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Schoen FJ, Gotlieb AI. Heart valve health, disease, replacement, and repair: a 25-year cardiovascular pathology perspective. Cardiovasc Pathol 2016; 25:341-352. [PMID: 27242130 DOI: 10.1016/j.carpath.2016.05.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/04/2016] [Accepted: 05/05/2016] [Indexed: 01/24/2023] Open
Abstract
The past several decades have witnessed major advances in the understanding of the structure, function, and biology of native valves and the pathobiology and clinical management of valvular heart disease. These improvements have enabled earlier and more precise diagnosis, assessment of the proper timing of surgical and interventional procedures, improved prosthetic and biologic valve replacements and repairs, recognition of postoperative complications and their management, and the introduction of minimally invasive approaches that have enabled definitive and durable treatment for patients who were previously considered inoperable. This review summarizes the current state of our understanding of the mechanisms of heart valve health and disease arrived at through innovative research on the cell and molecular biology of valves, clinical and pathological features of the most frequent intrinsic structural diseases that affect the valves, and the status and pathological considerations in the technological advances in valvular surgery and interventions. The contributions of many cardiovascular pathologists and other scientists, engineers, and clinicians are emphasized, and potentially fruitful areas for research are highlighted.
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Affiliation(s)
- Frederick J Schoen
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115; Pathology and Health Sciences and Technology (HST), Harvard Medical School, 75 Francis Street, Boston, MA 02115.
| | - Avrum I Gotlieb
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Laboratory Medicine Program, University Health Network, Medical Sciences Building, 1 King's College Circle, Rm. 6275A, Toronto, Ontario M5S 1A8, Canada.
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Liu MM, Flanagan TC, Lu CC, French AT, Argyle DJ, Corcoran BM. Culture and characterisation of canine mitral valve interstitial and endothelial cells. Vet J 2015; 204:32-9. [PMID: 25747697 DOI: 10.1016/j.tvjl.2015.01.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 01/07/2015] [Accepted: 01/18/2015] [Indexed: 10/24/2022]
Abstract
Valve interstitial cells (VICs) have an important role in the aetiopathogenesis of myxomatous mitral valve disease (MMVD) in the dog. Furthermore, there is evidence that valve endothelial cells (VECs) also contribute to disease development. In addition to examining native valve tissue to understand MMVD, another strategy is to separately examine VIC and VEC biology under in vitro culture conditions. The aim of this study was to isolate and characterise canine mitral VICs and VECs from normal dog valves using a combination of morphology, immunohistochemistry and reverse transcription PCR (RT-PCR). Canine mitral VECs and VICs were isolated and cultured in vitro. The two cell populations exhibited different morphologies and growth patterns. VECs, but not VICs, expressed the endothelial markers, platelet endothelial cell adhesion molecule (PECAM-1 or CD31) and acetylated low density lipoprotein (Dil-Ac-LDL). Both VECs and VICs expressed vimentin and embryonic non-smooth muscle myosin heavy chain (SMemb), an activated mesenchymal cell marker. The myofibroblast marker, alpha smooth muscle actin (α-SMA), was detected at the mRNA level in both VEC and VIC cultures, but only at the protein level in VIC cultures. The morphological heterogeneity and expression of non-endothelial phenotypic markers in VEC cultures suggested that a mixture of cell types was present, which might be due to cell contamination and/or endothelial-mesenchymal transition (EndoMT). The use of a specific endothelial culture medium for primary VEC cultures enhanced the endothelial properties of the cells and reduced α-SMA and SMemb expression.
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Affiliation(s)
- M-M Liu
- Royal (Dick) School of Veterinary Studies, The Roslin Institute, the University of Edinburgh, Easter Bush, Roslin, Mid-Lothian, Scotland EH25 9RG, United Kingdom
| | - T C Flanagan
- School of Medicine & Medical Science, Health Sciences Centre, University College Dublin, Belfield, Dublin 4, Ireland
| | - C-C Lu
- Royal (Dick) School of Veterinary Studies, The Roslin Institute, the University of Edinburgh, Easter Bush, Roslin, Mid-Lothian, Scotland EH25 9RG, United Kingdom
| | - A T French
- University of Glasgow School of Veterinary Medicine, Bearsden Road, Glasgow, Scotland G61 1QH, United Kingdom
| | - D J Argyle
- Royal (Dick) School of Veterinary Studies, The Roslin Institute, the University of Edinburgh, Easter Bush, Roslin, Mid-Lothian, Scotland EH25 9RG, United Kingdom
| | - B M Corcoran
- Royal (Dick) School of Veterinary Studies, The Roslin Institute, the University of Edinburgh, Easter Bush, Roslin, Mid-Lothian, Scotland EH25 9RG, United Kingdom.
