The Experts below are selected from a list of 48 Experts worldwide ranked by ideXlab platform

Jens M Kelm - One of the best experts on this subject based on the ideXlab platform.

  • method for generation of homogeneous multicellular tumor spheroids applicable to a wide variety of cell types
    Biotechnology and Bioengineering, 2003
    Co-Authors: Jens M Kelm, Nicholas E Timmins, Catherine Brown, Martin Fussenegger, Lars K Nielsen
    Abstract:

    Multicellular tumor spheroids (MCTS) are used as organotypic models of normal and solid tumor Tissue. Traditional techniques for generating MCTS, such as growth on nonadherent surfaces, in suspension, or on scaffolds, have a number of drawbacks, including the need for manual selection to achieve a homogeneous population and the use of nonphysiological matrix compounds. In this study we describe a mild method for the generation of MCTS, in which individual spheroids form in hanging drops suspended from a microtiter plate. The method has been successfully applied to a broad range of cell lines and shows nearly 100% efficiency (i.e., one spheroid per drop). Using the hepatoma cell line, HepG2, the hanging drop method generated well-rounded MCTS with a narrow size distribution (coefficient of variation [CV] 10% to 15%, compared with 40% to 60% for growth on nonadherent surfaces). Structural analysis of HepG2 and a mammary gland adenocarcinoma cell line, MCF-7, composed spheroids, revealed highly organized, three-dimensional, Tissue-like structures with an extensive extracellular matrix. The hanging drop method represents an attractive alternative for MCTS production, because it is mild, can be applied to a wide variety of cell lines, and can produce spheroids of a homogeneous size without the need for sieving or manual selection. The method has applications for basic studies of physiology and metabolism, tumor biology, toxicology, cellular organization, and the development of Bioartificial Tissue.

  • method for generation of homogeneous multicellular tumor spheroids applicable to a wide variety of cell types
    Biotechnology and Bioengineering, 2003
    Co-Authors: Jens M Kelm, Nicholas E Timmins, Martin Fussenegger, Catherine J Brown, Lars K Nielsen
    Abstract:

    Multicellular tumor spheroids (MCTS) are used as organotypic models of normal and solid tumor Tissue. Traditional techniques for generating MCTS, such as growth on nonadherent surfaces, in suspension, or on scaffolds, have a number of drawbacks, including the need for manual selection to achieve a homogeneous population and the use of nonphysiological matrix compounds. In this study we describe a mild method for the generation of MCTS, in which individual spheroids form in hanging drops suspended from a microtiter plate. The method has been successfully applied to a broad range of cell lines and shows nearly 100% efficiency (i.e., one spheroid per drop). Using the hepatoma cell line, HepG2, the hanging drop method generated well-rounded MCTS with a narrow size distribution (coefficient of variation [CV] 10% to 15%, compared with 40% to 60% for growth on nonadherent surfaces). Structural analysis of HepG2 and a mammary gland adenocarcinoma cell line, MCF-7, composed spheroids, revealed highly organized, three-dimensional, Tissue-like structures with an extensive extracellular matrix. The hanging drop method represents an attractive alternative for MCTS production, because it is mild, can be applied to a wide variety of cell lines, and can produce spheroids of a homogeneous size without the need for sieving or manual selection. The method has applications for basic studies of physiology and metabolism, tumor biology, toxicology, cellular organization, and the development of Bioartificial Tissue. (C) 2003 Wiley Periodicals, Inc.

Lars K Nielsen - One of the best experts on this subject based on the ideXlab platform.

  • method for generation of homogeneous multicellular tumor spheroids applicable to a wide variety of cell types
    Biotechnology and Bioengineering, 2003
    Co-Authors: Jens M Kelm, Nicholas E Timmins, Catherine Brown, Martin Fussenegger, Lars K Nielsen
    Abstract:

