Project description:The retina is often subjected to tractional forces in a variety of conditions, for instance, pathological myopia, proliferative vitreoretinopathy. As the predominant glial element in the sensory retina, Muller cells are responsible for the homeostatic and metabolic support of retinal neurons and active players in virtually all forms of retinal injury and disease. Besides, Muller cells span the entire retinal thickness, extending from the inner to the outer limiting membranes, with cell bodies located in the inner nuclear layer and lateral processes expanding into the plexiform layers of the tissue. Because of this unique morphology, Muller cells can sense even minute changes in the retinal structure because of the mechanical stretching of their long processes or side branches. Thus, itM-bM-^@M-^Ys reasonable to infer that Muller cells also participate in ocular diseases when the retina is overstretched. In this study, we aim to investigate the whole genome regulation of Muller cells under mechanical stretching, which may help in excluding possible molecular mechanisms that would account for many retinal diseases in which the retina is often subjected to mechanical forces. We used microarrays to identify patterns of gene expression changes induced by cyclic mechanical stretching in Muller cells. Rat Muller cells were seeded onto flexible bottom culture plates and subjected to a cyclic stretching regimen of 15% equibiaxial stretching for 1 and 24 h.Muller cells cultured under the same conditions but with no applied mechanical strain were considered as the unstretched control. At each time points (1 and 24 h), three totally independent experiments (3 stretched samples and 3 control samples) were conducted. Muller cells were selected for RNA extraction and hybridization on Affymetrix microarrays. Stretch (S); Control (C)
Project description:The retina is often subjected to tractional forces in a variety of conditions, for instance, pathological myopia, proliferative vitreoretinopathy. As the predominant glial element in the sensory retina, Muller cells are responsible for the homeostatic and metabolic support of retinal neurons and active players in virtually all forms of retinal injury and disease. Besides, Muller cells span the entire retinal thickness, extending from the inner to the outer limiting membranes, with cell bodies located in the inner nuclear layer and lateral processes expanding into the plexiform layers of the tissue. Because of this unique morphology, Muller cells can sense even minute changes in the retinal structure because of the mechanical stretching of their long processes or side branches. Thus, it’s reasonable to infer that Muller cells also participate in ocular diseases when the retina is overstretched. In this study, we aim to investigate the whole genome regulation of Muller cells under mechanical stretching, which may help in excluding possible molecular mechanisms that would account for many retinal diseases in which the retina is often subjected to mechanical forces. We used microarrays to identify patterns of gene expression changes induced by cyclic mechanical stretching in Muller cells.
Project description:Several different mechanical signals have been proposed to control the extent and pattern of myocardial growth and remodeling, though this has largely been studied using in vitro model systems that are not representative of intact myocardium or in vivo models in which isolating the effects of individual candidate stimuli is exceedigly difficult. We used a unique tissue culture system that allows the simultaneous control of multiple mechanical inputs and other potentially confounding stimuli (e.g., hormonal). Following a 12 hour culture period under prescribed mechanics, we used microarrays to identify genes that are up- or down-regulated in response to different amounts of mean stretch and cyclic shortening. Muscles were dissected (one from each of 12 different male LBN-F1 rats) and cultured for 12 hours in a pseudo-sterile muscle culture system under one of four mechanical input schemes (i.e., three biological replicates per mechanical input group). We prescribed low or high values of both time averaged stretch and cyclic shortening. Specifically, we targeted 4% or 16% mean stretch (from slack length) and 4% of 16% cylic shortening (% of slack length) over the 12 hour culture period to give the following four groups: high mean stretch x high shortening (group A); high mean stretch x low shortening (group B); low mean stretch x low shortening (group C); low mean stretch x high shortening (group D). This 2 x 2 factorial design allowed us to identify individual genes and/or molecular pathways that might be regulated by one or both of these mechanical inputs indpendent from other candidate mechanical or hormonal stimuli.
Project description:Cyclic stretch of alveoli is characteristic of mechanical ventilation, and is postulated to be partly responsible for the lung injury and inflammation in ventilator induced lung injury. We propose that miRNAs may regulate some of the stretch response and, therefore, hypothesized that miRNAs would be differentially expressed between stretched and unstretched rat alveolar epithelial cells (RAECs).
Project description:Acute respiratory distress syndrome (ARDS) is a catastrophic form of acute lung injury (ALI). The necessity for mechanical ventilation (MV) renders patients at risk for ventilator induced lung injury (VILI). Exposure to repetitive cyclic stretch (CS) and/or over-inflation exacerbates injury. Reducing tidal volume (VT) is the only therapeutic strategy shown to mitigate morbidity and mortality. Cyclic stretch has been shown to differentially regulate gene expression in part through the activation of mammalian mitogen-activated protein kinase (MAPK). Although these studies have shown both molecular and cellular alterations, no unifying hypothesis to explain MV-induced lung injury has emerged. In the current study, we hypothesized that coordinated expression of cyclic stretch (CS)-responsive genes relies on the presence of common CS-sensitive regulatory elements. To identify CS-responsive genes, we undertook a comparative examination of the gene expression profile of human bronchial epithelial airway (Beas-2B) cells in response to various injurious stimuli involved in the pathogenesis of acute lung injury (ALI)/Ventilator induced lung injury (VILI): cyclic stretch, tumor necrosis factor alpha (TNF-a), and lipopolysaccharide (LPS). Experiment Overall Design: Human Bronchial Epithelial Cells (Beas-B2) cells grown on silicon elastic plates coated with Type I collagen (Flexercell International, McKeesport, PA) were exposed to six regiments for 4 h: 1) control (static, [control]); 2) mechanical stretch (25 PKa, 30 cycles per min, [stretch]); 3) LPS (1 mcg/ml [LPS]); 4) TNF-α (20 ng/ml; [TNF]); 5) mechanical stretch plus LPS [LPS+S], and 6) mechanical stretch plus TNF-α [TNF+S]. Total RNA (duplicate experiments) was extracted using TRIZOL reagent (as per manufactures specifications) and purified using Qiagen mRNA purification Kit (as per manufacturers specifications). mRNA was hybridized to Affymetrix Human U133plus2.0 chips. Probe based analysis, background reduction, and quantile data normalization was performed in MeV 4.0 of TM4 using Robust Multi-array Average (RMA).
Project description:In order to investigate the effects of downregulated autophagy in TM cells response to mechanical stretch, we conducted gene expression analysis in human TM cells deficient in autophagy and subjected to cyclic mechanical stretch. For this, three independent strains of primary human TM cells were transfected with a cocktail of siRNAs to specifically silence the expression of the autophagy genes Atg5 and Atg7 (siAtg5/7), and subjected to cyclic mechanical stress (15% elongation, 1 cycle/sec, 24h).
Project description:Mechanical overload in the heart induces pathological remodeling that typcially leads to heart failure. We sought to build an in vitro model of heart failure by applying cyclic stretch to engineered isotropic (iso) and anisotropic (aniso) NRVM tissues. We used micoarrays to determine the effects of longitudinal and transvserse cyclic stretch on gene expression in engineered NRVM cardiac tissues. We found that cyclic stretch induced up-regulation of several known indicators of heart faliure, independent of the direction of stretch.