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Huang S, Huang HYS. Virtualisation of stress distribution in heart valve tissue. Comput Methods Biomech Biomed Engin 2013; 17:1696-704. [PMID: 23477432 DOI: 10.1080/10255842.2013.763937] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This study presents an image-based finite element analysis incorporating histological photomicrographs of heart valve tissues. We report stress fields inside heart valve tissues, where heterogeneously distributed collagen fibres are responsible for transmitting forces into cells. Linear isotropic and anisotropic tissue material property models are incorporated to quantify the overall stress distributions in heart valve tissues. By establishing an effective predictive method with new computational tools and by performing virtual experiments on the heart valve tissue photomicrographs, we clarify how stresses are transferred from matrix to cell. The results clearly reveal the roles of heterogeneously distributed collagen fibres in mitigating stress developments inside heart valve tissues. Moreover, most local peak stresses occur around cell nuclei, suggesting that higher stress may be mediated by cells for biomechanical regulations.
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Affiliation(s)
- Siyao Huang
- a Mechanical and Aerospace Engineering Department , North Carolina State University , 3002 EBIII, Campus Box 7910, 911 Oval Drive, Raleigh , NC 27695-7910 , USA
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Cordeiro JV, Jacinto A. The role of transcription-independent damage signals in the initiation of epithelial wound healing. Nat Rev Mol Cell Biol 2013; 14:249-62. [PMID: 23443750 DOI: 10.1038/nrm3541] [Citation(s) in RCA: 179] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Wound healing is an essential biological process that comprises sequential steps aimed at restoring the architecture and function of damaged cells and tissues. This process begins with conserved damage signals, such as Ca(2+), hydrogen peroxide (H2O2) and ATP, that diffuse through epithelial tissues and initiate immediate gene transcription-independent cellular effects, including cell shape changes, the formation of functional actomyosin structures and the recruitment of immune cells. These events integrate the ensuing transcription of specific wound response genes that further advance the wound healing response. The immediate importance of transcription-independent damage signals illustrates that healing a wound begins as soon as damage occurs.
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Affiliation(s)
- João V Cordeiro
- Centro de Estudos de Doenças Crónicas (CEDOC), Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Campo Mártires da Pátria, 130, 1169-056 Lisboa, Portugal
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Han L, Gotlieb AI. Fibroblast growth factor-2 promotes in vitro heart valve interstitial cell repair through the Akt1 pathway. Cardiovasc Pathol 2012; 21:382-9. [DOI: 10.1016/j.carpath.2011.12.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 11/29/2011] [Accepted: 12/04/2011] [Indexed: 10/14/2022] Open
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The response to valve injury. A paradigm to understand the pathogenesis of heart valve disease. Cardiovasc Pathol 2011; 20:183-90. [DOI: 10.1016/j.carpath.2010.09.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 08/23/2010] [Accepted: 09/09/2010] [Indexed: 12/21/2022] Open
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Xu S, Liu AC, Kim H, Gotlieb AI. Cell density regulates in vitro activation of heart valve interstitial cells. Cardiovasc Pathol 2011; 21:65-73. [PMID: 21397521 DOI: 10.1016/j.carpath.2011.01.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2010] [Revised: 10/30/2010] [Accepted: 01/26/2011] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Valve interstitial cells, the most prominent cell type in the heart valve, are activated and express α-smooth muscle actin in valve repair and in diseased valves. We hypothesize that cell density, time in culture, and the establishment of cell-cell contacts may be involved in regulating valve interstitial cell activation in vitro. METHODS To study cell density, valve interstitial cells were plated at passages 3 to 5, at a density of 17,000 cells/22 × 22 mm(2) coverslip, and grown for 1, 2, 4, 7, and 10 days. Valve interstitial cells were stained for α-smooth muscle actin and viewed under confocal microscopy to characterize the intensity of staining. To study time in culture, valve interstitial cells were plated at a 10-fold higher density to