Échangeons nos lunettes

«Jai carte blanche complète, les élus me laissent faire ce que je veux, c\u27est confortable, je suis complètement autonome, mais j\u27ai peur que cela change quand on va passer en intercommunalité", explique un adjoint du patrimoine responsable d\u27une bibliothèque minicipale, en début de formation

Organization of the Drosophila larval visual circuit

Visual systems transduce, process and transmit light-dependent environmental cues. Computation of visual features depends on the types of photoreceptor neurons (PR) present, the organization of the eye and the wiring of the underlying neural circuit. Here, we describe the circuit architecture of the visual system of Drosophila larvae by mapping the synaptic wiring diagram and neurotransmitters. By contacting different targets, the two larval PR-subtypes create parallel circuits potentially underlying the computation of absolute light intensity and temporal light changes already within this first visual processing center. Locally processed visual information then signals via dedicated projection interneurons to higher brain areas including the lateral horn and mushroom body. The stratified structure of the LON suggests common organizational principles with the adult fly and vertebrate visual systems. The complete synaptic wiring diagram of the LON paves the way to understanding how circuits with reduced numerical complexity control wide ranges of behaviors

25 years of epidermal stem cell research.

This is a chronicle of concepts in the field of epidermal stem cell biology and a historic look at their development over time. The past 25 years have seen the evolution of epidermal stem cell science, from first fundamental studies to a sophisticated science. The study of epithelial stem cell biology was aided by the ability to visualize the distribution of stem cells and their progeny through lineage analysis studies. The excellent progress we have made in understanding epidermal stem cell biology is discussed in this article. The challenges we still face in understanding epidermal stem cells include defining molecular markers for stem and progenitor sub-populations, determining the locations and contributions of the different stem cell niches, and mapping regulatory pathways of epidermal stem cell proliferation and differentiation. However, our rapidly evolving understanding of epidermal stem cells has many potential uses that promise to translate into improved patient therapy

Reconstruction of Endometrium from Human Endometrial Side Population Cell Lines

Endometrial regeneration is mediated, at least in part, by the existence of a specialized somatic stem cell (SSC) population recently identified by several groups using the side population (SP) technique. We previously demonstrated that endometrial SP displays genotypic, phenotypic and the functional capability to develop human endometrium after subcutaneous injection in NOD-SCID mice. We have now established seven human endometrial SP (hESP) cell lines (ICE 1–7): four from the epithelial and three from the stromal fraction, respectively. SP cell lines were generated under hypoxic conditions based on their cloning efficiency ability, cultured for 12–15 passages (20 weeks) and cryopreserved. Cell lines displayed normal 46XX karyotype, intermediate telomerase activity pattern and expressed mRNAs encoding proteins that are considered characteristic of undifferentiated cells (Oct-4, GDF3, DNMT3B, Nanog, GABR3) and those of mesodermal origin (WT1, Cardiac Actin, Enolase, Globin, REN). Phenotype analysis corroborated their epithelial (CD9+) or stromal (vimentin+) cell origin and mesenchymal (CD90+, CD73+ and CD45−) attributes. Markers considered characteristic of ectoderm or endoderm were not detected. Cells did not express either estrogen receptor alpha (ERα) or progesterone receptor (PR). The hESP cell lines were able to differentiate in vitro into adipocytes and osteocytes, which confirmed their mesenchymal origin. Finally, we demonstrated their ability to generate human endometrium when transplanted beneath the renal capsule of NOD-SCID mice. These findings confirm that SP cells exhibit key features of human endometrial SSC and open up new possibilities for the understanding of gynecological disorders such as endometriosis or Asherman syndrome. Our cell lines can be a valuable model to investigate new targets for endometrium proliferation in endometriosis

Bone Marrow-Derived Cells from Male Donors Do Not Contribute to the Endometrial Side Population of the Recipient

Accumulated evidence demonstrates the existence of bone marrow-derived cells origin in the endometria of women undergoing bone marrow transplantation (BMT). In these reports, cells of a bone marrow (BM) origin are able to differentiate into endometrial cells, although their contribution to endometrial regeneration is not yet clear. We have previously demonstrated the functional relevance of side population (SP) cells as the endogenous source of somatic stem cells (SSC) in the human endometrium. The present work aims to understand the presence and contribution of bone marrow-derived cells to the endometrium and the endometrial SP population of women who received BMT from male donors. Five female recipients with spontaneous or induced menstruations were selected and their endometrium was examined for the contribution of XY donor-derived cells using fluorescent in situ hybridization (FISH), telomapping and SP method investigation. We confirm the presence of XY donor-derived cells in the recipient endometrium ranging from 1.7% to 2.62%. We also identify 0.45–0.85% of the donor-derived cells in the epithelial compartment displaying CD9 marker, and 1.0–1.83% of the Vimentin-positive XY donor-derived cells in the stromal compartment. Although the percentage of endometrial SP cells decreased, possibly being due to chemotherapy applied to these patients, they were not formed by XY donor-derived cells, donor BM cells were not associated with the stem cell (SC) niches assessed by telomapping technique, and engraftment percentages were very low with no correlation between time from transplant and engraftment efficiency, suggesting random terminal differentiation. In conclusion, XY donor-derived cells of a BM origin may be considered a limited exogenous source of transdifferentiated endometrial cells rather than a cyclic source of BM donor-derived stem cells

