The Experts below are selected from a list of 216 Experts worldwide ranked by ideXlab platform
Lisa E Freed - One of the best experts on this subject based on the ideXlab platform.
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perfusion improves tissue architecture of engineered Cardiac Muscle
Tissue Engineering, 2002Co-Authors: Maria Rupnick, Robert Langer, Lisa E Freed, Frederick J Schoen, Gordana VunjaknovakovicAbstract:Cardiac Muscle with a certain threshold thickness, uniformity of tissue architecture, and functionality would expand the therapeutic options currently available to patients with congenital or acquired Cardiac defects. Cardiac constructs cultured in well-mixed medium had an approximately 100-μm-thick peripheral tissue-like region around a relatively cell-free interior, a structure consistent with the presence of concentration gradients within the tissue. We hypothesized that direct perfusion of cultured constructs can reduce diffusional distances for mass transport, improve control of oxygen, pH, nutrients and metabolites in the cell microenvironment, and thereby increase the thickness and spatial uniformity of engineered Cardiac Muscle. To test this hypothesis, constructs (9.5-mm-diameter, 2-mm-thick discs) based on neonatal rat Cardiac myocytes and fibrous polyglycolic acid scaffolds were cultured either directly perfused with medium or in control spinner flasks. Perfusion improved the spatial uniformity...
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tissue engineering of functional Cardiac Muscle molecular structural and electrophysiological studies
American Journal of Physiology-heart and Circulatory Physiology, 2001Co-Authors: Maria Papadaki, Nenad Bursac, Robert Langer, J Merok, Gordana Vunjaknovakovic, Lisa E FreedAbstract:The primary aim of this study was to relate molecular and structural properties of in vitro reconstructed Cardiac Muscle with its electrophysiological function using an in vitro model system based on neonatal rat Cardiac myocytes, three-dimensional polymeric scaffolds, and bioreactors. After 1 wk of cultivation, we found that engineered Cardiac Muscle contained a 120- to 160-μm-thick peripheral region with Cardiac myocytes that were electrically connected through gap junctions and sustained macroscopically continuous impulse propagation over a distance of 5 mm. Molecular, structural, and electrophysiological properties were found to be interrelated and depended on specific model system parameters such as the tissue culture substrate, bioreactor, and culture medium. Native tissue and the best experimental group (engineered Cardiac Muscle cultivated using laminin-coated scaffolds, rotating bioreactors, and low-serum medium) were comparable with respect to the conduction velocity of propagated electrical impulses and spatial distribution of connexin43. Furthermore, the structural and electrophysiological properties of the engineered Cardiac Muscle, such as cellularity, conduction velocity, maximum signal amplitude, capture rate, and excitation threshold, were significantly improved compared with our previous studies.
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Cardiac Muscle tissue engineering toward an in vitro model for electrophysiological studies
American Journal of Physiology-heart and Circulatory Physiology, 1999Co-Authors: Maria Papadaki, Nenad Bursac, Gordana Vunjaknovakovic, Frederick J Schoen, Richard J Cohen, Solomon R Eisenberg, R Carrier, Lisa E FreedAbstract:The objective of this study was to establish a three-dimensional (3-D) in vitro model system of Cardiac Muscle for electrophysiological studies. Primary neonatal rat ventricular cells containing lower or higher fractions of Cardiac myocytes were cultured on polymeric scaffolds in bioreactors to form regular or enriched Cardiac Muscle constructs, respectively. After 1 wk, all constructs contained a peripheral tissue-like region (50–70 μm thick) in which differentiated Cardiac myocytes were organized in multiple layers in a 3-D configuration. Indexes of cell size (protein/DNA) and metabolic activity (tetrazolium conversion/DNA) were similar for constructs and neonatal rat ventricles. Electrophysiological studies conducted using a linear array of extracellular electrodes showed that the peripheral region of constructs exhibited relatively homogeneous electrical properties and sustained macroscopically continuous impulse propagation on a centimeter-size scale. Electrophysiological properties of enriched const...
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Towards a functional tissue engineered Cardiac Muscle
Proceedings of the First Joint BMES EMBS Conference. 1999 IEEE Engineering in Medicine and Biology 21st Annual Conference and the 1999 Annual Fall Mee, 1999Co-Authors: Maria Papadaki, Nenad Bursac, Robert Langer, P. Gupta, G. Vunjak-novakovic, Lisa E FreedAbstract:Previous studies showed that engineered Cardiac Muscle with features resembling those of native Cardiac tissues can be designed in vitro. In the present study, laminin coating of the polymer scaffolds was used in conjunction with cultivation in low serum medium, in order to improve tissue properties. Primary ventricular Cardiac Muscle cells were seeded onto polymer scaffolds, laminin coated or not, and cultured at low or high serum concentration. Positive immunofluorescence staining for the gap junctional protein connexin-43 provided evidence that cells in the engineered tissues were electrically coupled. Low serum increased the amount of myosin heavy chain, while laminin increased the amount of creatine kinase isoform MM. Electrophysiological properties for the laminin-low serum group, such as conduction velocity, approached the levels of neonatal ventricles; the maximum capture rate and maximum amplitude were also significantly improved.
