Effect of PACAP on sweat secretion by immortalized human sweat gland cells

The process of sweating plays an important role in the human body, including thermoregulation and maintenance of the environment and health of the skin. It is known that the conditions of hyperhidrosis and anhidrosis are caused by abnormalities in sweat secretion and can result in severe skin conditions such as pruritus and erythema, which significantly reduce the patient's quality of life. However, there are many aspects of the signaling mechanisms in the process of sweating that have not been clarified, and no effective therapies or therapeutic agents have yet been discovered. Previously, it was reported that pituitary adenylate cyclase-activating polypeptide (PACAP) promotes sweating, but details of the underlying mechanism has not been clarified. We used immortalized human eccrine gland cells (NCL-SG3 cell) to investigate how sweat secretion is induced by PACAP. Intracellular Ca²⁺ levels were increased in these cells following their exposure to physiological concentrations of PACAP. Intracellular Ca²⁺ was not elevated when cells were concomitantly treated with PA-8, a specific PAC1-R antagonist, suggesting that PAC1-R is involved in the elevation of intracellular Ca²⁺ levels in response to PACAP treatment. Furthermore, immunocytochemistry experiments showed that aquaporin-5 was translocated from the cytoplasm to the cell membrane by PACAP. These results suggest that PACAP acts on eccrine sweat glands to promote sweat secretion by translocation of aquaporin-5 to the cell membrane in response to increased levels of intracellular Ca²⁺. These findings also provide a solid basis for future research initiatives to develop new therapies to treat sweating disorders.

Sweat Gland Organoids Originating from Reprogrammed Epidermal Keratinocytes Functionally Recapitulated Damaged Skin

Restoration of sweat glands (SwGs) represents a great issue in patients with extensive skin defects. Recent methods combining organoid technology with cell fate reprogramming hold promise for developing new regenerative methods for SwG regeneration. Here, a practical strategy for engineering functional human SwGs in vitro and in vivo is provided. First, by forced expression of the ectodysplasin-A in human epidermal keratinocytes (HEKs) combined with specific SwG culture medium, HEKs are efficiently converted into SwG cells (iSwGCs). The iSwGCs show typical morphology, gene expression pattern, and functions resembling human primary SwG cells. Second, by culturing the iSwGCs in a special 3D culturing system, SwG organoids (iSwGOs) that exhibit structural and biological features characteristic of native SwGs are obtained. Finally, these iSwGOs are successfully transplanted into a mouse skin damage model and they develop into fully functioning SwGs in vivo. Regeneration of functional SwG organoids from reprogrammed HEKs highlights the great translational potential for personalized SwG regeneration in patients with large skin defects.

TNF-α suppresses sweat gland differentiation of MSCs by reducing FTO-mediated m6A-demethylation of Nanog mRNA

An effect of inhibition of tumor necrosis factor-α (TNF-α) on differentiation of mesenchymal stromal cells (MSCs) has been demonstrated, but the exact mechanisms that govern MSCs differentiation remain to be further elucidated. Here, we show that TNF-α inhibits the differentiation of MSCs to sweat glands in a specific sweat gland-inducing environment, accompanied with reduced expression of Nanog, a core pluripotency factor. We elucidated that fat mass and obesity-associated protein (FTO)-mediated m⁶A demethylation is involved in the regulation of MSCs differentiation potential. Exposure of MSCs to TNF-α reduced expression of FTO, which demethylated Nanog mRNA. Reduced expression of FTO increased Nanog mRNA methylation, decreased Nanog mRNA and protein expression, and significantly inhibited MSCs capacity for differentiation to sweat gland cells. Our finding is the first to elucidate the functional importance of m⁶A modification in MSCs, providing new insights that the microenvironment can regulate the multipotency of MSCs at the post-transcriptional level. Moreover, to maintain differentiation capacity of MSCs by regulating m⁶A modification suggested a novel potential therapeutic target for stem cell-mediated regenerative medicine.

Enhancing glucose flux into sweat by increasing paracellular permeability of the sweat gland

Non-invasive wearable biosensors provide real-time, continuous, and actionable health information. However, difficulties detecting diluted biomarkers in excreted biofluids limit practical applications. Most biomarkers of interest are transported paracellularly into excreted biofluids from biomarker-rich blood and interstitial fluid during normal modulation of cellular tight junctions. Calcium chelators are reversible tight junction modulators that have been shown to increase absorption across the intestinal epithelium. However, calcium chelators have not yet been shown to improve the extraction of biomarkers. Here we show that for glucose, a paracellularly transported biomarker, the flux into sweat can be increased by >10x using citrate, a calcium chelator, in combination with electroosmosis. Our results demonstrate a method of increasing glucose flux through the sweat gland epithelium, thereby increasing the concentration in sweat. Future work should examine if this method enhances flux for other paracellularly transported biomarkers to make it possible to detect more biomarkers with currently available biosensors.

Targeting ectodysplasin promotor by CRISPR/dCas9-effector effectively induces the reprogramming of human bone marrow-derived mesenchymal stem cells into sweat gland-like cells

BACKGROUND

Patients with a deep burn injury are characterized by losing the function of perspiration and being unable to regenerate the sweat glands. Because of their easy accession, multipotency, and lower immunogenicity, bone marrow-derived mesenchymal stem cells (BM-MSCs) represent as an ideal biological source for cell therapy. The aim of this study was to identify whether targeting the promotor of ectodysplasin (EDA) by CRISPR/dCas9-effector (dCas9-E) could induce the BM-MSCs to differentiate into sweat gland-like cells (SGCs).

METHODS

Activation of EDA transcription in BM-MSCs was attained by transfection of naive BM-MSCs with the lenti-CRISPR/dCas9-effector and single-guide RNAs (sgRNAs). The impact of dCas9-E BM-MSCs on the formation of SGCs and repair of burn injury was identified and evaluated both in vitro and in a mouse model.

RESULTS

After transfection with sgRNA-guided dCas9-E, the BM-MSCs acquired significantly higher transcription and expression of EDA by doxycycline (Dox) induction. Intriguingly, the specific markers (CEA, CK7, CK14, and CK19) of sweat glands were also positive in the transfected BM-MSCs, suggesting that EDA plays a critical role in promoting BM-MSC differentiation into sweat glands. Furthermore, when the dCas9-E BM-MSCs with Dox induction were implanted into a wound in a laboratory animal model, iodine-starch perspiration tests revealed that the treated paws were positive for perspiration, while the paws treated with saline showed a negative manifestation. For the regulatory mechanism, the expression of downstream genes of NF-κB (Shh and cyclin D1) was also enhanced accordingly.

CONCLUSIONS

These results suggest that EDA is a pivotal factor for sweat gland regeneration from BM-MSCs and may also offer a new approach for destroyed sweat glands and extensive deep burns.

A novel organotypic 3D sweat gland model with physiological functionality

Dysregulated human eccrine sweat glands can negatively impact the quality-of-life of people suffering from disorders like hyperhidrosis. Inability of sweating can even result in serious health effects in humans affected by anhidrosis. The underlying mechanisms must be elucidated and a reliable in vitro test system for drug screening must be developed. Here we describe a novel organotypic three-dimensional (3D) sweat gland model made of primary human eccrine sweat gland cells. Initial experiments revealed that eccrine sweat gland cells in a two-dimensional (2D) culture lose typical physiological markers. To resemble the in vivo situation as close as possible, we applied the hanging drop cultivation technology regaining most of the markers when cultured in its natural spherical environment. To compare the organotypic 3D sweat gland model versus human sweat glands in vivo, we compared markers relevant for the eccrine sweat gland using transcriptomic and proteomic analysis. Comparing the marker profile, a high in vitro-in vivo correlation was shown. Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5), muscarinic acetylcholine receptor M3 (CHRM3), Na⁺-K⁺-Cl^- cotransporter 1 (NKCC1), calcium-activated chloride channel anoctamin-1 (ANO1/TMEM16A), and aquaporin-5 (AQP5) are found at significant expression levels in the 3D model. Moreover, cholinergic stimulation with acetylcholine or pilocarpine leads to calcium influx monitored in a calcium flux assay. Cholinergic stimulation cannot be achieved with the sweat gland cell line NCL-SG3 used as a sweat gland model system. Our results show clear benefits of the organotypic 3D sweat gland model versus 2D cultures in terms of the expression of essential eccrine sweat gland key regulators and in the physiological response to stimulation. Taken together, this novel organotypic 3D sweat gland model shows a good in vitro-in vivo correlation and is an appropriate alternative for screening of potential bioactives regulating the sweat mechanism.

