Proliferation Of Epidermal Stem Cells Research Articles

Morroniside promotes skin wound re-epithelialization by facilitating epidermal stem cell proliferation through GLP-1R-mediated upregulation of β-catenin expression.

Epidermal stem cells (EpSCs) play a vital role in skin wound healing through re-epithelialization. Identifying chemicals that can promote EpSC proliferation is helpful for treating skin wounds. This study investigates the effect of morroniside on cutaneous wound healing in mice and explores the underlying mechanisms. Application of 10‒50 μg/mL of morroniside to the skin wound promotes wound healing in mice. In vitro studies demonstrate that morroniside stimulates the proliferation of mouse and human EpSCs in a time- and dose-dependent manner. Mechanistic studies reveal that morroniside promotes the proliferation of EpSCs by facilitating the cell cycle transition from the G1 to S phase. Morroniside increases the expression of β-catenin via the glucagon-like peptide-1 receptor (GLP-1R)-mediated PKA, PKA/PI3K/AKT and PKA/ERK signaling pathways, resulting in an increase in cyclin D1 and cyclin E1 expression, either directly or by upregulating c-Myc expression. This process ultimately leads to EpSC proliferation. Administration of morroniside to mouse skin wounds increases the phosphorylation of AKT and ERK, the expressions of β-catenin, c-Myc, cyclin D1, and cyclin E1, as well as the proliferation of EpSCs, in periwound skin tissue, and accelerates wound re-epithelialization. These effects of morroniside are mediated by the GLP-1R. Overall, these results indicate that morroniside promotes skin wound healing by stimulating the proliferation of EpSCs via increasing β-catenin expression and subsequently upregulating c-Myc, cyclin D1, and cyclin E1 expressions through GLP-1R signaling pathways. Morroniside has clinical potential for treating skin wounds.

Angiopoietin-like 4 promotes epidermal stem cell proliferation and migration and contributes to cutaneous wound re-epithelialization.

Proliferation and migration of epidermal stem cells (EpSCs) are essential for epithelialization during skin wound healing. Angiopoietin-like 4 (ANGPTL4) has been reported to play an important role in wound healing, but the mechanisms involved are not fully understood. Here, we investigate the contribution of ANGPTL4 to full-thickness wound re-epithelialization and the underlying mechanisms using Angptl4-knockout mice. Immunohistochemical staining reveals that ANGPTL4 is significantly upregulated in the basal layer cells of the epidermis around the wound during cutaneous wound healing. ANGPTL4 deficiency impairs wound healing. H&E staining shows that ANGPTL4 deficiency significantly reduces the thickness, length and area of the regenerated epidermis postwounding. Immunohistochemical staining for markers of EpSCs (α6 integrin and β1 integrin) and cell proliferation (PCNA) shows that the number and proliferation of EpSCs in the basal layer of the epidermis are reduced in ANGPTL4-deficient mice. In vitro studies show that ANGPTL4 deficiency impedes EpSC proliferation, causes cell cycle arrest at the G1 phase and reduces the expressions of cyclins D1 and A2, which can be reversed by ANGPTL4 overexpression. ANGPTL4 deletion suppresses EpSC migration, which is also rescued by ANGPTL4 overexpression. Overexpression of ANGPTL4 in EpSCs accelerates cell proliferation and migration. Collectively, our results indicate that ANGPTL4 promotes EpSC proliferation by upregulating cyclins D1 and A2 expressions and accelerating the cell cycle transition from G1 to S phase and that ANGPTL4 promotes skin wound re-epithelialization by stimulating EpSC proliferation and migration. Our study reveals a novel mechanism underlying EpSC activation and re-epithelialization during cutaneous wound healing.

EGFL7 affects the migration of epidermal stem cells in refractory diabetic wounds by regulating Notch signaling pathway.

