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Title: Exploring mechanisms for improvement of cardiovascular disease : studies on mature endothelial cells and CD34⁺ stem cells
Author: Bakhashab, S. M. K.
ISNI:       0000 0004 5994 2887
Awarding Body: Newcastle University
Current Institution: University of Newcastle upon Tyne
Date of Award: 2015
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Cardiovascular disease (CVD) is the major cause of morbidity and mortality worldwide and in particular in diabetes mellitus (DM). Although metformin has been shown to reduce CVD in Type-2 DM clinical trials, the underlying cardioprotective mechanism remains unexplored. Objective: to determine the effect of metformin on mature endothelial and stem cells exposed to hypoxia, hyperglycaemia or both conditions combined. Human umbilical vein endothelial cells (HUVEC) were studied by scratch test for migration and flow cytometry for apoptosis after culture in euglycaemia or hyperglycaemia, and/or hypoxia with or without metformin. mRNA was assayed by whole transcript microarrays. Genes of interest were confirmed by quantitative real-time PCR (qRT-PCR), proteins by western blot assay or flow cytometry. Metformin increased cell survival and migration via activation of vascular endothelial growth factor (VEGF) signalling, through upregulation of matrix metalloproteinase 16, and ERK/mitogen-activated protein kinase signalling under hyperglycaemia-hypoxia. Paracrine secretion of CD34+ cells treated with euglycaemia or hyperglycaemia, and/or hypoxia with or without metformin was assessed by measuring pro-inflammatory cytokines, VEGFA, chemokine (C-X-C Motif) ligand 10 (CXCL10), tissue inhibitor of metalloproteinase 1 (TIMP1) and efficacy to promote in vitro tube formation by HUVECs. Additionally, miR-126 was evaluated in exosomes and exosome-depleted medium, which was found to be increased by metformin. mRNA from treated CD34+ cells was assayed by microarray and genes of interest were validated by qRT-PCR. An anti-inflammatory effect of metformin was detected under euglycaemia and euglycaemia-hypoxia through upregulation of STEAP family member 4. Metformin enhanced angiogenesis via increased VEGFA and miR-126 under hyperglycaemia-hypoxia. Metformin downregulated the expression of angiogenic inhibitors CXCL10 and TIMP1, which were upregulated under hyperglycaemia-hypoxia. Abstract iii In conclusion, our data from HUVEC and CD34+ cells are commensurate with a vascular protective effect of metformin in a model of a diabetic state combined with hypoxia, and add to understanding of the underlying mechanism.
Supervisor: Not available Sponsor: KAU, Jeddah, Saudi Arabia ; King Abdulaziz City for Science and Technology (KACST), Saudi Arabia
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available