Enrichment of putative human epidermal stem cells based on cell size and collagen type IV adhesiveness

The enrichment and identification of human epidermal stem cells （EpSCs） are of paramount importance for both basic research and clinical application. Although several approaches for the enrichment of EpSCs have been established, enriching a pure population of viable EpSCs is still a challenging task. An improved approach is worth developing to enhance the purity and viability of EpSCs. Here we report that cell size combined with collagen type IV adhesiveness can be used in an improved approach to enrich pure and viable human EpSCs. We separated the rap- idly adherent keratinocytes into three populations that range in size from 5-7 μm （population A）, to 7-9 μm （population B）, to ≥9μm （population C） in diameter, and found that human putative EpSCs could be further enriched in population A with the smallest size. Among the three populations, population A displayed the highest density of plintegrin receptor, contained the highest percentage of cells in G0/G1 phase, showed the highest nucleus to cytoplasm ratio, and possessed the highest colony formation efficiency （CFE）. When injected into murine blastocysts, these cells participated in multi-tissue formation. More significantly, compared with a previous approach that sorted putative EpSCs according to pl-integrin antibody staining, the viability of the EpSCs enriched by the improved approach was significantly enhanced. Our results provide a putative strategy for the enrichment of human EpSCs, and encourage further study into the role of cell size in stem cell biology.

Ultrafast optical modulation of the fluorescence from a single-photon emitter in silicon carbide

The quest for the room-temperature optical transistor based on nonlinearities in single atoms or molecules is attracting a lot of attention.In this work,a single-photon emitter in cubic silicon carbide is verified that can operate as an optical switch at room temperature under pulsed green laser illumination with a near-infrared pulsed laser as the control gate.We demonstrated an ultrafast and reversible optical modulation with a high photoluminescence intensity suppression ratio up to 97.9%and a response time as short as 287.9±5.7 ps.The current development provides insights for high-precision and ultrafast optical switches,with possibilities for integration with emerging electronic installations to realize more intelligent photoelectric integrated devices.

Role of αVβ3 integrin in embryo implantation in the mouse

Integrin, a heterodimeric adhesive molecule composed of a and (5 subunits, can regulate cell adhesion and trafficking. Recent data have documented that, at the 'implantation window' stage, aVp3 integrin participates in the maternal-fetal interaction and becomes a potential marker of uterine receptivity. Furthermore, it can affect invasiveness of embryo. This work made a further study about its action mechanism. Results of indirect immunofluorescence and laser scanning confocal microscopy showed that αVβ3 integrin was clearly expressed in the mouse blastocyst. Injection of αVβS integrin antiserum into a uterine horn of a pregnant mouse on day 3 markedly decreased the number of embryos implanted (P 【 0.001). In a co-culture model, aVp3 integrin antisera at 1 : 100 and 1 : 200 dilutions significantly depressed the attachment and outgrowth reactions of blastocysts on monolayer of uterine epithelial cells. Analysis of correlation manifested that the inhibitory effect of αVβ3 integrin antiserum was

Effect of fibronectin and leukaemia inhibitory factor on matrix metalloproteinases in mouse blastocyst

This study was designed to detect the effects of fibronectin (FN) and leukaemia inhibitory factor (LIF) on matrix metallopoteinases (MMPs) of mouse blastocysts. The experiments comprised four groups: first, blastocysts grew on the dishes with FN-coated; the second, without FN-coated; the third group, without FN coated, but with 20 ng/μL LIF added to culture medium; and the fourth group, with both FN-coated and 20 ng/μL LIF added. Using MMP-2 and MMP-9 primers respectively, the expressions of MMP-2 and MMP-9 were detected by RT-PCR and cloning identification. The results showed that in the first group, MMP-2 and MMP-9 were produced after 12 and 24 h culturing; in the third group, there were both MMP-2 and MMP-9 bands when blastocysts were cultured for 24 h; and in the fourth group, MMP-2 and MMP-9 bands appeared when blastocysts were cultured for 6, 12 and 24 h. But in the second group no MMP-2 or MMP-9 band appeared. These results show that FN may initiate the transcription of MMP-2 and MMP-9 genes

mTOR signaling promotes stem cell activation via counterbalancing BMP-mediated suppression during hair regeneration

Hair follicles(HFs)undergo cycles of degeneration(catagen),rest(telogen),and regeneration(anagen)phases.Anagen begins when the hair follicle stem cells(HFSCs)obtain sufficient activation cues to overcome suppressive signals,mainly the BMP pathway,from their niche cells.Here,we unveil that mTOR complex 1(mTORC1)signaling is activated in HFSCs,which coincides with the HFSC activation at the telogen-to-anagen transition.By using both an inducible conditional gene targeting strategy and a pharmacological inhibition method to ablate or inhibit mTOR signaling in adult skin epithelium before anagen initiation,we demonstrate that HFs that cannot respond to mTOR signaling display significantly delayed HFSC activation and extended telogen.Unexpectedly,BMP signaling activity is dramatically prolonged in mTOR signaling-deficient HFs.Through both gain-and loss-of-function studies in vitro,we show that mTORC1 signaling negatively affects BMP signaling,which serves as a main mechanism whereby mTORC1 signaling facilitates HFSC activation.Indeed,in vivo suppression of BMP by its antagonist Noggin rescues the HFSC activation defect in mTORC1-null skin.Our findings reveal a critical role for mTOR signaling in regulating stem cell activation through counterbalancing BMP-mediated repression during hair regeneration.

The expression and function of VEGF at embryo implantation "window" in the mouse

Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen that plays a critical role in angiogenesis. Recent reports indicated that VEGF was closely involved in embryo implantation and embryonic vasculogenesis. However, very little information is available about the detailed expression and function of VEGF at implantation 'window'. In this work, VEGFs were primarily present on uterine epithelial cell monolayer and blasto-cysts including the outgrew trophoblasts at implantation window. VEGF antibodies decreased the number of mice embryos implanted and the percentage of blastocysts with attachment and outgrowth in a co-culture model in a dose-dependant manner. These findings demonstrate that VEGF is one of the essential cytokines for embryo implantation in mouse. VEGF may act as a local mediator to regulate the maternal-fetal interaction, and facilitate blastocyst implantation.

Identification and characterization of an ancient class of small RNAs enriched in serum associating with active infection

Dear Editor,The identification of novel serum biomarkers holds great value for diagnosing and monitoring disease conditions due to its convenient and non-invasive nature.Recently,great interests have been shed on serum microRNAs(miRNAs),which emerge as promising biomarkers for a variety of diseases including cancer and metabolic disorders(Cortez et al.,2011).Despite the concentrated attention on serum miRNAs,the reports on the existence and diagnostic value of other serum small RNAs remain surprisingly few.In present study.

Cooperation-based sperm clusters mediate sperm oviduct entry and fertilization

Dear Editor,Sperm cooperation has been observed in multiple species(Pizzari and Foster,2008),yet its existenee and benefit for reproductive success in mammals remains underexplored.Here,combining tissue-clearing with deep three-dimensional(3D)imagi ng,we dem on strate that postcopulatory mouse sperm congregate into unidirectional sperm cooperative clusters at the utero-tubal junction(UTJ),a key physical barrier for passage into the oviduct.