Aim: This study aimed to explore the role of EGFL7 in the healing process of refractory diabetic wounds. Methods: Epidermal stem cells (ESCs) were isolated from healthy mice and diabetic mice, identified by immunofluorescence, transfected with EGFL7 overexpression and silencing lentiviral vectors, and treated with Notch pathway inhibitor (DAPT). Results: SiEGFL7 significantly inhibited the proliferation, invasion and migration of ESCs of healthy mice. DAPT prominently inhibited the expressions of Notch1, Notch2, Hes1 and Jag1 in ESCs of healthy mice induced by overexpressed EGFL7. Overexpressed EGFL7 promoted wound healing in diabetic mice with refractory wounds. Conclusion: EGFL7 affects the proliferation and migration of ESCs in refractory diabetic wounds by regulating the Notch signaling pathway.

Dendritic epidermal T cells secreting exosomes promote the proliferation of epidermal stem cells to enhance wound re-epithelialization

BackgroundEfficient re-epithelialization is important for successful skin wound healing. The proportion of epidermal stem cells (EpSCs) and dendritic epidermal T cells (DETCs) determines the extent of wound re-epithelialization, especially in large areas of skin tissue loss. However, it remains unknown whether and how DETCs regulate the status of EpSCs to impact wound re-epithelialization.MethodsTo investigate how DETCs regulate EpSCs in skin re-epithelialization, we utilized normal or full-thickness skin deficient wide type (WT) mice and Tcrσ knockout (Tcrσ−/−) mice with DETCs or DETCs-derived exosomes (Exos) treatment. Flow cytometry analysis (FCAS), BrdU labelled experiments, immunofluorescence and immunohistochemical assays were performed to detect the proportion of EpSCs in the epidermis. Wound closure rate and re-epithelialization were assayed by a macroscopical view and hematoxylin–eosin (H&E) staining. EpSCs in vitro were co-cultured with DETCs in a transwell-dependent or -independent manner, or supplement with GW4869 or Exos (5 µg/mL, 15 µg/mL and 45 µg/mL), and the proliferation of EpSCs was detected by means of FCAS and CFSE.ResultsOur data showed that the proportion of CD49fbriCD71dim cells, K15+ cells and BrdU+ cells in the normal epidermis of Tcrδ−/− mice had no significant difference compared to WT mice. For wounded Tcrδ−/− mice, DETCs treatment increase the proportion of CD49fbriCD71dim cells, K15+ cells and BrdU+ cells in the epidermis around the wound in comparison to PBS treatment. DETCs significantly increased the number of CD49fbriCD7dim cells and K15+ cells through transwell-dependent or -independent manners relative to control group. Furthermore, Exos stimuli remarkedly promote the proliferation of EpSCs compared to control group, while the increasement was suppressed when DETCs were interfered with GW4869. Gross observation and H&E staining showed that Exos significantly accelerated wound closure and increased re-epithelialization length in Tcrδ−/− mice when compared to control mice. Additionally, we found in vivo that Exos observably facilitated the proliferation of CD49fbriCD7dim cells and K15+ cells.ConclusionsWe revealed that DETCs enhanced the proliferation of EpSCs in the epidermis around the wounds to accelerate re-epithelialization in which Exos played important roles in the remote regulation of EpSCs proliferation. Together, these findings suggest a mechanistic link among DETC-derived exosomes, the proliferation of EpSCs, and wound re-epithelialization in the skin.

Mechanism study of dendritic epidermal T lymphocytes in promoting healing of full-thickness skin defects wound on mice by regulating the proliferation and differentiation of epidermal stem cells in mice

Mechanism study of dendritic epidermal T lymphocytes in promoting healing of full-thickness skin defects wound on mice by regulating the proliferation and differentiation of epidermal stem cells in mice

Involvement of miRNA203 in the proliferation of epidermal stem cells during the process of DM chronic wound healing through Wnt signal pathways

