Qatar Cardiovascular Research Center

Doha, Qatar

Qatar Cardiovascular Research Center

Doha, Qatar
Time filter
Source Type

Gajendrarao P.,Qatar Cardiovascular Research Center | Krishnamoorthy N.,Qatar Cardiovascular Research Center | Kassem H.S.,National Programme at Aswan Heart Center | Moharem-Elgamal S.,National Programme at Aswan Heart Center | And 6 more authors.
PLoS ONE | Year: 2013

Cardiac myosin binding protein-C (cMyBP-C) is a multi-domain (C0-C10) protein that regulates heart muscle contraction through interaction with myosin, actin and other sarcomeric proteins. Several mutations of this protein cause familial hypertrophic cardiomyopathy (HCM). Domain C1 of cMyBP-C plays a central role in protein interactions with actin and myosin. Here, we studied structure-function relationship of three disease causing mutations, Arg177His, Ala216Thr and Glu258Lys of the domain C1 using computational biology techniques with its available X-ray crystal structure. The results suggest that each mutation could affect structural properties of the domain C1, and hence it's structural integrity through modifying intra-molecular arrangements in a distinct mode. The mutations also change surface charge distributions, which could impact the binding of C1 with other sarcomeric proteins thereby affecting contractile function. These structural consequences of the C1 mutants could be valuable to understand the molecular mechanisms for the disease. © 2013 Gajendrarao et al.

Johnson-Kerner B.L.,Rproject Als Jenifer Estess Laboratory For Stem Cell Research | Johnson-Kerner B.L.,Columbia University | Johnson-Kerner B.L.,University of California at San Francisco | Ahmad F.S.,New York Stem Cell Foundation | And 14 more authors.
Human Molecular Genetics | Year: 2015

Giant axonal neuropathy (GAN) is a progressive neurodegenerative disease caused by autosomal recessive mutations in the GAN gene resulting in a loss of a ubiquitously expressed protein, gigaxonin. Gene replacement therapy is a promising strategy for treatment of the disease; however, the effectiveness and safety of gigaxonin reintroduction have not been tested in human GAN nerve cells. Herewe report the derivation of induced pluripotent stem cells (iPSCs) from three GAN patients with different GAN mutations. Motor neurons differentiated from GAN iPSCs exhibit accumulation of neurofilament (NF-L) and peripherin (PRPH) protein and formation of PRPH aggregates, the key pathological phenotypes observed in patients. Introduction of gigaxonin either using a lentiviral vector or as a stable transgene resulted in normalization of NEFL and PRPH levels in GAN neurons and disappearance of PRPH aggregates. Importantly, overexpression of gigaxonin had no adverse effect on survival of GAN neurons, supporting the feasibility of gene replacement therapy. Our findings demonstrate that GAN iPSCs provide a novel model for studying human GAN neuropathologies and for the development and testing of new therapies in relevant cell types. © The Author 2014.

Sohier J.,Imperial College London | Sohier J.,Qatar Cardiovascular Research Center | Sohier J.,French National Center for Scientific Research | Carubelli I.,Imperial College London | And 6 more authors.
Biomaterials | Year: 2014

Cells environment is increasingly recognized as an important function regulator through cell-matrix interactions. Extracellular matrix (ECM) anisotropy being a key component of heart valves properties, we have devised a method to create highly porous anisotropic nanofibrillar scaffolds and studied their suitability as cell-support and interactions with human adipose derived stem cells (hADSCs) and human valve interstitial cells (hVICs). Anisotropic nanofibrillar scaffolds were produced by a modified jet-spraying method that allows the formation of aligned nanofibres (600nm) through air-stream diffraction of a polymer solution (poly (ε-caprolactone, PCL) and collection onto a variably rotating drum. The resulting matrices of high porosity (99%) mimicked valve mechanical anisotropy. Dynamically seeded hADSC and hVIC cultured on scaffolds up to 20 days revealed that hADSC and hVIC penetration within the matrices was improved by anisotropic organization. Within 10 days, cells populated the entire scaffolds thickness and produced ECM (collagen I, III and elastin). As a result, mechanical properties of the constructs were improved over culture, while remaining anisotropic. In contrast to isotropic matrices, anisotropy induced elongated hADSCs and hVICs morphology that followed nanofibres orientation. Interestingly, these morphological changes did not induce hADSC differentiation towards the mesoderm lineages while hVIC recovered a physiological phenotype over culture in the biomimetic matrices. Overall, this study indicates that highly porous anisotropic jet-sprayed matrices are interesting candidates for valve tissue engineering, through anisotropic mechanical properties, efficient cell population, conservation of stem cells phenotype and recovery of hVIC physiological phenotype. © 2013 Elsevier Ltd.