    Multicellular tumor spheroids (MCTS) are used as organotypic models of normal and solid tumor Tissue. Traditional techniques for generating MCTS, such as growth on nonadherent surfaces, in suspension, or on scaffolds, have a number of drawbacks, including the need for manual selection to achieve a homogeneous population and the use of nonphysiological matrix compounds. In this study we describe a mild method for the generation of MCTS, in which individual spheroids form in hanging drops suspended from a microtiter plate. The method has been successfully applied to a broad range of cell lines and shows nearly 100% efficiency (i.e., one spheroid per drop). Using the hepatoma cell line, HepG2, the hanging drop method generated well-rounded MCTS with a narrow size distribution (coefficient of variation [CV] 10% to 15%, compared with 40% to 60% for growth on nonadherent surfaces). Structural analysis of HepG2 and a mammary gland adenocarcinoma cell line, MCF-7, composed spheroids, revealed highly organized, three-dimensional, Tissue-like structures with an extensive extracellular matrix. The hanging drop method represents an attractive alternative for MCTS production, because it is mild, can be applied to a wide variety of cell lines, and can produce spheroids of a homogeneous size without the need for sieving or manual selection. The method has applications for basic studies of physiology and metabolism, tumor biology, toxicology, cellular organization, and the development of Bioartificial Tissue.

  • method for generation of homogeneous multicellular tumor spheroids applicable to a wide variety of cell types
    Biotechnology and Bioengineering, 2003
    Co-Authors: Jens M Kelm, Nicholas E Timmins, Martin Fussenegger, Catherine J Brown, Lars K Nielsen
    Abstract:

    Multicellular tumor spheroids (MCTS) are used as organotypic models of normal and solid tumor Tissue. Traditional techniques for generating MCTS, such as growth on nonadherent surfaces, in suspension, or on scaffolds, have a number of drawbacks, including the need for manual selection to achieve a homogeneous population and the use of nonphysiological matrix compounds. In this study we describe a mild method for the generation of MCTS, in which individual spheroids form in hanging drops suspended from a microtiter plate. The method has been successfully applied to a broad range of cell lines and shows nearly 100% efficiency (i.e., one spheroid per drop). Using the hepatoma cell line, HepG2, the hanging drop method generated well-rounded MCTS with a narrow size distribution (coefficient of variation [CV] 10% to 15%, compared with 40% to 60% for growth on nonadherent surfaces). Structural analysis of HepG2 and a mammary gland adenocarcinoma cell line, MCF-7, composed spheroids, revealed highly organized, three-dimensional, Tissue-like structures with an extensive extracellular matrix. The hanging drop method represents an attractive alternative for MCTS production, because it is mild, can be applied to a wide variety of cell lines, and can produce spheroids of a homogeneous size without the need for sieving or manual selection. The method has applications for basic studies of physiology and metabolism, tumor biology, toxicology, cellular organization, and the development of Bioartificial Tissue. (C) 2003 Wiley Periodicals, Inc.

Robert C Robbins - One of the best experts on this subject based on the ideXlab platform.

  • novel injectable Bioartificial Tissue facilitates targeted less invasive large scale Tissue restoration on the beating heart after myocardial injury
    Circulation, 2005
    Co-Authors: Theo Kofidis, Darren R Lebl, Eliana C Martinez, Grant Hoyt, Masashi Tanaka, Robert C Robbins
    Abstract:

    Background— Implantation of Bioartificial patches distorts myocardial geometry, and functional improvement of the recipient heart is usually attributed to reactive angiogenesis around the graft. With the liquid Bioartificial Tissue compound used in this study, we achieved targeted large-scale support of the infarcted left ventricular wall and improvement of heart function. Methods and Results— A liquid compound consisting of growth factor-free Matrigel and 10 6 green fluorescent protein (GFP)-positive mouse (129sv) embryonic stem cells (ESCs) was generated and injected into the area of ischemia after ligation of the left anterior descending artery in BALB/c mice (group I). Left anterior descending artery-ligated mice (group II) and mice with Matrigel (group III) or ESC treatment alone (group IV) were used as the control groups (n=5 in all groups). The hearts were harvested for histology 2 weeks later after echocardiographic assessment with a 15-MHz probe. The liquid injectable Tissue solidified at body temperature and retained the geometry of the infarcted lateral wall. Immunofluorescence stains revealed voluminous GFP grafts. The quality of restoration (graft/infarct area ratio) was 45.5±10.8% in group I and 29.1±6.7% in group IV ( P =0.034). ESCs expressed connexin 43 at intercellular contact sites. The mice treated with the compound had a superior heart function compared with the controls ( P Conclusions— Injectable Bioartificial Tissue restores the heart’s geometry and function in a targeted and nondistorting fashion. This new method paves the way for novel interventional approaches to myocardial repair, using both stem cells and matrices.