BackgroundThe biological role of miR-203 and the underlying mechanisms on the proliferation of epidermal stem cells (ESCs) have not yet been reported during the progression of chronic wound healing in diabetes mellitus. Our previous studies have observed that the expression of miR-203 showed a marked upregulation and ESC proliferation capacity was impaired in diabetes mellitus skin wounds in rats.MethodsWound models were established in normal rats and rats with type 2 diabetes. Expression level of miR-203 and the alteration of ESCs’ number and function were detected. ESCs were isolated from the back skin of fetal rats to assess the effects of glucose in vitro. An antagomir to miR-203 was used to assess its effect on ESCs. Using microarray analysis, we further identified potential target genes and signaling pathways of miR-203.ResultsWe found that high glucose significantly upregulated the expression of miR-203 and subsequently reduced the number of ESCs and impaired their proliferation capacity. Meanwhile, over-expression of miR-203 reduced the ESCs’ numbers and impaired the proliferation capacity via downregulation of the Notch and Wnt signaling pathways. Conversely, inhibition of miR-203 enhanced the proliferation capacity. Additionally, silencing miR-203 in skin of rats with type 2 diabetes accelerated wound healing and improved healing quality via the upregulation of the Notch and Wnt signaling pathways. Finally, over-expression of miR-203 downregulated genes ROCK2, MAPK8, MAPK9, and PRKCA.ConclusionOur findings demonstrated that induced expression of miR-203 by high glucose in type 2 diabetic rats decreased the number of ESCs and impaired ESC proliferation capacity via downregulating genes related to Notch and Wnt signaling pathways, resulting in a delayed wound healing.

Effects and mechanism of rat epidermal stem cells treated with exogenous vascular endothelial growth factor on healing of deep partial-thickness burn wounds in rats

Effects and mechanism of rat epidermal stem cells treated with exogenous vascular endothelial growth factor on healing of deep partial-thickness burn wounds in rats

Fibronectin precoating wound bed enhances the therapeutic effects of autologous epidermal basal cell suspension for full-thickness wounds by improving epidermal stem cells\u2019 utilization

BackgroundAutologous epidermal basal cell suspension therapy has been proven to be one of the most effective treatments for full-thickness wounds. However, we found there remain obvious defects that significantly confined the utilization and function of the epidermal basal cells (EBCs), especially the epidermal stem cells (ESCs) in it. This study investigated whether precoating fibronectin (FN) on the wound bed before spraying EBCs could overcome these defects and further explored its possible mechanisms.MethodsIn the in vitro study, EBCs were isolated from the donor skin of patients who needed skin grafting. Different concentrations of FN were used to precoat culture dishes before cell culture; the adherent efficiency, proliferation and migration ability of ESCs were analyzed and compared with traditional collagen IV precoating.In the in vivo study, Sprague–Dawley (SD) rats with full-thickness skin wounds were selected as full-thickness wounds’ model. For the experiment groups, 20 μg/ml FN was precoated on the wound bed 10 min before EBC spray. The quality of wound healing was estimated by the residual wound area rate, wound healing time, and hematoxylin and eosin (H&E) staining. Expression of ESC markers, neovascular markers, inflammation markers, and collagen formation and degradation markers was elucidated by immunohistochemistry (IHC), immunofluorescence (IF), western blot (WB), and RT-qPCR analysis.ResultsThe in vitro study showed that the dishes precoated with 20 μg/ml FN had a similar adherent efficiency and colony formation rate with collagen IV, but it could improve the proliferation and migration of ESCs significantly. Similarly, in the in vivo study, precoating FN on wound bed before EBC spray also significantly promote wound healing by improving ESCs’ utilization efficiency, promoting angiogenesis, decreasing inflammations, and regulating collagen formation and degradation.ConclusionFN precoating wound bed before EBC spray could significantly promote full-thickness wound healing by improving the utilization and function of the ESCs and further by promoting angiogenesis, decreasing inflammations, and regulating collagen formation and degradation.Graphical abstract

Research of Luteoloside in promoting proliferation and migration of human epidermal stem cells