achieve similar growth densities over a shorter time period compared with valve interstitial cells plated at low density. α-Smooth muscle actin staining was compared at the same time points between those plated at high and low densities. To confirm valve interstitial cell activation as indicated by α-smooth muscle actin staining, valve interstitial cells were stained for cofilin at days 2, 5, 8, and 14 days postplating. To study the association of transforming growth factor β with valve interstitial cell activation with respect to cell density, valve interstitial cells were stained for α-smooth muscle actin and transforming growth factor β at 2, 4, 6, and 8 days postplating. To study the activation of the transforming growth factor β signaling pathway, valve interstitial cells were stained for pSmad2/3 at days 2, 4, 6, 8, 10, and 12 days postplating. To study cell contacts and activation, subconfluent and confluent cultures of valve interstitial cells were stained for β-catenin, N-cadherin, and α-smooth muscle actin. Also, whole-cell lysates of subconfluent and confluent valve interstitial cell cultures were probed by Western blot analysis for phospho-β-catenin at Ser33/37/Thr41, which is the form of β-catenin targeted for proteosomal degradation. RESULTS The percentage valve interstitial cells with high-intensity α-smooth muscle actin staining decreases significantly between days 1 and 4, and at confluency, most cells show absent or low-intensity staining, regardless of time in culture. Similar results are obtained with cofilin staining. Transforming growth factor β and nuclear pSmad2/3 staining in valve interstitial cells decreases concurrently with valve interstitial cell activation as cell density increases. Examining β-catenin and N-cadherin staining, single valve interstitial cells show no cell-cell contact with strong cytoplasmic staining, with some showing nuclear staining of β-catenin, while confluent monolayers show strong staining of fully established cell-cell contacts, weak cytoplasmic staining, and absent nuclear staining. The presence of cell-cell contacts is associated with a decreased α-smooth muscle actin. The level of phospho-β-catenin at Ser33/37/Thr41 is lower in confluent cultures compared with low-density subconfluent valve interstitial cell cultures. CONCLUSION Cell-cell contacts may inhibit valve interstitial cell activation, while absence of cell-cell contacts may contribute to activation.
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Affiliation(s)
- Songyi Xu
- Department of Pathology, Toronto General Research Institute, University Health Network, Ontario, Canada
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Han L, Gotlieb AI. Fibroblast growth factor-2 promotes in vitro mitral valve interstitial cell repair through transforming growth factor-β/Smad signaling. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 178:119-27. [PMID: 21224050 DOI: 10.1016/j.ajpath.2010.11.038] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2010] [Revised: 09/25/2010] [Accepted: 09/30/2010] [Indexed: 12/30/2022]
Abstract
Transforming growth factor (TGF)-β and fibroblast growth factor (FGF)-2 both promote repair in valve interstitial cell (VIC) injury models; however, the relationship between TGF-β and FGF-2 in wound repair are not well understood. VIC confluent monolayers were wounded by mechanical injury and incubated separately or in combination with FGF-2, neutralizing antibody to FGF-2, neutralizing antibody to TGF-β, and betaglycan antibody for 24 hours after wounding. Phosphorylated Smad2/3 (pSmad2/3) was localized at the wound edge (WE) and at the monolayer away from the WE. Down-regulation of pSmad2/3 protein expression via small-interfering RNA transfection was performed. The extent of wound closure was monitored for up to 96 hours. FGF-2 incubation resulted in a significant increase in nuclear pSmad2/3 staining at the WE. Neutralizing antibody to TGF-β alone or with FGF-2 present resulted in a similar significant decrease in pSmad2/3. Neutralizing antibody to FGF-2 alone or with FGF-2 present showed a similar significant decrease in pSmad2/3; however, significantly more staining was observed than treatment with neutralizing antibody to TGF-β. Incubation with betaglycan antibody inhibited FGF-2-mediated pSmad2/3 signaling. Wound closure corresponded with pSmad2/3 staining at the WE. Down-regulation of pSmad2/3 via small-interfering RNA transfection significantly reduced the extent to which FGF-2 promoted wound closure. Fibroblast growth factor-2 promotes in vitro VIC wound repair, at least in part, through the TGF-β/Smad2/3 signaling pathway.