Three-dimensional cell shapes and arrangements in human sweat glands as revealed by whole-mount immunostaining

Because sweat secretion is facilitated by mechanical contraction of sweat gland structures, understanding their structure-function relationship could lead to more effective treatments for patients with sweat gland disorders such as heat stroke. Conventional histological studies have shown that sweat glands are three-dimensionally coiled tubular structures consisting of ducts and secretory portions, although their detailed structural anatomy remains unclear. To better understand the details of the three-dimensional (3D) coiled structures of sweat glands, a whole-mount staining method was employed to visualize 3D coiled gland structures with sweat gland markers for ductal luminal, ductal basal, secretory luminal, and myoepithelial cells. Imaging the 3D coiled gland structures demonstrated that the ducts and secretory portions were comprised of distinct tubular structures. Ductal tubules were occasionally bent, while secretory tubules were frequently bent and formed a self-entangled coiled structure. Whole-mount staining of complex coiled gland structures also revealed the detailed 3D cellular arrangements in the individual sweat gland compartments. Ducts were composed of regularly arranged cuboidal shaped cells, while secretory portions were surrounded by myoepithelial cells longitudinally elongated along entangled secretory tubules. Whole-mount staining was also used to visualize the spatial arrangement of blood vessels and nerve fibers, both of which facilitate sweat secretion. The blood vessels ran longitudinally parallel to the sweat gland tubules, while nerve fibers wrapped around secretory tubules, but not ductal tubules. Taken together, whole-mount staining of sweat glands revealed the 3D cell shapes and arrangements of complex coiled gland structures and provides insights into the mechanical contraction of coiled gland structures during sweat secretion.

[Effects of PRX-2 gene on the phenotype changes of epidermal stem cells differentiating into sweat gland cells]

OBJECTIVE

To investigate the effects of PRX-2 gene on phenotype changes in epidermal stem cells differentiating into sweat gland cells.

METHODS

Epidermal stem cells and sweat gland cells separated and cultured from healthy foreskin and adult full-thick skin respectively, were identified by immunofluorescence staining. Lentiviral vector-mediated overexpression and knockdown of PRX-2 gene in epidermal stem cells were performed respectively,with empty vector-mediated epidermal stem cells as a control group. Overexpression blank control and know down group's PRX-2 expressions in gene and protein levels were detected using RT-PCR and Western blot technology. The ESCs of each group were co-cultured with sweat gland cells through transwell plate, and the expressions of CEA and β1 integrin in epidermal stem cells were determined by flow cytometry before and after co-culturing.

RESULTS

Epidermal stem cells and sweat gland cells were in line with their respective specific antigens .Before co-cultured, epidermal stem cells highly expressed β1 integrin (98.69 ± 0.67)％,hardly expressed CEA (6.20 ± 3.15)％.After co-cultured,β1 integrin expression levels were showed as knockdown group (19.30 ± 0.53) ％ ＜blank control group (65.77 ± 2.32)％ ＜ overexpress group (92.63 ± 10.97)％,and CEA expression levels as knockdown (95.43 ±2.36)％ ＞ blank control group (51.20 ±0.79)％ ＞ overexpress group (45.91 ±0.93)％.There had significant differences between those of each two groups.

CONCLUSIONS

PRX-2 gene can inhibit the phenotypic change of Epidermal Stem Cells differentiating into Sweat Gland Cells and improve the ability to maintain their own specific antigens.

[PHENOTYPIC CHANGES OF EPIDERMAL STEM CELLS DIFFERENTIATING INTO SWEAT GLANDS CELLS IN VITRO AND ITS MECHANISM]

OBJECTIVE

To explore the phenotypic changes of epidermal stem cells (ESCs) differentiating into sweat glands cells (SGCs) in vitro and its mechanisms.

METHODS

ESCs and SGCs were isolated and cultured in vitro, which were identified using immunofluorescence staining. ESCs at passage 2 were divided into 4 groups: ESCs and SGCs co-cultured by Transwell plates in group A, ESCs cultured by simply adding sweat supernatant in group B, ESCs and SGCs co-cultured on Transwell plate adding epidermal growth factor (EGF) (60 ng/mL) in group C, and ESCs and SGCs co-cultured on transwell plate adding PD98059 (10 mmol/L) in group D. The inverted microscope was used for observing the morphology of ESCs, flow cytometry for detecting ESCs positive phenotype, and Western blot for exploring mitogen-activated protein kinase/extracellular signal regulated kinase (MAPK/ERK) pathway.

RESULTS

The morphology observation and immunofluorescence staining suggested that cultured cells were ESCs and SGCs. The inverted phase contrast microscope observation showed that cells had similar morphological changes, with flat polygonal shape at 9 days in groups A, C, and D; cells had slow morphological change in group B, and had similar change to that of other groups at 12 days. Significant decreasing of beta1-integrin expression and increasing of carcino-embryonic antigen (CEA) expression of ESCs were observed in group A when compared with group B, which was inhibited by EGF (group C) and enhanced by PD98059 (group D), and there were significant differences among groups A, C, and D (P<0.05). High level of ERK expression was displayed in 4 groups, but it was significantly lower in group B than the other 3 groups (P<0.05). The expression of phosphorylation ERK was the highest in group A and was the lowest in group C, showing significant difference among 4 groups (P<0.05).

CONCLUSION

ESCs can be induced to differentiate into SGCs with the phenotypic changes under the condition of co-cultured by Transwell plates. The MAPK/ERK pathway plays a key role in the diffrentation of ESCs into GCCs

Role of Keratinocyte Growth Factor in the Differentiation of Sweat Gland-Like Cells From Human Umbilical Cord-Derived Mesenchymal Stem Cells

The role of keratinocyte growth factor (KGF) in human umbilical cord-derived mesenchymal stem cell (hUC-MSC) differentiation remains unknown. Building on previous work, the authors found KGF expression in sweat gland-like cells (SGCs) and determined that recombinant human KGF could induce hUC-MSC differentiation into SGCs. These differentiated SGCs were applied to a mouse burn model and sweat glands were regenerated. These cells may have potential therapeutic application for regeneration of destroyed sweat glands and injured skin.

Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) have higher proliferation potency and lower immune resistance than human bone marrow MSCs and can differentiate into various functional cells. Many regulatory factors, including keratinocyte growth factor (KGF), are involved in the development of skin and cutaneous appendages. Although KGF is important in wound healing, the role of KGF in hUC-MSC differentiation remains unknown. In our previous work, we found the mixing medium (nine parts of basic sweat-gland [SG] medium plus one part of conditioned heat-shock SG medium) could induce hUC-MSC differentiation to sweat gland-like cells (SGCs). In this study, we further improved the inducing medium and determined the effects of KGF in hUC-MSC differentiation. We found KGF expression in the SGCs and that recombinant human KGF could induce hUC-MSC differentiation into SGCs, suggesting KGF plays a pivotal role in promoting hUC-MSC differentiation to SGCs. Furthermore, the SGCs differentiated from hUC-MSCs were applied to severely burned skin of the paw of an in vivo severe combined immunodeficiency mouse burn model. Burned paws treated with SGCs could regenerate functional sparse SGs 21 days after treatment; the untreated control paws could not. Collectively, these results demonstrated that KGF is a critical growth factor for SGC differentiation from hUC-MSCs and the differentiated SGCs from hUC-MSCs may have a potential therapeutic application for regeneration of destroyed SGs and injured skin.

Significance

There is growing evidence demonstrating a potential therapeutic application of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) in injured skin. In the current study, conditioned media and chemically defined media with recombinant human keratinocyte growth factor (KGF) could induce hUC-MSC differentiation into sweat gland-like cells (SGCs). Moreover, the differentiated SGCs from hUC-MSCs could regenerate functional sparse sweat glands in a mouse burn model, which provides further insight into the mechanisms of the role of KGF and a potential therapeutic application of differentiated SGCs for regeneration of destroyed sweat glands and injured skin.

[microRNA-203 INDUCING DIFFERENTIATION OF HUMAN EPIDERMAL STEM CELLS INTO SWEAT GLAND CELLS IN VITRO]

OBJECTIVE

To observe the possibility and mechanism of microRNA (miRNA)-203 inducing the human epidermal stem cells to differentiate into sweat gland cells.

METHODS

Five normal human foreskin tissues were harvested to prepare a single cell suspension by 0.25% trypsin-EDTA digestion method, then the human epidermal stem cells were isolated and cultured by type IV collagen differential adherent method. The cell morphology was observed by inverted phase contrast microscope. The monoclonal antibodies of integrin β1 (ITGB1), cytokeratin19 (CK19), CK1, CK10, CK18, and carcinoembryonic antigen (CEA) were used for identification by immunocytochemical staining. Double stranded mimics of has-miR-203 were transfected into the human epidermal stem cells with Lipofectamine 2000 (experimental group) and the human epidermal stem cells transfected with nonsense miRNA mimics served as control group. The monoclonal antibodies of ITGB1, CK19, CK1, CK10, CK18, and CEA were used for identifying the cells after transfection by immunocytochemical staining; the mRNA relative expressions of miRNA-203, P63, ITGB1, CK19, CK1, CK1O, CK18, and CEA were detected by real-time fluorescence quantitative RT-PCR before transfected and at 72 hours after transfected. The protein relative expressions of P63, ITGB1, CK19, CK1, CK10, CK18, and CEA were detected by Western blot. The mRNA expression of miRNA-203 and the mRNA and protein expressions of P63 were analyzed respectively with Pearson correlation.

