Wnt signaling pathway is a complex protein interaction network, and its function can most commonly or often be seen in embryonic development and cancer treatments, and meanwhile it is also involved in normal physiological processes in adult animals. Recently, with the rapid development of skin tissue engineering, there have been more and more researches on signal pathway in skin wound healing. At present, it is known that Wnt signaling pathway plays a vital role in the epidermal stem cells, epidermal growth factors, hair follicle development and other important factors related to the epidermal repair. The systemic research on Wnt signaling pathway has important clinical significance in the demonstration and functional process of the skin tissue. In this paper, we review the research development of the Wnt signaling pathway in the epidermal repair process.
Epidermal Growth Factor ; metabolism ; Epidermis ; cytology ; injuries ; Humans ; Stem Cells ; cytology ; Wnt Signaling Pathway ; physiology ; Wound Healing ; physiology

Hair follicles reconstitute themselves though the hair cycle, suggesting the presence of stem cells. Slow-cycling cells were found in the bulge area and were considered as stem cells of the epidermis. Multiple studies have constantly demonstrated that bulge cells possess stem cell properties such as high proliferative capacity and multiple potencies to regenerate into not only hair follicles but also sebaceous glands and epidermis. Recently, the knowledge of the bulge cell biology is rapidly increasing along with the identification of novel cell surface markers, the ability to isolate living bulge cells, and the microarray analysis of multiple gene expression.
Biomarkers ; metabolism ; Cell Proliferation ; Epidermis ; cytology ; physiology ; Hair Follicle ; cytology ; physiology ; Humans ; Oligonucleotide Array Sequence Analysis ; Regeneration ; Sebaceous Glands ; physiology ; Stem Cells ; cytology ; physiology

Tight junction (TJ) is recognized as a second barrier of the skin. Altered expression of TJ proteins in various skin diseases characterized by the abnormal permeability barrier such as psoriasis suggests that TJ could be affected by stratum corneum (SC) barrier status. However, the physiological relationship between SC and TJ barrier remains to be investigated. Therefore, we examined the effect of SC barrier disruption on the expression of TJ proteins, claudin (Cldn)-1 and Cldn-4, and TJ barrier function in hairless mouse skin. We also investigated whether the alterations in epidermal Ca2+ affected TJ proteins expression in vivo. Repeated tape-stripping induced a sequential change of the expression and function of TJ. As early as 15-30 minutes after tape-stripping, downregulation of Cldn-1 and Cldn-4 immunoreactivity and protein level without change in mRNA level was found. This was accompanied by the abnormal leakage of lanthanum. However, by 1 hour Cldn-1 and Cldn-4 immunolocalization recovered along with normalized lanthanum permeation pattern. Moreover, the mRNA and protein levels of Cldn-1 and Cldn-4 were increased by 1 to 6 hours after tape-stripping. Inhibition of calcium loss by immersion of barrier-disrupted skin into a high Ca2+ solution prevented the dislocation of Cldn-1 and Cldn-4. Occlusion of barrier-disrupted skin delayed the restoration of Cldn-1 and Cldn-4. Our results suggest that the alteration of epidermal Ca2+ gradient caused by SC barrier perturbation affects the TJ structure and function and the faster recovery of TJ as compared to the SC barrier may imply the protective homeostatic mechanism of skin barrier.
Animals ; Calcium/*metabolism ; Claudin-1/genetics/*metabolism ; Claudin-4/genetics/*metabolism ; Epidermis/metabolism/*physiology ; Female ; Gene Expression Regulation ; Mice ; Mice, Hairless ; Permeability ; RNA, Messenger/metabolism ; Tight Junctions/metabolism/*physiology

