained with H and E method and observed by graduated objective lens. To study the reticular, elastic and collagen fibers and mast cells, appropriate staining methods such as PAS, Verhoeff, Van Gesson and toluidin blue were used, respectively. This study showed that the differentiation of epidermis begins from the end of the second month and rate of epidermal growth in the hind-limb was more than that in other regions studied. Melanocytes appeared in 61-65 days of fetal period in epidermis. The hair follicles were seen as cell accumulations in epidermis that protruded toward dermis in the first half of the third month. The hair follicles growth rate was found to be more in the hind-limb and less in shoulder than that in the other regions studied. Sebaceous and sweat glands appeared from the second half of the third month. They quickly increased in the first half of the fourth month in all studied regions. The sweat glands growth rate on the hind-limb was more than the other sites. The growth of sebaceous glands in shoulder continued till the fifth month. The relationship between thickness of epidermis and its cell layer numbers in all areas were significant [P<0.05] and their correlation coefficient [r = 0.78] in the hind-limb was more than that observed in other regions studied. Collagen fibers appeared during 65-75 days of fetal life, and their accumulation in deep regions of dermis [90-95 days] caused differentiation of dermis to papillary and reticular layers. Reticular and elastic fibers appeared during 55-60 and 70-75 days of fetal life, respectively. Mast cells were scattered in deep regions of dermis in fifth month of fetal period

Tricologia / Tricology

A queda de cabelos ou alopécia possui muitas causas e pode surgir em qualquer momento da vida. É um assunto de extrema importância médica e social, já que podemos diagnosticar doenças sistêmicas a partir dessa queixa e, dependendo da extensäo do quadro clínico pode desencandear alteraçöes na vida social e profissional do paciente. Nesse artigo, os autores fazem uma revisäo das principais apresentaçöes clínicas, diagnóstico e avanços no tratamento das alopécias.