RESULTS

The CK19 and ITGB1 were positively expressed before transfection, but CK1, CK10, CK18, and CEA were expressed positively after transfection. The mRNA relative expression of miRNA-203 after transfection in experimental group was significantly higher than that before transfection (P < 0.05). The mRNA and protein relative expressions of CK1, CK10, CK18, and CEA after transfection in experimental group were significantly higher than those before transfection and control group (P < 0.05), while the mRNA and protein relative expressions of P63, CK19, and ITGB1 were significantly lower than those before transfection and control group (P < 0.05). These indicators showed no significant difference between the control group and before transfection (P > 0.05). The expression level of miRNA-203 was negatively correlated with the mRNA and protein relative expressions of P63 before and after transfection, the correlation coefficients before transfection were -0.91 (t = 3.862, P = 0.042) and -0.96 (t = 5.971, P = 0.009) respectively; the correlation coefficients after transfection were -0.92 (t = 4.283, P = 0.031) and -0.95 (t = 5.842, P = 0.011) respectively.

CONCLUSION

miRNA-203 can induce epidermal stem cells to differentiate into sweat gland cells by targeting inhibition of P63 probably.

Latent heat loss and sweat gland histology of male goats in an equatorial semi-arid environment

The objective of this work was to quantify the heat loss by cutaneous evaporation of goats in an equatorial semi-arid environment. The latent heat loss from the body surfaces of these ten undefined breed goats was measured using a ventilated capsule in sun and shade and in the three body regions (neck, flank and hindquarters). Skin samples from these three regions were histologically analyzed to relate the quantity of sweat glands, the area of sweat glands and the epithelium thickness of each of these regions to the heat loss by cutaneous evaporation of the examined goats. The epithelium thickness that was measured varied significantly for body regions with different quantities and areas of sweat glands (P < 0.01). Among the body regions that were examined, the samples from the neck demonstrated the highest epithelium thickness (16.23 ± 0.13 μm). However, the samples of sweat glands from the flank had the biggest area (43330.51 ± 778.71 μm(2)) and quantity per square centimeter (390 ± 9 cm(-2)). After the animals were exposed to sun, the flanks lost the greatest amount of heat by cutaneous evaporation (73.03 ± 1.75 W m(-2)) and possessed the highest surface temperatures (39.47 ± 0.18°C). The histological characteristics may have influenced the heat loss by cutaneous evaporation that was observed in the flank region after the animals were exposed to sun.

Epimorphin-induced differentiation of human umbilical cord mesenchymal stem cells into sweat gland cells

OBJECTIVES

Mesenchymal stem cells (MSCs) have the potential for multi-directional differentiation and can be induced to differentiate into sweat gland cells under certain conditions. Epimorphin (EPM) plays an important role in the promotion of epithelial cell morphogenesis; however, its effect on sweat gland-cell differentiation of MSCs remains unknown. The purpose of this study was to investigate how EPM regulates sweat gland cell differentiation of human umbilical cord mesenchymal stem cells (hUCMSCs).

MATERIALS AND METHODS

hUCMSCs were labeled with 5-bromo-2-deoxyuridine (BrdU) before differentiation induction; were cultured in common culture medium, conditioned medium, or EPM-conditioned medium; and then induced to differentiate into sweat gland cells. Five days after induction, the expression rates of the sweat gland-cell antigens cytokeratin 14 (CK14), cytokeratin 19 (CK19), and carcinoembryonic antigen (CEA) in hUCMSCs were detected by flow cytometry, and the messenger ribonucleic acid (mRNA) and protein levels of CK14, CK19, and CEA were determined by reverse transcription polymerase chain reaction (RT-PCR) and western blot, respectively.

RESULTS

hUCMSCs can be induced to differentiate into sweat gland cells in conditioned medium, and expression of CEA was detected by immunofluorescence assay. Flow cytometry results showed that the expression rate of the sweat gland-cell antigens CK14, CK19, and CEA in the conditioned medium were significantly lower than that in the EPM conditioned medium (p < 0.05). RT-PCR and western blot results showed that the mRNA and protein levels of CK14, CK19, and CEA in the conditioned medium were all significantly lower than that in the EPM-conditioned medium (p < 0.01).

CONCLUSIONS

These results suggest that EPM can effectively induce the differentiation of hUCMSCs into sweat gland cells.

Lineage analysis of epidermal stem cells

Lineage tracing involves labeling cells to track their subsequent behavior within the normal tissue environment. The advent of genetic lineage tracing and cell proliferation assays, together with high resolution three-dimensional (3D) imaging and quantitative methods to infer cell behavior from lineage-tracing data, has transformed our understanding of murine epidermal stem and progenitor cells. Here, we review recent insights that reveal how a progenitor cell population maintains interfollicular epidermis, whereas stem cells, quiescent under homeostatic conditions, are mobilized in response to wounding. We discuss progress in understanding how the various stem cell populations of the hair follicle sustain this complex and highly dynamic structure, and recent analysis of stem cells in sweat and sebaceous glands. The extent to which insights from mouse studies can be applied to human epidermis is also considered.

Three-dimensional culture and identification of human eccrine sweat glands in matrigel basement membrane matrix

Interactions between the extracellular matrix (ECM) and epithelial cells are necessary for the proper organization and function of the epithelium. In the present study, we show that human eccrine sweat gland epithelial cells cultured in matrigel, a representation of ECM components, constitute a good model for studying three-dimensional reconstruction, wound repair and regeneration and differentiation of the human eccrine sweat gland. In matrigel, epithelial cells from the human eccrine sweat gland form tubular-like structures and then the tubular-like structures coil into sphere-like shapes that structurally resemble human eccrine sweat glands in vivo. One sphere-like shape can be linked to another sphere-like shape or to a cell monolayer via tubular-like structures. Hematoxylin and eosin staining has revealed that the tubular-like structures have a single layer or stratified epithelial cells located peripherally and a lumen at the center, similar to the secretory part or duct part, respectively, of the eccrine sweat gland in sections of skin tissue. Immunohistochemical analysis of the cultures has demonstrated that the cells express CK7, CK19, epithelial membrane antigen and actin. Thus, matrigel promotes the organization and differentiation of epithelial cells from the human eccrine sweat gland into eccrine sweat gland tissues.

[Expression of urea transporters in sweat gland tissue of normal subjects and uremic patients]

OBJECTIVE

To explore the expression of urea transporters (UTs) in the skin and sweat glands of normal subjects and patients with uremia.

METHODS

Abdominal skin biopsy samples of patients with uremia and normal patients and apocrine sweat gland tissue from patients with bromidrosis were examined for the expression of UTs using immunohistochemistry and fluorescence immunoassay for quantitative analysis.

RESULTS

Both UT-A1 and UT-B1 proteins were expressed in the skin basal cell layer, eccrine sweat gland and apocrine sweat gland tissues. In uremic patients, N-UT-A1 and UT-B1 expressions were significantly higher than those in the control (P<0.05) but C-UT-A1 expression was similar (P>0.05).

CONCLUSION

UTs are expressed in human skin basal cell layer, eccrine sweat gland and apocrine sweat gland tissues, and their expressions are upregulated in uremic patients.

Future application of hair follicle stem cells: capable in differentiation into sweat gland cells

BACKGROUND

Sweat glands (SGs) can not regenerate after complete destruction in the severe skin injury, so it is important to find a ideal stem cell source in order to regenerate functional SGs. Hair follicle stem cells (HFSCs) possess the obvious properties of the adult stem cells, which are multipotent and easily accessible. In this research, we attempted to direct the HFSCs suffered from the sweat gland cells (SGCs) special differentiation by a co-operative coculture system in vitro.

METHODS

The designed co-culture microenvironment in the transwell was consist of two critial factors: heat shocked SGCs and dermis-like mesenchymal tissue, which appeared independently in the two control groups; after induction, the purified induced SGC-like cells were transplanted into the full-thickness scalded wounds of the nude mice, after 4 weeks, the reconstructed SG-like structures were identified by immunohistochemical and immunofluorescence analysis.

RESULTS

A part of HFSCs in experimental group finally expressed SGCs phenotypes, by contrast, the control group 1 which just containing dermis-like mesenchymal tissue failed and the control group 2 consisted of heat shocked SGCs was in a poor efficiency; by immunofluorescence staining and flow cytometry analysis, the expression of HFSCs special biomarkers was down regulated, instead of the positive efficiency of SGCs special antigens increased; besides, the induced SGCs displayed a high expression of ectodysplasin A (EDA) and ectodysplasin A receptor (EDAR) genes and proteins; after cell transplantation, the youngest SG-like structures formed and be positive in SGCs special antigens, which never happened in untreated wounds (P < 0.05).

CONCLUSION

The HFSCs are multipotential and capable in differentiating into SGCs which promise a potential stem cells reservoir for future use; our special co-culture microenvironment is promising for HFSCs differentiating; the induced SGCs are functional and could work well in the regeneration of SGs.

[The rationale for the application of laserophoresis of biologically active compounds]

Laserophoresis is a technique for the transcutaneous administration of biologically active compounds by means of low-intensity laser radiation (LFLR). It is currently regarded as a most promising method for the integrated application of a pharmaceutical substance and a physical factor. At present laserophoresis of various medicinal preparations is successfully used after preliminary experimental studies of their phoretic properties for the treatment of various inflammatory and dystrophic conditions as well as for the prevention of skin ageing. The most important route for the administration of the majority of drug preparations is through the shunts provided by perspiratory glands and hair follicles. Another essential factor determining the potential possibility of drug penetration through the skin is the characteristic of the substance chosen for the administration, such as its molecular weight, chemical structure, conformation, and hydrophilic properties. However, the most likely mechanism underlying the transport of the substance through the glandular cells of perspiratory glands and epithelial cells of hair follicles is pinocytosis, i.e. the process integrating exocytosis and endocytosis. To-day, the majority of the researchers lay emphasis on thermodynamic triggering of Ca2+-dependent processes as the primary mechanism behind the biological action of low-intensity laser radiation. Both exocytosis and endocytosis being the Ca2+-dependent processes, the liberation of Ca2+-ions under the influence of LFLR causes the activation of pinocytosis as a whole.

