ABSTRACT: Transcriptome characterization of venous endothelium during the formation of neointimal hyperplasia and stenosis in a rat arteriovenous fistula model for kidney dialysis
Project description:In patients with severe kidney disease AVF are surgically placed in order to create good access for hemodialysis. In these dialysis patients the failure rates of AVF can be as high as 24% within 6 months after surgery, causing ineffective dialysis and necessitating additional clinical interventions. The pathological processes known to lead to AVF failure are beginning to be unravelled include the formation of venous neointimal hyperplasia (VNIH), thrombosis (Chang et al. PMID 16105066), and venous stenosis (Kanterman et al. PMID7892454, Tang et al. 1998), resulting in a reduced blood flow through the fistula. We established a rat model for AVF failure in human kidney dialysis patients. The characterization of this model has been previously described (Globerman et al. 2011, PubmedID:22002501). In this model the AVFs are surgically constructed in the right leg by connecting the superficial epigastric vein SEV to the common femoral artery (CFA), resulting in exposure of the SEV to arterial pressure with pulsatile and low resistant flow patterns (Globerman et al. 2011, PMID22002501). In the present study we utilized this AVF model in order to assess the effects of arterialized flow, with consequent pathological changes of the vessel wall due to surgical AVF instalment, on the transcriptome of endothelium from the SEV. Within the SEV these pathologies of the vessel wall include the formation of NIH in the main branch, and stenosis in the side branches. By employing this rat model we assessed the changes of the endothelial transcriptome in relation to these pathologies in order to gain mechanistic understanding of the potential roles of venous endothelium in AVF failure, as well as to identify potential biomarkers preceding AVF failure. AVF surgery was performed on N=6 rats, and 13-14 days after surgery the rats were sacrificed. AVFs were extracted from the rats, and microarray transcriptome analyses were performed on luminal endothelial cells that isolated from four different sites of the AVF by employing Laser Capture Microdissection (LCM). These sites included (i) N=5 AVF sections of the superficial epigastric vein (SEV) with neointimal hyperplasia (NIH), (ii) N=3 AVF sections of SEV side branches with luminal stenosis, (iii), N=6 sections of the SEV located distally from a ligation thereby omitting exposure to arterialized flow and consequently preventing the development of NIH or stenosis, and (iv) N=3 sections of the AVF common femoral artery without signs of NIH or stenosis.
Project description:In patients with severe kidney disease AVF are surgically placed in order to create good access for hemodialysis. In these dialysis patients the failure rates of AVF can be as high as 24% within 6 months after surgery, causing ineffective dialysis and necessitating additional clinical interventions. The pathological processes known to lead to AVF failure are beginning to be unravelled include the formation of venous neointimal hyperplasia (VNIH), thrombosis (Chang et al. PMID 16105066), and venous stenosis (Kanterman et al. PMID7892454, Tang et al. 1998), resulting in a reduced blood flow through the fistula. We established a rat model for AVF failure in human kidney dialysis patients. The characterization of this model has been previously described (Globerman et al. 2011, PubmedID:22002501). In this model the AVFs are surgically constructed in the right leg by connecting the superficial epigastric vein SEV to the common femoral artery (CFA), resulting in exposure of the SEV to arterial pressure with pulsatile and low resistant flow patterns (Globerman et al. 2011, PMID22002501). In the present study we utilized this AVF model in order to assess the effects of arterialized flow, with consequent pathological changes of the vessel wall due to surgical AVF instalment, on the transcriptome of endothelium from the SEV. Within the SEV these pathologies of the vessel wall include the formation of NIH in the main branch, and stenosis in the side branches. By employing this rat model we assessed the changes of the endothelial transcriptome in relation to these pathologies in order to gain mechanistic understanding of the potential roles of venous endothelium in AVF failure, as well as to identify potential biomarkers preceding AVF failure.
Project description:Arteriovenous hemodialysis graft (AVG) stenosis results in thrombosis and AVG failure, and develops chiefly as a consequence of neotinimal hyperplasia (NH) formation in the graft-venous anastomosis region. Of note, the juxta-anastomotic vein regions are relatively resistant to NH. AVG stenosis has not been resolved partly due to our limited understanding of the molecular processes involved in the pathophysiology. We hypothesized that the gene expression profiles of the NH prone and NH-resistant regions will be different after graft placement, and analysis of their genomic profiles may yield therapeutic targets to address AVG stenosis. To test this hypothesis we evaluated the global genomic profiles of the graft-venous anastomosis (NH-prone) and juxta-anastomotic (NH-resistant) vein regions in a porcine model of AVG stenosis using a porcine microarray. Gene expression changes in these two distinct vein regions, relative to the gene expression in un-operated veins, were examined at an early (5 days) and later (14 days) time period following graft placement. Global genomic changes were much greater in the NH-prone region than in the NH-resistant region at both time points. In the NH-prone region, genes related to regulation of cell proliferation and osteo/chondrogenic vascular remodeling were most enriched among the significantly up-regulated genes at day 5 and day 14, respectively. At both time points, genes related to muscle phenotype were significantly down-regulated. These results provide insights into the spatial and temporal genomic modulation underlying NH formation in AVG, and suggest potential therapeutic strategies to prevent and/or limit AVG stenosis.
Project description:Disturbed flow in the juxta-anastomotic area of an arteriovenous fistula correlates with endothelial loss, acute thrombus formation and neointimal hyperplasia
Project description:Background: Clinical failure of arteriovenous fistulae (AVF) is frequently due to juxta-anastomotic neointimal hyperplasia (JANIH). Although the mouse AVF model recapitulates human AVF maturation, previous studies focused on the outflow vein distal to the anastomosis. We hypothesized that the juxta-anastomotic area (JAA) has increased NIH compared to the outflow vein. Method: AVF were created in C57BL/6 mice without or with chronic kidney disease (CKD). Temporal and spatial changes of the JAA were examined using histology and immunofluorescence. Computational techniques were used to model the AVF. RNA-seq and bioinformatic analyses were performed to compare the JAA with the outflow vein. The jugular vein to carotid artery AVF model was created in Wistar rats. Result: The neointima in the JAA shows increased volume compared to the outflow vein. Computational modeling shows increased volume of disturbed flow at the JAA compared to the outflow vein. Endothelial cells are immediately lost from the wall contralateral to the fistula exit, followed by thrombus formation and JANIH. Gene Ontology (GO) enrichment analysis of the 1862 differentially expressed genes (DEG) between the JANIH and the outflow vein identified 525 overexpressed genes. The rat jugular vein to carotid artery AVF showed changes similar to the mouse AVF. Conclusion: Disturbed flow through the JAA correlates with rapid endothelial cell loss, thrombus formation, and JANIH; late endothelialization of the JAA channel correlates with late AVF patency. Early thrombus formation in the JAA may influence later development of JANIH.
Project description:Neointimal hyperplasia (NIH) are the major causes of re-stenosis in coronary intervention. Fibroblasts, vascular smooth muscle cells and endothelial cells are the main disease-causing cells in NIH. However, Yet how these cells contribute to the pathophysiology of NIH remains elusive. This study was aimed at gaining new insights into the heterogeneity of these cells by using single-cell RNA sequencing and up-to-date analytical method.
