3,240 research outputs found

    Role of Chronic Shear Stress in Endothelial Form and Function

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    Endothelial cells in vivo exist in a dynamic environment, subject to the physical forces of blood flow as it is regulated through the cardiac cycle. Arguably, the most important force endothelial cells are subject to is shear stress, the frictional force of blood flow across the cell surface. Areas of the vasculature that experience laminar shear stress appear resistant to the development of atherosclerotic plaques, whereas those that experience low shear stress, due to complex patterns of blood flow, appear susceptible. In vitro study of the effects of chronic shear stress on the endothelium has been somewhat limited, due to the methods of modelling shear stress available, which are for the most part only suitable for culture for up to 24 hours. I have validated an orbital shaker method of modelling two flow environments seen in the vasculature, unidirectional flow and non-directional flow, with associated shear stress profiles, for chronic time periods of up to 7 days. I have shown clear differences between the two environments in terms of endothelial cell morphology and protein expression and identified many ways in which sheared cells differ from their static counterparts, in terms of morphology, protein expression, vascular mediator release and transcriptional profile. Shear stress appears to be a protective force, inhibiting expression of inflammatory mediators and significantly altering response to inflammatory stimulus. The orbital shaker may prove a useful model for in vitro study of the endothelium in a situation similar to that of physiological conditions

    Reformulating Pro-Oxidant Microglia in Neurodegeneration

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    In neurodegenerative diseases, microglia-mediated neuroinflammation and oxidative stress are central events. Recent genome-wide transcriptomic analyses of microglial cells under different disease conditions have uncovered a new subpopulation named disease-associated microglia (DAM). These studies have challenged the classical view of the microglia polarization state's proinflammatory M1 (classical activation) and immunosuppressive M2 (alternative activation). Molecular signatures of DAM and proinflammatory microglia (highly pro-oxidant) have shown clear differences, yet a partial overlapping gene profile is evident between both phenotypes. The switch activation of homeostatic microglia into reactive microglia relies on the selective activation of key surface receptors involved in the maintenance of brain homeostasis (a.k.a. pattern recognition receptors, PRRs). Two relevant PRRs are toll-like receptors (TLRs) and triggering receptors expressed on myeloid cells-2 (TREM2), whose selective activation is believed to generate either a proinflammatory or a DAM phenotype, respectively. However, the recent identification of endogenous disease-related ligands, which bind to and activate both TLRs and TREM2, anticipates the existence of rather complex microglia responses. Examples of potential endogenous dual ligands include amyloid β, galectin-3, and apolipoprotein E. These pleiotropic ligands induce a microglia polarization that is more complicated than initially expected, suggesting the possibility that different microglia subtypes may coexist. This review highlights the main microglia polarization states under disease conditions and their leading role orchestrating oxidative stress

    Embryo metabolism : what does it really mean?

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    The study of early embryo metabolism has fascinated researchers in the field for nearly a century. Herein, we give a brief account of the general features of embryo metabolism and some consideration of the research performed to reach such conclusions. It is becoming increasingly obvious that metabolism informs many fate decisions and outcomes beyond ATP generation, such as DNA methylation, Reactive Oxygen Species generation and cell signaling. We discuss the reasons for studying metabolism in the face of our current knowledge of the effect that the culture environment on the developing embryo and the downstream effects that can cause. The study of in vitro embryo metabolism can also give us insight into developmental perturbations in vivo. The strengths and limitations of the methods we use to study metabolism are reviewed with reference to species-specific fundamental biology and plasticity and we discuss what the future holds for metabolic studies and the unanswered questions that remain

