RESUMO
BACKGROUND: In order to obtain the smaller delivery diameter, porcine pericardium had been used as a substitute material of bovine pericardium for the leaflet materials of transcatheter heart valve (THV). However, the differences between them had not been fully studied. Therefore, this study compared the microstructure, biochemical and mechanical properties of two materials and hydrodynamics of THV made by the two materials in detail. METHODS: In this study, firstly, the microstructure of pericardium was analyzed by staining and scanning electron microscope; secondly, the biochemical properties of pericardium after different processes were compared by heat shrinkage temperature test, free amino and carboxyl concentration test, enzyme degradation test, subcutaneous implantation calcification analysis in rats; finally, the mechanical properties were evaluated by uniaxial tensile test before and after the pericardium being crimped, and then, the hydrodynamics of THV was studied according to the ISO5840 standard. RESULTS: Compared with bovine pericardium, after the same process, porcine pericardium showed a looser and tinier fiber bundle, a similar free carboxyl concentration, a lower resistance to enzyme degradation, a significantly lower calcification, bearing capacity and damage after being crimped, a better hydrodynamic and adaption with lower cardiac output and deformation of implantation position. Meanwhile the dehydration process of pericardium almost had preserved all the biochemical advantages of two materials. CONCLUSION: In this study, porcine and bovine pericardium showed some significant differences in biochemical, mechanical properties and hydrodynamics. According to the results, it was presumed that the thinner porcine pericardium might be more suitable for THV of right heart system. Meanwhile, more attention should be taken for the calcification of THV made by the bovine pericardium.
Assuntos
Bioprótese , Próteses Valvulares Cardíacas , Pericárdio , Animais , Calcinose/diagnóstico por imagem , Bovinos , Teste de Materiais , Microscopia Eletrônica de Varredura , Pericárdio/diagnóstico por imagem , Pericárdio/fisiologia , Pericárdio/ultraestrutura , Suínos , Microtomografia por Raio-XRESUMO
Bioprosthetic heart valves still have poor long-term durability due to calcification and mechanical failure. The function and performance of bioprostheses is known to depend on the collagen architecture and mechanical behavior of the target tissue. So it is necessary to select an appropriate tissue for such prostheses. In this study, porcine, equine, and bovine pericardia were compared histologically and mechanically. The specimens were analyzed under light microscopy. The planar biaxial tests were performed on the tissue samples by applying synchronic loads along the axial (fiber direction) and perpendicular directions. The measured biaxial data were then fitted into both the modified Mooney-Rivlin model and the anisotropic four parameter Fung-type model. The modified Mooney-Rivlin model was applied to the modeling of the bovine, equine, and porcine pericardia using finite element analysis. The equine pericardium illustrated a wavy collagen bundle architecture similar to bovine pericardium, whereas the collagen bundles in the porcine pericardium were thinner and structured. Wavy pericardia may be preferable candidates for transcutaneous aortic valves because they are less likely to be delaminated during crimping. Based on the biaxial tensile test, the specimens indicated some degree of anisotropy; the anisotropy rates of the equine specimens were almost identical, and higher than the other two specimens. In general, porcine pericardium appeared stiffer, based on the greater strain energy magnitude and the average slope of the stress-stretch curves. Moreover, it was less distensible (due to lower areal strain) than the other two pericardial tissues. Furthermore, the porcine model induced localized high stress regions during the systolic and diastolic phases of the cardiac cycle. However, increased mechanical stress on the bioprosthetic leaflets may cause tissue degeneration and reduce the long-term durability of the valve. Based on our observations, the pericardial specimens behaved as anisotropic and nonlinear tissues-well-characterized by both the modified Mooney-Rivlin and the Fung-type models. The results indicate that, compared to bovine pericardium, equine tissue is mechanically and histologically more appropriate for manufacturing heart valve prostheses. The results of this study can be used in the design and manufacture of bioprosthetic heart valves.