Latif N.,Harefield Hospital | Latif N.,Qatar Cardiovascular Research Center | Sarathchandra P.,Harefield Hospital | Chester A.H.,Harefield Hospital | And 3 more authors.
European Heart Journal | Year: 2015

Aims Similar risk factors and mediators are involved in calcific aortic stenosis (CAS) and atherosclerosis. Since normal valves harbour a low percentage of smooth muscle cells (SMCs), we hypothesize that the SMC phenotype participates in the pathogenesis of CAS. Method and results We analysed 12 normal and 22 calcified aortic valves for SMC markers and the expression of co-activators of SMC gene expression,myocardin andmyocardin-related transcription factors (MRTF-A/B). Transforming growth factorb(TGFb1) was used to upregulateSMC markers and co-activators in valve interstitial cells (VICs) and transmission electron microscopy (TEM)was used to detect the presence of SMC in atypical regions of the valve leaflets. Smooth muscle cell markers and co-activators, myocardin, MRTF-A, and MRTF-B, demonstrated an increased incidence and aberrant expression around calcified nodules in all 22 calcified valves as well as in surface and microvessel endothelial cells. Smooth muscle cell markers and MRTF-A were significantly increased in calcified valves. Transforming growth factor b1 (TGFb1) (10 ng/mL) was able to significantly upregulate the expression of some SMC markers and MRTF-A in VICs. Transmission electron microscopy of the fibrosa layer of calcified valves demonstrated the presence of bundles of SMCs and smooth muscle-derived foam cells. Conclusion Smooth muscle cell markers and co-activators, myocardin and MRTFs, were aberrantly expressed in calcified valves. Transforming growth factorb1 wasable to significantly upregulateSMCmarkers andMRTF-Ain VICs.Transmission electron microscopy unequivocally identified the presence of SMCs in calcified regions of valve leaflets. These findings provide evidence that the SMC phenotype plays a role in the development of CAS. © The Author 2014.

Khzam L.B.,Montreal Heart Institute | Boulahya R.,Montreal Heart Institute | Abou-Saleh H.,Qatar Cardiovascular Research Center | Hachem A.,Montreal Heart Institute | And 3 more authors.
PLoS ONE | Year: 2013

The role of endothelial progenitor cells in vascular repair is related to their incorporation at sites of vascular lesions, differentiation into endothelial cells, and release of various angiogenic factors specifically by a subset of early outgrowth endothelial progenitor cells (EOCs). It has been shown that patients suffering from cardiovascular disease exhibit increased levels of circulating and soluble CD40 ligand (sCD40L), which may influence the function of EOCs. We have previously shown that the inflammatory receptor CD40 is expressed on EOCs and its ligation with sCD40L impairs the anti-platelet function of EOCs. In the present study, we aimed at investigating the effect of sCD40L on the function of EOCs in endothelial repair. Human peripheral blood mononuclear cell-derived EOCs express CD40 and its adaptor proteins, the tumor necrosis factor receptor-associated factors; TRAF1, TRAF2 and TRAF3. Stimulation of EOCs with sCD40L increased the expression of TRAF1, binding of TRAF2 to CD40 and phosphorylation of p38 mitogen activated protein kinase (MAPK). In an in vitro wound healing assay, stimulation of EOCs with sCD40L increased the release of matrix metalloproteinase 9 (MMP-9) in a concentration-dependent manner and significantly enhanced the angiogenic potential of cultured human umbilical vein endothelial cells (HUVECs). Inhibition of p38 MAPK reversed sCD40L-induced MMP-9 release by EOCs, whereas inhibition of MMP-9 reversed their proangiogenic effect on HUVECs. This study reveals the existence of a CD40L/CD40/TRAF axis in EOCs and shows that sCD40L increases the pro-angiogenic function of EOCs on cultured HUVECs by inducing a significant increase in MMP-9 release via, at least, the p38 MAPK signaling pathway. © 2013 Bou Khzam et al.

PubMed | Imperial College London, Qatar Cardiovascular Research Center, Analog Devices Inc., University College London and Aswan Heart Center
Type: Journal Article | Journal: Journal of cardiovascular translational research | Year: 2016

Personalised treatment of heart disease requires an understanding of the patient-specific characteristics, which can vary over time. A newly developed implantable surface acoustic wave pressure sensor, capable of continuous monitoring of the left ventricle filling pressure, is a novel device for personalised management of patients with heart disease. However, a one-size-fits-all approach to device sizing will affect its positioning within the pulmonary artery and its relationship to the interrogating device on the chest wall on a patient-specific level. In this paper, we analyse the spatial orientation and morphology of the pulmonary artery and its main branches in patients who could benefit from the device and normal controls. The results could optimise the design of the sensor, its stent, and importantly its placement, ensuring long-term monitoring in patient groups.