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Affiliation(s)
- Li Han
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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Sucosky P, Balachandran K, Elhammali A, Jo H, Yoganathan AP. Altered shear stress stimulates upregulation of endothelial VCAM-1 and ICAM-1 in a BMP-4- and TGF-beta1-dependent pathway. Arterioscler Thromb Vasc Biol 2008; 29:254-60. [PMID: 19023092 DOI: 10.1161/atvbaha.108.176347] [Citation(s) in RCA: 183] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE Hemodynamics has been associated with aortic valve (AV) inflammation, but the underlying mechanisms are not well understood. Here we tested the hypothesis that altered shear stress conditions stimulate the expression of cytokines and adhesion molecules in AV leaflets via a bone morphogenic protein (BMP)- and transforming growth fact (TGF)-beta1-dependent pathway. METHODS AND RESULTS The ventricularis or aortic surface of porcine AV leaflets were exposed for 48 hours to unidirectional pulsatile and bidirectional oscillatory shear stresses ex vivo. Immunohistochemistry was performed to detect expressions of the 4 inflammatory markers VCAM-1, ICAM-1, BMP-4, and TGF-beta1. Exposure of the aortic surface to pulsatile shear stress (altered hemodynamics), but not oscillatory shear stress, increased expression of the inflammatory markers. In contrast, neither pulsatile nor oscillatory shear stress affected expression of the inflammatory markers on the ventricularis surface. The shear stress-dependent expression of VCAM-1, ICAM-1, and BMP-4, but not TGF-beta1, was significantly reduced by the BMP inhibitor noggin, whereas the TGF-beta1 inhibitor SB431542 blocked BMP-4 expression on the aortic surface exposed to pulsatile shear stress. CONCLUSIONS The results demonstrate that altered hemodynamics stimulates the expression of AV leaflet endothelial adhesion molecules in a TGF-beta1- and BMP-4-dependent manner, providing some potential directions for future drug-based therapies for AV diseases.
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Affiliation(s)
- Philippe Sucosky
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556-5637, USA.
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Liu AC, Gotlieb AI. Transforming growth factor-beta regulates in vitro heart valve repair by activated valve interstitial cells. THE AMERICAN JOURNAL OF PATHOLOGY 2008; 173:1275-85. [PMID: 18832581 DOI: 10.2353/ajpath.2008.080365] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The regulation of valve interstitial cell (VIC) function in response to tissue injury and valve disease is not well understood. Because transforming growth factor-beta (TGF-beta) has been implicated in tissue repair, we tested the hypothesis that TGF-beta is a regulator of VIC activation and associated cell responses that occur during early repair processes. We used a well-characterized wound model that was created by mechanical denudation of a confluent VIC monolayer to study activation and repair 24 hours after wounding. VIC activation was demonstrated by immunofluorescent localization of alpha-smooth muscle actin (alpha-SMA), and alpha-SMA mRNA levels were quantified by real-time polymerase chain reaction. Proliferation and apoptosis were quantified by bromodeoxyuridine staining and terminal deoxynucleotidyl transferase dUTP nick end labeling, respectively. Repair was quantified by measuring VIC extension into the wound, and TGF-beta expression was shown by immunofluorescent localization of intracellular TGF-beta. Compared with nonwounded monolayers, VICs at the wound edge showed alpha-SMA staining, increased alpha-SMA mRNA content, elongation into the wound with stress fibers, proliferation, and apoptosis. VICs at the wound edge also showed increased TGF-beta and pSmad2/3 staining with co-expression of alpha-SMA. Addition of TGF-beta neutralizing antibody to the wound decreased VIC activation, alpha-SMA mRNA content, proliferation, apoptosis, wound closure rate, and stress fibers. Conversely, exogenous addition of TGF-beta to the wound increased VIC activation, proliferation, wound closure rate, and stress fibers. Thus, wounding activates VICs, and TGF-beta signaling modulates VIC response to injury.
