Project description:Engineered cardiac tissues (ECTs) are platforms to investigate cardiomyocyte maturation and functional integration, to evaluate the feasibility of generating implantable tissues for cardiac repair and regeneration, and may be useful models for pharmacology and toxicology bioassays. These ECTs rapidly mature in vitro to acquire the features of functional cardiac muscle and respond to mechanical load with increased proliferation and maturation. ECTs can be generated from various immature cardiac cell sources and little is known regarding the broad changes in regulatory transcript expression that occur in these in vitro tissues during normal maturation and in response to mechanical or pharmacologic interventions. We tested the hypothesis that global ECT gene expression patterns are sensitive to mechanical loading conditions and tyrosine kinase inhibitors, similar to the maturing myocardium. We generated 3D ECTs from day 14.5 rat embryo ventricular cells, as previously published, and then treated constructs after 5 days in culture for 48 hours with mechanical stretch (5%, 0.5 Hz) and/or the p38MAPK (p38 mitogen-activated protein kinase) selective inhibitor BIRB796. RNA was isolated from 3 sets of experiments and assayed using a standard Agilent rat 4x44k V3 microarray and Pathway Analysis software for transcript expression fold changes and changes in regulatory molecules and networks. At the threshold of a 1.5 fold change in expression, mechanical stretch altered 1,559 transcripts, versus 1,411 for BIRB796, and 1,846 for stretch plus BIRB796. As anticipated, top pathways altered in response to these stimuli include Cellular Development, Cellular Growth and Proliferation; Tissue Development; Cell Death, Cell Signaling, and Small Molecule Biochemistry as well as numerous other pathways. Changes in transcript expression were confirmed by quantitative-PCR for selected regulatory molecules. Thus, ECTs display a broad spectrum of altered gene expression in response to mechanical load and/or tyrosine kinase inhibition, reflecting the complex regulation of proliferation, differentiation, and architectural alignment that occurs during ECT maturation and adaptation. This approach can now be used to test the role of individual molecules and pathways on the regulation of ECT maturation and remodeling. 7 and 4 biological replicates with four groups (control, mechanical stretch, BIRB and mechanical stretch with BIRB)
Project description:Engineered cardiac tissues (ECTs) are platforms to investigate cardiomyocyte maturation and functional integration, to evaluate the feasibility of generating implantable tissues for cardiac repair and regeneration, and may be useful models for pharmacology and toxicology bioassays. These ECTs rapidly mature in vitro to acquire the features of functional cardiac muscle and respond to mechanical load with increased proliferation and maturation. ECTs can be generated from various immature cardiac cell sources and little is known regarding the broad changes in regulatory transcript expression that occur in these in vitro tissues during normal maturation and in response to mechanical or pharmacologic interventions. We tested the hypothesis that global ECT gene expression patterns are sensitive to mechanical loading conditions and tyrosine kinase inhibitors, similar to the maturing myocardium. We generated 3D ECTs from day 14.5 rat embryo ventricular cells, as previously published, and then treated constructs after 5 days in culture for 48 hours with mechanical stretch (5%, 0.5 Hz) and/or the p38MAPK (p38 mitogen-activated protein kinase) selective inhibitor BIRB796. RNA was isolated from 3 sets of experiments and assayed using a standard Agilent rat 4x44k V3 microarray and Pathway Analysis software for transcript expression fold changes and changes in regulatory molecules and networks. At the threshold of a 1.5 fold change in expression, mechanical stretch altered 1,559 transcripts, versus 1,411 for BIRB796, and 1,846 for stretch plus BIRB796. As anticipated, top pathways altered in response to these stimuli include Cellular Development, Cellular Growth and Proliferation; Tissue Development; Cell Death, Cell Signaling, and Small Molecule Biochemistry as well as numerous other pathways. Changes in transcript expression were confirmed by quantitative-PCR for selected regulatory molecules. Thus, ECTs display a broad spectrum of altered gene expression in response to mechanical load and/or tyrosine kinase inhibition, reflecting the complex regulation of proliferation, differentiation, and architectural alignment that occurs during ECT maturation and adaptation. This approach can now be used to test the role of individual molecules and pathways on the regulation of ECT maturation and remodeling.