Assuntos
Bioprótese , Próteses Valvulares Cardíacas , Pericárdio/ultraestrutura , Resistência à Tração , Animais , Fenômenos Biomecânicos , Bovinos , Colágeno/análise , Simulação por Computador , Elasticidade , Análise de Elementos Finitos , Cavalos , Teste de Materiais , Modelos Biológicos , Pericárdio/química , SuínosRESUMO
Decellularized human pericardium is under study as an allogenic material for cardiovascular applications. The effects of crosslinking on the mechanical properties of decellularized pericardium were determined with a uniaxial tensile test, and the effects of crosslinking on the collagen structure of decellularized pericardium were determined by multiphoton microscopy. The viability of human umbilical vein endothelial cells seeded on decellularized human pericardium and on pericardium strongly and weakly crosslinked with glutaraldehyde and with genipin was evaluated by means of an MTS assay. The viability of the cells, measured by their metabolic activity, decreased considerably when the pericardium was crosslinked with glutaraldehyde. Conversely, the cell viability increased when the pericardium was crosslinked with genipin. Coating both non-modified pericardium and crosslinked pericardium with a fibrin mesh or with a mesh containing attached heparin and/or fibronectin led to a significant increase in cell viability. The highest degree of viability was attained for samples that were weakly crosslinked with genipin and modified by means of a fibrin and fibronectin coating. The results indicate a method by which in vivo endothelialization of human cardiac allografts or xenografts could potentially be encouraged.
Assuntos
Materiais Biocompatíveis , Pericárdio/transplante , Aloenxertos , Animais , Materiais Biocompatíveis/química , Fenômenos Biomecânicos , Sobrevivência Celular , Colágeno/química , Colágeno/ultraestrutura , Reagentes de Ligações Cruzadas , Fibrina , Fibronectinas , Glutaral , Xenoenxertos , Células Endoteliais da Veia Umbilical Humana/citologia , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Iridoides , Teste de Materiais , Microscopia de Fluorescência por Excitação Multifotônica , Pericárdio/química , Pericárdio/ultraestrutura , Ressonância de Plasmônio de Superfície , Resistência à TraçãoRESUMO
The epicardium plays a crucial role in embryonic heart development and adult heart repair; however, the molecular events underlying its maturation remain unknown. Wt1, one of the main markers of the embryonic epicardium, is essential for epicardial development and function. Here, we analyse the transcriptomic profile of epicardial-enriched cells at different stages of development and from control and epicardial-specific Wt1 knockout (Wt1KO) mice. Transcriptomic and cell morphology analyses of epicardial cells from epicardial-specific Wt1KO mice revealed a defect in the maturation process of the mutant epicardium, including sustained upregulation of Bmp4 expression and the inability of mutant epicardial cells to transition into a mature squamous phenotype. We identified Bmp4 as a transcriptional target of Wt1, thus providing a molecular basis for the retention of the cuboidal cell shape observed in the Wt1KO epicardium. Accordingly, inhibition of the Bmp4 signalling pathway both ex vivo and in vivo rescued the cuboidal phenotype of the mutant epicardium. Our findings indicate the importance of the cuboidal-to-squamous transition in epicardial maturation, a process regulated by Wt1.
Assuntos
Proteína Morfogenética Óssea 4/metabolismo , Proteína Morfogenética Óssea 4/farmacologia , Pericárdio/citologia , Pericárdio/metabolismo , Proteínas WT1/metabolismo , Animais , Forma Celular/efeitos dos fármacos , Forma Celular/genética , Células Cultivadas , Feminino , Citometria de Fluxo , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Regulação da Expressão Gênica no Desenvolvimento/genética , Coração/efeitos dos fármacos , Masculino , Camundongos , Camundongos Knockout , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Miocárdio/metabolismo , Miocárdio/ultraestrutura , Pericárdio/efeitos dos fármacos , Pericárdio/ultraestrutura , Proteínas WT1/genéticaRESUMO
Transcatheter aortic valve implantation (TAVI) has gained considerable acceptance in the past decade due to its lower risks than conventional open-heart surgery. However, the deformation and delamination of the leaflets during the crimping procedure have raised questions about the durability and long-term serviceability of the pericardium tissue from which the leaflets are made. The collagen architecture, wall thickness and mechanical properties of donkey pericardium were investigated to assess its suitability as an alternative material for the manufacture of heart valves. Coupons sampled from different locations of donkey pericardium were investigated. Bovine, equine, and porcine pericardium specimens served as controls. The donkey pericardium had a similar surface morphology to that of the control pericardia except for the wavy topology on both the fibrous and serous sides. The average thickness of donkey pericardium (ca. 120 µm) was significantly lower than that from bovine (375 µm) and equine (410 µm), but slightly higher than that from porcine (99 µm) specimens. The interlaced wavy collagen bundles in the pericardium were composed of collagen fibers about 100 nm in diameter. This unique structure ensures that the donkey pericardium has a comparable ultimate tensile strength (UTS) and a much higher failure strain than the commercial pericardia used for the manufacture of heart valves. The donkey pericardium has an organized wavy collagen bundle architecture similar to that of bovine pericardium and has a satisfactory UTS and high failure strain. The thin and strong donkey pericardium might be a good candidate valve leaflet material for TAVI.