Transplantation of human bone marrow-derived mesenchymal stem cells transfected with ectodysplasin for regeneration of sweat glands

BACKGROUND

Patients with severe full-thickness burn injury suffer from their inability to maintain body temperature through perspiration because the complete destructed sweat glands can not be regenerated. Bone marrow-derived mesenchymal stem cells (BM-MSCs) represent an ideal stem-cell source for cell therapy because of their easy purification and multipotency. In this study, we attempted to induce human BM-MSCs to differentiate into sweat gland cells for sweat gland regeneration through ectodysplasin (EDA) gene transfection.

METHODS

The dynamic expression of EDA and EDA receptor (EDAR) were firstly observed in the sweat gland formation during embryological development. After transfection with EDA expression vector, human BM-MSCs were transplanted into the injured areas of burn animal models. The regeneration of sweat glands was identified by perspiration test and immunohistochemical analysis.

RESULTS

Endogenous expression of EDA and EDAR correlated with sweat gland development in human fetal skin. After EDA transfection, BM-MSC acquired a sweat-gland-cell phenotype, evidenced by their expression of sweat gland markers by flow cytometry analysis. Immunohistochemical staining revealed a markedly contribution of EDA-transfected BM-MSCs to the regeneration of sweat glands in the scalded paws. Positive rate for perspiration test for the paws treated with EDA-transfected BM-MSCs was significantly higher than those treated with BM-MSCs or EDA expression vector (P < 0.05).

CONCLUSIONS

Our results confirmed the important role of EDA in the development of sweat gland. BM-MSCs transfected with EDA significantly improved the sweat-gland regeneration. This study suggests the potential application of EDA-modified MSCs for the repair and regeneration of injured skin and its appendages.

[Study on differentiation of human umbilical cord-derived mesenchymal stem cells into human sweat gland cells in vitro and the relative signal pathway]

OBJECTIVE

To study the differentiation potential of human umbilical cord-derived mesenchymal stem cells (UCMSC) into human sweat gland cells (hSGC) and the role of extracellular signal-regulated kinase (ERK) pathway.

METHODS

UCMSC and hSGC were isolated and cultured in vitro. The former was identified with expression of CD14, CD29, CD34, CD44, CD45, CD105, cytokeratin 7 (CK7), CK19, and carcinoembryonic antigen (CEA), while the latter was identified with expression of CK19 and CEA. UCMSC with density of 5 x 10(4) cells per well placed in lower compartment of Transwell chamber were divided into control group (C, cultured with nutrient solution without any stimulation), thermal injury group (TI, treated with heat-shocked hSGC with density of 1 x 10(4) cells per well inoculated into the upper compartment of Transwell chamber for indirect co-culture), thermal injury + EGF group (TIE, treated with indirect co-culture as used in TI group, with addition of 50 ng/mL EGF), thermal injury + PD98059 group (TIP, treated with indirect co-culture as used in TI group, with addition of 10 nmol/mL ERK specific inhibitor PD98059) according to the random number table. One week after culture, the positive expression rates of CK7 and CK19 in UCMSC were detected by flow cytometry, the expression of CK19 and CEA in UCMSC were examined with immunohistochemical staining and the positive expression rate of CEA was calculated, and the expression level of phosphorylated ERK (pERK) was determined by Western blotting. Data were processed with one-way analysis of variance.

RESULTS

(1) CD29, CD44, and CD105 were highly expressed in UCMSC, accompanied by low or negative expression of CD14, CD34, CD45, CK7, CK19, and CEA. The expression of CK19 and CEA were positive in hSGC. The two results showed that UCMSC and hSGC were pure. (2) Compared with those of C group [(2.2 +/- 1.5)%, (2.2 +/- 0.7)%, (3.3 +/- 0.7)%, 0.640 +/- 0.026], the expression levels of CK7, CK19, CEA, and pERK in UCSMC of TI group [(6.4 +/- 0.7)%, (5.7 +/- 0.3)%, (7.4 +/- 1.0)%, 0.790 +/- 0.049] and TIE group [(14.3 +/- 1.0)%, (12.6 +/- 1.1)%, (17.6 +/- 2.3)%, 1.200 +/- 0.032] were significantly increased (with F value respectively 78.49, 139.36, 87.13, and 191.74, P values all below 0.01), and those of TIE group were higher than those of TI group (with F value from 50.14 to 145.47, P values all below 0.01). There were no obvious difference in the 4 indexes between TIP group and C group (with F value from 0.00 to 0.13, P values all above 0.05).

CONCLUSIONS

UCMSC co-cultured with heat-shocked hSGC can differentiate into hSGC, and ERK signal pathway participates in the process of differentiation of UCMSC into hSGC.

Transglutaminases, involucrin, and loricrin as markers of epidermal differentiation in skin substitutes derived from human sweat gland cells

BACKGROUND/PURPOSE

In a multi-project research line, we are currently testing whether a morphologically and functionally near normal epidermis can be cultured from human sweat gland (SG) cells and be used as a skin substitute. The present study focuses on the stratum corneum of the epidermis that assumes a vital barrier function for the skin. The main process in the formation of the cornified cell envelope in human epidermis, i.e. crosslinking of proteins and lipids, is catalyzed by several transglutaminases (TG). Therefore, we compared the expression patterns of various TG and their substrates in SG-derived versus keratinocyte-derived epidermal substitutes.

METHODS

Sweat gland cells, keratinocytes, and fibroblasts were isolated from human skin samples and cultivated separately to generate epidermal substitutes. These were transplanted onto the back of athymic rats. After 2 weeks, the transplants were excised and analyzed histologically as well as by indirect immunofluorescence. We looked at the expression of TG1, 3, 5, and their substrates involucrin and loricrin (=markers of epidermal differentiation) in SG-derived and keratinocyte-derived skin substitutes as well as in normal skin.

RESULTS

The SG cell-derived epidermis was near normal anatomically, formed a cornified cell envelope and demonstrated TG1, 3, and 5 as well as involucrin and loricrin expression patterns similar to those found in keratinocyte-derived epidermis and normal control skin.

CONCLUSION

These findings support the thesis that SG cells have the potential to form a near normal stratified epidermal analog that might be used as a skin substitute. The expression of TG1 and 3, not normally expressed in human SG, suggests the presence of re-programmed SG cells and/or stem cells capable of both de novo generating and maintaining an epidermis.

[A new way for isolation and cultivation of sweat gland ductal cells from human split-thickness skin in vitro]

OBJECTIVE

To explore a new method of isolation and culture of eccrine sweat gland ductal cells from human split-thickness skin graft in vitro.

METHODS

Human split-thickness skin graft which was presented by volunteer (n = 10) was digested with type II collagenase, and then sweat gland duct were isolated from the split-thickness skin graft, primary cultures were incubated at 37 degrees C in humidified atmosphere of 5% CO2, 95% O2. The cultured eccrine sweat gland ductal cells were identified by analysis CEA, CK8, CK18, CK19 antigens expression with flow cytometry, RT-PCR and Western Blot, and by detecting the electrophysiology with whole cell patch clamp technology.

RESULTS

The isolated eccrine sweat gland ductal cells could grow by adhering to the wall, proliferate in vitro after 48 h of adhering to the wall, and confluens after 2 - 4 weeks of adhering to the wall. The FACs analysis showed the expression of CEA was (90.26 +/- 1.12)%, (89.70 +/- 1.43)%, and CK8 was (94.41 +/- 1.84)%, (93.65 +/- 1.63)% in primary cultured sweat gland ductal cells and primary cultured eccrine sweat gland cells, respectively, and there is no significant difference between the two groups (P > 0.05). Immunocytochemistry staining showed CEA, CK8, CK18, CK19 was positive in sweat gland duct cells, RT-PCR revealed that CEA, CK8, CK18 and CK19 gene expression in sweat gland ductal cells, and Western Blot analysis showed the expression of CEA brand, CK8 brand, CK18 brand, and CK19 brand in sweat gland ductal cells, patch clamp indicated that this cells has distinct amiloride sensitive Na(+) channels.

CONCLUSIONS

The cultured human eccrine sweat gland duct cells in vitro display the markers and biological characteristics of sweat gland epithelial lineage, and this method of digest the split-thickness skin graft to get the sweat gland duct cells is better than classical dissect sweat gland under dissect microscope.

[The changing pattern of stem cell markers of sweat gland in deep partial-thickness burn wound]

OBJECTIVE

To investigate the rules of proliferation of epithelial cells of sweat glands in deep partial-thickness burn wound and its transdifferentiation towards epidermal cells during healing process to explore its mechanisms.

