Proliferation Of Human Epidermal Cells Research Articles

The Potential of 2-aza-8-Oxohypoxanthine as a Cosmetic Ingredient

In this study, we verified the effects of 2-aza-8-oxohypoxanthine (AOH) on human epidermal cell proliferation by performing DNA microarray analysis. Cell proliferation was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, which measures mitochondrial respiration in normal human epidermal keratinocyte (NHEK) cells. Gene expression levels were determined by DNA microarray analysis of 177 genes involved in skin aging and disease. AOH showed a significant increase in cell viability at concentrations between 7.8 and 31.3 μg/mL and a significant decrease at concentrations above 250 μg/mL. DNA microarray analysis showed that AOH significantly increased the gene expression of CLDN1, DSC1, DSG1, and CDH1 (E-cadherin), which are involved in intercellular adhesion and skin barrier functioning. AOH also up-regulated the expression of KLK5, KLK7, and SPIMK5, which are proteases involved in stratum corneum detachment. Furthermore, AOH significantly stimulated the expression of KRT1, KRT10, TGM1, and IVL, which are considered general differentiation indicators, and that of SPRR1B, a cornified envelope component protein. AOH exerted a cell activation effect on human epidermal cells. Since AOH did not cause cytotoxicity, it was considered that the compound had no adverse effects on the skin. In addition, it was found that AOH stimulated the expression levels of genes involved in skin barrier functioning by DNA microarray analysis. Therefore, AOH has the potential for practical use as a cosmetic ingredient. This is the first report of efficacy evaluation tests performed for AOH.

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

Experimental study on effects of IL-10 on the content of DNA during the proliferation and differentiation of human epidermal cells

Objective To study the impact of IL-10 on the content of DNA during the proliferation and differentiation of human epidermal cells.Methods The normal human skin was transplanted to nude mice to establish a skin-nude mice chimeric model in 60 mice.According to requirements in matched-pairs design,the mice were randomly divided into a study group and a control group,30 cases for each group.In the study group,IL-10 of 0.1ml (10 ng/ml) was injected into the skin graft,while 0.9％ sodium chloride of 0.1 ml was injected into the skin graft once daily for 28 days.The value of DNA fluorescence intensity of human epidermal cells was detected with a laser scanning confocal microscope.Result IL-10 markedly reduced the value of DNA fluorescence intensity of human epidermal cells (t=5.97,P ＜ 0.05).Conclusion IL-10 can reduce the content of DNA during the proliferation and differentiation of human epidermal cells. Key words: IL-10; Human epidermal cells; DNA; Fluorescence intensity

Effect of IL-17 on fluorescence density of DNA in human epidermal cells

Objective To explore the impact of IL-17 on the fluorescence density of DNA in human epidermal cells.Methods The normal human skin was transplanted to nude mice to establish a skin-nude mice chimeric model in 60 mice.According to requirements in matched-pairs design,the mice were randomly divided into a study group and a control group,30 for each group.In the study group,IL-17 of 0.1 ml (10 ng/ml) was injected into the skin graft,while 0.9％ sodium chloride of 0.1 ml was injected into the skin graft once daily for 28 days.The value of DNA fluorescence density of human epidermal cells was detected with a laser scanning confocal microscope.Results IL-17 could markedly increase the fluorescence density of DNA in skin cells (t =7.6102,P＜0.05).Conclusions IL-17 can promote an increase in DNA content during the proliferation of human epidermal cells. Key words: IL-17; Human epidermal cells; DNA

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

On circadian rhythms in human epidermal cell proliferation.

The ascertainment of consistent diurnal variations in human epidermal cell proliferation may have important implications for the treatment of many skin diseases. For the evaluation of diurnal rhythms in the growth of human epidermis, skin biopsies were taken every 4th hour for 48 h from each of two persons under synchronized living conditions. The epidermal cell proliferation was assessed by the fraction of cells in S and in G2-M phase as determined by measurements of the DNA content in the individual cells in single-cell suspensions. The existence of diurnally consistent body functions in the test persons was verified by monitoring the excretion of cortisol by urine. The fraction of cells in G2-M phase indicated circadian rhythmicity for the first 32 h of the test period. No regular variation according to time of day could be established in the fraction of cells in S-phase.

Evidence of diurnal variation of human epidermal cell proliferation. I. Epidermal 3H-labeling index and serum cortisol rhythm.

Performing two longitudinal studies over 48 and 66 h, respectively, in 12 healthy male adult volunteers the epidermal LI were measured by in vitro 3H-thymidine labeling technique every 6 h and serum cortisol levels simultaneously by RIA examination. While serum cortisol showed a circadian rhythm over the whole test period, a circadian rhythmic pattern of epidermal LI yet became evident 12 h after the onset of experiments. This initial time lag in appearance of LI periodicity may be due to some temporal desynchronization in the cell cycle of keratinocytes. Circadian peaks and minima of both cortisol and LI were found to be inversely correlated, with a time-shifting of 6 h according to the experimental conditions. The present results reveal strong evidence that circadian fluctuation of endogenous cortisol secretion does influence the regulation of epidermal DNA-synthesis in man.