Assuntos
Materiais Biocompatíveis/química , Bioprótese , Colágeno/análise , Próteses Valvulares Cardíacas , Pericárdio/química , Animais , Valva Aórtica/cirurgia , Fenômenos Biomecânicos , Bovinos , Elasticidade , Equidae , Valvas Cardíacas/cirurgia , Cavalos , Teste de Materiais , Pericárdio/ultraestrutura , Suínos , Resistência à Tração , Substituição da Valva Aórtica TranscateterRESUMO
Bovine pericardium (BP) is an extensively used biomaterial utilised in a wide range of biomedical devices such as bioprosthetic heart valves. However, the mechanical testing techniques that assess soft biomaterial tissue like BP are varied with no common method utilised across the literature, producing variations and contradictions in reported values. Uniaxial testing is a common technique used to measure traditional mechanical characteristics of ultimate tensile strength (UTS), modulus and the percentage strain at failure. The aim of this study was to take two standard uniaxial test parameters, strain rate and the number of preconditioning cycles and to elucidate recommendations for the standardisation of a uniaxial method, while also measuring not so common parameters of low modulus and hysteresis. Samples post uniaxial testing were treated and analysed with scanning electron microscopy (SEM) and an imaging software (ImageJ) to measure the effect of the parameters on the crimping structure and orientation of the collagen fibres. The study recommends an extension rate of 10â¯mm/min and 5 preconditioning load-unload cycles as a starting point for the standardisation of a uniaxial testing method. The image analysis of the collagen structure carried out provides a quantitative assessment of the BP post mechanical testing and allows for a better understanding of the behaviour of BP under stress.
Assuntos
Teste de Materiais , Fenômenos Mecânicos , Pericárdio , Animais , Fenômenos Biomecânicos , Bovinos , Microscopia Eletrônica de Varredura , Pericárdio/ultraestruturaRESUMO
BACKGROUND: The kangaroo pericardium might be considered to be a good candidate material for use in the manufacture of the leaflets of percutaneous heart valves based upon the unique lifestyle. The diet consists of herbs, forbs and strubs. The kangaroo pericardium holds an undulated structure of collagen. MATERIAL AND METHOD: A Red Kangaroo was obtained after a traffic fatality and the pericardium was dissected. Four compasses were cut from four different sites: auricular (AUR), atrial (ATR), sternoperitoneal (SPL) and phrenopericardial (PPL). They were investigated by means of scanning electron microscopy, light microscopy and transmission electron microscopy. RESULTS: All the samples showed dense and wavy collagen bundles without vascularisation from both the epicardium and the parietal pericardium. The AUR and the ATR were 150±25µm thick whereas the SPL and the PPL were thinner at 120±20µm. The surface of the epicardium was smooth and glistening. The filaments of collagen were well individualized without any aggregation, but the banding was poorly defined and somewhat blurry. CONCLUSION: This detailed morphological analysis of the kangaroo pericardium illustrated a surface resistant to thrombosis and physical characteristics resistant to fatigue. The morphological characteristics of the kangaroo pericardium indicate that it represents an outstanding alternative to the current sources e.g., bovine and porcine. However, procurement of tissues from the wild raises supply and sanitary issues. Health concerns based upon sanitary uncertainty and reliability of supply of wild animals remain real problems.
Assuntos
Bioprótese , Próteses Valvulares Cardíacas , Ligamentos/ultraestrutura , Macropodidae/anatomia & histologia , Pericárdio/ultraestrutura , Animais , Austrália , Doenças das Valvas Cardíacas/cirurgia , Humanos , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de TransmissãoRESUMO
The stability and bioactivity of biologic implants rely mainly on the control of the crosslinking process of collagen. However, the most common methods have no control on the crosslinking degree producing it excessively. This study outlines the role of crosslinking of collagen-based implants with oligourethane on the host response following reconstruction of a rat full-thickness abdominal wall defect. We decellularized and crosslinked bovine pericardial tissue to achieve two crosslinking degrees. For the decellularized implants, named as non-crosslinked (N-CL), the collagen-amines were 0.42 ± 0.02 mmol/mg. Crosslinking by the oligourethane reduced the primary amine concentration to 0.28 ± 0.01 and 0.19 ± 0.01 mmol/mg; these values were classified as low (â¼30%, L-CL) and medium crosslinking (â¼50%, M-CL), respectively. By imaging the implants using second harmonic generation microscopy, we observed undulated bundles of collagen fibers organized in multi-directed layers localized in N-CL and L-CL samples. Post-implantation, a negligible change in the organization of collagen fibers in the crosslinked implants was observed, suggesting that the in vivo biodegradation was delayed. An enlargement of the implant area was also observed, without rupture, in all three (N-CL, L-CL, M-CL) materials, whereas adhesion to the omentum, but not to the bowel, was observed. The number of blood vessels after 90-day implantation in N-CL and L-CL was 13 ± 1 and 12 ± 1 per field, respectively, while the number significantly decreased to 2 ± 1 in M-CL. The results suggest that the controlled degree of crosslinking in oligourethane-modified biologic implants can be used as a strategy to balance biodegradation and remodeling in surgical repair of soft tissues.
