Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Int J Mol Sci ; 22(12)2021 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-34199303

RESUMO

The main purpose of new stent technologies is to overcome unfavorable material-related incompatibilities by producing bio- and hemo-compatible polymers with anti-inflammatory and anti-thrombogenic properties. In this context, wettability is an important surface property, which has a major impact on the biological response of blood cells. However, the influence of local hemodynamic changes also influences blood cell activation. Therefore, we investigated biodegradable polymers with different wettability to identify possible aspects for a better prediction of blood compatibility. We applied shear rates of 100 s-1 and 1500 s-1 and assessed platelet and monocyte activation as well as the formation of CD62P+ monocyte-bound platelets via flow cytometry. Aggregation of circulating platelets induced by collagen was assessed by light transmission aggregometry. Via live cell imaging, leukocytes were tracked on biomaterial surfaces to assess their average velocity. Monocyte adhesion on biomaterials was determined by fluorescence microscopy. In response to low shear rates of 100 s-1, activation of circulating platelets and monocytes as well as the formation of CD62P+ monocyte-bound platelets corresponded to the wettability of the underlying material with the most favorable conditions on more hydrophilic surfaces. Under high shear rates, however, blood compatibility cannot only be predicted by the concept of wettability. We assume that the mechanisms of blood cell-polymer interactions do not allow for a rule-of-thumb prediction of the blood compatibility of a material, which makes extensive in vitro testing mandatory.


Assuntos
Plaquetas/citologia , Comunicação Celular/efeitos dos fármacos , Monócitos/citologia , Monócitos/efeitos dos fármacos , Poliésteres/farmacologia , Plaquetas/efeitos dos fármacos , Adesão Celular/efeitos dos fármacos , Hemodinâmica/efeitos dos fármacos , Humanos , Agregação Plaquetária/efeitos dos fármacos , Água , Molhabilidade
2.
BMC Mol Cell Biol ; 22(1): 32, 2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-34078283

RESUMO

BACKGROUND: Endothelial healing after deployment of cardiovascular devices is particularly important in the context of clinical outcome. It is therefore of great interest to develop tools for a precise prediction of endothelial growth after injury in the process of implant deployment. For experimental investigation of re-endothelialization in vitro cell migration assays are routinely used. However, semi-automatic analyses of live cell images are often based on gray value distributions and are as such limited by image quality and user dependence. The rise of deep learning algorithms offers promising opportunities for application in medical image analysis. Here, we present an intelligent cell detection (iCD) approach for comprehensive assay analysis to obtain essential characteristics on cell and population scale. RESULTS: In an in vitro wound healing assay, we compared conventional analysis methods with our iCD approach. Therefore we determined cell density and cell velocity on cell scale and the movement of the cell layer as well as the gap closure between two cell monolayers on population scale. Our data demonstrate that cell density analysis based on deep learning algorithms is superior to an adaptive threshold method regarding robustness against image distortion. In addition, results on cell scale obtained with iCD are in agreement with manually velocity detection, while conventional methods, such as Cell Image Velocimetry (CIV), underestimate cell velocity by a factor of 0.5. Further, we found that iCD analysis of the monolayer movement gave results just as well as manual freehand detection, while conventional methods again shows more frayed leading edge detection compared to manual detection. Analysis of monolayer edge protrusion by ICD also produced results, which are close to manual estimation with an relative error of 11.7%. In comparison, the conventional Canny method gave a relative error of 76.4%. CONCLUSION: The results of our experiments indicate that deep learning algorithms such as our iCD have the ability to outperform conventional methods in the field of wound healing analysis. The combined analysis on cell and population scale using iCD is very well suited for timesaving and high quality wound healing analysis enabling the research community to gain detailed understanding of endothelial movement.

