Effects of NaCl and Ca^2+on Membrane Potential of Epidermal Cells of Maize Roots

The effects of salt-stress on plants involve not only the water stress caused by low osmotic pressure, but also the toxicity of excess Na^＋. A large amount of Na^＋ entering cells would reduce K^＋ uptake, which leads to an imbalance of K：Na ratio in cells. One of the reasons for the reduced K^＋-uptake is the closure of K^＋-channel which is controlled by membrane potential. Calcium is usually applied to improve the growth of plants on saline soils and shows positive influence in the integrality of cell membrane. This study applied glass microelectrode technique to monitoring the NaCl-induced changes of membrane potential of root epidermal cells of maize （Zea mays L., Denghai 11） seedlings at NaCl concentrations of 0, 8, 20, 50, 100, 200 mmol L^-1, respectively. The effect of Ca^2＋ on the changes of membrane potential caused by NaCl was also studied. The results showed that： NaCl caused cell membrane depolarization. The depolarization became greater and faster with increasing of NaCl concentration. Moreover, the extent of depolarization was positively correlated with NaCl concentration. The addition of calcium postponed the depolarization, and decreased the degree of depolarization caused by NaCl. High NaCl concentration leads to depolarization of maize root cell membrane, which can partly be counteracted by calcium.

Leaf Epidermal Cells： A Trap for Lipophilic Xenobiotics

Plant surfaces are covered by a layer of cuticle, which functions as a natural barrier to protect plants from mechanical damage, desiccation, and microbial invasion. Results presented in this report show that the epicuticular wax and the cuticle of plant leaves also play an important role in resisting xenobiotic invasion. Although the epicuticular wax is impermeable to hydrophilic xenobiotics, the cuticle not only restricts the penetration of hydrophilic compounds into leaf cells, but also traps lipophilic ones. The role of the epidermal cells of plant leaves in resisting xenobiotic invasion has been neglected until now. The present study shows, for the first time, that the epidermal cells may reduce or retard the transport of lipophilic xenobiotics into the internal tissues through vacuolar sequestration. Although the guard cells appear to be an easy point of entry for xenobiotics, only a very small proportion of xenobiotics present on the leaf surface actually moves into leaf tissues via the guard cells .

Substance P combined with epidermal stem cells promotes wound healing and nerve regeneration in diabetes mellitus

Exogenous substance P accelerates wound healing in diabetes,but the mechanism remains poorly understood.Here,we established a rat model by intraperitoneally injecting streptozotocin.Four wounds（1.8 cm diameter） were drilled using a self-made punch onto the back,bilateral to the vertebral column,and then treated using amniotic membrane with epidermal stem cells and/or substance P around and in the middle of the wounds.With the combined treatment the wound-healing rate was 100% at 14 days.With prolonged time,type I collagen content gradually increased,yet type III collagen content gradually diminished.Abundant protein gene product 9.5-and substance P-immunoreactive nerve fibers regenerated.Partial nerve fiber endings extended to the epidermis.The therapeutic effects of combined substance P and epidermal stem cells were better than with amniotic membrane and either factor alone.Our results suggest that the combination of substance P and epidermal stem cells effectively contributes to nerve regeneration and wound healing in diabetic rats.

Inhibition of epidermal growth factor receptor signaling protects human malignant glioma cells from hypoxia - induced cell death

Epidermal growth factor receptor(EGFR)signaling has become an importanttarget for drug development becauseEGFR signaling enhances tumor cell proliferation,migration,and invasion and inhibits apoptosis.However,theresults of clinical trials using EGFR inhibitors in patients with solid tumors have been disappointing.Here,wereport a protective effect of the EGFR inhibitors AG1478 and PD153035 against cell death induced by acute hy-poxia,which contrasts with their proapoptotic effects under normoxia.Under hypoxic conditions,both agents re-

Study on the Physiological,Cellular,and Morphological Aspects of the Postharvest Development of Cut Lily Flowers

It is of great practical significance to study the development process of cut lily for regulating flowering and preservation.In this study,the developmental process of lily cut flower was explored from cellular,morphological,and physiological aspects.Froma morphological aspect,the tepal edge grows faster than the midrib.The midrib groove of the flowering stage is wider than that of bud stage.The fast-growing edge of the petals results in the midrib bending outward.Moreover,the rapid growth of the stamens and stigmas also contributes to bud cracking.From the cellular aspect,in the bud stage there were more wrinkles in the outer epidermal cell wall of the tepal than those in the inner epidermal cell wall,indicating that asymmetric structural differences exist from the beginning of lily development.From a physiological aspect,from the bud cracking stage to the senescence stage,a variety of substances in the tepal cells gradually decreased,including total nitrogen,total phosphorus,total potassium,total calcium,starch,soluble sugar,and soluble protein,but not malondialdehyde.These results indicate that the asymmetric growth caused by this structural difference is responsible for flowering.The wrinkles in the cell wall can be regarded as indicators of senescent cells and are caused by the degradation of the cell wall and the loss of intracellular turgor pressure.The differences in the epidermal cells between the inner and outer tepal indicated ultrastructural changes in the tepal cells.The bud and flowering stages are maintained by the tepals acting as a sink.After flowering,the tepals gradually change from a sink to a source organ.Senescence of the cut lily flowers was caused by the decomposition of intracellular compounds in the tepals and the remobilization of nutrients from the tepals to the developing organs.