METHODS

Twenty-eight patients with limbs and trunk burn hospitalized in the Fourth People's Hospital of Taizhou City of Jiangsu Province and the Second Hospital of Shandong University from January 2004 to December 2007 were enrolled in the study. Tissue samples of deep partial-thickness burn wound (DPBW, n = 37), superficial partial-thickness burn wound (SPBW, n = 21), and normal skin (NS, n = 10) were harvested. Expressions of cytokeratin 10 (CK10), bcl-2, P63, CK14 and CK19 of epithelial cells in glandular secretory portion (GSP) in DPBW, SPBW and NS were detected with immunohistochemical double staining method.

RESULTS

In NS, CK19, CK14 and CK10 expressed in medium intensity in GSP epithelial cells, P63 and CK14 weakly expressed in basal myoepithelial cells, while no expression of bcl-2 or P63 was observed in all CK10 positive terminally differentiated cells. In SPBW, no change of the construction of GSP and above-mentioned proteins during healing process was observed. In DPBW, as examined on 7(th) post burn day (PBD), expression of P63 and bcl-2 in GSP epithelial cells was enhanced. In DPBW on 8 - 10 PBD, bcl-2, P63, CK19 and CK14 strongly positive solid island-like epithelial structure was formed by proliferation, migration and squamous epithelization of basal cells. Such structure, along with granulation tissue, migrated towards the superficial layer of wounds. The hyperplasia of squamous epithelium resulted in complete reepithelialization. In DPBW, bcl-2, CK14, CK19 and P63 still strongly expressed in hyper-proliferative epidermal basal and suprabasal layers on 13 - 30 day after healing.

CONCLUSIONS

During the natural healing process of DPBW, monolayer epithelium (CK19 and CK10 positive) of GSP slowly develops into stratified squamous epithelium (bcl-2, P63, CK19, and CK14 positive), suggesting that the epithelial-epidermal transdifferentiation of GSP undergoes slow retrodifferentiation process of stem cells and transient amplifying cells, resulting in the imbalance between lagged growth of epithelium and the hyperplasia of granulation tissue, constituting one of the important mechanisms of disturbance in DPBW repair.

[Preliminary study on formation of eccrine sweat gland-like structure in three-dimensional cell culture]

OBJECTIVE

To explore a method to reconstruct eccrine sweat gland-like structure in vitro.

METHODS

Isolated from the normal axillary full-thickness skin donated by volunteers sweat gland epithelial cells were cultured in vitro and were observed under inverted phase contrast microscope. These cells at the density of 2 x 10(5)/cm2 were inoculated underneath the Matrigel (group A), on the top of the Matrigel (group B) and in the Matrigel (group C), respectively, for three-dimensional culture. The formation of eccrine sweat gland-like structure was observed by confocal laser scanning microscope, HE staining and immunohistochemistry staining.

RESULTS

Primary epithelial cells in the secretory portion of sweat gland were attached and spindle-shaped 24 hours after inoculation, and were under polyclonal grain-like growth 2-3 days thereafter. Cobblestone-like appearances of these cells were evident 14 days after inoculation and the confluent cells were flat and polygonal with relatively big round cell nucleus. Morphologically, subcultured cells at passage 1 were similar to the primary cells; cells at passage 2 were irregular and most of them had long pseudopodium; cells at passage 3 were star-shaped and big and had fusion with adjacent cells. For group A, tubular structure was formed 11 days after three-dimensional culture. For group B, stretched and filamentous-shaped cytoplasm was observed 8 hours after three-dimensional culture, with the formation of lumen or half-lumen structure, but no significant proliferation was evident. For group C, cell division and proliferation occurred 2-3 days after three-dimensional culture; the proliferated cells were closely arranged into tubular structure with obvious lacunae in the middle, which gradually developed into irregular ball-shaped structure with the increase of neonatal cells. The laser scanning confocal microscope observation showed the formation of spherical structure in group C, with tubular structure in the center of cell mass; HE staining testified the spherical structure in group C was tubular structure. The immunohistochemistry staining demonstrated keratin 18 and carcinoembryonic antigen were positively expressed in group C, which was similar to the tubular structure of secretory portion of sweat gland.

CONCLUSION

The sweat gland epithelial cells can be induced to form eccrine sweat gland-like structure through three-dimensional culture in Matrigel.

Dynamic analysis of internal and external mental sweating by optical coherence tomography

Mental sweating is human sweating that is accelerated via the sympathetic nerve by application of mental or physical stress. In the neurosciences, there is keen interest in this type of sweating, because the amount of sweat in response to a stress applied to a volunteer directly reflects activity of the sympathetic nerve. It is therefore of particular value that optical coherence tomography (OCT) can provide clear in vivo imaging of the spiral lumen of an eccrin sweat gland in the epidermis with a spatial resolution around 10 mum. We demonstrate dynamic OCT of mental sweating of an eccrin sweat gland on a human fingertip, where the sweating dynamics can be tracked by time-sequential OCT images with a frame spacing of one second. An instantaneous amount of sweat stored in the spiral lumen is evaluated quantitatively in each OCT image, resulting in time variation measurements of excess sweat in response to mental or physical stress. In the dynamic OCT of mental sweating, as demonstrated here, we note for the first time internal sweating without ejection of excess sweat from the spiral lumen to the skin surface. Internal sweating has not been previously detected without the availability of our dynamic OCT technique. Until now, it has been commonly accepted that sweating is always accompanied with ejection of excess sweat to the skin surface. On the basis of our findings reported here, this type of sweating should now be referred to as external sweating. In this study, we demonstrate that internal sweating occurs more often in the case where mental stress is applied to a volunteer, and that it is more useful for evaluation of activity of the sympathetic nerve. The dynamic OCT for both external and internal sweating is demonstrated.

Characterization of liver X receptor expression and function in human skin and the pilosebaceous unit

The nuclear receptors liver X receptor alpha (LXRalpha) and liver X-receptor beta (LXRbeta) have a well documented role in cholesterol homeostasis and lipid metabolism within tissues and cells including the liver, small intestine and macrophages. In keratinocytes, LXRs have been shown to up-regulate differentiation in vitro via increased transcription of proteins of the AP1 complex and to down-regulate proliferation in vivo. In this study, we provide a detailed description of the location and possible role of LXRs within human skin and its associated glands and appendages. Using RT-PCR, Western blotting and immunohistochemistry, we have demonstrated expression of LXRalpha and LXRbeta mRNA and proteins in whole human skin as well as within a range of primary and immortalized human cell lines derived from human skin, hair follicle and sebaceous glands. Furthermore, we have shown that synthetic LXR specific agonists GW683965 and TO901317 significantly inhibit cell proliferation in primary epidermal keratinocytes, immortalized N/TERT keratinocytes and the immortalized SZ95 sebocyte line, and significantly increase lipogenesis in SZ95 sebocytes. In addition, we showed that the synthetic agonist TO901317 significantly reduced hair growth, in vitro.

A preliminary study of the short circuit current (Isc) responses of sweat gland cells from normal and anhidrotic horses to purinergic and adrenergic agonists

The causal factors of equine anhidrosis have not yet been elucidated but defective electrolyte transport mechanisms in the gland are likely to be involved. To investigate this possibility, experiments were performed on cultured equine sweat gland epithelia from five free-sweating UK horses (3 intact males, 2 mares, aged 2-4 years) and from three free-sweating Singapore horses (1 intact male, 2 mares, aged 3-5 years) and three anhidrotic (Singapore) horses (1 intact male, 1 gelding, 1 mare, aged 3-6 years). Cultured cells from each animal were grown on permeable supports and loaded into Ussing chambers to quantify transepithelial resistance and agonist-induced electrolyte transport by the short circuit current (Isc) technique. Transepithelial resistances across the layers of cultured cells were not significantly different between cells from UK and Singapore free-sweating horses, but were significantly reduced in anhidrotic animals. Purinergic agonists added to the apical and basolateral aspects of the cultured cells caused similar increases in Isc between the two populations of unaffected cells, but Isc increases were significantly reduced in anhidrotic animals. Beta-adrenergic agonist stimulation of the anhidrotic cell layers failed to elicit any change in Isc. These pilot results not only confirm earlier conclusions from anatomical findings that failure in the secretory process occurs in anhidrosis but also indicate that both of the known ion transport mechanisms are involved. The trigger for these failures warrants further investigation.

Expression patterns of programmed cell death 4 protein in normal human skin and some representative skin lesions

Expression of a tumor suppressor gene, programmed cell death 4 (PDCD4), was investigated at the protein level in the human skin. Immunohistochemically, PDCD4 protein expressed mainly in suprabasal layers, while PDCD4-positive and -negative areas were observed discontinuously in the basal cell layer of the epidermis. In hair follicles, the suprabulbar area including the hair and inner root sheath was immunoreactive, while the bulbar area, containing germinative cells which were strongly proliferating cell nuclear antigen (PCNA)-positive, was not or less. PDCD4 therefore appears to be important in the differentiation of hair follicles. PDCD4-positive cells were localized in the inside layers while PCNA-positive cells were located in the basal layer in the outer root sheath of hair follicles. The cells of sebaceous glands and sweat glands also were PDCD4-positive. The PDCD4 protein was localized mostly in nuclei of cutaneous cells. PDCD4 expression was found to be suppressed in the epidermis overlying an adult T-cell lymphoma (ATL), possibly reflecting a paracrine effect of factors produced by ATL cells. PDCD4 expression was suppressed in the keratinocyte cell line HaCaT by exposure of cultures to epidermal growth factor, transforming growth factor-beta1 or hepatocyte growth factor. Immunohistochemically, various skin cancers tended to show less PDCD4 expression than normal skin. Promotion of expression might prove useful in preventing or treating certain skin cancers.