Assuntos
Parede Abdominal/cirurgia , Materiais Biocompatíveis/química , Colágeno/química , Reagentes de Ligações Cruzadas/química , Pericárdio/química , Uretana/química , Parede Abdominal/patologia , Animais , Bioprótese , Bovinos , Masculino , Pericárdio/transplante , Pericárdio/ultraestrutura , Ratos , Ratos Wistar , Procedimentos de Cirurgia Plástica , Resistência à TraçãoRESUMO
Valvular heart diseases lead to over 300,000 heart valve replacements worldwide each year. Commercially available bioprosthetic heart valves (BHVs) are mostly made from porcine or bovine pericardiums which were crosslinked by glutaraldehyde (GLUT). However, valve failures can occur within 10 years due to progressive degradation and calcification. GLUT could crosslink collagen but it fails to stabilize elastin. In this current study, we developed a new BHVs preparation strategy named as "GLUT/TE/LOXL/EGCG" that utilizes exogenous tropoelastin (TE)/lysyl oxidase (LOXL) and epigallocatechin gallate (EGCG) to increase the elastin content as well as the stabilization of elastin. The feeding ratios of tropoelastin and lysyl oxidase were optimized. The contents of desmosine and insoluble elastin, biomechanics, cytotoxicity, hemocompatibility, in vivo componential stability and anti-calcification potential were characterized. Pericardiums with increased elastin content had improved the mechanical properties. GLUT/TE/LOXL/EGCG-treated pericardiums had similar cytotoxicity and coagulation properties compared to GLUT and GLUT/EGCG control. We demonstrated that GLUT/TE/LOXL/EGCG-treated pericardiums had high amount of insoluble elastin in 90 days' rat subdermal implantation model, and better resistance for calcification. This new tropoelastin and lysyl oxidase treatments strategy would be a promising method to make BHVs which have better structural stability and anti-calcification properties.
Assuntos
Bioprótese , Elastina/química , Próteses Valvulares Cardíacas , Pericárdio/química , Animais , Fenômenos Biomecânicos , Bioprótese/efeitos adversos , Calcinose/etiologia , Catequina/análogos & derivados , Catequina/química , Reagentes de Ligações Cruzadas/química , Glutaral/química , Próteses Valvulares Cardíacas/efeitos adversos , Masculino , Pericárdio/transplante , Pericárdio/ultraestrutura , Estabilidade Proteica , Proteína-Lisina 6-Oxidase/química , Ratos Sprague-Dawley , Suínos , Tropoelastina/químicaRESUMO
Tissue engineering and regenerative medicine have adopted the use of extracellular matrix (ECM) as a cell delivery device and bioactive regenerative agent. To this end, many ECMs have been investigated for cardiac tissue engineering and regenerative medicine applications with variable success. Many sources of natural ECMs have been tested for cardiac applications. Typically, natural ECMs have been made from decellularized organs or tissues and processed into either sheets or injectable hydrogels. This chapter will review natural sources of ECM materials that have been tested as therapeutic agents in models of heart failure.
Assuntos
Procedimentos Cirúrgicos Cardíacos/métodos , Matriz Extracelular , Insuficiência Cardíaca/cirurgia , Medicina Regenerativa/métodos , Alicerces Teciduais , Animais , Processos de Crescimento Celular , Matriz Extracelular/fisiologia , Previsões , Humanos , Intestino Delgado/ultraestrutura , Camundongos , Modelos Animais , Miocárdio/ultraestrutura , Especificidade de Órgãos , Pericárdio/ultraestrutura , Coelhos , Especificidade da Espécie , Transplante de Células-Tronco/métodos , Suínos , Bexiga Urinária/ultraestrutura , Peixe-ZebraRESUMO
The lifetime of bioprosthetic heart valves (BHVs) is limited by the mechanical damage and calcification. The major components of BHVs are collagen and elastin. Collagen could be well protected by glutaraldehyde (GLUT) crosslinking, while elastin is not stabilized and has a high risk of degradation, which could lead to the calcification of BHVs. We aimed to develop methods for stabilizing elastin and decreasing calcification. We investigated the combined tannic acid (TA) or epigallocatechin gallate (EGCG) with ferric chloride to stabilize elastin and prevent calcification. We found that the amount of TA/EGCG bound to elastin was in a time-dependent pattern and this reaction showed better efficiency in acidic condition and ethanol-water mixed solvents. Moreover, Fe3+ could compete with Ca2+ to bind to polyphenol, which could reduce the calcium deposition on BHVs. Cytotoxicity test showed that all extracts from different treatments had similar cell viabilities (85-100%). Through the combined treatments of polyphenol and ferric chloride, the pericardium had a better resistance to elastase degradation and more excellent anticalcification performance.