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Affiliation(s)
- Amber C Liu
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada
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Liu AC, Joag VR, Gotlieb AI. The emerging role of valve interstitial cell phenotypes in regulating heart valve pathobiology. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 171:1407-18. [PMID: 17823281 PMCID: PMC2043503 DOI: 10.2353/ajpath.2007.070251] [Citation(s) in RCA: 435] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The study of the cellular and molecular pathogenesis of heart valve disease is an emerging area of research made possible by the availability of cultures of valve interstitial cells (VICs) and valve endothelial cells (VECs) and by the design and use of in vitro and in vivo experimental systems that model elements of valve biological and pathobiological activity. VICs are the most common cells in the valve and are distinct from other mesenchymal cell types in other organs. We present a conceptual approach to the investigation of VICs by focusing on VIC phenotype-function relationships. Our review suggests that there are five identifiable phenotypes of VICs that define the current understanding of their cellular and molecular functions. These include embryonic progenitor endothelial/mesenchymal cells, quiescent VICs (qVICs), activated VICs (aVICs), progenitor VICs (pVICs), and osteoblastic VICs (obVICs). Although these may exhibit plasticity and may convert from one form to another, compartmentalizing VIC function into distinct phenotypes is useful in bringing clarity to our understanding of VIC pathobiology. We present a conceptual model that is useful in the design and interpretation of studies on the function of an important phenotype in disease, the activated VIC. We hope this review will inspire members of the investigative pathology community to consider valve pathobiology as an exciting new frontier exploring pathogenesis and discovering new therapeutic targets in cardiovascular diseases.
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Affiliation(s)
- Amber C Liu
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, M5G 1L5, ON, Canada
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Fayet C, Bendeck MP, Gotlieb AI. Cardiac valve interstitial cells secrete fibronectin and form fibrillar adhesions in response to injury. Cardiovasc Pathol 2007; 16:203-11. [PMID: 17637428 DOI: 10.1016/j.carpath.2007.02.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Revised: 12/21/2006] [Accepted: 02/21/2007] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Fibronectin, an extracellular matrix protein, is associated with the general process of tissue repair and is present in heart valves. In order to understand the cellular mechanisms of heart valve repair, we hypothesized that fibronectin is produced and secreted by valvular interstitial cells (VICs), and when up-regulated in VICs involved in active repair, it is associated with prominent fibrillar adhesions composed of tensin and alpha(5)beta(1) integrin. We investigated the interaction of porcine mitral VICs with the underlying fibronectin matrix and the formation and localization of focal and fibrillar adhesion complexes in an in vitro wound model. METHODS Confluent monolayers of VICs were wounded with a 1-mm-wide cell scraper, maintained in standard media and 10% fetal bovine serum, and fixed at various time points after wounding. Immunohistochemistry was used to localize fibronectin, paxillin, tensin, and alpha(5)beta(1) integrin. F-actin was localized with an Alexa-Fluor-568-labeled phalloidin. Cells were examined with a scanning confocal laser microscope. RESULTS In response to in vitro mechanical wounding, migrating VICs at the wound edge expressed cytoplasmic fibronectin compared to nonwounded confluent monolayers. Over 24 to 48 h, fibrils were deposited into the subcellular space. Coincident with this, staining for alpha(5)beta(1) appeared, and tensin redistributed from focal adhesions to fibrillar adhesions, which colocalized with alpha(5)beta(1). CONCLUSIONS Fibronectin in association with fibrillar adhesions is a component of the matrix that may be secreted by migrating VICs to regulate repair at sites of valve injury.
