| 1. |
- Röhl, Samuel
(författare)
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Aspects of arterial wall healing : re-endothelialization, intimal hyperplasia and vascular remodeling
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cardiovascular disease is the leading cause of mortality in the world. Despite prevention, the need for interventions remains high. Patients with type 2 diabetes mellitus have an increased cardiovascular burden and are at higher risk of complications following invasive vascular interventions. Complications related to an excessive healing response are a major clinical problem, which results in increased morbidity and possibly death. The arterial wall healing response consists of re-endothelialization, intimal hyperplasia (IH) formation and vascular remodeling. Current pharmacological treatment relies on non-selective anti-proliferative drugs, which reduces IH formation but increases the risk of thrombosis due to a delayed re-endothelialization. Hence, there is a need for development of selective treatments. Evaluation of the re-endothelialization process in the rat carotid balloon injury model has previously been limited to histological staining and invasive imaging techniques. We demonstrate that it is possible to estimate the re-endothelialization process in ultrasound biomicroscopy using IH morphology as a surrogate marker. This technique will be a useful tool for non-invasive real-time evaluation of the re-endothelialization process in pharmacological studies. Incretin-modulating drugs is a group of antidiabetic drugs, which targets the glucagon-like peptide-1 (GLP-1) receptor by either direct activation or suppressing breakdown of native GLP-1 with dipeptidylpeptidase-4 (DPP-4) inhibitors. GLP-1 receptor activation has been shown to reduce IH formation by selective inhibition of smooth muscle cell (SMC) proliferation. However, we show that treatment with linagliptin, a DPP-4 inhibitor, does not influence the arterial wall healing in normal or type 2 diabetic conditions. Large-scale transcriptomic analysis is an important tool for confirmation and identification of novel molecular mechanisms in experimental research. In Study III, we generated an encyclopedia of the transcriptomic landscape over time in the rat carotid balloon injury model. We could detect three separate phases of the healing process and contribution of novel molecular mechanisms. This resource includes a biobank of tissue samples, which will be a powerful tool for validation and identification of novel treatment targets. The utilization of transcriptomic data to identify new biological pathways in the arterial wall healing process can be exemplified with proprotein convertase subtilisin/kexin 6 (PCSK6). Previously, we could identify an increased expression of PCSK6 in patients with symptomatic carotid artery stenosis. PCSK6 has been associated with tumor invasiveness and extracellular matrix modulation in cancer but its function in the vasculature remains elusive. We demonstrate that PCSK6 deletion increases outward remodeling, reduces SMC differentiation and influences contractility in a murine model of flow-mediated remodeling. These results indicate that PCSK6 could be a potential target to reduce the risk of constrictive remodeling and restenosis.
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| 2. |
- Röhl, Samuel, et al.
(författare)
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Noninvasive in vivo Assessment of the Re-endothelialization Process Using Ultrasound Biomicroscopy in the Rat Carotid Artery Balloon Injury Model.
- 2019
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Ingår i: Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine. - : Wiley. - 1550-9613. ; 38:7, s. 1723-1731
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Tidskriftsartikel (refereegranskat)abstract
- Ultrasound biomicroscopy (UBM), or ultra high-frequency ultrasound, is a technique used to assess the anatomy of small research animals. In this study, UBM was used to assess differences in intimal hyperplasia thickness as a surrogate measurement of the re-endothelialization process after carotid artery balloon injury in rats.Ultrasound biomicroscopic data from 3 different experiments and rat strains (Sprague Dawley, Wistar, and diabetic Goto-Kakizaki) were analyzed. All animals were subjected to carotid artery balloon injury and examined with UBM (30-70 MHz) 2 and 4 weeks after injury. Re-endothelialization on UBM was defined as the length from the carotid bifurcation to the most distal visible edge of the intimal hyperplasia. En face staining with Evans blue dye was performed at euthanasia 4 weeks after injury, followed by tissue harvesting for histochemical and immunohistochemical evaluations.A significant correlation (Spearman r=0.63; P<.0001) was identified when comparing all measurements of re-endothelialization obtained from UBM and en face staining. The findings revealed a similar pattern for all rat strains: Sprague Dawley (Spearman r=0.70; P<.0001), Wistar (Spearman r=0.36; P<.081), and Goto-Kakizaki (Spearman r=0.70; P<.05). A Bland-Altman test showed agreement between en face staining and UBM. Immunohistochemical staining confirmed the presence of the endothelium in the areas detected as re-endothelialized by the UBM assessment.Ultrasound biomicroscopy can be used for repeated in vivo assessment of re-endothelialization after carotid artery balloon injury in rats.
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| 3. |
- Röhl, Samuel, et al.
(författare)
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Transcriptomic profiling of experimental arterial injury reveals new mechanisms and temporal dynamics in vascular healing response
- 2020
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Ingår i: JVS-Vascular Science. - : Elsevier BV. - 2666-3503. ; 315, s. E14-E14
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Endovascular interventions cause arterial injury and induce a healing response to restore vessel wall homeostasis. Complications of defective or excessive healing are common and result in increased morbidity and repeated interventions. Experimental models of intimal hyperplasia are vital for understanding the vascular healing mechanisms and resolving the clinical problems of restenosis, vein graft stenosis, and dialysis access failure. Our aim was to systematically investigate the transcriptional, histologic, and systemic reaction to vascular injury during a prolonged time. Methods: Balloon injury of the left common carotid artery was performed in male rats. Animals (n = 69) were euthanized before or after injury, either directly or after 2 hours, 20 hours, 2 days, 5 days, 2 weeks, 6 weeks, and 12 weeks. Both injured and contralateral arteries were subjected to microarray profiling, followed by bioinformatic exploration, histologic characterization of the biopsy specimens, and plasma lipid analyses. Results: Immune activation and coagulation were key mechanisms in the early response, followed by cytokine release, tissue remodeling, and smooth muscle cell modulation several days after injury, with reacquisition of contractile features in later phases. Novel pathways related to clonal expansion, inflammatory transformation, and chondro-osteogenic differentiation were identified and immunolocalized to neointimal smooth muscle cells. Analysis of uninjured arteries revealed a systemic component of the reaction after local injury, underlined by altered endothelial signaling, changes in overall tissue bioenergy metabolism, and plasma high-density lipoprotein levels. Conclusions: We demonstrate that vascular injury induces dynamic transcriptional landscape and metabolic changes identifiable as early, intermediate, and late response phases, reaching homeostasis after several weeks. This study provides a temporal “roadmap” of vascular healing as a publicly available resource for the research community.
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