Ceramides are the main lipids in the stratum corneum and are generated during cellular stress and apoptosis by de novo synthesis or by the action of sphingomyelinase. In addition, they are lipid second messengers produced by sphingolipid metabolism and trigger important cell responses, including protein kinase C-alpha (PKC-alpha) activation and the stimulation of signal transduction pathways with apoptosis and stress-activated protein kinases (SAPK), such as c-jun N-terminal kinase (JNK). Thus, ceramides have anti-proliferative and apoptotic effects. This study measured the changes in the levels of epidermal ceramides and ceramide-related apoptotic signaling molecules in psoriasis patients. Samples from lesional and non-lesional epidermis were obtained from psoriasis patients. Total ceramides were fractionated using thin-layer chromatography, and the levels of PKC-alpha and JNK expression were measured using Western blot analysis with specific antibodies. The ceramide level was reduced significantly, and this was associated with the downregulation of apoptotic signaling molecules, such as PKC-alpha and JNK, in the lesional epidermis of psoriasis patients. These results suggest that the decreased level of ceramides downregulates the apoptotic pathway, leading to epidermal proliferation in psoriasis.
Adult ; Apoptosis/physiology ; Blotting, Western ; Ceramides/*metabolism ; Chromatography, Thin Layer ; Epidermis/metabolism/pathology/physiopathology ; Female ; Humans ; JNK Mitogen-Activated Protein Kinases/metabolism ; Male ; Protein Kinase C-alpha/metabolism ; Psoriasis/metabolism/*pathology/physiopathology ; Severity of Illness Index ; Signal Transduction/*physiology

OBJECTIVETo study the relationship between the morphologic mechanism of human embryonic epidermic cells and mesenchymal-epithelial transformation (MET) and its modulation factor.

METHODSMorphological occurrence of epidermis was detected with histologic methods in earlier period [estimated gestational age (EGA) 6-14 weeks] human embryonic skin samples. At the same time, the characteristic expression and their distribution markers of mesenchymal cells [vimentin and alpha-smooth muscle actin (alpha-SMA)], embryonic specific epidermic protein CK8&18, specific protein of epidermic stem cell CK19, transforming growth factor-beta1) (TGF-beta1) and its receptor (TGFbetaRI) in embryonic epidermis were examined with immunohistochemistry and indirect-immunofluorescent doble-labelling method.

RESULTSDuring EAG 6-8 weeks, ectodermal cells containing Vim+/alpha-SMA(-) were found to transform into epidermal stem cells with CK8&18+/CK19+. In ectodermal cells, protein expression density of TGFbetaRI was moderate (+ +), while positive signal of TGFbeta1 was weak (+/-). After EGA10 weeks, epidermal cells showed typical morphological characteristics.

CONCLUSIONSAt EGA 6-8 weeks, human embryonic skin epidermal cells began to form through MET, in which the signal pathway mediated by TGFbetaRI might play important roles, but the role of TGFbeta1 need to be further studied.

Cell Differentiation ; physiology ; Epidermis ; cytology ; embryology ; Epithelial Cells ; cytology ; Humans ; In Vitro Techniques ; Mesoderm ; cytology ; Receptors, Transforming Growth Factor beta ; metabolism ; Transforming Growth Factor beta1 ; metabolism

OBJECTIVETo evaluate the effects of epicutaneous application of anticoagulant warfarin, by examining the presence of tissue injury and immune/inflammatory activity in exposed skin.

METHODSRats were exposed to warfarin by applying 10 μg of warfarin-sodium to 10-12 cm(2) skin (range 0.8-1 μg per 1 cm(2)) for 3 consecutive days. Tissue injury was evaluated by lipid peroxidation, histomorphological changes and signs of reparative activity in skin. T cell infiltration and selected aspects of epidermal cell activity were examined as indicators of immune/inflammatory skin response to warfarin application.

RESULTSRepeated warfarin application exerted no effect on skin metabolic viability, but resulted in tissue injury (increased malondialdehyde, MDA, production, evident histo-morphological changes in epidermis and dermis depicting cell injury and death). Increased numbers of proliferating cell nuclear antigen (PCNA(+)) cells indicated reparative processes in injured skin. Infiltration of CD3(+) cells (T lymphocytes) along with the increased production of tumor necrosis factor-a (TNF-a) by epidermal cells from warfarin-treated skin and their co-stimulatory effect in an in vitro T-cell activation assay demonstrated immunomodulatory effects of epicutaneous warfarin.

CONCLUSIONPresented data have documented tissue damage associated with immune/inflammatory activity in skin exposed to warfarin. Observed effects are relevant to immunotoxic potential of this anticoagulant in settings of external exposure.

