Epidermal stem cells play an pivotal role in skin self-renewal, wound repair, and re-epithelialization process. The emergence of new technologies and concepts such as single-cell sequencing and gene knockout further revealed a new mechanism of epidermal stem cells in epidermal self-renewal and wound repair, providing new ideas for wound repair. In this review, the mechanisms of proliferation, differentiation, and migration of epidermal stem cells are discussed. Combined with the analysis of researches on stem cell heterogeneity and cell plasticity, the physiological function of epidermal stem cells can be further understood. The application advances of epidermal stem cells in wound repair is also summarized, which would provide some advice for workers engaged in clinical and basic research on wound repair.
Epidermal Cells/physiology* ; Epidermis ; Humans ; Re-Epithelialization ; Skin ; Soft Tissue Injuries ; Stem Cells

Background: Fibroblasts were the main seed cells in the studies of tissue engineering of the pelvic floor ligament. Basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) were widely studied but at various concentrations. This study aimed to optimize the concentrations of combined bFGF and EGF by evaluating their effects on proliferation and collagen secretion of fibroblasts. Methods: Fibroblasts were differentiated from rat adipose mesenchymal stem cells (ADSCs). Flow cytometry and immunohistochemistry were used for cell identification. The growth factors were applied at concentrations of 0, 1, 10, and 100 ng/ml as three groups: (1) bFGF alone, (2) EGF alone, and (3) bFGF mixed with EGF. Cell proliferation was evaluated by Cell Counting Kit-8 assays. Expression of Type I and III collagen (Col-I and Col-III) mRNAs was evaluated by real-time quantitative reverse transcription-polymerase chain reaction. Statistical analysis was performed with SPSS software and GraphPad Prism using one-way analysis of variance and multiple t-test. Results: ADSCs were successfully isolated from rat adipose tissue as identified by expression of typical surface markers CD29, CD44, CD90, and CD45 in flow cytometry. Fibroblasts induced from ADSC, compared with ADSCs, were with higher mRNA expression levels of Col I and Col III (F = 1.29, P = 0.0390). bFGF, EGF, and the mixture of bFGF with EGF can enhanced fibroblasts proliferation, and the concentration of 10 ng/ml of the mixture of bFGF with EGF displayed most effectively (all P < 0.05). The expression levels of Col-I and Col-III mRNAs in fibroblasts displayed significant increases in the 10 ng/ml bFGF combined with EGF group (all P < 0.05). Conclusions The optimal concentration of both bFGF and EGF to promote cell proliferation and collagen expression in fibroblasts was 10 ng/ml at which fibroblasts grew faster and secreted more Type I and III collagens into the extracellular matrix, which might contribute to the stability of the pelvic floor microenvironment.
Animals ; Cell Proliferation ; Cells, Cultured ; Collagen ; metabolism ; Epidermal Growth Factor ; physiology ; Fibroblast Growth Factor 2 ; physiology ; Fibroblasts ; physiology ; Pelvic Floor ; Rats ; Regeneration

OBJECTIVETo investigate the effect of annexin A2 (AnxA2) on epithelial growth factor receptor (EGFR)/nuclear factor-κB (NF-κB) signal transduction and mucin expression in human airway epithelial H292 cells treated with Mycoplasma pneumoniae (MP).

METHODSH292 cells were divided into control group, MP group, NC-siRNA+MP group, and AnxA2 siRNA+MP group. The cells in the MP group were incubated with 5 μg/mL MP antigen for 2 hours. The cells in the NC-siRNA+MP and AnxA2 siRNA+MP groups were transfected with NC-siRNA and AnxA2 siRNA for 24 hours, followed by MP antigen stimulation for 2 hours. The MTT method was used to measure cell viability; quantitative real-time PCR was used to measure the mRNA expression of AnxA2; Western blot was used to measure the protein expression of AnxA2, phosphorylated EGFR (p-EGFR), and phosphorylated p65 NF-κB (p-p65 NF-κB); ELISA was used to measure the secretion of mucin 5AC (MUC5AC) and mucin 5B (MUC5B).