Assuntos
Bioprótese , Calcinose/prevenção & controle , Cloretos/química , Elastina/química , Compostos Férricos/química , Próteses Valvulares Cardíacas , Pericárdio/química , Polifenóis/química , Animais , Catequina/análogos & derivados , Catequina/química , Colágeno/química , Reagentes de Ligações Cruzadas/química , Glutaral/química , Masculino , Pericárdio/ultraestrutura , Estabilidade Proteica , Ratos Sprague-Dawley , Suínos , Taninos/química , Resistência à TraçãoRESUMO
Here we show that a labyrinth channel compartment and slit diaphragms, which are the histological structures enabling insect nephrocytes ultrafiltration, are established during embryogenesis first by the garland nephrocytes (GCNs). The later pericardial nephrocytes, which represent the majority of functional nephrocytes in larvae and adults, lack these characteristic features at the embryonic stage. During larval development, a subpopulation of the pericardial cells survives and matures into functional nephrocytes (PCNs) displaying a fully differentiated slit diaphragm and a labyrinth channel compartment. Likely the embryonic pericardial cells have primary functions other than ultrafiltration (e.g. in production and secretion of ECM constituents). We also show, for the first time, that PCNs in the adult fly undergo dramatic histological degeneration upon ageing. The slit diaphragms disappear, the labyrinth channel system degenerates and the lysosomal compartment becomes highly enriched with electron-dense material. When using nephrocytes as a model for genetic screening purposes or to investigate the specific role of genes involved in endocytosis, histological changes occurring upon ageing need to be taken into account when interpreting structural data.
Assuntos
Envelhecimento/patologia , Endocitose , Lisossomos/ultraestrutura , Pericárdio/ultraestrutura , Envelhecimento/metabolismo , Animais , Drosophila melanogaster , Lisossomos/metabolismo , Pericárdio/metabolismoRESUMO
Bovine and porcine pericardia are currently used for manufacturing prosthetic heart valves: their design has become an increasingly important area of investigation in parallel with progressively expanding indications for the transcutaneous approach to heart valves replacement. Before being cut and shaped, pericardial tissues are expected to be properly characterized. Actually, the mechanical assessment of these biomaterials lacks standardized protocols. In particular, the role of preconditioning for achieving a constant mechanical response of tissue samples is still controversial. In the present work, the mechanical response to uniaxial load of native bovine and porcine pericardia, with and without preconditioning was assessed; moreover, the mechanical behavior of pericardia was investigated and explained. It was demonstrated that: (i) pericardial tissue samples hold memory of the loading history but just within the extent of the deformation applied; (ii) the behavior of native bovine and porcine pericardia in response to load is explained by a mechanism based on the additive recruitment of collagen fibers; (iii) the current concept that plasticity is absent in pericardium has to be at least in part reconsidered.
Assuntos
Colágeno/análise , Pericárdio/fisiologia , Pericárdio/ultraestrutura , Animais , Fenômenos Biomecânicos , Bioprótese , Bovinos , Colágeno/metabolismo , Próteses Valvulares Cardíacas , Teste de Materiais , Pericárdio/química , Suínos , Resistência à Tração , Suporte de CargaRESUMO
INTRODUCTION: Cross-linking and anti-calcification of prosthetic heart valves have been continuously improved to prevent degeneration and calcification. However, non-calcific structural deteriorations such as cuspal dehiscences along the stent still require further analysis. MATERIAL AND METHOD: Based upon the previous analysis of an explanted valve after 7 years, a fresh commercial aortic valve was embedded in poly(methyl methacrylate) (PMMA) and cut into slices to ensure the detailed observation of the assembly and material structures. A pericardial patch embossed to provide the adequate shape of the cusps was investigated after paraffin embedding and appropriate staining. The microstructural damages that occurred during manufacturing process were identified and evaluated by light microscopy, polarized microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). RESULTS: The wavy collagen bundles, the key structure of the pericardium patch, were damaged to a great extent at suture sites along the stent and in the compressed areas around the stent post. The fixation of the embossed pericardium patch along the plots of the stent aggravated the microstructural modifications. The damages mainly appeared as the elimination of collagen bundle waviness and delamination between the bundles. CONCLUSION: Considering the modes of failure of the explant, the damages to the collagen bundles may identify the vulnerable sites that play an important role in the cusp dehiscence of heart valve implants. Such information is important to the manufacturers. Recommendations to prevent in vivo cusp dehiscence can therefore be formulated.