Objective To investigate the effects of Luteoloside on the proliferation and migration of human epidermal stem cells (EpSCs) and the proliferation of epidermal cells in skin tissue in vitro. Methods EpSCs were isolated from human skin tissue by type Ⅳ collagenase digestion and collagen fast adherence. EpSCs were identified by immunofluorescence staining of CK19 and β1 integrin. The effects of Luteoloside (0 to 5.0 μmol/L) on the proliferation of EpSCs were measured by MTT assay. The effects of Luteoloside on EpSCs migration and wound healing were observed by scratch-wound model in vitro. The effects of Luteoloside on the thickness of epidermis in vitro were observed by HE staining. Results EpSCs formed a cobblestone-shaped cell monolayer when cultured on a collagen coated dish. Immunofluorescence staining showed that more than 90% cells were CK19 and β1 integrin positive. Luteoloside at 0.1 to 1.0 μmol/L could significantly promote the EpSCs proliferation; Luteoloside at 1.0 μmol/L could significantly enhance EpSCs migration and scratch healing. Culture of skin tissues with 1.0 μmol/L Luteoloside for 5 days could significantly increase the thickness of the epidermis. Conclusion Luteoloside can promote the proliferation and migration of EpSCs, promote the proliferation of epidermal tissue, and play an important role in skin self-renewal and injury repair. Key words: Cell proliferation; In vitro; Luteoloside; Epidermal stem cells; Migration

Anti-Aging Properties of Plant Stem Cell Extracts

Skin aging is a complex process which involves all the layers of the epidermis and dermis. In order to slow skin aging, methods are researched which would strengthen and protect skin stem cells. Science is in search of the right method to stimulate the proliferation of epidermal stem cells. Plant stem cells show outstanding anti-aging properties, as they can, among other activities, stimulate fibroblasts to synthesise collagen, which, in turn, stimulates skin regeneration. One of the most important agents which give anti-aging properties to plant stem cell extracts is kinetin (6-furfuryladenine). This compound belongs to a cytokine group and is considered to be a strong antioxidant which protects protein and nucleic acids from oxidation and glycoxidation processes. It enables cells to remove the excess of free radicals to protect them from oxidative stress.

The Antiaging Properties of Andrographis paniculata by Activation Epidermal Cell Stemness.

Andrographis paniculata (A. paniculata, Chuanxinlian), a medicinal herb with an extremely bitter taste that is native to China and other parts of Southeast Asia, possesses immense therapeutic value; however, its therapeutic properties have rarely been applied in the field of skin care. In this study, we investigated the effect of an A. paniculata extract (APE) on human epidermal stem cells (EpSCs), and confirmed its anti-aging effect through in vitro, ex vivo, and in vivo study. An MTT assay was used to determine cell proliferation. A flow cytometric analysis, with propidium iodide, was used to evaluate the cell cycle. The expression of integrin β1 (CD29), the stem cell marker, was detected with antibodies, using flow cytometry in vitro, and immunohistochemical assays in ex vivo. Type 1 collagen and VEGF (vascular endothelial growth factor) were measured using an enzyme-linked immunosorbent assay (ELISA). During the clinical study, skin hydration, elasticity, wrinkling, sagging, and dermal density were evaluated before treatment and at four and eight weeks after the treatment with the test product (containing the APE) on the face. The proliferation of the EpSCs, treated with the APE, increased significantly. In the cell cycle analysis, the APE increased the G2/M and S stages in a dose-dependent manner. The expression of integrin β1, which is related to epidermal progenitor cell expansion, was up-regulated in the APE-treated EpSCs and skin explants. In addition, the production of VEGF in the EpSCs increased significantly in response to the APE treatment. Consistent with these results, the VEGF and APE-treated EpSCs conditioned medium enhanced the Type 1 collagen production in normal human fibroblasts (NHFs). In the clinical study, the APE improved skin hydration, dermal density, wrinkling, and sagging significantly. Our findings revealed that the APE promotes a proliferation of EpSCs, through the up-regulation of the integrin β1 and VEGF expression. The VEGF might affect the collagen synthesis of NHF as a paracrine factor. Clinical studies further suggested that treatment with formulations containing APE confers anti-aging benefits. Based on these results, we suggest that APE may be introduced as a possible anti-aging agent.