  • injectable Bioartificial myocardial Tissue for large scale intramural cell transfer and functional recovery of injured heart muscle
    The Journal of Thoracic and Cardiovascular Surgery, 2004
    Co-Authors: Theo Kofidis, Darren R Lebl, Grant Hoyt, Masashi Tanaka, Jorg L De Bruin, Toshiyuki Yamane, Ching Pin Chang, Robert C Robbins
    Abstract:

    Objectives Most Tissue-engineering approaches to restore injured heart muscle result in distortion of left ventricular geometry. In the present study we suggest seeding embryonic stem cells in a liquid matrix for myocardial restoration. Methods Undifferentiated green fluorescent protein–labeled mouse embryonic stem cells (2 × 10 6 ) were seeded in Matrigel (BD group II, 6.6% ± 2.1%; group III, 10.3% ± 2.2%; group IV, 14.5% ± 2.5%; and group V, 7.8% ± 1.8%). Conclusions Liquid Bioartificial Tissue containing embryonic stem cells constitutes a powerful new approach to restoring injured heart muscle without distorting its geometry and structure.

  • myocardial restoration with embryonic stem cell Bioartificial Tissue transplantation
    Journal of Heart and Lung Transplantation, 2004
    Co-Authors: Theo Kofidis, Darren R Lebl, Grant Hoyt, Masashi Tanaka, Jorg L De Bruin, Toshiyuki Yamane, Rutgerjan Swijnenburg, Ching Pin Chang, Thomas Quertermous, Robert C Robbins
    Abstract:

    Background The optimal cell-matrix combination for robust and sustained myocardial restoration has not been identified. The present study utilizes embryonic stem cells as the substrate of Bioartificial myocardial Tissue and evaluates engraftment in, and functional recovery of, the recipient heart. Methods Collagen type I was populated with undifferentiated green fluorescent protein (GFP)-positive mouse embryonic stem cells. An intramural left ventricular pouch was fashioned after ligation of the left anterior descending artery in an athymic nude rat heterotopic heart transplant model. The Bioartificial mixture (0.125 ml) was implanted in the infarcted area within the pouch. Echocardiography was performed to assess fractional shortening in: Group I, infarcted rats that received cell-matrix implants; Group II, rats given matrix implant without cells; Group III, rats given no matrix or cells; and Group IV, rats receiving transplanted hearts without ligation ( n = 5/group). Hearts were stained for GFP, cardiac markers (connexin-43, α-sarcomeric actin), hematoxylin-eosin (HE Group II, 1.0 ± 0.1 mm, Group III, 0.9 ± 0.2 mm; and Group IV, 1.3 ± 0.2 mm). The inoculated cells expressed connexin-43 and α-sarcomeric actin in vivo. Fractional shortening was better in embryonic stem cell-treated animals (Group I, 21.5 ± 3.5%; Group II, 12.4 ± 2.8%; Group III, 8.2 ± 2.9%; Group IV, 23.2 ± 4.2%). Conclusions Embryonic stem cells are an efficient alternative substrate for myocardial Tissue engineering and can prevent myocardial wall thinning and improve contractility after implantation into injured myocardium in a 3-dimensional matrix.

Theo Kofidis - One of the best experts on this subject based on the ideXlab platform.

  • novel injectable Bioartificial Tissue facilitates targeted less invasive large scale Tissue restoration on the beating heart after myocardial injury
    Circulation, 2005
    Co-Authors: Theo Kofidis, Darren R Lebl, Eliana C Martinez, Grant Hoyt, Masashi Tanaka, Robert C Robbins
    Abstract:

    Background— Implantation of Bioartificial patches distorts myocardial geometry, and functional improvement of the recipient heart is usually attributed to reactive angiogenesis around the graft. With the liquid Bioartificial Tissue compound used in this study, we achieved targeted large-scale support of the infarcted left ventricular wall and improvement of heart function. Methods and Results— A liquid compound consisting of growth factor-free Matrigel and 10 6 green fluorescent protein (GFP)-positive mouse (129sv) embryonic stem cells (ESCs) was generated and injected into the area of ischemia after ligation of the left anterior descending artery in BALB/c mice (group I). Left anterior descending artery-ligated mice (group II) and mice with Matrigel (group III) or ESC treatment alone (group IV) were used as the control groups (n=5 in all groups). The hearts were harvested for histology 2 weeks later after echocardiographic assessment with a 15-MHz probe. The liquid injectable Tissue solidified at body temperature and retained the geometry of the infarcted lateral wall. Immunofluorescence stains revealed voluminous GFP grafts. The quality of restoration (graft/infarct area ratio) was 45.5±10.8% in group I and 29.1±6.7% in group IV ( P =0.034). ESCs expressed connexin 43 at intercellular contact sites. The mice treated with the compound had a superior heart function compared with the controls ( P Conclusions— Injectable Bioartificial Tissue restores the heart’s geometry and function in a targeted and nondistorting fashion. This new method paves the way for novel interventional approaches to myocardial repair, using both stem cells and matrices.