Project description:Mechanobiologic signals play critical roles in regulating cellular responses under both physiologic and pathologic conditions. Using a combination of synthetic biology and tissue engineering, we developed a mechanically-responsive bioartificial tissue that responds to mechanical loading to produce a pre-programmed therapeutic biologic drug. By deconstructing the signaling networks induced by activation the mechanically-sensitive ion channel transient receptor potential vanilloid 4 (TRPV4), we synthesized synthetic TRPV4-responsive genetic circuits in chondrocytes. These cells were then engineered into living tissues that respond to mechanical compression to drive the production of the anti-inflammatory drug interleukin-1 receptor antagonist. Mechanical loading of these tissues in the presence of the cytokine interleukin-1 protected constructs from inflammatory degradation. This “mechanogenetic” approach enables long-term autonomous delivery of therapeutic compounds that is driven by physiologically-relevant mechanical loading with cell-scale mechanical force resolution. The development of synthetic mechanogenetic gene circuits provides a novel approach for the autonomous regulation of cell-based drug delivery systems.
Project description:This study aimed to evaluate the effects of mechanical loading and unloading via CHP and SMG, respectively, on the OA-related profile changes of engineered meniscus tissues and explore biological sex-related differences
Project description:Skeletal integrity in humans and animals is maintained by daily mechanical loading. It has been widely accepted that osteocytes function as mechanosensors. Many biochemical signaling molecules are involved in the response of osteocytes to mechanical stimulation. The aim of this study was to identify genes involved in the translation of mechanical stimuli into bone formation. The four-point bending model was used to induce a single period of mechanical loading (comprising 300 cycles (2 Hz) using a peak magnitude of 60 N) on the right tibia, while the contra lateral left tibia served as control. Six hours after loading, the effects of mechanical loading on gene-expression were determined with microarray analysis. Protein expression of differentially regulated genes was evaluated with immunohistochemistry. Nine genes were found to exhibit a significant differential gene expression in LOAD compared to control. MEPE, Garnl1, V2R2B, and QFG TN1 olfactory receptor were up-regulated, and creatine kinase (muscle form), fibrinogen-B beta-polypeptide, monoamine oxidase A, troponin-C and kinesin light chain-C were down-regulated. Validation with real-time RT-PCR analysis confirmed the up regulation of MEPE and the down-regulation of creatine kinase (muscle form) and troponin-C in the loaded tibia. Immunohistochemistry showed that the increase of MEPE protein expression was already detectable six hours after mechanical loading. In conclusion, these genes probably play a role during translation of mechanical stimuli six hours after mechanical loading. The modulation of MEPE expression may indicate a connection between bone mineralization and bone formation after mechanical stimulation. Two groups: LOAD vs contralateral control and SHAM vs contralateral control (n=5/group)
Project description:Myocardial damage caused for example by cardiac ischemia leads to ventricular volume overload resulting in increased stretch of the remaining myocardium. In adult mammals, these changes trigger an adaptive cardiomyocyte hypertrophic response which, if the damage is extensive, will ultimately lead to pathological hypertrophy and heart failure. Conversely, in response to extensive myocardial damage, cardiomyocytes in the adult zebrafish heart and neonatal mice proliferate and completely regenerate the damaged myocardium. We therefore hypothesized that in adult zebrafish, changes in mechanical loading due to myocardial damage may act as a trigger to induce cardiac regeneration. Based, on this notion we sought to identify mechanosensors which could be involved in detecting changes in mechanical loading and triggering regeneration. Here we show using a combination of knockout animals, RNAseq and in vitro assays that the mechanosensitive ion channel Trpc6a is required by cardiomyocytes for successful cardiac regeneration in adult zebrafish. Furthermore, using a cyclic cell stretch assay, we have determined that Trpc6a induces the expression of components of the AP1 transcription complex in response to mechanical stretch. Our data highlights how changes in mechanical forces due to myocardial damage can be detected by mechanosensors which in turn can trigger cardiac regeneration.
Project description:The cardiac stroma contains multipotent mesenchymal progenitors. However, lineage relationships within cardiac stromal cells are poorly defined. Here, we identify heart-resident PDGFRa+ SCA-1+ cells as cardiac Fibro/Adipogenic Progenitors (cFAPs) and show that they respond to ischemic damage by generating SCA-1- fibrogenic cells. Pharmacological blockade of this differentiation step with an anti-fibrotic tyrosine kinase inhibitor decreases post-myocardial infarction (MI) remodeling and leads to improvement in heart function.
Project description:The cardiac stroma contains multipotent mesenchymal progenitors. However, lineage relationships within cardiac stromal cells are poorly defined. Here, we identify heart-resident PDGFRa+ SCA-1+ cells as cardiac Fibro/Adipogenic Progenitors (cFAPs) and show that they respond to ischemic damage by generating SCA-1- fibrogenic cells. Pharmacological blockade of this differentiation step with an anti-fibrotic tyrosine kinase inhibitor decreases post-myocardial infarction (MI) remodeling and leads to improvement in heart function.