RESULTSThe MP and NC-siRNA+MP groups had lower cell viability than the control group (P<0.05). The AnxA2 siRNA+MP group had higher cell viability than the MP and NC-siRNA+MP groups and lower cell viability than the control group (P<0.05). The MP and NC-siRNA+MP groups had significantly higher mRNA and protein expression of AnxA2 than the AnxA2 siRNA+MP group (P<0.05). Compared with the control group, the MP and NC-siRNA+MP groups had significant increases in the protein expression of p-EGFR, p-p65 NF-κB, MUC5AC, and MUC5B (P<0.05); the AnxA2 siRNA+MP group had lower protein expression than the MP and NC-siRNA+MP groups, but higher protein expression than the control group (P<0.05).

CONCLUSIONSAnxA2 is involved in the airway lesion induced by MP antigen via mediating EGFR/NF-κB signaling activation and mucin expression in human airway epithelial cells.

Annexin A2 ; physiology ; Bronchi ; physiology ; Cells, Cultured ; Epithelial Cells ; microbiology ; Humans ; Mucins ; analysis ; Mycoplasma pneumoniae ; pathogenicity ; NF-kappa B ; physiology ; Receptor, Epidermal Growth Factor ; physiology ; Signal Transduction ; physiology

Oval cells have a potential to differentiate into a variety of cell lineages including hepatocytes and biliary epithelia. Several models have been established to activate the oval cells by incorporating a variety of toxins and carcinogens, alone or combined with surgical treatment. Those models are obviously not suitable for the study on human hepatic oval cells. It is necessary to establish a new and efficient model to study the human hepatic oval cells. In this study, the hepatocyte growth factor (HGF) and epidermal growth factor (EGF) were used to induce differentiation of mouse embryonic stem (ES) cells into hepatic oval cells. We first confirmed that hepatic oval cells derived from ES cells, which are bipotential, do exist during the course of mouse ES cells' differentiation into hepatic parenchymal cells. RT-PCR and transmission electron microscopy were applied in this study. The ratio of Sca-1+/CD34+ cells sorted by FACS in the induction group was increased from day 4 and reached the maximum on the day 8, whereas that in the control group remained at a low level. The differentiation ratio of Sca-1+/CD34+ cells in the induction group was significantly higher than that in the control group. About 92.48% of the sorted Sca-1+/CD34+ cells on the day 8 were A6 positive. Highly purified A6+/Sca-1+/CD34+ hepatic oval cells derived from ES cells could be obtained by FACS. The differentiation ratio of hepatic oval cells in the induction group (up to 4.46%) was significantly higher than that in the control group. The number of hepatic oval cells could be increased significantly by HGF and EGF. The study also examined the ultrastructures of ES-derived hepatic oval cells' membrane surface by atomic force microscopy. The ES-derived hepatic oval cells cultured and sorted by our protocols may be available for the future clinical application.
Animals ; Antigens, CD34 ; genetics ; metabolism ; Antigens, Ly ; genetics ; metabolism ; Cell Differentiation ; drug effects ; genetics ; physiology ; Cell Line ; Embryonic Stem Cells ; cytology ; metabolism ; ultrastructure ; Epidermal Growth Factor ; pharmacology ; Flow Cytometry ; Gene Expression Regulation, Developmental ; drug effects ; Hepatocyte Growth Factor ; pharmacology ; Liver ; cytology ; metabolism ; Membrane Proteins ; genetics ; metabolism ; Mice ; Mice, Inbred BALB C ; Microfilament Proteins ; metabolism ; Microscopy, Atomic Force ; Microscopy, Electron, Transmission ; Reverse Transcriptase Polymerase Chain Reaction ; Stem Cells ; cytology ; metabolism ; ultrastructure ; Time Factors

BACKGROUNDDecorin is a small leucine-rich proteoglycan and it plays an important role in regulation of cell growth and migration in various tumor cell lines. Decorin was found down-regulated in non-small cell lung cancer tissue and may be involved in regulation of lung cancer development.