  • injectable Bioartificial myocardial Tissue for large scale intramural cell transfer and functional recovery of injured heart muscle
    The Journal of Thoracic and Cardiovascular Surgery, 2004
    Co-Authors: Theo Kofidis, Darren R Lebl, Grant Hoyt, Masashi Tanaka, Jorg L De Bruin, Toshiyuki Yamane, Ching Pin Chang, Robert C Robbins
    Abstract:

    Objectives Most Tissue-engineering approaches to restore injured heart muscle result in distortion of left ventricular geometry. In the present study we suggest seeding embryonic stem cells in a liquid matrix for myocardial restoration. Methods Undifferentiated green fluorescent protein–labeled mouse embryonic stem cells (2 × 10 6 ) were seeded in Matrigel (BD group II, 6.6% ± 2.1%; group III, 10.3% ± 2.2%; group IV, 14.5% ± 2.5%; and group V, 7.8% ± 1.8%). Conclusions Liquid Bioartificial Tissue containing embryonic stem cells constitutes a powerful new approach to restoring injured heart muscle without distorting its geometry and structure.

  • myocardial restoration with embryonic stem cell Bioartificial Tissue transplantation
    Journal of Heart and Lung Transplantation, 2004
    Co-Authors: Theo Kofidis, Darren R Lebl, Grant Hoyt, Masashi Tanaka, Jorg L De Bruin, Toshiyuki Yamane, Rutgerjan Swijnenburg, Ching Pin Chang, Thomas Quertermous, Robert C Robbins
    Abstract:

    Background The optimal cell-matrix combination for robust and sustained myocardial restoration has not been identified. The present study utilizes embryonic stem cells as the substrate of Bioartificial myocardial Tissue and evaluates engraftment in, and functional recovery of, the recipient heart. Methods Collagen type I was populated with undifferentiated green fluorescent protein (GFP)-positive mouse embryonic stem cells. An intramural left ventricular pouch was fashioned after ligation of the left anterior descending artery in an athymic nude rat heterotopic heart transplant model. The Bioartificial mixture (0.125 ml) was implanted in the infarcted area within the pouch. Echocardiography was performed to assess fractional shortening in: Group I, infarcted rats that received cell-matrix implants; Group II, rats given matrix implant without cells; Group III, rats given no matrix or cells; and Group IV, rats receiving transplanted hearts without ligation ( n = 5/group). Hearts were stained for GFP, cardiac markers (connexin-43, α-sarcomeric actin), hematoxylin-eosin (HE Group II, 1.0 ± 0.1 mm, Group III, 0.9 ± 0.2 mm; and Group IV, 1.3 ± 0.2 mm). The inoculated cells expressed connexin-43 and α-sarcomeric actin in vivo. Fractional shortening was better in embryonic stem cell-treated animals (Group I, 21.5 ± 3.5%; Group II, 12.4 ± 2.8%; Group III, 8.2 ± 2.9%; Group IV, 23.2 ± 4.2%). Conclusions Embryonic stem cells are an efficient alternative substrate for myocardial Tissue engineering and can prevent myocardial wall thinning and improve contractility after implantation into injured myocardium in a 3-dimensional matrix.

  • Bioartificial grafts for transmural myocardial restoration a new cardiovascular Tissue culture concept
    European Journal of Cardio-Thoracic Surgery, 2003
    Co-Authors: Theo Kofidis, A Lenz, Jan Boublik, Payam Akhyari, Bjoern Wachsmann, Knut Mueller Stahl, Axel Haverich, Rainer G Leyh
    Abstract:

    Objective: Survival of Bioartificial grafts that are destined to restore cardiac function stands and falls with their nutrient supply. Engineering of myocardial Tissue is limited because of lack of vascularization. We introduce a new concept to obtain Bioartificial myocardial grafts in which perfusion by a macroscopic core vessel is simulated. Methods: We have designed an experimental reactor with multiple chambers for the production of Bioartificial Tissue or Tissue precursors. By introduction of in- and output lines of distinct diameter and insertion of a core vessel into each chamber, we established pulsatile, continuous flow through the embodied three-dimensional Tissue culture. In the present study, collagen components served as the ground matrix wherein neonatal rat cardiomyocytes were inoculated. For the assessment of cellular viability and distribution in comparison to static, non-perfused culture, fluor-desoxy-glucose-positron-emissiontomography and life/dead assays were employed. Results: We obtained 3D constructs of 8-mm thickness, which display high viability and metabolism (6.0 ^ 1.3 e-03 in the perfused vs. 4.0 ^ 0.3 e-03 in the unperfused chambers). The core vessel has the size of a human coronary and remained patent during the entire culture process. We observed centripetal migration of the embedded cardiomyocytes to the site of the core vessel. Cardiomyocytes partially resumed a spindle like form without additional stretch. Conclusions: The present dynamic Tissue culture concept is highly effective in manufacturing thick, viable grafts for cardiac muscle restoration, which could be surgically anastomosable. The bioreactor may accommodate multiple types of cells and Tissues for innumerable in vitro and in vivo applications. q 2003 Elsevier B.V. All rights reserved.

Nicholas E Timmins - One of the best experts on this subject based on the ideXlab platform.

  • method for generation of homogeneous multicellular tumor spheroids applicable to a wide variety of cell types
    Biotechnology and Bioengineering, 2003
    Co-Authors: Jens M Kelm, Nicholas E Timmins, Catherine Brown, Martin Fussenegger, Lars K Nielsen
    Abstract:

    Multicellular tumor spheroids (MCTS) are used as organotypic models of normal and solid tumor Tissue. Traditional techniques for generating MCTS, such as growth on nonadherent surfaces, in suspension, or on scaffolds, have a number of drawbacks, including the need for manual selection to achieve a homogeneous population and the use of nonphysiological matrix compounds. In this study we describe a mild method for the generation of MCTS, in which individual spheroids form in hanging drops suspended from a microtiter plate. The method has been successfully applied to a broad range of cell lines and shows nearly 100% efficiency (i.e., one spheroid per drop). Using the hepatoma cell line, HepG2, the hanging drop method generated well-rounded MCTS with a narrow size distribution (coefficient of variation [CV] 10% to 15%, compared with 40% to 60% for growth on nonadherent surfaces). Structural analysis of HepG2 and a mammary gland adenocarcinoma cell line, MCF-7, composed spheroids, revealed highly organized, three-dimensional, Tissue-like structures with an extensive extracellular matrix. The hanging drop method represents an attractive alternative for MCTS production, because it is mild, can be applied to a wide variety of cell lines, and can produce spheroids of a homogeneous size without the need for sieving or manual selection. The method has applications for basic studies of physiology and metabolism, tumor biology, toxicology, cellular organization, and the development of Bioartificial Tissue.

  • method for generation of homogeneous multicellular tumor spheroids applicable to a wide variety of cell types
    Biotechnology and Bioengineering, 2003
    Co-Authors: Jens M Kelm, Nicholas E Timmins, Martin Fussenegger, Catherine J Brown, Lars K Nielsen
    Abstract:

    Multicellular tumor spheroids (MCTS) are used as organotypic models of normal and solid tumor Tissue. Traditional techniques for generating MCTS, such as growth on nonadherent surfaces, in suspension, or on scaffolds, have a number of drawbacks, including the need for manual selection to achieve a homogeneous population and the use of nonphysiological matrix compounds. In this study we describe a mild method for the generation of MCTS, in which individual spheroids form in hanging drops suspended from a microtiter plate. The method has been successfully applied to a broad range of cell lines and shows nearly 100% efficiency (i.e., one spheroid per drop). Using the hepatoma cell line, HepG2, the hanging drop method generated well-rounded MCTS with a narrow size distribution (coefficient of variation [CV] 10% to 15%, compared with 40% to 60% for growth on nonadherent surfaces). Structural analysis of HepG2 and a mammary gland adenocarcinoma cell line, MCF-7, composed spheroids, revealed highly organized, three-dimensional, Tissue-like structures with an extensive extracellular matrix. The hanging drop method represents an attractive alternative for MCTS production, because it is mild, can be applied to a wide variety of cell lines, and can produce spheroids of a homogeneous size without the need for sieving or manual selection. The method has applications for basic studies of physiology and metabolism, tumor biology, toxicology, cellular organization, and the development of Bioartificial Tissue. (C) 2003 Wiley Periodicals, Inc.