Animals ; CD3 Complex ; genetics ; metabolism ; Dermatitis, Contact ; pathology ; Epidermis ; cytology ; Gene Expression Regulation ; physiology ; Inflammation ; metabolism ; Lipid Peroxidation ; Male ; Proliferating Cell Nuclear Antigen ; genetics ; metabolism ; Rats ; Rodenticides ; pharmacology ; Skin ; cytology ; drug effects ; metabolism ; T-Lymphocytes ; physiology ; Warfarin ; pharmacology

OBJECTIVETo investigate the effect of fetal bovine serum (FBS) on expression of pigment epithelium-derived factor (PEDF) in normal epidermal keratinocytes and dermal fibroblasts.

METHODSKeratinocytes and fibroblasts were incubated with 10% FBS. PEDF protein level in the cells was determined by immunofluorescence and Western blot.

RESULTSPEDF was localized mostly in the cytoplasm,while some in the nuclei. The distribution of PEDF in cytoplasm was in a granular pattern. 10% FBS increased the expression of PEDF both in keratinocytes and fibroblasts,but histamine and Phorbol 12-myristate 13-acetate (PMA) did not interfere the distribution of PEDF in cells.

CONCLUSION10% FBS can upregulate expression of PEDF in epidermal keratinocytes and dermal fibroblasts.

Animals ; Cattle ; Cells, Cultured ; Epidermis ; cytology ; metabolism ; Eye Proteins ; genetics ; metabolism ; Fetus ; Fibroblasts ; cytology ; metabolism ; Keratinocytes ; cytology ; metabolism ; Nerve Growth Factors ; genetics ; metabolism ; Serpins ; genetics ; metabolism ; Serum ; physiology ; Skin ; cytology ; metabolism ; Up-Regulation

To explore the role of dentritic epidermal T lymphocytes ( DETCs) in immune rejection of skin allograft in mice and its related mechanism. Methods (1) Full-thickness skin was harvested from back of one male wild type (WT) C57BL/6 mouse. Epithelial cells were isolated for detection of the expression of DETCs and their phenotype with flow cytometer. Another male WT C57BL/6 mouse was used to harvest full-thickness skin from the back. Epidermis was isolated for observation of the morphological characteristics of DETCs with immunofluorescence technology. (2) Four male green fluorescence protein (GFP)-marked C57BL/6 mice, 7 female WT C57BL/6 mice (group WT), and 7 female ybT lymphocytes 8 gene knock-out (GK) C57BL/6 mice (group GK) were used. Full-thickness skin in the size of 1.4 cm x 1.4 cm on the back of mice in groups WT and GK were excised, and the wounds were transplanted with full-thickness skin in the size of 1.2 cm x 1.2 cm obtained from male GFP-marked C57BL/6 mice. The survival time of skin grafts was affirmed with small animal in vivo imager and naked eyes and recorded. (3) Two male WT C57BL/6 mice were used to isolate epithelial cells. Cells were inoculated into 48-well plate and divided into activation group (A) and control group (C) according to the random number table, with 4 wells in each group. Cells in group A were treated with 10 pL concanavalin A in the concentration of 2 microg/mL for 24 hours, while those in group C with PBS in the same volume as that in group A. The expression of interferon y in DETCs was detected with flow cytometer. (4) Four male GFP-marked C57BL/6 mice were used as donors. Fourteen female WT C57BL/6 mice were used as receptors and divided into interferon gamma neutralizing group (IN) and control group (C) according to the random number table, with 7 mice in each group. The skin transplantation model of C57BL/6 male to C57BL/6 female was established as in part (2). Before surgery and 72 hours after, mice in group IN were intraperitoneally injected with 200 pL interferon y neutralizing antibody in the concentration of 1 mg/mL, and those in group C with normal saline in the same volume as that in group IN. The survival time of skin grafts was observed and recorded using the methods in part (2), and the result of group IN was compared with that of group GK in part (2). The survival curve of skin grafts was processed with Log-rank ( Mantel-Cox) test. Results (1) The positive expression rate of DETCs in epithelial cells of skin in mouse was 7.27%, and they were all CD3 cells. DETCs were found to be scattered in the epidermis of skin in mouse with dendritic morphology. (2) The survival time of skin grafts of mice in group GK was 22-35 d, obviously longer than that in group WT (12-16 d, y2 = 14. 10 , P < 0.001). (3) Expression of interferon gamma was detected in 22. 70% DETCs in group A, which was obviously higher than that in group C (0.51%). (4) The survival time of skin grafts of mice in group IN was 19-24 d, which was obviously longer than that in group C (12-16 d, chi 2 = 13.60, P < 0.001) but close to that in group GK as in part (2) (chi2 = 0.06, P = 0.810). Conclusions DETCs are involved in promotion of immune rejection of skin allograft probably by secretinf interferon gamma.
Allografts ; Animals ; Epidermis ; Female ; Graft Survival ; immunology ; physiology ; Interferon-gamma ; immunology ; metabolism ; Lymphocytes ; Male ; Mice ; Mice, Inbred C57BL ; Skin ; Skin Transplantation ; T-Lymphocytes ; immunology