3.
Vascul Pharmacol ; 136: 106808, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33130016

RESUMO

BACKGROUND: The G-protein-coupled apelin receptor and its apelin ligand are an emerging regulatory system of the vascular homeostasis. To date, the implications of the apelin/apelin receptor system in athero-thrombosis are not completely clarified yet. This study determines the expression of the apelin receptor on human platelets, the effect of different apelin isoforms on platelet aggregation and the potential role of the apelin/apelin receptor system in acute myocardial infarction. METHODS: We applied immunofluorescence staining, Western Blot analysis, aggregometry, and flow cytometry to elucidate the role of the apelin receptor in activated platelets. Furthermore, in an observational pilot study, we assessed platelet apelin recpetor expression and apelin-17 plasma levels in patients with acute myocardial infarction (AMI, n = 27). RESULTS: Immunofluorescence staining indicates that the apelin receptor is located at the cell membrane in resting platelets and diminishes upon activation with a selective thrombin receptor-activating peptide (AP1, 3 to 100 µM). Western Blot analyses of AP1-activated platelets and their supernatants suggest that the apelin receptor is not predominantly internalized but is released from activated platelets. The isoform apelin-17 attenuated AP-1-induced platelet activation in-vitro, presumably via a NO-dependent mechanism. Furthermore, platelet apelin receptor expression was significantly reduced in patients with AMI (n = 27) compared to age-matched controls (n = 14; p < 0.05) and inversely correlated with troponin I plasma levels (r = -0.46; p = 0.03). Besides that, circulating apelin-17 was significantly reduced in MI patients compared to the control group. CONCLUSION: Taken together, our data support a crucial role of the platelet apelinergic system assuming an antithrombotic effect and therefore holding a potential diagnostic and therapeutic impact.

4.
J Cell Physiol ; 233(8): 6250-6261, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29369349

RESUMO

The adaption of endothelial cells to local flow conditions is a multifunctional process which leads to distinct alterations in cell shape, the subcellular distribution of structural proteins, and cellular function. G-protein-coupled receptors (GPCRs) have been identified to be fundamentally involved in such processes. Recently, we and others have shown that the expression of the endothelial GPCR apelin receptor (APJ) is regulated by fluid flow and that activation of APJ participates in signaling pathways which are related to processes of mechanotransduction. The present study aims to illuminate these findings by further visualization of APJ function. We show that APJ is located to the cellular junctions and might thus be associated with platelet endothelial cell adhesion molecule-1 (PECAM-1) in human umbilical vein endothelial cells (HUVEC). Furthermore, siRNA-mediated silencing of APJ expression influences the shear-induced adaption of HUVEC in terms of cytoskeletal remodeling, cellular elasticity, cellular motility, attachment, and distribution of adhesion complexes. Taken together, our results demonstrate that APJ is crucial for complemented endothelial adaption to local flow conditions.


Assuntos
Receptores de Apelina/metabolismo , Apelina/metabolismo , Células Endoteliais/metabolismo , Linhagem Celular , Movimento Celular/fisiologia , Elasticidade/fisiologia , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Mecanotransdução Celular/fisiologia , Molécula-1 de Adesão Celular Endotelial a Plaquetas/metabolismo , RNA Interferente Pequeno/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais/fisiologia
5.
Int J Mol Sci ; 17(2)2016 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-26805825

RESUMO

Drug-eluting stents (DES) have reduced in-stent-restenosis drastically. Yet, the stent surface material directly interacts with cascades of biological processes leading to an activation of cellular defense mechanisms. To prevent adverse clinical implications, to date almost every patient with a coronary artery disease is treated with statins. Besides their clinical benefit, statins exert a number of pleiotropic effects on endothelial cells (ECs). Since maintenance of EC function and reduction of uncontrolled smooth muscle cell (SMC) proliferation represents a challenge for new generation DES, we investigated the effect of atorvastatin (ATOR) on human coronary artery cells grown on biodegradable polymers. Our results show a cell type-dependent effect of ATOR on ECs and SMCs. We observed polymer-dependent changes in IC50 values and an altered ATOR-uptake leading to an attenuation of statin-mediated effects on SMC growth. We conclude that the selected biodegradable polymers negatively influence the anti-proliferative effect of ATOR on SMCs. Hence, the process of developing new polymers for DES coating should involve the characterization of material-related changes in mechanisms of drug actions.