Assuntos
Valva Aórtica/ultraestrutura , Bioprótese , Próteses Valvulares Cardíacas , Pericárdio/ultraestrutura , Manejo de Espécimes/efeitos adversos , Animais , Valva Aórtica/patologia , Calcinose/prevenção & controle , Bovinos , Colágeno/ultraestrutura , Reagentes de Ligações Cruzadas/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Inclusão em Parafina , Pericárdio/anatomia & histologia , Pericárdio/patologia , Inclusão em Plástico/métodos , Polimetil Metacrilato/química , Falha de Prótese , Manejo de Espécimes/métodos , StentsRESUMO
INTRODUCTION: Transcathether heart valve replacement has gained considerable acceptance during the last decades. It is now part of the armamentarium for aortic valve replacement. The procedure proved to be highly efficient. However the issues of the blood compatibility and tissue durability were not raised and the adverse events were probably under-reported, according to observations of thrombosis after deployment. MATERIAL AND METHOD: Bovine pericardium leaflets were sewn inside a 26mm diameter stainless steel stent to manufacture these valves (one control and two experimental). The correlation between the trauma and the acute thombogenicity of bovine pericardium leaflets, after crimping and ballooning, was investigated via an in vitro blood flow with labeled platelets. These leaflets were processed for histology: scanning electron microscopy, light microscopy, and transmission electron microscopy. RESULTS: The control specimens showed a regular pericardium structure with some blood cells deposited on the collagen fibrous surface (inflow) and scarce blood cells deposited on the serous surface (outflow). After crimping and ballooning, the structure of the pericardium was severely injured, eventually with delaminations and ruptures. The blood cell uptake was considerably increased compared to the control. CONCLUSION: It would therefore be appropriate to pay more attention to the design of the valves. Specifically, the incorporation of a buffer tissue or fabric between the pericardium and the metallic stent is suggested. The issue of ballooning deserves detailed and in depth investigation regarding the lifetime of the device.
Assuntos
Valvuloplastia com Balão/instrumentação , Bioprótese/efeitos adversos , Próteses Valvulares Cardíacas/efeitos adversos , Desenho de Prótese/efeitos adversos , Trombose/etiologia , Substituição da Valva Aórtica Transcateter/instrumentação , Animais , Valva Aórtica/cirurgia , Circulação Sanguínea , Bovinos , Voluntários Saudáveis , Humanos , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Pericárdio/patologia , Pericárdio/cirurgia , Pericárdio/ultraestrutura , Stents/efeitos adversos , Propriedades de Superfície , Trombose/prevenção & controle , Substituição da Valva Aórtica Transcateter/efeitos adversosRESUMO
BACKGROUND: To assess the relationship of parameters of obesity in relationship to coronary angiography findings with correlation of epicardial fat (EF) thickness in uppermentioned context. METHODS: There were 80 patients examined (43 males, 37 postmenopausal females) undergoing elective coronary angiography. We examined the regular obesity parameters - BMI, waist circumference (WC), neck circumference (NC), total body fat (TBF), and visceral fat (VF) using bioimpedance. We assessed the echocardiographically measured EF thickness. We added examination of lipidogram, glycaemia, HOMA-IR (insulin resistance index) and AIP (aterogenic index of plasma). The set was divided into group with coronarographically proved stenosis or stenoses (withCS), and a group without finding of quantifiable stenosis or stenoses (withoutCS). RESULTS: The average thickness of EF in withCS group was 6.3 vs 5.6 mm in group withoutCS (p < 0.025). The differences in the thickness of EF in mentioned groups were 6.5 vs 5.2 mm in males (p < 0.025, = 20 %) and 6.1 vs 6.0 mm in females (p < 0.025, = 1.64 %). In males in withCS group, there was a dominant fat increase in epicardial region and TBF, and in females in withCS group, the fat deposits were increased in general. BMI was not a dominant parameter of adiposity in neither group (males in withCS group 31.11 vs withoutCS 30.41 kg/m(2); females in withCS group 31.40 vs withoutCS 31.20 kg/m(2)). EF was correlated the most by WC in males (r = 0.488; p < 0.005), and in females too (r = 0.564, p < 0.005). The patients in withCS group had increased HOMA-IR 4.75 vs 3.56 in withoutCS group, and AIP 0.22 vs 0.17. CONCLUSION: Thickness of EF in males and VT in females could be considered obesity parameters in assessment of pre-clinical stages of coronary atherosclerosis and prediction of risk of coronary heart disease. In adipose parameters, EF thickness was correlated the most by WC. Risk stratification of coronary artery disease is supplemented by increased HOMA-IR and AIP.