Nenad Bursac - One of the best experts on this subject based on the ideXlab platform.
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tissue engineering of functional Cardiac Muscle molecular structural and electrophysiological studies
American Journal of Physiology-heart and Circulatory Physiology, 2001Co-Authors: Maria Papadaki, Nenad Bursac, Robert Langer, J Merok, Gordana Vunjaknovakovic, Lisa E FreedAbstract:The primary aim of this study was to relate molecular and structural properties of in vitro reconstructed Cardiac Muscle with its electrophysiological function using an in vitro model system based on neonatal rat Cardiac myocytes, three-dimensional polymeric scaffolds, and bioreactors. After 1 wk of cultivation, we found that engineered Cardiac Muscle contained a 120- to 160-μm-thick peripheral region with Cardiac myocytes that were electrically connected through gap junctions and sustained macroscopically continuous impulse propagation over a distance of 5 mm. Molecular, structural, and electrophysiological properties were found to be interrelated and depended on specific model system parameters such as the tissue culture substrate, bioreactor, and culture medium. Native tissue and the best experimental group (engineered Cardiac Muscle cultivated using laminin-coated scaffolds, rotating bioreactors, and low-serum medium) were comparable with respect to the conduction velocity of propagated electrical impulses and spatial distribution of connexin43. Furthermore, the structural and electrophysiological properties of the engineered Cardiac Muscle, such as cellularity, conduction velocity, maximum signal amplitude, capture rate, and excitation threshold, were significantly improved compared with our previous studies.
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Cardiac Muscle tissue engineering toward an in vitro model for electrophysiological studies
American Journal of Physiology-heart and Circulatory Physiology, 1999Co-Authors: Maria Papadaki, Nenad Bursac, Gordana Vunjaknovakovic, Frederick J Schoen, Richard J Cohen, Solomon R Eisenberg, R Carrier, Lisa E FreedAbstract:The objective of this study was to establish a three-dimensional (3-D) in vitro model system of Cardiac Muscle for electrophysiological studies. Primary neonatal rat ventricular cells containing lower or higher fractions of Cardiac myocytes were cultured on polymeric scaffolds in bioreactors to form regular or enriched Cardiac Muscle constructs, respectively. After 1 wk, all constructs contained a peripheral tissue-like region (50–70 μm thick) in which differentiated Cardiac myocytes were organized in multiple layers in a 3-D configuration. Indexes of cell size (protein/DNA) and metabolic activity (tetrazolium conversion/DNA) were similar for constructs and neonatal rat ventricles. Electrophysiological studies conducted using a linear array of extracellular electrodes showed that the peripheral region of constructs exhibited relatively homogeneous electrical properties and sustained macroscopically continuous impulse propagation on a centimeter-size scale. Electrophysiological properties of enriched const...
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Towards a functional tissue engineered Cardiac Muscle
Proceedings of the First Joint BMES EMBS Conference. 1999 IEEE Engineering in Medicine and Biology 21st Annual Conference and the 1999 Annual Fall Mee, 1999Co-Authors: Maria Papadaki, Nenad Bursac, Robert Langer, P. Gupta, G. Vunjak-novakovic, Lisa E FreedAbstract:Previous studies showed that engineered Cardiac Muscle with features resembling those of native Cardiac tissues can be designed in vitro. In the present study, laminin coating of the polymer scaffolds was used in conjunction with cultivation in low serum medium, in order to improve tissue properties. Primary ventricular Cardiac Muscle cells were seeded onto polymer scaffolds, laminin coated or not, and cultured at low or high serum concentration. Positive immunofluorescence staining for the gap junctional protein connexin-43 provided evidence that cells in the engineered tissues were electrically coupled. Low serum increased the amount of myosin heavy chain, while laminin increased the amount of creatine kinase isoform MM. Electrophysiological properties for the laminin-low serum group, such as conduction velocity, approached the levels of neonatal ventricles; the maximum capture rate and maximum amplitude were also significantly improved.
Gordana Vunjaknovakovic - One of the best experts on this subject based on the ideXlab platform.