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Affiliation(s)
- Cristina Fayet
- Toronto General Research Institute and Department of Pathology, University Health Network, Toronto, Ontario, Canada M5G 2C4
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Pedersen LG, Offenberg H, Moesgaard SG, Thomsen PD, Pedersen HD, Olsen LH. Transcription levels of endothelin-1 and endothelin receptors are associated with age and leaflet location in porcine mitral valves. ACTA ACUST UNITED AC 2007; 54:113-8. [PMID: 17381672 DOI: 10.1111/j.1439-0442.2007.00894.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The aim of the study was to investigate the expression levels of endothelin-1 (ET-1) and ET(A) and ET(B) receptors (ET(A)-R and ET(B)-R) in porcine mitral valves and associate the transcription levels to age, leaflet location and deposition of mucopolysaccharides (MPS). Tissue samples from the chordal and inter-chordal insertion area of the anterior mitral valve leaflet from 11 sows (> or = 2 years of age) and 10 slaughter pigs (approximately 6 months old) were obtained and the relative gene expression levels of ET-1, ET(A)-R and ET(B)-R measured by semi-quantitative real-time PCR. A separate tissue sample was taken for histopathological grading of MPS deposition. The transcription levels of ET-1 (P < 0.0001) and ET(A)-R (P < 0.0004) were significantly higher in leaflets from the sows compared with slaughter pigs. The gene expression of ET(B)-R was not associated to age (P = 0.38), but increased in chordal insertion areas compared with inter-chordal areas (P = 0.01). The expression of ET-1 and ET(A)-R mRNA did not differ significantly between the two leaflet locations. The valve leaflets from sows had a significantly increased degree of MPS deposition compared with slaughter pigs upon histological examination (P = 0.04). In conclusion, an age-related valvular degeneration is observed in porcine mitral valve leaflets and ET-1 is suggested to be involved through action of both ET(A) and ET(B) receptors.
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Affiliation(s)
- L G Pedersen
- Department of Basic Animal and Veterinary Sciences, The Royal Vetinary and Agricultural University, Copenhagen, Denmark
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Moesgaard SG, Olsen LH, Aasted B, Viuff BM, Pedersen LG, Pedersen HD, Harrison AP. Direct measurements of nitric oxide release in relation to expression of endothelial nitric oxide synthase in isolated porcine mitral valves. ACTA ACUST UNITED AC 2007; 54:156-60. [PMID: 17381681 DOI: 10.1111/j.1439-0442.2007.00915.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The aim of this study was to measure the direct release of nitric oxide (NO) from the porcine mitral valve using a NO microelectrode. Furthermore, the expression and localization of endothelial nitric oxide synthase (eNOS) in the mitral valve was studied using immunohistochemistry, Western blotting and RT-PCR. Results show that bradykinin increases NO release from mitral valves (DeltaBradykinin: 33.71 +/- 10.41 nm NO, P < 0.001, n = 10), whereas N-nitro-l-arginine methyl esther (l-NAME) decreases NO release when compared with basal level (Deltal-NAME: 82.69 +/- 15.66 nm NO, P < 0.005, n = 4). Both protein and mRNA expression of eNOS in mitral valves and in isolated valvular endothelial cells suggest that the NO release is mainly associated with the mitral valve endothelium. It is concluded that direct NO release from porcine mitral valves coincides with eNOS expression. This study documents useful techniques for investigations into the role of local NO release in mitral valve diseases.
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Affiliation(s)
- S G Moesgaard
- Department of Basic Animal and Veterinary Sciences, The Royal Vetinary and Agricultural University, Fredriksberg, Denmark.
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Tamura K, Murakami M, Washizu M. Healing of wound sutures on the mitral valve: an experimental study. Gen Thorac Cardiovasc Surg 2007; 55:98-104. [PMID: 17447507 DOI: 10.1007/s11748-006-0085-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The aim of this study was to examine the histopathological changes that occur during the heading process of a sutured wound on the mitral valve. METHODS In 12 mongrel dogs, an incision was made at a right angle to the annulus at the center of the free edge of the anterior mitral leaflet and then sutured. Animals were killed 2-16 weeks later and the wounds were examined histologically. RESULTS Two weeks after the operation, fibrin thrombi were found on the atrial surfaces of the wound, and organized thrombi became part of the neointima thereafter. There were capillaries in the thrombi, but only a few extended from the valvular ring. On the ventricular surfaces, fibrous neointima extending from adjacent intima without capillary proliferation covered the wound at 2 weeks. These heading processes started from the valvular ring side of the wound. Processes were delayed near the free edge area, and myxomatous granulation tissue extended from the adjacent spongiosa. There were abundant collagen fibers obscuring the suture line at 4 weeks in the basal region and at 12-16 weeks near the free edge. Calcified deposits with cartilage were found in a thick scar in the basal region at 4 weeks and extended to the central area thereafter. CONCLUSION The healing of mitral valvular wounds is slow, especially near the free edge area. The wound is covered by organized thrombi at the atrial surface and by fibrous sheaths at the ventricular surface. These processes should be taken into consideration during the patients' care after valvoplasty, especially during the first several months after surgery.