Assuntos
Tecido Adiposo/diagnóstico por imagem , Doença da Artéria Coronariana/diagnóstico por imagem , Obesidade/complicações , Pericárdio/ultraestrutura , Índice de Massa Corporal , Angiografia Coronária , Feminino , Humanos , Resistência à Insulina , Masculino , Pessoa de Meia-Idade , Medição de Risco , Ultrassonografia , Circunferência da CinturaRESUMO
The transcription factor Wilms' Tumor-1 (WT1) is essential for cardiac development. Deletion of Wt1 in mice results in disturbed epicardial and myocardial formation and lack of cardiac vasculature, causing embryonic lethality. Little is known about the role of WT1 in the human fetal heart. Therefore, as a first step, we analyzed the expression pattern of WT1 protein during human cardiac development from week 4 till week 20. WT1 expression was apparent in epicardial, endothelial and endocardial cells in a spatiotemporal manner. The expression of WT1 follows a pattern starting at the epicardium and extending towards the lumen of the heart, with differences in timing and expression levels between the atria and ventricles. The expression of WT1 in cardiac arterial endothelial cells reduces in time, whereas WT1 expression in the endothelial cells of cardiac veins and capillaries remains present at all stages studied. This study provides for the first time a detailed description of the expression of WT1 protein during human cardiac development, which indicates an important role for WT1 also in human cardiogenesis.
Assuntos
Células Endoteliais/metabolismo , Coração Fetal/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Proteínas WT1/genética , Endocárdio/crescimento & desenvolvimento , Endocárdio/metabolismo , Endocárdio/ultraestrutura , Células Endoteliais/ultraestrutura , Endotélio Vascular/crescimento & desenvolvimento , Endotélio Vascular/metabolismo , Endotélio Vascular/ultraestrutura , Coração Fetal/crescimento & desenvolvimento , Coração Fetal/ultraestrutura , Feto , Humanos , Miocárdio/metabolismo , Miocárdio/ultraestrutura , Pericárdio/crescimento & desenvolvimento , Pericárdio/metabolismo , Pericárdio/ultraestrutura , Proteínas WT1/metabolismoRESUMO
An important pool of cardiovascular progenitor cells arises from the epicardium, a single layer of mesothelium lining the heart. Epicardium-derived progenitor cell (EPDC) formation requires epithelial-to-mesenchymal transition (EMT) and the subsequent migration of these cells into the sub-epicardial space. Although some of the physiological signals that promote EMT are understood, the functional mediators of EPDC motility and differentiation are not known. Here, we identify a novel regulatory mechanism of EPDC mobilization. Myocardin-related transcription factor (MRTF)-A and MRTF-B (MKL1 and MKL2, respectively) are enriched in the perinuclear space of epicardial cells during development. Transforming growth factor (TGF)-ß signaling and disassembly of cell contacts leads to nuclear accumulation of MRTFs and the activation of the motile gene expression program. Conditional ablation of Mrtfa and Mrtfb specifically in the epicardium disrupts cell migration and leads to sub-epicardial hemorrhage, partially stemming from the depletion of coronary pericytes. Using lineage-tracing analyses, we demonstrate that sub-epicardial pericytes arise from EPDCs in a process that requires the MRTF-dependent motile gene expression program. These findings provide novel mechanisms linking EPDC motility and differentiation, shed light on the transcriptional control of coronary microvascular maturation and suggest novel therapeutic strategies to manipulate epicardium-derived progenitor cells for cardiac repair.