Introduction of telomerase reverse transcriptase gene into epidermal stem cells derived from human skins

Telomerase extends the proliferation and prevent replicative senescence in most somatic cells. Whether it has similar function in human epidermal stem cells remains to be determined. In this study, the human telomerase reverse transcriptase (hTERT) cytalytic subunit was introduced into epidermal stem cells derived from human fetal skins. The expression of hTERT mRNA, protein and telomerase activity in the transduced cells was observed by real time PCR (RT-PCR) techniques, western blot analysis and telomeric repeat amplification protocol enzyme-linked immunosorbent assay (TRAP-ELISA) assay, respectively. The proliferation of the transduced cells was examined. The results showed the introduction of hTERT into the epidermal stem cells upregulated the expression of the hTERT gene and protein. And also the hTERT-transduced epidermal stem cells exhibited significantly elevated telomerase activity and proliferation. These works establish the base of further gene modification, monoclone screening and cell differentiation mechanism. The ability to maintain the biological characteristics and proliferation of epidermal stem cells could have important applications in wound healing and skin tissue engineering.

Wnt and Notch signaling pathway involved in wound healing by targeting c-Myc and Hes1 separately.

IntroductionWnt and Notch signaling pathways are critically involved in relative cell fate decisions within the development of cutaneous tissues. Moreover, several studies identified the above two pathways as having a significant role during wound healing. However, their biological effects during cutaneous tissues repair are unclear.MethodsWe employed a self-controlled model (Sprague–Dawley rats with full-thickness skin wounds) to observe the action and effect of Wnt/β-catenin and Notch signalings in vivo. The quality of wound repair relevant to the gain/loss-of-function Wnt/β-catenin and Notch activation was estimated by hematoxylin-and-eosin and Masson staining. Immunofluorescence analysis and Western blot analysis were used to elucidate the underlying mechanism of the regulation of Wnt and Notch signaling pathways in wound healing. Meanwhile, epidermal stem cells (ESCs) were cultured in keratinocyte serum-free medium with Jaggedl or in DAPT (N-[(3,5-difluorophenyl)acetyl]-L-alanyl-2-phenyl]glycine-1,1-dimethylethyl) to investigate whether the interruption of Notch signaling contributes to the expression of Wnt/β-catenin signaling.ResultsThe results showed that in vivo the gain-of-function Wnt/β-catenin and Notch activation extended the ability to promote wound closure. We further determined that activation or inhibition of Wnt signaling and Notch signaling can affect the proliferation of ESCs, the differentiation and migration of keratinocytes, and follicle regeneration by targeting c-Myc and Hes1, which ultimately lead to enhanced or delayed wound healing. Furthermore, Western blot analysis suggested that the two pathways might interact in vivo and in vitro.ConclusionThese results suggest that Wnt and Notch signalings play important roles in cutaneous repair by targeting c-Myc and Hes1 separately. What’s more, interaction between the above two pathways might act as a vital role in regulation of wound healing.

Effect of electric fields on proliferation and migration of epidermal stem cells

Objective To investigate the effect of endogenous electric fields on proliferation and migration of epidermal stem cells (EpSCs) in vitro. Methods EpSCs in the first passage were cultured on simulated endogenous electric field. Galvanic stimulation set at an intensity of 0 mV/mm (GroupⅠ), 100 mV/mm (GroupⅡ) and 200 mV/mm(Group Ⅲ) was given twice a day for 3 days with each time continuing1 hour and resting 1 hour. Effect of bio-electric field on cell proliferation was measured by direct cell counting in fixed visual field. Repeated experiment but continued stimulation for 3 hours was performed. Live cell migration was monitored to determine the effect of bio-electric field on the process of cell migration. Results For the EpSCs cultured in endogenous bio-electric simulation platform for 24, 48 and 72 hours, cell proliferation rate was the highest in Group Ⅲ[(107.4±21.9)%, (270.2±71.4)%, (544.0±95.1)% ] (P<0. 01). And higher cell proliferation was observed in Group Ⅰ[(35.1±21.0)%, (138.6±31.0)%, (323.5±23.0)%] than in Group Ⅱ[(66.9±24.2)% , (192.1±36.2)%, (406.7±50.7)%] (P<0. 01). After continued galvanic stimulation for 3 hours, cells in Groups Ⅱ and Ⅲ oriented towards cathode, but cells in Group Ⅰ moved randomly. In measurements of track velocity (Vt), displacement velocity (Vd) and electric field migration rate (Vx), Group Ⅲ revealed increased values[(42.5±2.8), (32.3 ±1.8), (29.7±1.3)μm/h] as compared with GroupⅠ[(36.2±2.2), (23.6±2.9), (18.2±1.8)μm/h] and Group Ⅱ[(34.3±1.6), (23.8±1.2), (21.2±1.6)μm/h] (P<0.01). Conclusion In vitro experiments reveal that endogenous electric fields can promote the proliferation of EpSCs and induce oriented movements towards the cathode. Key words: Stem cells; Cell proliferation; Cell movement; In vitro