Isolation and Characterization of Human Trophoblast Side-Population (SP) Cells in Primary Villous Cytotrophoblasts and HTR-8/SVneo Cell Line

Recently, numerous studies have identified that immature cell populations including stem cells and progenitor cells can be found among “side-population” (SP) cells. Although SP cells isolated from some adult tissues have been reported elsewhere, isolation and characterization of human trophoblast SP remained to be reported. In this study, HTR-8/SVneo cells and human primary villous cytotrophoblasts (vCTBs) were stained with Hoechst 33342 and SP and non-SP (NSP) fractions were isolated using a cell sorter. A small population of SP cells was identified in HTR-8/SVneo cells and in vCTBs. SP cells expressed several vCTB-specific markers and failed to express syncytiotrophoblast (STB) or extravillous cytotrophopblast (EVT)-specific differentiation markers. SP cells formed colonies and proliferated on mouse embryonic fibroblast (MEF) feeder cells or in MEF conditioned medium supplemented with heparin/FGF2, and they also showed long-term repopulating property. SP cells could differentiate into both STB and EVT cell lineages and expressed several differentiation markers. Microarray analysis revealed that IL7R and IL1R2 were exclusively expressed in SP cells and not in NSP cells. vCTB cells sorted as positive for both IL7R and IL1R2 failed to express trophoblast differentiation markers and spontaneously differentiated into both STB and EVT in basal medium. These features shown by the SP cells suggested that IL7R and IL1R2 are available as markers to detect the SP cells and that vCTB progenitor cells and trophoblast stem cells were involved in the SP cell population

Human Endometrial Side Population Cells Exhibit Genotypic, Phenotypic and Functional Features of Somatic Stem Cells

During reproductive life, the human endometrium undergoes around 480 cycles of growth, breakdown and regeneration should pregnancy not be achieved. This outstanding regenerative capacity is the basis for women's cycling and its dysfunction may be involved in the etiology of pathological disorders. Therefore, the human endometrial tissue must rely on a remarkable endometrial somatic stem cells (SSC) population. Here we explore the hypothesis that human endometrial side population (SP) cells correspond to somatic stem cells. We isolated, identified and characterized the SP corresponding to the stromal and epithelial compartments using endometrial SP genes signature, immunophenotyping and characteristic telomerase pattern. We analyzed the clonogenic activity of SP cells under hypoxic conditions and the differentiation capacity in vitro to adipogenic and osteogenic lineages. Finally, we demonstrated the functional capability of endometrial SP to develop human endometrium after subcutaneous injection in NOD-SCID mice. Briefly, SP cells of human endometrium from epithelial and stromal compartments display genotypic, phenotypic and functional features of SSC

Aging Alters Functionally Human Dermal Papillary Fibroblasts but Not Reticular Fibroblasts: A New View of Skin Morphogenesis and Aging

Understanding the contribution of the dermis in skin aging is a key question, since this tissue is particularly important for skin integrity, and because its properties can affect the epidermis. Characteristics of matched pairs of dermal papillary and reticular fibroblasts (Fp and Fr) were investigated throughout aging, comparing morphology, secretion of cytokines, MMPs/TIMPs, growth potential, and interaction with epidermal keratinocytes. We observed that Fp populations were characterized by a higher proportion of small cells with low granularity and a higher growth potential than Fr populations. However, these differences became less marked with increasing age of donors. Aging was also associated with changes in the secretion activity of both Fp and Fr. Using a reconstructed skin model, we evidenced that Fp and Fr cells do not possess equivalent capacities to sustain keratinopoiesis. Comparing Fp and Fr from young donors, we noticed that dermal equivalents containing Fp were more potent to promote epidermal morphogenesis than those containing Fr. These data emphasize the complexity of dermal fibroblast biology and document the specific functional properties of Fp and Fr. Our results suggest a new model of skin aging in which marked alterations of Fp may affect the histological characteristics of skin