Assuntos
Movimento Celular , Vasos Coronários/crescimento & desenvolvimento , Pericárdio/citologia , Transativadores/metabolismo , Fatores de Transcrição/metabolismo , Animais , Células COS , Diferenciação Celular/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Chlorocebus aethiops , Vasos Coronários/efeitos dos fármacos , Vasos Coronários/metabolismo , Embrião de Mamíferos/efeitos dos fármacos , Embrião de Mamíferos/metabolismo , Embrião de Mamíferos/patologia , Camundongos Endogâmicos C57BL , Neovascularização Fisiológica/efeitos dos fármacos , Pericárdio/metabolismo , Pericárdio/ultraestrutura , Pericitos/citologia , Pericitos/efeitos dos fármacos , Fator de Resposta Sérica/metabolismo , Transativadores/genética , Fatores de Transcrição/genética , Fator de Crescimento Transformador beta1/farmacologiaRESUMO
Bovine pericardium is used for heart valve leaflet replacement where the strength and thinness are critical properties. Pericardium from neonatal animals (4-7 days old) is advantageously thinner and is considered as an alternative to that from adult animals. Here, the structures of adult and neonatal bovine pericardium tissues fixed with glutaraldehyde are characterized by synchrotron-based small angle X-ray scattering (SAXS) and compared with the mechanical properties of these materials. Significant differences are observed between adult and neonatal tissue. The glutaraldehyde fixed neonatal tissue has a higher modulus of elasticity (83.7 MPa) than adult pericardium (33.5 MPa) and a higher normalised ultimate tensile strength (32.9 MPa) than adult pericardium (19.1 MPa). Measured edge on to the tissue, the collagen in neonatal pericardium is significantly more aligned (orientation index (OI) 0.78) than that in adult pericardium (OI 0.62). There is no difference in the fibril diameter between neonatal and adult pericardium. It is shown that high alignment in the plane of the tissue provides the mechanism for the increased strength of the neonatal material. The superior strength of neonatal compared with adult tissue supports the use of neonatal bovine pericardium in heterografts.
Assuntos
Colágeno/metabolismo , Valvas Cardíacas/ultraestrutura , Pericárdio/ultraestrutura , Animais , Animais Recém-Nascidos , Procedimentos Cirúrgicos Cardíacos , Bovinos , Colágeno/ultraestrutura , Glutaral/química , Valvas Cardíacas/metabolismo , Valvas Cardíacas/transplante , Pericárdio/patologia , Pericárdio/transplante , Espalhamento a Baixo Ângulo , Fixação de Tecidos , Difração de Raios XRESUMO
INTRODUCTION: The current study was designed to determine the effect of home-based treadmill training on epicardial and abdominal adipose tissue in postmenopausal women with metabolic syndrome (MS). A secondary objective was to identify significant correlations between imaging and conventional anthropometric parameters. MATERIAL AND METHODS: Sixty postmenopausal women with MS volunteered for the current trial. Thirty were randomly assigned to perform a supervised home-based 16-week treadmill training program, 3 sessions/week, consisting of a warm-up, 30-40 min treadmill exercise (increasing 5-minutes each 4-weeks) at a work intensity of 60-75% of peak heart rate (increasing 5% each 4-weeks) and cooling-down. Epicardial fat thickness (EFT) was assessed by echocardiography. Abdominal fat mass in the lumbar regions L1-L4 and L4-L5 was determined by dual X-ray absorptiometry. RESULTS: Epicardial fat thickness and abdominal fat percentages were significantly improved after the completion of the training program. Another striking feature of the current study was the moderate correlation that was found between EFT and waist circumference (WC). CONCLUSION: Home-based treadmill training reduced epicardial and abdominal fat in postmenopausal women with MS. A secondary finding was that a moderate correlation was found between EFT and WC. While current investigations are promising, future studies are still required to consolidate this approach in clinical application.
Introducción: El presente estudio se diseñó para conocer la influencia de un programa de entrenamiento aeróbico domiciliario en la masa grasa epicárdica y abdominal de mujeres postmenopausicas con síndrome metabólico (SM). Un segundo objetivo fue identificar correlaciones significativas entre las variables antropométricas ensayadas. Material y Método: Participaron voluntariamente un total de 60 mujeres postmenopausicas con diagnóstico de SM que se distribuyeron aleatoriamente en el grupo de intervención (n=30) o control (n=30). El programa de intervención, desarrollado en el domicilio, consistió en un entrenamiento en tapiz rodante de 16 semanas, 3 sesiones/ semana. La parte principal se realizó a una intensidad del 60-75%FCmax (incrementando 5% cada 4 semanas) durante 30-40 minutos (incrementando 5-minutos cada 4-semanas). La masa grasa epicárdica se determinó mediante ecocardiografía. La masa grasa abdominal de las regiones de interés L1-L4 y L4-L5 se determinó mediante densitometría. Resultados: Se observó un descenso significativo tanto de la masa grasa epicárdica como abdominal tras completar el entrenamiento. Se identificó una correlación moderada entre la masa grasa epicárdica y el perímetro de la cintura de las participantes que podría facilitar su seguimiento clínico. Conclusión: Un programa de entrenamiento de resistencia redujo la masa grasa epicárdica y abdominal. Futuros estudios en esta línea son aún necesarios.