Stromal cell-derived factor 1 (SDF-1) accelerated skin wound healing by promoting the migration and proliferation of epidermal stem cells.

Epidermal stem cells could contribute to skin repair through the migration of cells from the neighboring uninjured epidermis, infundibulum, hair follicle, or sebaceous gland. However, little is known about the factors responsible for the complex biological processes in wound healing. Herein, we will show that the attracting chemokine, SDF-1/CXCR4, is a major regulator involved in the migration of epidermal stem cells during wound repair. We found that the SDF-1 levels were markedly increased at the wound margins following injury and CXCR4 expressed in epidermal stem cells and proliferating epithelial cells. Blocking the SDF-1/CXCR4 axis resulted in a significant reduction in epidermal stem cell migration toward SDF-1 in vitro and delayed wound healing in vivo, while an SDF-1 treatment enhanced epidermal stem cell migration and proliferation and accelerated wound healing. These results provide direct evidence that SDF-1 promotes epidermal stem cell migration, accelerates skin regeneration, and makes the development of new regenerative therapeutic strategies for wound healing possible.

Role of epidermal stem cells in repair of partial-thickness burn injury after using Moist Exposed Burn Ointment (MEBO®) histological and immunohistochemical study

Moist Exposed Burn Ointment (MEBO(®)) is widely used topical agent applied on skin burn. This study investigated the effect of MEBO topical application on activation and proliferation of epidermal stem cells through the immunohistochemical localization of cytokeratin 19 (CK19) as a known marker expressed in epidermal stem cells. Biopsies from normal skin and burn wounds were taken from 21 patients with partial thickness burn 1, 4, 7, 14, 21, and 28 days after treatment with MEBO. Tissue sections were prepared for histological study and for CK19 immunohistochemical localization. In control skin, only few cells showed a positive CK19 immune-reaction. Burned skin showed necrosis of full thickness epidermis that extended to dermis. Gradual regeneration of skin accompanied with an enhancement in CK19 immune-reactivity was noted 4, 7, 14 and 21 days after treatment with MEBO. On day 28, a complete regeneration of skin was observed with a return of CK19 immune-reactivity to the basal pattern again. In conclusion, the enhancement of epidermal stem cell marker CK19 after treatment of partial thickness burn injuries with MEBO suggested the role of MEBO in promoting epidermal stem cell activation and proliferation during burn wound healing.

Effects of low frequency electromagnetic field on proliferation of human epidermal stem cells: An in vitro study

To investigate the effects of low frequency electromagnetic fields (EMF) on the proliferation of epidermal stem cells, human epidermal stem cells (hESC) were isolated, expanded ex vivo, and then exposed to a low frequency EMF. The test and control cells were placed under the same environment. The test cells were exposed for 30 min/day to a 5 mT low frequency EMF at 1, 10, and 50 Hz for 3, 5, or 7 days. The effects of low frequency EMF on cell proliferation, cell cycle, and cell-surface antigen phenotype were investigated. Low frequency EMF significantly enhanced the proliferation of hESC in the culture medium in a frequency-dependent manner, with the highest cell proliferation rate at 50 Hz (P < 0.05). Exposure to a low frequency EMF significantly increased the percentage of cells at the S phase of the cell cycle, coupled with a decrease in the percentage of cells in the G1 phase (P < 0.05) but the effect was not frequency dependent. The percentage of CD29(+) /CD71(-) cells remained unchanged in the low frequency EMF-exposed hESC. The results suggested that low frequency EMF influenced hESC proliferation in vitro, and this effect was related to the increased proportion of cells at the S phase.