    Metabolic and vascular effect of the mediterranean diet

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    Several studies indicated how dietary patterns that were obtained from nutritional cluster analysis can predict disease risk or mortality. Low-grade chronic inflammation represents a background pathogenetic mechanism linking metabolic risk factors to increased risk of chronic degenerative diseases. A Mediterranean diet (MeDi) style has been reported as associated with a lower degree of inflammation biomarkers and with a protective role on cardiovascular and cerebrovascular events. There is heterogeneity in defining the MedDiet, and it can, owing to its complexity, be considered as an exposome with thousands of nutrients and phytochemicals. Recently, it has been reported a novel positive association between baseline plasma ceramide concentrations and cardiovascular events and how adherence to a Mediterranean Diet-style may influence the potential negative relationship between elevated plasma ceramide concentrations and cardiovascular diseases (CVD). Several randomized controlled trials (RCTs) showed the positive effects of the MeDi diet style on several cardiovascular risk factors, such as body mass index, waist circumference, blood lipids, blood pressure, inflammatory markers and adhesion molecules, and diabetes and how these advantages of the MeDi are maintained in comparison of a low-fat diet. Some studies reported a positive effect of adherence to a Mediterranean Diet and heart failure incidence, whereas some recent studies, such as the PREDIMED study, showed that the incidence of major cardiovascular events was lower among those assigned to MeDi supplemented with extra-virgin olive oil or nuts than among those assigned to a reduced-fat diet. New studies are needed to better understand the molecular mechanisms, whereby the MedDiet may exercise its effects. Here, we present recent advances in understanding the molecular basis of MedDiet effects, mainly focusing on cardiovascular diseases, but also discussing other related diseases. We review MedDiet composition and assessment as well as the latest advances in the genomic, epigenomic (DNA methylation, histone modifications, microRNAs, and other emerging regulators), transcriptomic (selected genes and whole transcriptome), and metabolomic and metagenomic aspects of the MedDiet effects (as a whole and for its most typical food components). We also present a review of the clinical effects of this dietary style underlying the biochemical and molecular effects of the Mediterranean diet. Our purpose is to review the main features of the Mediterranean diet in particular its benefits on human health, underling the anti-inflammatory, anti-oxidant and anti-atherosclerotic effects to which new knowledge about epigenetic and gut-microbiota relationship is recently added

    Induced pluripotent stem cell reporter systems for smooth muscle cell sheet engineering

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    Smooth muscle cells exist in many different locations within the body, including blood vessels and airways, where their principal function is contraction and relaxation. The heterogeneity of smooth muscle cells has been related to their embryological origins and could have implications in many diseases, including atherosclerosis, pulmonary hypertension, and asthma. Many of these diseases require an expandable cell source of smooth muscle cells for regenerative medicine or disease modeling. Here, we have developed Acta2hrGFP and ACTA2eGFP (GFP reporters for smooth muscle α-actin) reporter mouse and human induced pluripotent stem cells lines to track and isolate populations of smooth muscle-like cells. iPSCs were patterned to a KDR-expressing (kinase insert domain receptor) mesodermal progenitor, which was further specified towards a smooth muscle-like lineage through exposure to platelet derived growth factor (PDGF-BB) and transforming growth factor (TGF-β). The Acta2hrGFP+ or ACTA2eGFP+ cells were enriched for characteristic markers of smooth muscle cells, and these cells expressed low levels of contractile markers, reminiscent of an immature or synthetic smooth muscle cell. Aligned smooth muscle-like cell sheets were generated using these iPSC-derived populations in an enzymatically degradable hydrogel system. The cell sheets displayed mechanical behavior similar to native blood vessels, with the Acta2hrGFP+ cell sheets displaying a higher ultimate tensile strength than Acta2hrGFP- cell sheets. Furthermore, we performed global transcriptomic profiling of primary adult mouse lung vascular (Acta2hrGFP+ Cspg4DsRed+) and airway (Acta2hrGFP+ Cspg4DsRed-) smooth muscle cells from a double transgenic reporter mouse, where we identified distinct gene signatures of lung vascular SMCs and airway SMCs, with Hhip and Acta2 co-expression distinguishing airway SMCs from lung vascular SMCs. When comparing our miPSC-derived Acta2hrGFP+ cells to these primary SMC signatures, the in vitro derived cells cluster closer to aortic SMCs and lung vascular SMCs, but their transcriptomic signatures still remain significantly distinct. In addition, we have generated an Acta2hrGFP Cspg4DsRed reporter mouse iPSC line, which can be used to understand the signaling pathways involved in specification of these different smooth muscle cell subtypes. Thus, we have developed systems for isolating smooth muscle-like populations which have potential in tissue engineering applications, and we have identified gene signatures of adult lung vascular and airway smooth muscle cells to begin to address the heterogeneity of smooth muscle cell lineages

    In vitro models for the study of liver biology and diseases - advances and limitations.

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    In vitro models of liver (patho)physiology, new technologies and experimental approaches are progressing rapidly. Based on cell lines, induced pluripotent stem cells (iPSCs) or primary cells derived from mouse or human liver as well as whole tissue (slices), such in vitro single- and multi-cellular models, including complex microfluidic organ-on-a-chip systems, provide tools to functionally understand mechanisms of liver health and disease. The International Society of Hepatic Sinusoidal Research (ISHSR) commissioned this working group to review the currently available in vitro liver models and describe the advantages and disadvantages of each in the context of evaluating their use for the study of liver functionality, disease modelling, therapeutic discovery and clinical applicability

    Biological and translational cancer proteomics

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