Wang K.,University of Oxford | Terrar D.,University of Oxford | Gavaghan D.J.,University of Oxford | Mu-u-min R.,Qatar Cardiovascular Research Center | And 3 more authors.
Progress in Biophysics and Molecular Biology | Year: 2014

Living cardiac tissue slices, a pseudo two-dimensional (2D) preparation, have received less attention than isolated single cells, cell cultures, or Langendorff-perfused hearts in cardiac biophysics research. This is, in part, due to difficulties associated with sectioning cardiac tissue to obtain live slices. With moderate complexity, native cell-types, and well-preserved cell-cell electrical and mechanical interconnections, cardiac tissue slices have several advantages for studying cardiac electrophysiology. The trans-membrane potential (Vm) has, thus far, mainly been explored using multi-electrode arrays. Here, we combine tissue slices with optical mapping to monitor Vm and intracellular Ca2+ concentration ([Ca2+]i). This combination opens up the possibility of studying the effects of experimental interventions upon action potential (AP) and calcium transient (CaT) dynamics in 2D, and with relatively high spatio-temporal resolution. As an intervention, we conducted proof-of-principle application of stretch. Mechanical stimulation of cardiac preparations is well-established for membrane patches, single cells and whole heart preparations. For cardiac tissue slices, it is possible to apply stretch perpendicular or parallel to the dominant orientation of cells, while keeping the preparation in a constant focal plane for fluorescent imaging of in-slice functional dynamics. Slice-to-slice comparison furthermore allows one to assess transmural differences in ventricular tissue responses to mechanical challenges. We developed and tested application of axial stretch to cardiac tissue slices, using a manually-controlled stretching device, and recorded Vm and [Ca2+]i by optical mapping before, during, and after application of stretch. Living cardiac tissue slices, exposed to axial stretch, show an initial shortening in both AP and CaT duration upon stretch application, followed in most cases by a gradual prolongation of AP and CaT duration during stretch maintained for up to 50 min. After release of sustained stretch, AP duration (APD) and CaT duration reverted to shorter values. Living cardiac tissue slices are a promising experimental model for the study of cardiac mechano-electric interactions. The methodology described here can be refined to achieve more accurate control over stretch amplitude and timing (e.g. using a computer-controlled motorised stage, or by synchronising electrical and mechanical events) and through monitoring of regional tissue deformation (e.g. by adding motion tracking). © 2014 The Authors.

Yacoub M.H.,Qatar Cardiovascular Research Center
Nature Reviews Cardiology | Year: 2014

Since Wallace Brigden first used the term 'cardiomyopathy' in 1952, this group of diseases has continued to attract the interest of clinicians, researchers, and importantly, patients. The past decade has seen a substantial accumulation of knowledge relating to various cardiomyopathies, which has partially lifted the mystery surrounding this topic. © 2014 Macmillan Publishers Limited. All rights reserved.

Botcherby E.J.,University of Oxford | Corbett A.,University of Oxford | Burton R.A.B.,University of Oxford | Smith C.W.,University of Oxford | And 7 more authors.
Circulation Research | Year: 2013

RATIONALE:: Sarcomere length (SL) is a key indicator of cardiac mechanical function, but current imaging technologies are limited in their ability to unambiguously measure and characterize SL at the cell level in intact, living tissue. OBJECTIVE:: We developed a method for measuring SL and regional cell orientation using remote focusing microscopy, an emerging imaging modality that can capture light from arbitrary oblique planes within a sample. METHODS AND RESULTS:: We present a protocol that unambiguously and quickly determines cell orientation from user-selected areas in a field of view by imaging 2 oblique planes that share a common major axis with the cell. We demonstrate the effectiveness of the technique in establishing single-cell SL in Langendorff-perfused hearts loaded with the membrane dye di-4-ANEPPS. CONCLUSIONS:: Remote focusing microscopy can measure cell orientation in complex 2-photon data sets without capturing full z stacks. The technique allows rapid assessment of SL in healthy and diseased heart experimental preparations. © 2013 American Heart Association, Inc.

Raynaud C.M.,Qatar Cardiovascular Research Center | Rafii A.,Cornell College
Stem Cells International | Year: 2013

Cell therapy has emerged as a potential therapeutic strategy in regenerative disease. Among different cell types, mesenchymal stem/stromal cells have been wildly studied in vitro, in vivo in animal models and even used in clinical trials. However, while clinical applications continue to increase markedly, the understanding of their physiological properties and interactions raises many questions and drives the necessity of more caution and supervised strategy in their use. © 2013 Christophe Michel Raynaud and Arash Rafii.

Loading Qatar Cardiovascular Research Center collaborators
Loading Qatar Cardiovascular Research Center collaborators