Patricia M Taylor

Imperial College London, Londinium, England, United Kingdom

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Publications (28)119.12 Total impact

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    ABSTRACT: Rapid prototyping is a novel process for the production of scaffolds of predetermined size and three-dimensional shape. The aim of the study was to determine the feasibility of this technology for producing scaffolds for tissue engineering an aortic valve and the optimal concentration of collagen processed in this manner that would maintain viability and promote proliferation of human valve interstitial cells. Scaffolds of 1%, 2% and 5% w/v bovine type-I collagen were manufactured using rapid prototyping. Valve interstitial cells isolated from three human aortic valves were seeded on the scaffolds and cultured for up to 4 weeks. Cell viability was assessed using the CellTiter 96 Aq(ueous) One Solution Cell Proliferation Assay and cell death by lactate dehydrogenase (LDH) measurement. Valve interstitial cells remained viable and proliferated within the collagen scaffolds. Cells consistently proliferated to a greater extent on 1% collagen scaffolds rather than either 2% or 5% collagen and after 4 weeks reached 212+/-33.1%, 139+/-25.9% and 129+/-38.3% (mean+/-SD) of their initial seeding density on 1%, 2% and 5% collagen scaffolds, respectively. LDH analysis demonstrated that there was minimal cell death indicating that the collagen scaffold was not toxic to human valve interstitial cells. Rapid prototyping provides a route to optimize biological scaffold designs for tissue engineering cardiac valves. This technology has the versatility to create scaffolds that are compatible with the specific needs of the valve interstitial cells and should enhance cell viability, proliferation and function.
    No preview · Article · Jun 2006 · Biomaterials