Effects of 50 Hz electromagnetic fields on human epidermal stem cells cultured on collagen sponge scaffolds

Purpose: This study is to investigate the effects of electromagnetic fields (EMF) on proliferation of epidermal stem cells (ESC), which could present a viable clinical option for skin tissue engineering. Materials and methods: The ESC obtained from human foreskin were grafted into type-I three-dimensional collagen sponge scaffolds, and then were exposed with EMF (frequency 50 Hz, intensity 5 mT) for 14 d (30 min per d). Meanwhile, the control group was set under the same conditions without EMF. The effects of EMF on growth and proliferation of ESC were analyzed with staining of hematoxylin and eosin (H&E) and 4′,6-diamidino-2-phenylindole (DAPI) under microscope or scanning electron microscope. The data of DAPI staining for 2 d, 7 d, 10 d and 14 d were collected respectively to investigate the cells proliferation. Results: ESC cultured in collagen sponge scaffolds could be steady grown and EMF could promote ESC proliferation compared with control (P < 0.05). Conclusions: EMF could significantly promote proliferation of ESC, which leads to a promising clinical option for skin tissue engineering.

Nanog and β-catenin: A new convergence point in EpSC proliferation and differentiation

Skin tissue homeostasis is maintained by the balanced proliferation and differentiation of certain types of proliferating cells such as epidermal stem cells (EpSCs). The proliferation and differentiation of EpSCs are complex processes which are not well understood. This study aimed to find the internal relationship between the Nanog pathway and the Wnt/β-catenin pathway in the proliferation and differentiation process of EpSCs. In brief, EpSCs were isolated from rat epidermis and cultured. The MTT assay, western blotting, polymerase chain reaction (PCR) and immunocytochemistry were performed during the proliferation and differentiation process of EpSCs. Our results showed that 10−7 M neuropeptide substance P could effectively stimulate proliferation of EpSCs and that a possible link exists between the Nanog pathway and the Wnt/β-catenin pathway.

The effects of low frequency electromagnetic fields on the proliferation of epidermal stem cells cultured on two different scaffolds

Objective To observe the effects of low frequency electromagnetic fields (LFEMFs) on the proliferation of human epidermal stem cells (hESCs) cultured in a three dimensional environment so as to provide an experimental basis for applying LFEMF in skin tissue engineering.Methods hESCs from human prepuces were isolated and purified by the method of rapid adherence to collagen type ⅣV. They were grafted into a type-I collagen sponge or chitosan scaffold in vitro, and then stimulated with different frequencies of LFEMF ( 1 Hz, 10 Hz or 50 Hz) at a magnetic field intensity of 5 mT for 30 min/d. The cells' growth and proliferation were tracked using hematoxylin and eosin (HE) and diamine pheny1 indole (DAPI) staining and observed under the scanning electron microscope at different time points ( on 2nd, 7th, 10th and 14th days of LFEMF intervention). The amounts of cell proliferation at every time point were analyzed and compared.Results LFEMFs of different frequencies showed significantly different efficacy in promoting hESC proliferation. The two scaffolds also showed significantly different effects.By the 10th day, hESCs had grown significantly better on collagen sponge scaffolds than on the chitosan ones. All LFEMF frequencies could promote proliferation of hESCs, but the differences in their effects were statistically significant.Conclusion Collagen sponge may be a preferable scaffold for hESCs cultured in vitro. Rapid proliferation of ESCs in three-dimensional settings can be promoted by LFEMF intervention. LFEMF has relatively great potential in skin tissue engineering. Key words: Low frequency electromagnetic fields; Epidermal stem cells; Proliferation; Collagen sponge scaffolds; Chitosan scaffolds; Tissue engineering