Assuntos
Atorvastatina/farmacologia , Plásticos Biodegradáveis/farmacologia , Vasos Coronários/citologia , Miócitos de Músculo Liso/efeitos dos fármacos , Polímeros/farmacologia , Técnicas de Cultura de Células , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Doença da Artéria Coronariana/tratamento farmacológico , Vasos Coronários/efeitos dos fármacos , Stents Farmacológicos , Células Endoteliais/citologia , Células Endoteliais/efeitos dos fármacos , Humanos , Miócitos de Músculo Liso/citologia , Especificidade de Órgãos , Propriedades de Superfície
6.
Cell Signal ; 27(7): 1286-96, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25817266

RESUMO

Although the apelin/APJ system is abundantly expressed in vascular endothelial cells (EC), it has not yet been considered to be regulated by fluid flow. The aim of this study was to explore the influence of shear stress on the expression of apelin/APJ in human EC. Therefore, gene and protein expression were assessed after flow exposure; cell supernatants were collected for measurements of NO and apelin; APJ or apelin knockdown were performed using siRNA. Our data show that gene and protein expression of apelin and APJ are modulated by fluid flow depending on the magnitude of shear stress. Moreover, apelin-12 activated NO production via PI3K/Akt signaling in human EC. In contrast, apelin-13 additionally activated Erk1/2 phosphorylation and enhanced EC proliferation. Knockdown of APJ inhibited phosphorylation of PI3K and impaired flow-induced eNOS and PECAM-1 expression. Knockdown of apelin had no influence on flow-induced APJ and PECAM-1 expression, but derogated eNOS expression under static and flow conditions. The present study reveals a flow-mediated adjustment of the apelin/APJ system in human EC in which APJ expression is induced by shear stress independently of its ligand. Furthermore, apelin-12 signaling is an essential regulatory element in endothelial NO synthesis.


Assuntos
Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Apelina , Linhagem Celular , Ensaio de Imunoadsorção Enzimática , Células Endoteliais da Veia Umbilical Humana , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/análise , Peptídeos e Proteínas de Sinalização Intercelular/farmacologia , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Músculo Liso Vascular/citologia , Músculo Liso Vascular/metabolismo , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Fosforilação , Molécula-1 de Adesão Celular Endotelial a Plaquetas/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores Acoplados a Proteínas G/genética , Resistência ao Cisalhamento , Transdução de Sinais/efeitos dos fármacos
7.
J Biomed Mater Res B Appl Biomater ; 102(2): 345-55, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24000221

RESUMO

Aiming at a speed up of the re-endothelialization process of biodegradable endovascular implants, novel approaches for the functionalization of poly(l-lactide) (PLLA) with anti-CD34 antibodies were established. We propose a three-step process involving PLLA surface activation with functional amino groups, attachment of a protein repelling peptide spacer, and covalent random or site-selective immobilization of the antibodies. Obtainable antibody surface densities and antigen binding capacities were thoroughly evaluated by means of enzyme-linked immunosorbent assay. Results indicate that a lower amount of anchoring sites on the antibody favors high coupling efficiency, while localization of the anchoring sites, facing the antigen binding moiety, strongly enhances the antigen capture capacity of the support. Besides minimization of physisorption and cell adhesion exemplarily shown with bovine serum albumin, avidin, and human umbilical vein endothelial cells, respectively, the inclusion of the protein-repelling spacer strengthened this effect, yielding antigen capture capacities exceeding values so far reported in literature. In contrast, the number of amino groups on the PLLA surfaces, which is indeed highly dependent on the applied activation procedure, does not seem to influence antibody coupling efficiency and antigen capture capacity considerably. This allows the choice of surface activation treatment, plasma or wet-chemical, regarding other processing parameters as for instance sterilizability or favored modification depth.