This study was conducted to identify the effectiveness of platelet-rich plasma (PRP) and efficacy of intralesional injection as a method of application to acute cutaneous wounds in dogs. Healthy adult beagles (n = 3) were used in this study. Autologous PRP was separated from anticoagulant treated whole blood in three dogs. Cutaneous wounds were created and then treated by intralesional injection of PRP in the experimental group, while they were treated with saline in the control group on days 0, 2 and 4. The healing process was evaluated by gross examination throughout the experimental period and histologic examination on day 7, 14 and 21. In PRP treated wounds, the mean diameter was smaller and the wound closure rate was higher than in the control. Histological study revealed that PRP treated wounds showed more granulation formation and angiogenesis on day 7, and faster epithelialization, more granulation formation and collagen deposition were observed on day 14 than in control wounds. On day 21, collagen deposition and epithelialization were enhanced in PRP treated groups. Overall, PRP application showed beneficial effects in wound healing, and intralesional injection was useful for application of PRP and could be a good therapeutic option for wound management in dogs.
Animals ; Collagen/metabolism ; Dermis/cytology/injuries/physiology ; Dogs ; Epidermis/cytology/injuries/*physiology ; Female ; Granulation Tissue/cytology ; Injections, Intralesional/veterinary ; Male ; Neovascularization, Physiologic ; *Platelet-Rich Plasma ; Regeneration ; Treatment Outcome ; *Wound Healing ; Wounds and Injuries/therapy/*veterinary

BACKGROUNDIn hypertrophic scar tissue, no sweet gland and hair follicle exist usually because of the dermal and epidermal damage in extensive thermal skin injury, thus imparing regulation of body temperature. This study was designed to reveal the morphological and distributional characteristics of the sweat glands in normal skin and hypertrophic scar obtained from children and adults, and to study the possible interfering effects of the scar on regeneration of the sweat gland after burn injury.

METHODSBiopsies of hypertrophic scar were taken from four children (4 - 10 years) and four adults (35 - 51 years). Normal, uninjured full-thickness skin adjacent to the scar of each patient was used as control. Keratin 19 (K19) was used as the marker for epidermal stem cells and secretory portion of the sweat glands, and keratin 14 (K14) for the tube portion, respectively. Immunohistochemical and histological evaluations were performed.

RESULTSHistological and immunohistochemical staining of skin tissue sections from both the children and adults showed K19 positive cells in the basement membrane of epidermis of normal skin. These cells were seen only single layer and arranged regularly. The secretory or duct portion of the eccrine sweat glands was situated in the dermis and epidermal layer. However, in the scar tissue, K19 positive cells were scant in the basal layer, and the anatomic location of the secretory portion of sweat glands changed. They were located between the border of the scar and reticular layer of the dermis. These secretory portions of sweat glands were expanded and were organized irregularly. But a few K14 positive cells were scattered in the scar tissues in cyclic form.

CONCLUSIONSThere are some residual sweat glands in scar tissues, in which the regeneration process of active sweat glands is present. Possibly the sweat glands could regenerate from adult epidermal stem cells or residual sweat glands in the wound bed after burn injury.

Adult ; Burns ; pathology ; Child ; Child, Preschool ; Cicatrix, Hypertrophic ; metabolism ; pathology ; Epidermis ; cytology ; Humans ; Immunohistochemistry ; Keratin-14 ; Keratins ; analysis ; Middle Aged ; Regeneration ; Skin ; cytology ; Stem Cells ; cytology ; Sweat Glands ; pathology ; physiology