Evidence of diurnal variation of human epidermal cell proliferation. II. Duration of epidermal DNA synthesis.

In the epidermis of six healthy male volunteers the DNA synthesis time was measured by in vitro double labeling technique in a longitudinal study (48 h) with taking skin punch biopsies every 6 h. The external conditions of the experiments and one group of volunteers were identical to those of a previous study on LI of the epidermal keratinocytes. 14C-thymidine and 3H-thymidine were used for double labeling the DNA-synthesizing nuclei of keratinocytes. The duration of DNA replication time proved to be nearly constant, with minor fluctuation, during the entire time span of experiments (mean 6.19 +/- 0.3 h). Thus, the present results are in accordance with the conception that a periodically changing entrance rate of G1-cells into the S-phase of the generation cycle of keratinocytes is predominantly responsible for circadian variations in the number of DNA-synthesizing epidermal keratinocytes.

Proliferative response to fluid injection in psoriatic and normal human epidermis.

Feulgen-DNA cytophotometry revealed that human epidermal cell proliferation is regulated at a pre-DNA synthetic phase and can be perturbed by mild trauma. Although uninvolved psoriatic skin appears clinically normal, its hypersensitivity indicates abnormal proliferative behaviour and may serve as a marker of latent disease.

Human epidermal cell proliferation with regard to circadian variation of plasma cortisol.

This study was performed in 6 healthy young men under analogous experimental conditions to investigate whether or not the epidermal proliferative activity is influenced by the physiological circadian rhythmicity of cortisol concentration in blood. Every 6 h of total duration of the experiments, blood samples were taken for radioimmunoassay of serum cortisol and skin punch biopsies (upper arm inside) were labelled in vitro by 3H-thymidine. In 4 out of 6 individuals, an inverse and time-shifted correlation between the combined serum cortisol levels and the epidermal 3H-LI could be found, i.e., a rise or decline of serum cortisol were followed by a lowered or elevated rate of epidermal LI 6 h later. In particular, a steep increase of serum cortisol from midnight to 6 a.m. correlated to a decrease of 3H-LI from 6 a.m. to noon. This indicates that in man the rate of the epidermal proliferative activity inversely depends, apart from other mechanisms of regulation, on the concentration and circadian periodicity of endogenous cortisol in blood. However, we failed to demonstrate a clear circadian rhythm of the epidermal proliferation, possibly due to the short duration of the experiments extended in each individual to 48 h only.

Autoradiographic in vitro studies on diurnal variation in human epidermal cell proliferation.

Five men with healthy skin ranging in age from 24 to 37 years were investigated for the presence of diurnal variation in epidermal cell proliferation by the in vitro 3H-thymidine labeling technique. The following parameters were studied: The basal cell LI; the numbers of labeled basas and supra-basal cell nuclei as well as the total number of labeled nuclei situated above a basal membrane length of 100 mum. All autoradiographic parameters showed marked diurnal variations, the amplitudes of which differed individually. The basal 3H labeling index always showed the highest diurnal variation. In all patients diurnal variations of the basal and suprabasal cell proliferation occurred simultaneously and in equal direction. However, each test person showed maxima and minima of epidermal DNA synthesis at different times. No synchronism could be found when comparing the individual variations of cell proliferation. Several possible reasons for the asynchronous in vitro behaviour of epidermal cells will be discussed.

Cytophotometric Studies Of Epidermal Proliferation In Psoriatic And Normal Skin

Cytophotometric measurements of single-cell DNA content were used to study human epidermal cell proliferation in vivo. It was found that Feulgen-DNA profiles can be used to assess proliferative activity in involved, uninvolved, and nonpsoriatic skin. Profiles of involved psoriatic skin were bimodal as is characteristic of actively proliferating populations. This was due to the presence of cells with twice (2C--presynthetic) or four times (4C--post-synthetic) the amount of DNA of the gametes, separated by the intermediate values of cells undergoing scheduled DNA synthesis. Profiles of uninvolved psoriatic as well as nonpsoriatic epidermis were unimodal with the majority of cells containing a 2C amount of DNA incating relatively low levels of proliferative activity. The observed variations in proliferative activity of these samples are discussed in terms of two alternative models. Since radioisotopes are not required, this technique presents a useful approach to studying human epidermal proliferation in vivo.

Kinetics of Human Epidermal Cell Proliferation: Diurnal Variation

Kinetics of Human Epidermal Cell Proliferation: Diurnal Variation