Potentiality of Mesenchymal Stem Cells in Regeneration of Sweat Glands

Sweat glands play some key roles in homeostasis maintenance and body temperature regulation. In full-thickness burn wounds, sweat glands cannot regenerate to form their three-dimensional organization via the division and terminal differentiation of sweat gland cells. However, the plasticity of mesenchymal stem cells (MSCs) may offer the hope and potentiality to regenerate sweat glands after severe burn injury.

[The involvement of ERK pathway in the cellular phenotype conversion in human mesenchymal stem cells cocultured with human sweat gland cells]

OBJECTIVE

To study the cellular phenotype conversion of human mesenchymal stem cells (MSCs) cocultured with human sweat gland cells (SGCs) and the contribution of extracellular signal-regulated kinase (ERK) pathway in the process.

METHODS

MSC and SGC were isolated, amplified , and identified with two-step immunohistochemistry method. The primary SGCs were heat-shocked at 47 degrees C. Then the supernatants were collected immediately and 24hr later. The 3rd passage of MSCs were divided into control, SGC supernatant (cells were cultured in DMEM/F12 medium containing 30% SGC supernatant), SGC supernatant + EGF (cells were cultured in DMEM/F12 medium containing 30% SGC supernatant and 50 microg/L EGF), and SGC supernatant + PD98059 (cells were cultured in DMEM/F12 medium containing 30% SGC supernatant and 10 micromol/L PD98059) groups. The positive expression of CK7and CEA in MSCs were detected on the 7th post-stimulation day (PSD) by flow cytometry. The expression of ERK and phosphorylated ERK were determined with Western blotting.

RESULTS

The positive expression rate of CK7 and CEA was (5.76 +/-0.10)%, (2.01 +/- 0.09)% in SGC supernatant group; (7.31 +/- 0.21)% and (7.27 +/- 0.12)% in SGC supernatant + EGF group; and (1.63 +/- 0.11)%, (1.54 +/- 0.07)% in SGC supernatant + PD98059 group; they were all obviously higher than that in control group (P < 0.01). Moreover, ERK expression was observed in all groups. The expression of pERK in SGC supernatant + EGF group was higher than that in SGC supernatant group, but almost no expression of pERK was found in the SGC supernatant + PD98059 and control groups.

CONCLUSION

Indirect coculture of MSCs with SGCs can induce the phenotype conversion of MSCs through ERK pathway.

Adult bone-marrow-derived mesenchymal stem cells contribute to wound healing of skin appendages

Adult bone-marrow-derived mesenchymal stem cells (MSCs) are well-established as having the capacity to differentiate into cells with mesodermal, ectodermal, and endodermal characteristics and can leave their niche to home toward and engraft within foreign tissues. To investigate whether adult MSCs contribute to the repair of skin appendages after injury, BrdU-labeled MSCs were co-cultured with heat-shocked confluent sweat gland cells (SGCs) in vitro and later intravenously injected into full-thickness skin wounds in rats. When adult MSCs were co-cultured with heat-shocked SGCs, a subset of adult MSCs differentiated into SGCs, the percentage of differentiation being enhanced by epidermal growth factor and the injured microenviroment, but weakened by PD98059. The ERK (extracellular signal-regulated kinase) pathway, especially pERK, was involved in the phenotype conversion of human MSCs into human SGC. Labeled MSCs were noted in hair follicles, sebaceous glands, blood vessels, and dermis in full-thickness wounds, and the incorporated cells in hair follicles and sebaceous glands were also positive for pan-cytokeratin. After wound healing, some labeled MSCs returned to the bone marrow, whereas other were retained in the dermis. We conclude that adult MSCs have the capacity to dock at specific sites, to contribute to wound healing of skin appendages, and to home toward marrow, and that engraftment of bone-marrow-derived cells is a functional event.

Ectodysplasin regulates the lymphotoxin-beta pathway for hair differentiation

Mutations in the EDA gene cause anhidrotic/hypohidrotic ectodermal dysplasia, a disorder characterized by defective formation of hair, sweat glands, and teeth in humans and in a mouse model, "Tabby" (Ta). The gene encodes ectodysplasin, a TNF ligand family member that activates the NF-kappaB-signaling pathway, but downstream targets and the mechanism of skin appendage formation have been only partially analyzed. Comparative transcription profiling of embryonic skin during hair follicle development in WT and Ta mice identified critical anhidrotic/hypohidrotic ectodermal dysplasia (EDA) effectors in four pathways, three already implicated in follicle formation. They included Shh and its effectors, as well as antagonists for the Wnt (Dkk4) and BMP (Sostdc1) pathways. The fourth pathway was unexpected, a variant NF-kappaB-signaling cascade based on lymphotoxin-beta (LTbeta)/RelB. Previously known to participate only in lymphoid organogenesis, LTbeta was enriched in developing hair follicles of WT but not in Ta mice. Furthermore, in mice lacking LTbeta, all three types of mouse hair were still formed, but all were structurally abnormal. Guard hairs became wavy and irregular, zigzag/auchen hairs lost their kinks, and in a phenocopy of features of Ta animals, the awl hairs doubled in number and were characteristically distorted and pinched. LTbeta-null mice that received WT bone marrow transplants maintained mutant hair phenotypes, consistent with autonomous LTbeta action in skin independent of its expression in lymphoid cells. Thus, as an EDA target, LTbeta regulates the form of hair in developing hair follicles; and when EDA is defective, failure of LTbeta activation can account for part of the Ta phenotype.

Histology of the sternal and suprapubic skin areas in lion tamarins (Leontopithecus sp. Callitrichidae–Primates)

Though knowledge regarding the biology and morphology of lion tamarins is scarce in the literature, it is very important for their conservation. This paper focuses on the anatomical and histological aspects of the glands involved in the scent-marking behavior of lion tamarins. It examines the histological aspects of sternal and suprapubic skin sections of specimens that were preserved in formaldehyde and were the property of the Rio de Janeiro Primatology Center Museum. Eighteen specimens from three lion tamarin (Leontopithecus sp.) species (L. rosalia, L. chrysomelas, and L. chrysopygus) were analyzed. Both sexes were represented, and macroscopic hypertrophy was quantified by direct observation of the tegument on the sternal area and classified as discrete, moderate, or accentuated for each specimen. The skin of both sexes had a high degree of histological resemblance to that of other primates, including humans. The epidermis presented stratified squamous keratinous epithelia, with a few cellular layers and dermis with cutaneous appendages (i.e., hair follicles and both sebaceous and sweat glands). The dermal papillae were short, and the sebaceous and apocrine sweat glands resembled those of humans. These glands were present in the dermis of the analyzed skin fragments of both sternal and suprapubic regions in great numbers. Furthermore, we were able to establish a relationship between the macroscopic appearance of the sternal tegument and the degree of microscopic gland hyperplasia.

[Cellular phenotype conversion induced by co-culture of human mesenchymal stem cells cocultured with human sweat gland cells]

OBJECTIVE

To investigate the cellular phenotype conversion during human mesenchymal stem cells (hMSCs) cocultured with injured human sweat gland cells (hSGCs) in vitro.

METHODS

HMSCs and hSGCs were isolated and cultured and expanded respectively. The antigens expression of hMSCs and hSGCs were detected by two-steps immunocytochemistry. HMSCs were labeled with BrdU. The hSGCs were heat-shocked at 47 degrees C for 40 min when they reached 70% confluency, then cooled for 1-2 h at 37 degrees C and (1 - 2) x 10(5) BrdU-labeled hMSCs were added before incubation for up to 2 weeks. The cocultures were observed by phase contrast microscopy and detected by double-staining immunocytochemistry using CEA and BrdU as primary antibodies.

RESULTS

The cultured hMSCs and hSGCs were clonogenic growth. HMSCs were positive for anti-CD44 and anti-CD105 staining and negative for anti-CD34 and anti-CEA staining. HSGCs express CK7, CK18, CK19 and CEA. The positive rate of BrdU labeled-hMSCs was 90%. The majority of hSGCs lost cell-cell contact after heat-shock. 2 weeks after cocultured, some cocultured cells were positive for both anti-CEA and anti-BrdU staining and some cocultures had more than two nuclei which stained with two different colors by double-staining immunocytochemistry. Statistic results showed 1%-5% of the hMSCs added to the coculture system were recovered as double-staining cells expressing BrdU and CEA while only 0.01%-0.05% cells stained with two different colors in nuclei. The multi-nucleated cells were wide and flatten.

CONCLUSION

HMSCs could differentiate into hSGCs in vitro under injured microenvironment. The mechanisms of which may be that hMSCs differentiate into hSGCs directly or by cell fusion, even nucleus fusion.