Assuntos
Anticorpos/química , Antígenos CD34 , Prótese Vascular , Proteínas Imobilizadas/química , Poliésteres/química , Desenho de Prótese , Animais , Bovinos , Humanos , Camundongos , Peptídeos/química
8.
Acta Biomater ; 10(2): 688-700, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24148751

RESUMO

Despite the development of new coronary stent technologies, in-stent restenosis and stent thrombosis are still clinically relevant. Interactions of blood and tissue cells with the implanted material may represent an important cause of these side effects. We hypothesize material-dependent interaction of blood and tissue cells. The aim of this study is accordingly to investigate the impact of vascular endothelial cells, smooth muscle cells and platelets with various biodegradable polymers to identify a stent coating or platform material that demonstrates excellent endothelial-cell-supportive and non-thrombogenic properties. Human umbilical venous endothelial cells, human coronary arterial endothelial cells and human coronary arterial smooth muscle cells were cultivated on the surfaces of two established biostable polymers used for drug-eluting stents, namely poly(ethylene-co-vinylacetate) (PEVA) and poly(butyl methacrylate) (PBMA). We compared these polymers to new biodegradable polyesters poly(l-lactide) (PLLA), poly(3-hydroxybutyrate) (P(3HB)), poly(4-hydroxybutyrate) (P(4HB)) and a polymeric blend of PLLA/P(4HB) in a ratio of 78/22% (w/w). Biocompatibility tests were performed under static and dynamic conditions. Measurement of cell proliferation, viability, glycocalix width, eNOS and PECAM-1 mRNA expression revealed strong material dependency among the six polymer samples investigated. Only the polymeric blend of PLLA/P(4HB) achieved excellent endothelial markers of biocompatibility. Data show that PLLA and P(4HB) tend to a more thrombotic response, whereas the polymer blend is characterized by a lower thrombotic potential. These data demonstrate material-dependent endothelialization, smooth muscle cell growth and thrombogenicity. Although polymers such as PEVA and PBMA are already commonly used for vascular implants, they did not sufficiently meet the criteria for biocompatibility. The investigated biodegradable polymeric blend PLLA/P(4HB) evidently represents a promising material for vascular stents and stent coatings.


Assuntos
Plaquetas/citologia , Comunicação Celular/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/citologia , Miócitos de Músculo Liso/citologia , Polímeros/farmacologia , Stents , Biomarcadores/metabolismo , Plaquetas/efeitos dos fármacos , Plaquetas/metabolismo , Plaquetas/ultraestrutura , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/farmacologia , Glicocálix/metabolismo , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/enzimologia , Humanos , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Selectina-P/metabolismo , Adesividade Plaquetária/efeitos dos fármacos , Agregação Plaquetária/efeitos dos fármacos , Molécula-1 de Adesão Celular Endotelial a Plaquetas/metabolismo , Reologia/efeitos dos fármacos , Estresse Mecânico , Propriedades de Superfície
9.
GMS Krankenhhyg Interdiszip ; 6(1): Doc26, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22242107

RESUMO

The health care region Baltic Coast is within the framework of the joint project HICARE (Health, Innovative Care & Regional Economy) to be developed from January 2011 to December 2014 into a model region to combat the spread of multi-resistant organisms (MRO). The concept of the project area "IT & Epidemiology" will be introduced here. An IT system is to be developed and implemented consisting of two interconnected elements, a central data management and a web-based support system for information and decision. Particular challenges are the consolidation of data decentrally collected from numerous and heterogeneous data sources, compliance with the data privacy protection laws and the complex management of patients' informed consent. The information collected by the central data management will be the basis of epidemiological evaluations. Prevalence and incidence of MRO in patients and staff of medical facilities, single risk factors as well as risk profiles, the range and extent of treatments including their effectiveness and sustainability will be investigated. Furthermore, cost and cost-utility analyses will be performed.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...