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perfusion improves tissue architecture of engineered Cardiac Muscle
Tissue Engineering, 2002Co-Authors: Maria Rupnick, Robert Langer, Lisa E Freed, Frederick J Schoen, Gordana VunjaknovakovicAbstract:Cardiac Muscle with a certain threshold thickness, uniformity of tissue architecture, and functionality would expand the therapeutic options currently available to patients with congenital or acquired Cardiac defects. Cardiac constructs cultured in well-mixed medium had an approximately 100-μm-thick peripheral tissue-like region around a relatively cell-free interior, a structure consistent with the presence of concentration gradients within the tissue. We hypothesized that direct perfusion of cultured constructs can reduce diffusional distances for mass transport, improve control of oxygen, pH, nutrients and metabolites in the cell microenvironment, and thereby increase the thickness and spatial uniformity of engineered Cardiac Muscle. To test this hypothesis, constructs (9.5-mm-diameter, 2-mm-thick discs) based on neonatal rat Cardiac myocytes and fibrous polyglycolic acid scaffolds were cultured either directly perfused with medium or in control spinner flasks. Perfusion improved the spatial uniformity...
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tissue engineering of functional Cardiac Muscle molecular structural and electrophysiological studies
American Journal of Physiology-heart and Circulatory Physiology, 2001Co-Authors: Maria Papadaki, Nenad Bursac, Robert Langer, J Merok, Gordana Vunjaknovakovic, Lisa E FreedAbstract:The primary aim of this study was to relate molecular and structural properties of in vitro reconstructed Cardiac Muscle with its electrophysiological function using an in vitro model system based on neonatal rat Cardiac myocytes, three-dimensional polymeric scaffolds, and bioreactors. After 1 wk of cultivation, we found that engineered Cardiac Muscle contained a 120- to 160-μm-thick peripheral region with Cardiac myocytes that were electrically connected through gap junctions and sustained macroscopically continuous impulse propagation over a distance of 5 mm. Molecular, structural, and electrophysiological properties were found to be interrelated and depended on specific model system parameters such as the tissue culture substrate, bioreactor, and culture medium. Native tissue and the best experimental group (engineered Cardiac Muscle cultivated using laminin-coated scaffolds, rotating bioreactors, and low-serum medium) were comparable with respect to the conduction velocity of propagated electrical impulses and spatial distribution of connexin43. Furthermore, the structural and electrophysiological properties of the engineered Cardiac Muscle, such as cellularity, conduction velocity, maximum signal amplitude, capture rate, and excitation threshold, were significantly improved compared with our previous studies.
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Cardiac Muscle tissue engineering toward an in vitro model for electrophysiological studies
American Journal of Physiology-heart and Circulatory Physiology, 1999Co-Authors: Maria Papadaki, Nenad Bursac, Gordana Vunjaknovakovic, Frederick J Schoen, Richard J Cohen, Solomon R Eisenberg, R Carrier, Lisa E FreedAbstract:The objective of this study was to establish a three-dimensional (3-D) in vitro model system of Cardiac Muscle for electrophysiological studies. Primary neonatal rat ventricular cells containing lower or higher fractions of Cardiac myocytes were cultured on polymeric scaffolds in bioreactors to form regular or enriched Cardiac Muscle constructs, respectively. After 1 wk, all constructs contained a peripheral tissue-like region (50–70 μm thick) in which differentiated Cardiac myocytes were organized in multiple layers in a 3-D configuration. Indexes of cell size (protein/DNA) and metabolic activity (tetrazolium conversion/DNA) were similar for constructs and neonatal rat ventricles. Electrophysiological studies conducted using a linear array of extracellular electrodes showed that the peripheral region of constructs exhibited relatively homogeneous electrical properties and sustained macroscopically continuous impulse propagation on a centimeter-size scale. Electrophysiological properties of enriched const...
Maria Papadaki - One of the best experts on this subject based on the ideXlab platform.
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Cardiac Muscle tissue engineering
IEEE Engineering in Medicine and Biology Magazine, 2003Co-Authors: Maria PapadakiAbstract:Cell-based therapy has emerged as a novel approach for replacing heart Muscle, which is known not to regenerate after injury such as that caused by infarction or reconstructive surgery. Two types of cell-based therapies have been employed: injection of isolated cells or the implantation of in-vitro-grown Cardiac Muscle tissue equivalents In the first case, several cell types - including skeletal myoblasts, cardiomyogenic cells derived from bone marrow stroma, fibroblasts, multipotent endothelial cells, and embryonic stem cells - have been directly injected into the myocardium and have shown to result in limited recovery from heart dysfunction in different animal models and humans (in the case of myoblasts). Despite the survival and differentiation of implanted cells, mechanical and electrical cell-cell contacts between graft and the host - a requirement for synchronous contractions - has only rarely been seen.