Efficacy of EGFR Tyrosine Kinase Inhibitors in Non-small Cell Lung Cancer Patients Harboring Different Types of EGFR Mutations:A Retrospective Analysis

With the development of molecular pathology, many types of epidermal growth factor receptor（EGFR） mutations have been identified. The efficacy of EGFR tyrosine kinase inhibitors（EGFR-TKIs） in non-small cell lung cancer（NSCLC） patients with different types of EGFR mutations, especially in patients with single rare mutations or complex mutations（co-occurrence of two or more different mutations）, has not been fully understood. This study aimed to examine the efficacy of EGFR-TKIs in NSCLC patients with different types of EGFR mutations. Clinical data of 809 NSCLC patients who harbored different types of EGFR mutations and treated from January 2012 to October 2016 at Renmin Hospital and Zhongnan Hospital, Wuhan, were retrospectively reviewed. The clinical characteristics of these patients and the efficacy of EGFR-TKIs were analyzed. Among these patients, 377 patients had only the EGFR del-19 mutation, 362 patients the EGFR L858R mutation in exon 21, 33 patients single rare mutations and 37 patients complex mutations. Among these 809 patients, 239 patients were treated with EGFR-TKIs. In all the 239 patients, the disease control rate（DCR） was 93.7% with two patients（0.2%） achieving complete response（CR）, the median progression free survival（PFS） was 13.0 months（95% confidence interval [CI], 11.6–14.4 months）, and the median overall survival（OS） was 55.0 months（95% CI, 26.3–83.7 months）. Subgroup analysis revealed that the DCR in patients harboring single rare or complex mutations of EGFR was significantly lower than in those with del-19 or L858 R mutation（P〈0.001）. Patients with classic mutations（del-19 and/or L858 R mutations） demonstrated longer PFS（P〈0.001） and OS（P=0.017） than those with uncommon mutations（single rare and/or complex mutations）. Furthermore, the patients with single rare mutations had shorter median OS than in those with other mutations. Multivariate Cox regression analysis identified that the type of EGFR mutations was an independent risk factor for PFS（hazard ratio [HR]=0.308, 95% CI, 0.191–0.494, P〈0.001） and OS（HR=0.221, 95% CI, 0.101–0.480, P〈0.001）. The results suggest that the single rare or complex EGFR mutations confer inferior efficacy of EGFR-TKIs treatment to the classic mutations. The prognosis of the single rare EGFR mutations is depressing. EGFR-TKIs may be not a good choice for NSCLC patients with single rare mutations of EGFR. Further studies in these patients with uncommon mutations（especially for the patients with single rare mutations） are needed to determine a better precision treatment.

Epithelial stem cell islands in the regenerated epidermis

Objective: The effects of growth factors on wound healing have been studied extensively, however, their molecular and genetic mechanisms that regulate epidermal regeneration are not fully understood. In this study, we explore the cell reversion characteristics and epithelial stem cell distribution in human regenerated epidermis treated with recombinant human epidermal growth factor (rhEGF). Methods:Tissue biospies from 8 regenerated skins treated with rhEGF were used to evaluate the cell reversion.

The molecular mechanisms supporting the homeostasis and activation of dendritic epidermal T cell and its role in promoting wound healing

The epidermis is the outermost layer of skin and the first barrier against invasion.Dendritic epidermal T cells(DETCs)are a subset ofT cells and an important component of the epidermal immune microenvironment.DETCs are involved in skin wound healing,malignancy and autoim-mune diseases.DETCs secrete insulin-like growth factor-1 and keratinocyte growth factor for skin homeostasis and re-epithelization and release inflammatory factors to adjust the inflammatory microenvironment of wound healing.Therefore,an understanding of their development,activation and correlative signalling pathways is indispensable for the regulation of DETCs to accelerate wound healing.Our review focuses on the above-mentioned molecular mechanisms to provide a general research framework to regulate and control the function of DETCs.