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Affiliation(s)
- Koichi Tamura
- Division of Surgical Pathology, Nippon Medical School Hospital, 1-1-5 Sendagi, Bunkyo-ku, Tokyo, Japan.
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Pedersen LG, Zhao J, Yang J, Thomsen PD, Gregersen H, Hasenkam JM, Smerup M, Pedersen HD, Olsen LH. Increased expression of endothelin B receptor in static stretch exposed porcine mitral valve leaflets. Res Vet Sci 2006; 82:232-8. [PMID: 17011002 DOI: 10.1016/j.rvsc.2006.07.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Accepted: 07/22/2006] [Indexed: 10/24/2022]
Abstract
The aim of this study was to evaluate the effect of mechanical stretch on the expression of ET-1 and ET(A)- and ET(B)-receptors in porcine mitral valve leaflets. Leaflet segments from 10 porcine mitral valves were exposed to a static stretch load of 1.5 N for 3.5h in buffer at 37 degrees C together with matching control segments. Subsequently, the mRNA expression of ET-1, ET(A)-R and ET(B)-R was measured by real-time RT-PCR in the chordal insertion areas. The analyses showed an increased transcription of ET(B)-receptors in stretch-exposed leaflet segments compared to unstretched segments median 2.23 (quartiles 1.37 and 2.70) vs. median 1.56 (quartiles 1.38 and 2.17, P=0.03) whereas the mRNA expression of ET(A)-receptors (P=0.90) and ET-1 (P=0.51) remained unchanged. Stretch increased the expression of ET(B)-receptors in porcine mitral valve leaflets. The finding could lead to a better understanding of the pathogenesis of myxomatous mitral valve disease.
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Affiliation(s)
- L G Pedersen
- Department of Basic Animal and Veterinary Sciences, The Royal Veterinary and Agricultural University, 7 Groennegaardsvej, DK-1870 Frederiksberg, Copenhagen, Denmark.
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Flanagan TC, Black A, O'Brien M, Smith TJ, Pandit AS. Reference Models for Mitral Valve Tissue Engineering Based on Valve Cell Phenotype and Extracellular Matrix Analysis. Cells Tissues Organs 2006; 183:12-23. [PMID: 16974091 DOI: 10.1159/000094902] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The advance of mitral valve repair techniques through tissue engineering is impeded by the lack of information regarding the cellular and extracellular components of the mitral valve. The present study aims to expand our understanding of the mitral valve structure by analysing the synthesis of extracellular matrix (ECM) proteins and the expression of nitric oxide synthase (NOS). Valvular endothelial cells (VECs) and valvular interstitial cells (VICs) were isolated from porcine mitral valves. Immunochemical staining of ECM components, including type I, II, III, IV and V collagen, laminin, fibronectin, elastin and chondroitin sulphate (CS), was performed on both mitral valve tissue and cell cultures. Reverse transcription polymerase chain reaction and immunochemistry were used to analyse NOS expression in native valve and in culture. Both VECs and VICs synthesised the basement membrane components, laminin and type IV collagen both in vivo and in vitro, amongst other fibrous ECM proteins. Synthesis of type I collagen and CS was absent in VEC cultures. Each cell type had a characteristic profile of NOS expression. VECs synthesised endothelial NOS both in vivo and in vitro, with a minority of VICs expressing neuronal NOS in vitro. The present study reports newly recognised aspects of the mitral valve structure and the in vitro behaviour of mitral valve cell populations based on ECM synthesis and NOS expression. The presented profiles can be used as base tools for the generation of data necessary for the selection of ideal cell sources and for the design of appropriate scaffolds for the development of effective tissue-engineered mitral valves.
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Affiliation(s)
- T C Flanagan
- Department of Anatomy, National University of Ireland Galway, Galway, Ireland.
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Gotlieb AI. Infections and inflammatory diseases of native and prosthetic heart valves and devices. Cardiovasc Pathol 2006; 15:241-242. [PMID: 29768907 DOI: 10.1016/j.carpath.2006.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Accepted: 07/18/2006] [Indexed: 10/24/2022] Open
Affiliation(s)
- Avrum I Gotlieb
- Banting Institute University of Toronto University Health Network 100 College St., Room 110 Toronto, ON, Canada M5G 1L5
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