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tissue engineering of functional Cardiac Muscle molecular structural and electrophysiological studies
American Journal of Physiology-heart and Circulatory Physiology, 2001Co-Authors: Maria Papadaki, Nenad Bursac, Robert Langer, J Merok, Gordana Vunjaknovakovic, Lisa E FreedAbstract:The primary aim of this study was to relate molecular and structural properties of in vitro reconstructed Cardiac Muscle with its electrophysiological function using an in vitro model system based on neonatal rat Cardiac myocytes, three-dimensional polymeric scaffolds, and bioreactors. After 1 wk of cultivation, we found that engineered Cardiac Muscle contained a 120- to 160-μm-thick peripheral region with Cardiac myocytes that were electrically connected through gap junctions and sustained macroscopically continuous impulse propagation over a distance of 5 mm. Molecular, structural, and electrophysiological properties were found to be interrelated and depended on specific model system parameters such as the tissue culture substrate, bioreactor, and culture medium. Native tissue and the best experimental group (engineered Cardiac Muscle cultivated using laminin-coated scaffolds, rotating bioreactors, and low-serum medium) were comparable with respect to the conduction velocity of propagated electrical impulses and spatial distribution of connexin43. Furthermore, the structural and electrophysiological properties of the engineered Cardiac Muscle, such as cellularity, conduction velocity, maximum signal amplitude, capture rate, and excitation threshold, were significantly improved compared with our previous studies.
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Cardiac Muscle tissue engineering toward an in vitro model for electrophysiological studies
American Journal of Physiology-heart and Circulatory Physiology, 1999Co-Authors: Maria Papadaki, Nenad Bursac, Gordana Vunjaknovakovic, Frederick J Schoen, Richard J Cohen, Solomon R Eisenberg, R Carrier, Lisa E FreedAbstract:The objective of this study was to establish a three-dimensional (3-D) in vitro model system of Cardiac Muscle for electrophysiological studies. Primary neonatal rat ventricular cells containing lower or higher fractions of Cardiac myocytes were cultured on polymeric scaffolds in bioreactors to form regular or enriched Cardiac Muscle constructs, respectively. After 1 wk, all constructs contained a peripheral tissue-like region (50–70 μm thick) in which differentiated Cardiac myocytes were organized in multiple layers in a 3-D configuration. Indexes of cell size (protein/DNA) and metabolic activity (tetrazolium conversion/DNA) were similar for constructs and neonatal rat ventricles. Electrophysiological studies conducted using a linear array of extracellular electrodes showed that the peripheral region of constructs exhibited relatively homogeneous electrical properties and sustained macroscopically continuous impulse propagation on a centimeter-size scale. Electrophysiological properties of enriched const...
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Towards a functional tissue engineered Cardiac Muscle
Proceedings of the First Joint BMES EMBS Conference. 1999 IEEE Engineering in Medicine and Biology 21st Annual Conference and the 1999 Annual Fall Mee, 1999Co-Authors: Maria Papadaki, Nenad Bursac, Robert Langer, P. Gupta, G. Vunjak-novakovic, Lisa E FreedAbstract:Previous studies showed that engineered Cardiac Muscle with features resembling those of native Cardiac tissues can be designed in vitro. In the present study, laminin coating of the polymer scaffolds was used in conjunction with cultivation in low serum medium, in order to improve tissue properties. Primary ventricular Cardiac Muscle cells were seeded onto polymer scaffolds, laminin coated or not, and cultured at low or high serum concentration. Positive immunofluorescence staining for the gap junctional protein connexin-43 provided evidence that cells in the engineered tissues were electrically coupled. Low serum increased the amount of myosin heavy chain, while laminin increased the amount of creatine kinase isoform MM. Electrophysiological properties for the laminin-low serum group, such as conduction velocity, approached the levels of neonatal ventricles; the maximum capture rate and maximum amplitude were also significantly improved.
Marie A Bogoyevitch - One of the best experts on this subject based on the ideXlab platform.
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the role of stem cells in skeletal and Cardiac Muscle repair
Journal of Histochemistry and Cytochemistry, 2002Co-Authors: Miranda D Grounds, Jason D White, Nadia Rosenthal, Marie A BogoyevitchAbstract:In postnatal Muscle, skeletal Muscle precursors (myoblasts) can be derived from satellite cells (reserve cells located on the surface of mature myofibers) or from cells lying beyond the myofiber, e.g., interstitial connective tissue or bone marrow. Both of these classes of cells may have stem cell properties. In addition, the heretical idea that post-mitotic myonuclei lying within mature myofibers might be able to re-form myoblasts or stem cells is examined and related to recent observations for similar post-mitotic cardiomyocytes. In adult hearts (which previously were not considered capable of repair), the role of replicating endogenous cardiomyocytes and the recruitment of other (stem) cells into cardiomyocytes for new Cardiac Muscle formation has recently attracted much attention. The relative contribution of these various sources of precursor cells in postnatal Muscles and the factors that may enhance stem cell participation in the formation of new skeletal and Cardiac Muscle in vivo are the focus of...