Calcium silicate accelerates cutaneous wound healing with enhanced re-epithelialization through EGF/EGFR/ERK-mediated promotion of epidermal stem cell functions

Background:Human epidermal stem cells(hESCs)play an important role in re-epithelialization and thereby in facilitating wound healing,while an effective way to activate hESCs remains to be explored.Calcium silicate(CS)is a form of bioceramic that can alter cell behavior and promote tissue regeneration.Here,we have observed the effect of CS on hESCs and investigated its possible mechanism.Methods:Using a mouse full-thickness skin excision model,we explored the therapeutic effect of CS on wound healing and re-epithelialization.In vitro,hESCs were cultured with diluted CS ion extracts(CSIEs),and the proliferation,migration ability and stemness of hESCs were evaluated.The effects of CS on the epidermal growth factor(EGF),epidermal growth factor receptor(EGFR)and extracellular signal-related kinase(ERK)signaling pathway were also explored.Results:In vivo,CS accelerated wound healing and re-epithelialization.Immunohistochemistry demonstrated that CS upregulated cytokeratin 19 and integrinβ1 expression,indicating that CS improved hESCs stemness.In vitro studies confirmed that CS improved the biological function of hESCs.And the possible mechanism could be due to the activation of the EGF/EGFR/ERK signaling pathway.Conclusion:CS can promote re-epithelialization and improve the biological functions of hESCs via activating the EGF/EGFR/ERK signaling pathway.

Spatial and Temporal Quantitative Analysis of Cell Division and Elongation Rate in Growing Wheat Leaves under Saline Conditions

Leaf growth in grasses is determined by the cell division and elongation rates, with the duration of cell elongation being one of the processes that is the most sensitive to salinity. Our objective was to investigate the distribution profiles of cell production, cell length and the duration of cell elongation in the growing zone of the wheat leaf during the steady growth phase. Plants were grown in loamy soil with or without 120 mmollL NaCI in a growth chamber, and harvested at day 3 after leaf 4 emerged. Results show that the elongation rate of leaf 4 was reduced by t20 mmollL NaCI during the steady growth phase. The distribution profile of the lengths of abaxial epidermal cells of leaf 4 during the steady growth stage shows a sigmoidal pattern along the leaf axis for both treatments. Although salinity did not affect or even increased the length of the epidermal cells in some locations in the growth zone compared to the control treatment, the final length of the epidermal cells was reduced by 14% at 120 mmollL NaCI. Thus, we concluded that the observed reduction in the leaf elongation rate derived in part from the reduced cell division rate and either the shortened cell elongation zone or shortened duration of cell elongation. This suggests that more attention should be paid to the effects of salinity on those properties of cell production and the period of cell maturation that are related to the properties of cell wall.

Genetic reporter analysis reveals an expandable reservoir of OCT4+cells in adult skin

The transcription factor Oct4(Pou5f1)is a critical regulator of pluripotency in embryonic and induced pluripotent stem cells.Therefore,Oct4 expression might identify somatic stem cell populations with inherent multipotent potential or a propensity for facilitated reprogramming.However,analysis of Oct4 expression is confounded by Oct4 pseudogenes or non-pluripotency-related isoforms.Systematic analysis of a transgenic Oct4-EGFP reporter mouse identified testis and skin as two principle sources of Oct4^(+)cells in postnatal mice.While the prevalence of GFP^(+)cells in testis rapidly declined with age,the skin-resident GFP^(+)population expanded in a cyclical fashion.These cells were identified as epidermal stem cells dwelling in the stem cell niche of the hair follicle,which endogenously expressed all principle reprogramming factors at low levels.Interestingly,skin wounding or non-traumatic hair removal robustly expanded the GFP^(+)epidermal cell pool not only locally,but also in uninjured skin areas,demonstrating the existence of a systemic response.Thus,the epithelial stem cell niche of the hair follicle harbors an expandable pool of Oct4^(+)stem cells,which might be useful for therapeutic cell transfer or facilitated reprogramming.

Petal Development in Lotus japonicus

Previous studies have demonstrated that petal shape and size in legume flowers are determined by two separate mechanisms, dorsoventral （DV） and organ internal （IN） asymmetric mechanisms, respectively. However, little is known about the molecular mechanisms controlling petal development in legumes. To address this question, we investigated petal development along the floral DV axis in Lotus japonicus with respect to cell and developmental biology by comparing wild-type legumes to mutants. Based on morphological markers, the entire course of petal development, from initiation to maturity, was grouped to define 3 phases or 13 stages. In terms of epidermal micromorphology from adaxial surface, mature petals were divided into several distinct domains, and characteristic epidermal cells of each petal differentiated at stage 9, while epidermal cells of all domains were observed until stage 12. TCP and MIXTA-like genes were found to be differentially expressed in various domains of petals at stages 9 and 12. Our results suggest that DV and IN mechanisms interplay at different stages of petal development, and their interaction at the cellular and molecular level guides the elaboration of domains within petals to achieve their ideal shape, and further suggest that TCP genes determine petal identity along the DV axis by regulatincl MIXTA-like clene expression.