Sympathetic cholinergic target innervation requires GDNF family receptor GFRα2

Many cholinergic parasympathetic and enteric neurons require neurturin signaling through GDNF family receptor GFRalpha2 for target innervation. Since a distinct minority of sympathetic neurons are cholinergic, we examined whether GFRalpha2 is important for their development. We detected GFRalpha2 in neonatal sympathetic cholinergic neurons and neurturin mRNA in their target tissues, sweat glands in footpads, and periosteum. Lack of GFRalpha2 in mice did not affect the number of sympathetic cholinergic neurons, but their soma size was decreased in comparison to wild types. In adult and in 3-week-old GFRalpha2 knockout mice, the density of sympathetic cholinergic innervation was reduced by 50-70% in the sweat glands, and was completely absent in the periosteum. Sympathetic noradrenergic innervation of blood vessels in the footpads was unchanged. The density of sympathetic axons in sweat glands was unaffected at postnatal day P4 reflecting successful growth into the target area. Our results indicate that the cholinergic subpopulation of sympathetic neurons requires GFRalpha2 signaling for soma size and for growth or maintenance of target innervation. Thus, neurturin may be a general target-derived innervation factor for postganglionic cholinergic neurons in all parts of the autonomic nervous system.

Combined in vivo confocal Raman spectroscopy and confocal microscopy of human skin

In vivo confocal Raman spectroscopy is a noninvasive optical method to obtain detailed information about the molecular composition of the skin with high spatial resolution. In vivo confocal scanning laser microscopy is an imaging modality that provides optical sections of the skin without physically dissecting the tissue. A combination of both techniques in a single instrument is described. This combination allows the skin morphology to be visualized and (subsurface) structures in the skin to be targeted for Raman measurements. Novel results are presented that show detailed in vivo concentration profiles of water and of natural moisturizing factor for the stratum corneum that are directly related to the skin architecture by in vivo cross-sectional images of the skin. Targeting of skin structures is demonstrated by recording in vivo Raman spectra of sweat ducts and sebaceous glands in situ. In vivo measurements on dermal capillaries yielded high-quality Raman spectra of blood in a completely noninvasive manner. From the results of this exploratory study we conclude that the technique presented has great potential for fundamental skin research, pharmacology (percutaneous transport), clinical dermatology, and cosmetic research, as well as for noninvasive analysis of blood analytes, including glucose.

Keratin 16 expression defines a subset of epithelial cells during skin morphogenesis and the hair cycle

The morphogenesis of skin epithelia and adult hair follicle cycling both require integrated signaling between the epithelium and underlying mesenchyme. Because of their unique regulation, keratin intermediate filaments represent useful markers for the analysis of determination and differentiation processes in complex epithelia, such as the skin. In this study, we analyzed the distribution of mouse type I keratin 16 during skin morphogenesis, in the adult hair cycle, and in challenged epidermis. In mature hair follicles, we find keratin 16 along with its type II keratin partner keratin 6 in the companion layer of the outer root sheath during anagen and in the club hair sheath during catagen and telogen. During embryonic development, the distribution of keratin 16 is uncoupled from its presumed polymerization partner, keratin 6. Keratin 16 initially localizes within early hair germs, but rapidly shifts to a subset of cells at the interface of basal and suprabasal cells above and around the hair germ. The presence of keratin 16 at the transition between mitotically active and differentiating cells is recapitulated in primary keratinocytes cultured in vitro and in phorbol 12-myristate 13-acetate-treated back skin in vivo. We propose that keratin 16 marks cells in an intermediate state of cellular properties in which keratinocytes retain the flexibility required for activities such as cell migration and even mitosis but are resilient enough to provide the structural integrity required of the early suprabasal layers in the context of development, adult hair cycling, and wound repair.

Changes in mouse sudomotor function and sweat gland innervation with ageing

Age-related changes in sudomotor neuroeffector function have been evaluated in mice aged 2 (young), 6, 12 (adult) and 18 (old) months. We evaluated sudomotor function by determining the number of sweat glands reactive to pilocarpine and the sweat output per gland on the plantar surface of the hindpaws with the impression mould technique. Protein gene product 9.5 (PGP) and vasoactive intestinal polypeptide (VIP) were immunohistochemically localised in footpads. A marked decrease (44%) in sweat output per gland was observed in old mice as well as a slight (17%), not significant decline in the number of secreting sweat glands. The sudomotor innervation, expressed as the area of sweat gland occupied by VIP and PGP immunoreactive nerve profiles, showed an initial increase from 2 to 6 months and a significant decline (35%) in 18- vs. 6-month-old mice. These results indicate that, in contrast to the number of secreting sweat glands, sweat output per gland does not reach the maximum in adult mouse until 6 months old and that sweating decreases in aged mice mainly due to a decline of sweat output per gland and to a lesser extent to a decrease in number of secreting glands. A reduction of sweat glands size in aged mice was also found, suggesting that the diminished sweat gland responsiveness with ageing may be attributed to sweat gland atrophy as well as to loss of innervation.

Transcriptional regulators of steroidogenesis, DAX-1 and SF-1, are expressed in human skin

DAX-1 and SF-1 are members of the orphan nuclear receptor superfamily that are critical regulatory components of the hypothalamic-pituitary-adrenal-gonadal axis. In adrenal and gonadal tissues they regulate the expression of the cytochrome P450 steroid hydroxylase genes, key mediators of steroidogenesis. The identification of a number of steroid hydroxylases in human skin prompted us to investigate the presence of DAX-1 and SF-1. Immuno histochemical analysis of human skin revealed a distinctive staining pattern for DAX-1 and SF-1 in skin and its appendages. Prominent staining for DAX-1 was confined to the epidermis, sebaceous glands, sweat glands, and outer root sheath of the hair follicle with weaker expression in the inner root sheath, matrix cells, and dermal papilla cells. Similarly, SF-1 was also detected in the epidermis but displayed a scattered nuclear pattern across all layers. SF-1 immunoreactivity was also detected in the exocrine glands and was stronger than DAX-1 in the inner root sheath, matrix cells, and dermal papilla cells. Co-localization of DAX-1 and SF-1 was demonstrated by immunocytochemistry in the HaCaT keratinocyte cell line, primary keratinocytes, preadipocytes, and dermal papilla cells. Reverse transcriptase-polymerase chain reaction analysis demonstrated the expression of DAX-1 and SF-1 mRNA in whole human skin and Western analysis also confirmed the presence of DAX-1 protein in skin-derived cells. Our investigations demonstrate that two important regulators of steroidogeneisis are present in human skin and its appendages. These transcription factors may have a role in cutaneous steroidogenesis and thus be involved in hair follicle cycling or pathologies associated with steroids. Further studies are needed to determine the functional roles of DAX-1 and SF-1 in human skin.

Immunohistochemical analysis of cytokeratin expression in dog skin

The expression of cytokeratins and involucrin was analyzed to identify the skin cells which compose the epidermis of dogs. The distribution of cytokeratins and involucrin in normal dog skin was immunohistochemically examined with 27 commercial monoclonal antibodies for human use. Antibodies, No.4. OV-TL12/13, 35betaH11, 4.1.18, CAM5.2, NCL5D3, Ks.13.1, Ks.18.04, Ks.19.1, 170.2.]4 and Ks.20.8 stained hair follicles and/or the sweat gland duct, but not the epidermis. Antibodies, 34betaB4, AE3, 34betaE12. LP34, RCK102, MNF116, AE1, KLI, DE-K10 and DE-K13 reacted with every layer of the epidermis, hair follicles and the sweat gland duct. These results were similar to those reported in the human skin. No positive staining, however, could be detected in the epidermis, hair follicles and the sweat gland duct with commercial antibodies, 6B10, Ks.7.18, Mu146-uc, E3, RCK108 and involucrin. Therefore, immunohistochemical investigation with these commercial antibodies developed for human skin examination might be available for investigating the origin of skin tumors in dogs.

Nucleotide-evoked ion transport and [Ca(2+)](i) changes in normal and hyperhidrotic human sweat gland cells

Apical and basolateral application of ATP and UTP evoked [Ca(2+)](i) and short circuit current (Isc) increases in normal and hyperhidrotic human eccrine sweat gland cells grown into functionally polarised epithelia on permeable supports. Basolateral application to hyperhidrotic cells exhibited a markedly greater increase in Isc than in normal cells. Hyperhidrotic cells also demonstrated differences from the normal in [Ca(2+)](i) and Isc responses to ATP when pre-treated with thapsigargin. The data demonstrate the presence of apical and basolateral receptors that allow nucleotides to increase [Ca(2+)](i) and Isc. The results suggest that changes from the normal in transepithelial ion transport contribute to the characteristic excessive fluid production of hyperhidrotic sweat glands.

Immunocytochemical localisation of PTHrP (parathormone-related peptide) in myoepithelial cells of human sweat and parotid glands

PTHrP is a HHM-inducing peptide. It exhibits certain structural similarity to PTH and the two hormones may act through the same receptors. PTHrP is known to be produced in various tissues as well as during development. In this study we decided to immunocytochemically demonstrate PTHrP in normal skin and squamous cell carcinomas as well as in parotid glands (normal, inflamed and neoplastic). In the skin, PTHrP expression was demonstrated in epidermis and in smooth muscle cell layer of blood vessels. In squamous cell carcinomas, the expression was noted in foci of keratinization. In parotid glands, the peptide was localised in excretory ducts and in blood vessels, while inflammation of the gland and its tumours resulted most frequently in the less intense immunoreaction. The results are consistent with those of other authors. The novel observations include demonstration of PTHrP expression in myoepithelial cells of sweat glands and in parotid glands, where it may be involved in the control of their contractile activity.