METHODSIn this study, lentivirus-mediated RNA interference and over expression were employed to change the expression levels of decorin in lung cancer A549 cells. We tested the cell cycle of A549 cells and the expression of transforming growth factor (TGF)-β, cyclin D1, epidermal growth factor receptor (EGFR), P53, and P21.

RESULTSWe found that up-regulation of decorin could inhibit proliferation, block cell cycle at G1 and decrease invasive activity of A549 cells. Moreover, we also show that up-regulation of decorin induced significant decreases of TGF-β1, cyclin D1 expression, phosphorylation of EGFR, and increases of P53 and P21 expression. Opposite results were observed in A549 cells with down-regulation of decorin.

CONCLUSIONOur results suggest that decorin is a key regulator involved in proliferation and migration of A549 cells.

Cell Cycle ; genetics ; physiology ; Cell Movement ; genetics ; physiology ; Cell Proliferation ; Cyclin D1 ; genetics ; metabolism ; Decorin ; genetics ; metabolism ; Humans ; Receptor, Epidermal Growth Factor ; genetics ; metabolism ; Transforming Growth Factor beta ; genetics ; metabolism ; Tumor Cells, Cultured

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

OBJECTIVETo explore the mechanism via which the epidermal growth factor (EGF) affects the migration of human amnion-derived mesenchymal stem cells (hAMSCs).

METHODSIn vitro cultured hAMSCs were divided into control (untreated), EGF group, inhibitor AG1478 + EGF group, inhibitor LY294002 + EGF group, and inhibitor U0126 + EGF group. The migration ability of hAMSCs in each group was measured using Transwell chamber. The expressions of phosphorylated EGFR (P-EGFR), phosphorylated AKT (P-AKT), and phosphorylated ERK1/2 (P-ERK1/2) as well as the expressions of metalloproteinase (MMP) -2 and MMP-9 were detected using Western blot analysis. The differentially expressed genes in the culture solutions in EGF groups and control group were analyzed with RNA-Seq technique.

RESULTSCells in EGF group had significantly stronger migration ability than in control group (P = 0.0361), inhibitor AG1478 + EGF group (P = 0.0113), inhibitor LY294002 + EGF group (P = 0.0169), and inhibitor U0126 + EGF group (P = 0.0293). EGF increased the phosphorylation levels of EGFR, AKT and ERK, and increased the expression of MMP-2. However, the increased expressions of P-AKT and P-ERK could be suppressed by AG1478 and LY294002. As shown by GO functional enrichment analysis and KEGG pathway analysis, EGF increased the transcription of genes, which were mainly involved in transcriptional regulation, protein modification, and apoptosis inhibition. Genes that were involved in the MARK pathway included DUSP5, IL1B, DUSP6, NGF, and HSPA2.

CONCLUSIONEGF-induced migration of hAMSCs may be mediated by the signaling pathways of PI3K and ERK, which needs MMP-2 expression and the co-expression of genes involved in transcriptional regulation, protein modification, and apoptosis inhibition.

Amnion ; cytology ; Cell Movement ; drug effects ; Cells, Cultured ; Epidermal Growth Factor ; pharmacology ; Humans ; Matrix Metalloproteinase 2 ; metabolism ; Matrix Metalloproteinase 9 ; metabolism ; Mesenchymal Stromal Cells ; metabolism ; physiology ; Proto-Oncogene Proteins c-akt ; metabolism

Epidermal growth factor receptor (EGFR) cell signaling plays a central role in beta-cell mass/function regulation, and provides a new strategy for the treatment of diabetes, but its mechanisms of action remain poorly understood. In developmental biology, pancreatic islet development is impaired in lacking EGFR of mice. The attenuation of EGFR signaling in the islets leads to markedly reduced beta-cell proliferation. EGFR ligands BTC can increase proliferation and neogenesis. In this article EGFR and their ligands in the pancreas, EGFR cell signaling, and EGFR effects in pancreatic beta-cell mass/function regulation were reviewed.
Betacellulin ; Humans ; Insulin-Secreting Cells ; metabolism ; Intercellular Signaling Peptides and Proteins ; metabolism ; Ligands ; Receptor, Epidermal Growth Factor ; metabolism ; Signal Transduction ; physiology