Platelet-rich plasma accelerates skin wound healing by promoting re-epithelialization

Background:Autologous platelet-rich plasma(PRP)has been suggested to be effective for wound healing.However,evidence for its use in patients with acute and chronic wounds remains insufficient.The aims of this study were to comprehensively examine the effectiveness,synergy and possible mechanism of PRP-mediated improvement of acute skin wound repair.Methods:Full-thickness wounds were made on the back of C57/BL6 mice.PRP or saline solution as a control was administered to the wound area.Wound healing rate,local inflammation,angiogenesis,re-epithelialization and collagen deposition were measured at days 3,5,7 and 14 after skin injury.The biological character of epidermal stem cells(ESCs),which reflect the potential for re-epithelialization,was further evaluated in vitro and in vivo.Results:PRP strongly improved skin wound healing,which was associated with regulation of local inflammation,enhancement of angiogenesis and re-epithelialization.PRP treatment significantly reduced the production of inflammatory cytokines interleukin-17A and interleukin-1β.An increase in the local vessel intensity and enhancement of re-epithelialization were also observed in animals with PRP administration and were associated with enhanced secretion of growth factors such as vascular endothelial growth factor and insulin-like growth factor-1.Moreover,PRP treatment ameliorated the survival and activated the migration and proliferation of primary cultured ESCs,and these effects were accompanied by the differentiation of ESCs into adult cells following the changes of CD49f and keratin 10 and keratin 14.Conclusion:PRP improved skin wound healing by modulating inflammation and increasing angiogenesis and re-epithelialization.However,the underlying regulatory mechanism needs to be investigated in the future.Our data provide a preliminary theoretical foundation for the clinical administration of PRP in wound healing and skin regeneration.

Photodynamic therapy accelerates skin wound healing through promoting re-epithelialization

Background:Epidermal stem cells(EpSCs)that reside in cutaneous hair follicles and the basal layer of the epidermis are indispensable for wound healing and skin homeostasis.Little is known about the effects of photochemical activation on EpSC differentiation,proliferation and migration during wound healing.The present study aimed to determine the effects of photodynamic therapy(PDT)on wound healing in vivo and in vitro.Methods:We created mouse full-thickness skin resection models and applied 5-aminolevulinic acid(ALA)for PDT to the wound beds.Wound healing was analysed by gross evaluation and haematoxylin–eosin staining in vivo.In cultured EpSCs,protein expression was measured using flow cytometry and immunohistochemistry.Cell migration was examined using a scratch model;apoptosis and differentiation were measured using flow cytometry.Results:PDT accelerated wound closure by enhancing EpSC differentiation,proliferation and migration,thereby promoting re-epithelialization and angiogenesis.PDT inhibited inflammatory infiltration and expression of proinflammatory cytokines,whereas the secretion of growth factors was greater than in other groups.The proportion of transient amplifying cells was significantly greater in vivo and in vitro in the PDT groups.EpSC migration was markedly enhanced after ALAinduced PDT.Conclusions:Topical ALA-induced PDT stimulates wound healing by enhancing re-epithelialization,promoting angiogenesis as well as modulating skin homeostasis.This work provides a preliminary theoretical foundation for the clinical administration of topical ALA-induced PDT in skin wound healing.

Study on the effects of alternating capacitive electric fields with different frequencies on promoting wound healing

Some researches to facilitate wound healing by using electrical stimulation are based on electric current stimulation,which may cause secondary damage and the imbalance of the microenvironment in vivo.In this study,alternating capacitive electric field(ACEF)was applied via a self-designed system so as to avoid direct contact with cells and to maintain stable microenvironment for cell growth.The influences of 58 mV/mm ACEFs with various frequencies of 10,60 and 110 Hz on epidermal cells,fibroblasts and macrophages which involve in wound healing were comprehensively explored.The results suggested that ACEFs of 10,60 and 110 Hz all significantly promoted the proliferation of human dermal fibroblasts(HDFs)and human epidermal keratinocyte cell line(HaCaT)cells,and 60 Hz ACEF furtherly accelerated the migration of these two kinds of cells.Moreover,ACEFs of all different studied frequencies facilitated M2-type polarization of macrophages,and YAP/TAZ expression of macrophages were enhanced under the stimulations of 10 and 60 Hz ACEFs.The enhancements in cell activity,migration rate and M2-type polarizability indicated that 58 mV/mm ACEFs especially at 60 Hz possessing potentially affirmative applications for wound healing without the risks of secondary damage and microenvironment imbalance.