Identification of calcium-activated potassium channels in cultured equine sweat gland epithelial cells

The patch-clamp recording technique was used to examine the properties of the K+ channels in cultured equine sweat gland epithelial cells. With symmetric K+ solutions (140 mM), a single population of K+ channels was identified with a slope conductance of 187 pS and a reversal potential of around 0 mV. The channel was selective for K+ over Na+. Channel activity was increased by membrane depolarization. A 10-fold increase in [Ca2+]i produced an approximate 60 mV negative shift in the open state probability (Popen)-voltage curve. Externally applied tetraethylammonium ions (TEA+) caused a rapid and flickery block of the channel and reduced the unitary current amplitude. TEA+ bound to the blocking site with stoichiometry of 1:1 and with a dissociation constant (Kd) of 186 +/- 27 microM at +40 mV. A weak voltage dependence of Kd was observed. Iberiotoxin (100 nM) reduced Popen but had no effect on single-channel conductance. Neither glibenclamide (10 microM) nor intracellular adenosine 5'-triphosphate (ATP, 1 mM) altered channel activity. In addition, ATP, when applied extracellularly, transiently activated the channel by increasing Popen. Channel activity was low around the resting membrane potential in the intact epithelia, indicating that these channels might not contribute to the resting K+ conductance. However, the channel could be activated in a regulated manner. The K+ channels may play a role in transepithelial fluid secretion in sweat gland.

The simultaneous measurement of epithelial ion transport and intracellular free Ca2+ in cultured equine sweat gland secretory epithelium

We explored the relationship between nucleotide-evoked changes in intracellular free calcium ([Ca2+]i) and anion secretion by measuring [Ca2+]i and I(SC) simultaneously in Fura-2-loaded, cultured equine sweat gland epithelia. Apical ATP, UTP or UDP elicited sustained increases in [Ca2+]i that were initiated by the mobilization of cytoplasmic Ca2+ but maintained by Ca2+ influx. However, although these nucleotides also increased I(SC), this response was transient whereas the [Ca2+]i signals were sustained. Experiments in which external Ca2+ was removed/replaced showed that Ca2+ entering nucleotide-stimulated cells elicited very little change in ISC. Cross desensitization experiments showed that UTP-stimulated epithelia became insensitive to ATP but that UTP could increase both [Ca2+]i and ISC in ATP-stimulated cells by activating 'pyrimidinoceptors' essentially insensitive to ATP. Thapsigargin evoked a sustained rise in [Ca2+]i that was accompanied by a maintained increase in ISC. However, this increase in ISC was dependent upon external Ca2+ and so the responses to nucleotides and thapsigargin have different properties. ATP increased ISC in thapsigargin-treated cells without causing any rise in [Ca2+]i while ionomycin increased both parameters. The data therefore show that apical P2Y receptors allow nucleotides to increase ISC via two mechanisms, one of which appears to be [Ca2+]i-independent control of anion channels.

Pyrimidine nucleotide-evoked inhibition of cyclic AMP accumulation in equine epithelial cells

Uridine triphosphate (UTP) evoked inhibition of adrenaline-evoked cAMP accumulation in cultured equine epithelial cells (EC50, 1.8 +/- 0.2 microM) and this effect was mimicked by 5-Br-UTP (EC50, 6.6 +/- 1.8 microM) and uridine diphosphate (UDP; EC50, 96 +/- 26 microM). This inhibitory action of UTP was abolished by pre-treating cells with pertussis toxin (10 ng ml-1, 24 h). UTP (EC50, 2.3 +/- 0.3 microM) and 5-Br-UTP (EC50, 29.4 +/- 9.4 microM) also increased intracellular free calcium ([Ca2+]i) whilst UDP did not; the two effects are thus differentially sensitive to these pyrimidine nucleotides. ATP evoked cAMP accumulation in control cells and this response was unaffected by pertussis toxin. There is, therefore, no indication that ATP activates the pertussis toxin-sensitive inhibitory pathway. The UTP-evoked inhibition of cAMP accumulation was abolished by isobutylmethylxanthine (IBMX, 5 mM) and so the negative control over cAMP levels appears to be mediated by receptors that are selectively activated by pyrimidine nucleotides and permit control over phosphodiesterase activity.

An immunohistochemical study of beta1,4-galactosyltransferase in human skin tissue

An immunohistochemical investigation of beta1,4-galactosyltransferase (beta1,4-GalT) on human skin tissue was performed on formalin-fixed paraffin-embedded sections using a monoclonal antibody, MAb8628, which specifically recognizes a protein moiety of human beta1,4-GalT. Distribution of the galactose beta1,4-N-acetylglucosamine (Gal beta1,4GlcNAc)-R epitope was also detected by staining with Ricinus communis agglutinin (RCA) 120. The beta1,4-GalT was observed to be localized at the perinuclear region of epidermal keratinocytes. The fine localization was also observed at the supranuclear region in the cells of apocrine glands, eccrine ducts and glands. The positive staining with RCA 120 was well colocalized with the cells expressing the beta1,4-GalT. An electron microscopic study revealed that positive signals of beta1,4-GalT definitely reside in the Golgi apparatus. No immunoreactivity was observed in any other intracellular structure or on the cell surface. These findings strongly indicated that the beta1,4-GalT is the major enzyme responsible for the Gal beta1,4GlcNAc-R epitope synthesis in human skin tissue.

Human sweat gland myoepithelial cells express a unique set of cytokeratins and reveal the potential for alternative epithelial and mesenchymal differentiation states in culture

We have characterized precisely the cytokeratin expression pattern of sweat gland myoepithelial cells and have identified conditions for propagating this cell type and modulating its differentiation in culture. Rare, unstratified epithelioid colonies were identified in cultures initiated from several specimens of full-thickness human skin. These cells divided rapidly in medium containing serum, epidermal growth factor (EGF), and hydrocortisone, and maintained a closely packed, epithelioid morphology when co-cultured with 3T3 feeder cells. Immunocytochemical and immunoblot analysis disclosed that the cells differed from keratinocytes in that they were E-cadherin-negative, vimentin-positive, and expressed an unusual set of cytokeratins, K5, K7, K14, and K17. When subcultured without feeder cells, they converted reversibly to a spindle morphology and ceased K5 and K14 expression. Under these conditions, EGF deprivation induced flattening, growth arrest, and expression of alpha-smooth muscle actin ((α)-sma). Coexpression of keratins and alpha-sma is a hallmark of myoepithelial cells, a constituent of secretory glands. Immunostaining of skin sections revealed that only sweat gland myoepithelial cells expressed the same pattern of keratins and alpha-sma and lack of E-cadherin as the cell type we had cultured. Interestingly, our immunocytochemical analysis of ndk, a skin-derived cell line of uncertain identity, suggests that this line is of myoepithelial origin. Earlier immunohistochemical studies by others had found myoepithelial cells to be K7-negative. We tested five K7-specific antibodies that can recognize this protein in western blots and in the assembled keratin filaments of mesothelial cells. Three of these antibodies did not recognize the K7 present in myoepithelial cell filaments or in HeLa cell filaments, indicating that some K7 epitopes are masked when K7 pairs with K17 instead of with its usual keratin filament partner, K19.

Detection of glycosidic residues in carpal glands of wild and domestic pig revealed by basic and lectin histochemistry

Carpal glands are compound tubuloalveolar glands, located on the medial surface of the carpus. This study was carried out on samples from carpal glands of adult wild and domestic pigs of both sexes. We elucidated the glycosidic composition of carpal gland secretion in situ using traditional histochemical methods and lectin histochemistry. Some secretory cells exhibited an intense reaction with PAS in both wild and domestic pigs. Lectin histochemistry showed differences in the localization and composition of glycoconjugates secreted by carpal glands. A cytoplasmic positivity was revealed in the wild pig by the sequence sialidase-PNA and WGA, whereas in the domestic pig the reactivity was localized at the apical surface of some cells. LTA positive cells were found only in the carpal glands of the domestic pig.

Morphological and ultrastructural study of carpal organ in adult female wild swine

The carpal organ of adult female wild swine is a sweat-type gland which secretes an odorous substance. The gland consists of 5-7 lobes, each made up of lobules with convoluted glandular tubules. The gland secretion is transported in large excretory canals which empty from 5 to 7 clearly visible pores. An ultrastructural examination showed that the glandular tubules are made up of single-layered epithelium with different types of cells. One type, with rather electron-dense cytoplasm, is secretory cells full of granular material which empties into the tubule lumen. A second cell type has a glycogen-rich, transparent cytoplasm. Its role appears to be secreting a watery, electrolyte-containing liquid. In the intermediate zone of the tubules, there is a third type of cell with transparent cytoplasm. Its ultrastructural characteristics seem to indicate that its function is to reabsorb the excess watery component. In the wall of the glandular tubules, outside the epithelium, there are myoepithelial cells which facilitate the movement of the secretions toward the collector canal.