OBJECTIVE: To evaluate the effect of biglycan on the signaling of cytokines (epidermal growth factor, osteogenic protein-1, and interleukin-1) in bovine intervertebral disc cells. METHODS: Nucleoplasty (NP) and annulus fibrosus (AF) cells of the intervertebral disc tissues were isolated from the tails of young adult bovine. First, the cells were treated in 3 ways: Biglycan alone, cytokines alone (epidermal growth factor, osteogenic protein-1, or interleukin-1), and biglycan combined with cytonkines. Western blot was used to observe the singling of biglycan and cytokines in bovine intervertebral disc cells, and to identify the effect of biglycan on cytokines mentioned above. RESULTS: Biglycan upregulated the signaling (3- 4 folds) with the optimal effect at 10 min and 20 μmol/L both in the AF cells and NP cells. Epidermal growth factor, osteogenic protein-1, or interleukin-1 also upregulated the protein expression in the extracellular matrix of intervertebral disc cells. When combined different biglycan concentrations with epidermal growth factor, osteogenic protein-1, or interleukin-1 to treat the intervertebral disc cells, the concentration of biglycan rose, whereas the cytokine signal decreased both in the bovine AF and NP cells (P<0.01). There was no significant difference between the AF and NP cells. CONCLUSION Biglycan can adhere to the intervertebral disc cells to activate the extracellular signal-regulated kinase (ERK) pathway and this effect is time and concentration dependent. Byglycan can decrease not only the anabolism effect of epidermal growth factor and osteogenic protein-1, but also the catabolism effect of interleukin-1. This regulatory role of biglycan may be very important to maintain the metabolism balance. Biglycan may be good for the repair of intervertebral disc.
Animals ; Biglycan ; physiology ; Bone Morphogenetic Protein 7 ; metabolism ; physiology ; Cattle ; Cells, Cultured ; Cytokines ; metabolism ; physiology ; Epidermal Growth Factor ; metabolism ; physiology ; Interleukin-1 ; metabolism ; physiology ; Intervertebral Disc ; cytology ; metabolism ; Signal Transduction

OBJECTIVETo investigate the relationship among a 50-Hz MF-induced epidermal growth factor receptor (EGFR) clustering, acid sphingomyelinase (A-SMase) and ceramide (CER), and to explore the possible mechanism of receptor clustering.

METHODSHuman amnion (FL) cells were exposed to a 50-Hz sinusoidal magnetic field at 0.4 mT for 15 min with or without imipramine, a specific inhibitor of A-SMase and ceramide pretreatment. EGF treatment served as the positive control and DMSO treatment served as the solvent control. The EGFR was labeled with polyclonal anti-EGFR antibody and the clustering of EGFR was analyzed using immunofluorescence and confocal microscopy. The percentage of cells with EGFR clustering was counted and compared.

RESULTSBoth EGF treatment and 50-Hz MF exposure could induce EGFR clustering. However, the effect could be eliminated by imipramine pretreatment for 4 hours. When FL cells were incubated with ceramide following the imipramine pretreatment for 30 min, EGFR clustering induced by 50-Hz MF exposure could be recovered.

CONCLUSIONEGFR clustering induced by 50-Hz MF depends on A-SMase activity, and ceramide, as the hydrolyzate from A-SMase might participate in the process of EGFR clustering.

Amnion ; cytology ; Cell Line ; Cell Membrane ; metabolism ; radiation effects ; Ceramides ; metabolism ; Epithelial Cells ; metabolism ; radiation effects ; Humans ; Magnetic Fields ; adverse effects ; Receptor, Epidermal Growth Factor ; metabolism ; Sphingomyelin Phosphodiesterase ; metabolism ; physiology