O2 Level Controls Hematopoietic Circulating Progenitor Cells Differentiation into Endothelial or Smooth Muscle Cells

BACKGROUND:Recent studies showed that progenitor cells could differentiate into mature vascular cells. The main physiological factors implicated in cell differentiation are specific growth factors. We hypothesized that simply by varying the oxygen content, progenitor cells can be differentiated either in mature endothelial cells (ECs) or contractile smooth muscle cells (SMCs) while keeping exactly the same culture medium. METHODOLOGY/PRINCIPAL FINDINGS:Mononuclear cells were isolated by density gradient were cultivated under hypoxic (5% O2) or normoxic (21% O2) environment. Differentiated cells characterization was performed by confocal microscopy examination and flow cytometry analyses. The phenotype stability over a longer time period was also performed. The morphological examination of the confluent obtained cells after several weeks (between 2 and 4 weeks) showed two distinct morphologies: cobblestone shape in normoxia and a spindle like shape in hypoxia. The cell characterization showed that cobblestone cells were positive to ECs markers while spindle like shape cells were positive to contractile SMCs markers. Moreover, after several further amplification (until 3(rd) passage) in hypoxic or normoxic conditions of the previously differentiated SMC, immunofluorescence studies showed that more than 80% cells continued to express SMCs markers whatever the cell environmental culture conditions with a higher contractile markers expression compared to control (aorta SMCs) signature of phenotype stability. CONCLUSION/SIGNIFICANCE:We demonstrate in this paper that in vitro culture of peripheral blood mononuclear cells with specific angiogenic growth factors under hypoxic conditions leads to SMCs differentiation into a contractile phenotype, signature of their physiological state. Moreover after amplification, the differentiated SMC did not reverse and keep their contractile phenotype after the 3rd passage performed under hypoxic and normoxic conditions. These aspects are of the highest importance for tissue engineering strategies. These results highlight also the determinant role of the tissue environment in the differentiation process of vascular progenitor cells

Multi-Layered Films Containing a Biomimetic Stimuli-Responsive Recombinant Protein

Electrostatic self-assembly was used to fabricate new smart multi-layer coatings, using a recombinant elastin-like polymer (ELP) and chitosan as the counterion macromolecule. The ELP was bioproduced, purified and its purity and expected molecular weight were assessed. Aggregate size measurements, obtained by light scattering of dissolved ELP, were performed as a function of temperature and pH to assess the smart properties of the polymer. The build-up of multi-layered films containing ELP and chitosan, using a layer-by-layer methodology, was followed by quartz-crystal microbalance with dissipation monitoring. Atomic force microscopy analysis permitted to demonstrate that the topography of the multi-layered films could respond to temperature. This work opens new possibilities for the use of ELPs in the fabrication of biodegradable smart coatings and films, offering new platforms in biotechnology and in the biomedical area

Fragile finance: The revenue models of oppositional news outlets in repressive regimes

For journalists promoting the free flow of information in repressive or restrictive media environments, the issue of financial sustainability is complex. Both media in exile (out-of-country news outlets feeding independent information into the country of origin) and news outlets in restrictive news environments (in-country providing counter-information) exist in flawed market situations and often rely on grant funding. This is the first academic study of the revenue streams of these media, providing scarce empirical data and a typology of funding structures of these media. This article examines three main revenue categories: grant funding, earned income and donations. The major factors influencing revenue streams compared to online media startups in open markets are discussed. The article finds significant barriers to revenue creation and identifies the need for alternative approaches, particularly partnerships, to promote economic resilience for media under threat

Cellularized alginate sheets for blood vessel reconstruction

International audienc

Influence des facteurs climatiques et démographiques sur le portage de Pneumocystis dans un groupe social de macaques à longue queue (Macaca fascicularis)

National audienc

Bovine leukaemia virus-induced lymphocytosis in sheep is associated with reduction of spontaneous B cell apoptosis

International audienc

Influence des facteurs climatiques et démographiques sur le portage de Pneumocystis dans un groupe social de macaques à longue queue (Macaca fascicularis)

National audienc

Bovine leukaemia virus-induced lymphocytosis in sheep is associated with reduction of spontaneous B cell apoptosis

International audienc

B-1-like cells exist in sheep. Characterization of their phenotype and behaviour

Two populations of B lymphocytes. B-1 (CD5- and or CD1 lb-) and B-2 (CD5- and CD1 lb-) cells have been described. In mice, which is the species of reference for B-1 and B-2 cell studies, these two subsets present different developmental schemes, phenotypes, antibody repertoires, localization and behaviours. Interestingly, in sheep. B cells rearrange their immunoglobulin (Ig) loci around the neonatal period, similarly to murine B-1 cells. However, the phenotype of the sheep B cells has not been characterized with regard to their developmental pathway. In this report, we show that two sheep B-cell subsets can be distinguished on the basis of CD1 lb expression. Relative to CD1 lb- B cells, the CD1 lb- B cells frequently co-express CD5. CD1 lc, higher levels of surface IgM (sIgM), show larger cell size and higher cell-cycling activity, and thus present a B-1 like phenotype. However, unlike murine B-1 cells, sheep B-1 like cells mainly localize in blood, display a higher propensity to spontaneous apoptosis relative to B-2-like cells, and proliferate after sIgM stimulation. Our data show that despite neonatal immunoglobulin loci rearrangements, sheep B cells do not all express a B-1 like phenotype. However. B-1 and B-2 like cells co-exist and present phenotypic and behavioural specificities. Nevertheless, sheep B-1 and B-2 like cells differ from the murine B-1 and B-2 cells in their cell behabiour. These subsets can thus not be considered as true homologues among species