  • No preview · Article · Jun 2006 · Journal of Molecular and Cellular Cardiology

  • No preview · Article · Jun 2006 · Journal of Molecular and Cellular Cardiology
  • Patricia M. Taylor · Anthony E.G. Cass · Magdi H. Yacoub
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    ABSTRACT: Currently available heart valve substitutes fail to emulate the sophisticated functions of the native aortic valve, a factor that contributes to their eventual failure. One possible strategy to generate a valve substitute that reproduces the function of the native valve would be to apply the principals of tissue engineering. A crucial step in this process will be the choice of scaffold, which serves as an initial support on which to seed the cells. Successful scaffold materials should be amenable to modification, have a controlled degradation, be compatible with the cells, lack cytotoxicity and not elicit an immune or inflammatory response. Importantly the ideal scaffold should possess cell attachment and signalling molecules that will promote cell population and function, resulting in remodelling of the scaffold into a tissue construct, which can mimic the function of the native valve, possessing the mechanical strength and integrity to withstand aortic pressures. Such molecules are naturally present in biological scaffolds to varying degrees. This chapter discusses the various biological scaffolds that have been considered and are being studied for use in tissue engineering a heart valve and primarily focuses on the aortic valve. Strategies to optimize the physical parameters of the scaffold and to introduce biological signals into synthetic scaffolds or augment biological scaffolds are also discussed.
    No preview · Article · Mar 2006 · Progress in Pediatric Cardiology
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    ABSTRACT: The pattern of expression and distribution of extracellular matrix (ECM) components in human cardiac leaflets was analyzed. Additionally, interstitial cells (ICs) from the four different leaflets were isolated and studied. Immunohistochemistry and immunocytochemistry were used for localization, and flow cytometric analysis to quantify the expression of specific markers on these ICs; the synthesis and expression of ECM components was assessed. Elastin was found predominantly on the inflow layer, but fine fibers were also present in the central and outflow layers. Collagen I was predominantly on the outflow layer but permeated throughout the leaflets. Collagen III was expressed ubiquitously. Proteoglycan expression was throughout the leaflet, but was predominant in the central layer. Fibronectin and vitronectin were expressed strongly in the inflow layer, moderately in the central layer, and weakly in the outflow layer. Biglycan expression was ubiquitous, with strong filamentous strands in the central layer. Keratan sulfate and decorin were ubiquitous. Chondroitin-4-sulfate and chondroitin-6-sulfate were strongly expressed in the outer layers, and laminin was restricted to the basal lamina of the endothelial cells. Cultured ICs showed synthesis and expression of various ECM components. This study of the pattern of expression of ECM components may provide a basis for a fingerprint on which to base future valve alternatives. The results provide useful information for valve tissue engineering and an understanding of the structural basis of some sophisticated functions of the valves.
    Full-text · Article · Apr 2005 · The Journal of heart valve disease
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    ABSTRACT: Cardiac valve interstitial cells (ICs) are a heterogeneous and dynamic population of specific cell types that have many unique characteristics. They are responsible for maintaining the extracellular scaffold that provides the mechanical characteristics vital for sustaining the unique dynamic behaviour of the valve. A number of cellular phenotypes can be distinguished: some are sparsely arranged throughout the valve leaflets, whilst others are arranged in thin bundles. These cells express molecular markers similar to those of skeletal, cardiac and smooth muscle cells (SMCs) and in particular, many ICs express smooth muscle (SM) alpha-actin, a marker of myofibroblasts. In this respect, these cells exhibit a profile unlike skin fibroblasts, which may allude to their role in valve function.
    Full-text · Article · Mar 2003 · The International Journal of Biochemistry & Cell Biology
  • Sally A Dreger · Patricia M Taylor · Sean P Allen · Magdi H Yacoub
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    ABSTRACT: Tissue turnover is one of many factors involved in the operational longevity of heart valves. An understanding of how valves remodel their matrix in response to the hemodynamic environment in health and disease is crucial to the design and biological responsiveness of tissue-engineered valve substitutes. Matrix metalloproteinases (MMPs) are proteolytic enzymes involved in matrix remodeling in several tissues, and include interstitial collagenase (MMP-1, MMP-13), the gelatinases (MMP-2, MMP-9) and stromelysin (MMP-3). Expression of MMPs and their tissue inhibitors (TIMPs) in human aortic, mitral, tricuspid and pulmonary valves from unused donor or transplant recipient hearts was determined by immunohistochemical staining using antibodies against human MMP-1, MMP-2, MMP-3 and MMP-9 and their inhibitors TIMP-1, TIMP-2, TIMP-3. Cell identification was achieved using antibodies against CD31(endothelial cells), smooth muscle alpha-actin (microfilaments) and CD68 (macrophages). MMP-1 was expressed in all valves, whereas MMP-2 was only expressed in aortic and pulmonary leaflets. MMP-3 and MMP-9 were not expressed. TIMP-1 and TIMP-2 were expressed in all leaflets, whereas TIMP-3 was observed only in tricuspid leaflets. Valves have a specific pattern of expression of MMPs and TIMPs, which appears to vary in different heart valves. The functional implications and central mechanisms responsible require further study. These findings have important implications in understanding the dynamic nature of valve remodeling and in aiding the development of tissue-engineered valves.
    No preview · Article · Dec 2002 · The Journal of heart valve disease
  • Patricia M Taylor · Sean P Allen · Sally A Dreger · Magdi H Yacoub
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    ABSTRACT: The use of a biological, biodegradable scaffold remodeled by cells to resemble a valve leaflet is an attractive approach to tissue engineering. The study aim was to evaluate the suitability of a three-dimensional biodegradable collagen sponge for maintenance of cell viability, proliferation and phenotype of cultured human cardiac valve interstitial cells (ICs). Pieces of valve leaflets were snap-frozen, sectioned and stained by immunoperoxidase. Interstitial cells were cultured from cardiac valves and plated onto glass coverslips or seeded in collagen sponge, then stained by immunofluorescence or immunoperoxidase. A panel of antibodies was used to determine cell phenotype. Cell viability was assessed using a dye-based cell proliferation assay, and cell death by lactate dehydrogenase measurement. ICs variably expressing the phenotypic markers were found throughout the native valve leaflet, but particularly on the ventricular side. Cultured ICs either on coverslips or in collagen sponge expressed vimentin, a fibroblast surface antigen and variable amounts of smooth muscle (SM) alpha-actin. Expression of the other phenotypic markers, SM myosin, desmin and prolyl 4-hydroxylase differed: interestingly, the ratio of cells in collagen sponge expressing these markers reflected that found in the native valve leaflet. Confocal microscopy of ICs in the collagen sponge revealed the presence of cells with long interconnecting extensions indicating cell communication. Cell proliferation and cell death assays established that cells were not only viable after four weeks in the sponge, but were also proliferating. This study demonstrates that collagen sponge is a suitable biodegradable scaffold that can maintain viable valve ICs and appears to enhance the capacity of the cell to express its original phenotype.
    No preview · Article · Jun 2002 · The Journal of heart valve disease

Publication Stats

1k Citations
119.12 Total Impact Points


  • 2002-2014
    • Imperial College London
      • Faculty of Medicine
      Londinium, England, United Kingdom
  • 2011
    • Queen Mary, University of London
      • School of Engineering and Materials Science
      Londinium, England, United Kingdom
  • 2007
    • University of Westminster
      Londinium, England, United Kingdom
  • 2003-2007
    • National Heart, Lung, and Blood Institute
      Maryland, United States