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Aims: Delayed re-endothelialization after balloon angioplasty in patients with coronary or peripheral artery disease impairs vascular healing and leads to neointimal proliferation. In the present study, we examined the effect of RNA-binding motif protein 38 (Rbm38) during re-endothelialization in a murine model of experimental vascular injury., Methods and Results: Left common carotid arteries of C57BL/6 mice were electrically denudated and endothelial regeneration was evaluated. Profiling of RNA-binding proteins revealed dysregulated expression of Rbm38 in the denudated and regenerated areas. We next tested the importance of Rbm38 in human umbilical vein endothelial cells (HUVECS) and analysed its effects on cellular proliferation, migration and apoptosis. Rbm38 silencing in vitro demonstrated important beneficial functional effects on migratory capacity and proliferation of endothelial cells. In vivo, local silencing of Rbm38 also improved re-endothelialization of denuded carotid arteries. Luciferase reporter assay identified miR-98 and let-7f to regulate Rbm38 and the positive proliferative properties of Rbm38 silencing in vitro and in vivo were mimicked by therapeutic overexpression of these miRNAs., Conclusion: The present data identified Rbm38 as an important factor of the regulation of various endothelial cell functions. Local inhibition of Rbm38 as well as overexpression of the upstream regulators miR-98 and let-7f improved endothelial regeneration in vivo and thus may be a novel therapeutic entry point to avoid endothelial damage after balloon angioplasty., (© The Author(s) 2019. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Aims: Adventitial cells have been suggested to contribute to neointima formation, but the functional relevance and the responsible signalling pathways are largely unknown. Sonic hedgehog (Shh) is a regulator of vasculogenesis and promotes angiogenesis in the adult., Methods and Results: Here we show that proliferation of vascular smooth muscle cells (SMC) after wire-induced injury in C57BL/6 mice is preceded by proliferation of adventitial fibroblasts. Simultaneously, the expression of Shh and its downstream signalling protein smoothened (SMO) were robustly increased within injured arteries. In vitro, combined stimulation with Shh and platelet-derived growth factor (PDGF)-BB strongly induced proliferation and migration of human adventitial fibroblasts. The supernatant of these activated fibroblasts contained high levels of interleukin-6 and -8 and strongly induced proliferation and migration of SMC. Inhibition of SMO selectively prevented fibroblast proliferation, cytokine release, and paracrine SMC activation. Mechanistically, we found that PDGF-BB activates protein kinase A in fibroblasts and thereby induces trafficking of SMO to the plasma membrane, where it can be activated by Shh. In vivo, SMO-inhibition significantly prevented the proliferation of adventitial fibroblasts and neointima formation following wire-induced injury., Conclusions: The initial activation of adventitial fibroblasts is essential for the subsequent proliferation of SMC and neointima formation. We identified SMO-dependent Shh signalling as a specific process for the activation of adventitial fibroblasts., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.)

Background: The novel nonsteroidal mineralocorticoid receptor (MR) antagonist finerenone holds promise to be safe and efficient in the treatment of patients with heart failure and/or chronic kidney disease. However, its effects on vascular function remain elusive., Purpose: The aim of this study was to determine the functional effect of selective MR antagonism by finerenone in vascular cells in vitro and the effect on vascular remodeling following acute vascular injury in vivo., Methods and Results: In vitro, finerenone dose-dependently reduced aldosterone-induced smooth muscle cell (SMC) proliferation, as quantified by BrdU incorporation, and prevented aldosterone-induced endothelial cell (EC) apoptosis, as measured with a flow cytometry based caspase 3/7 activity assay. In vivo, oral application of finerenone resulted in an accelerated re-endothelialization 3 days following electric injury of the murine carotid artery. Furthermore, finerenone treatment inhibited intimal and medial cell proliferation following wire-induced injury of the murine femoral artery 10 days following injury and attenuated neointimal lesion formation 21 days following injury., Conclusion: Finerenone significantly reduces apoptosis of ECs and simultaneously attenuates SMC proliferation, resulting in accelerated endothelial healing and reduced neointima formation of the injured vessels. Thus, finerenone appears to provide favorable vascular effects through restoring vascular integrity and preventing adverse vascular remodeling.

Maladaptive remodelling of the arterial wall after mechanical injury (e. g. angioplasty) is characterised by inflammation, neointima formation and media hypertrophy, resulting in narrowing of the affected artery. Moreover, mechanical injury of the arterial wall causes loss of the vessel protecting endothelial cell monolayer. Mitogen-activated protein kinase (MAPK)-activated protein kinase 2 (MK2), a major downstream target of p38 MAPK, regulates inflammation, cell migration and proliferation, essential processes for vascular remodelling and re-endothelialisation. Therefore, we investigated the role of MK2 in remodelling and re-endothelialisation after arterial injury in genetically modified mice in vivo. Hypercholesterolaemic low-density-lipoprotein-receptor-deficient mice (ldlr-/-) were subjected to wire injury of the common carotid artery. MK2-deficiency (ldlr-/-/mk2-/-) nearly completely prevented neointima formation, media hypertrophy, and lumen loss after injury. This was accompanied by reduced proliferation and migration of MK2-deficient smooth muscle cells. In addition, MK2-deficiency severely reduced monocyte adhesion to the arterial wall (day 3 after injury, intravital microscopy), which may be attributed to reduced expression of the chemokine ligands CCL2 and CCL5. In line, MK2-deficiency significantly reduced the content of monocytes, neutrophiles and lymphocytes of the arterial wall (day 7 after injury, flow cytometry). In conclusion, in a model of endothelial injury (electric injury), MK2-deficiency strongly increased proliferation of endothelial cells and improved re-endothelialisation of the arterial wall after injury. Deficiency of MK2 prevents adverse remodelling and promotes endothelial healing of the arterial wall after injury, suggesting that MK2-inhibition is a very attractive intervention to prevent restenosis after percutaneous therapeutic angioplasty.

Objective: Reendothelialization after vascular injury (ie, balloon angioplasty or stent implantation) is clinically extremely relevant to promote vascular healing. We here investigated the therapeutic potential of the toll-like receptor 2/6 agonist macrophage-activating lipopeptide (MALP)-2 on reendothelialization and neointima formation in a murine model of vascular injury., Approach and Results: The left common carotid artery was electrically injured, and reendothelialization was quantified by Evans blue staining after 3 days. A single injection of MALP-2 (1 or 10 µg, IV) after vascular injury accelerated reendothelialization (P<0.001). Proliferation of endothelial cells at the wound margins determined by 5-ethynyl-2'-deoxyuridine incorporation was significantly higher in MALP-2-treated animals (P<0.05). Furthermore, wire injury-induced neointima formation of the left common carotid artery was completely prevented by a single injection of MALP-2 (10 µg, IV). In vitro, MALP-2 induced proliferation (BrdU incorporation) and closure of an artificial wound of endothelial cells (P<0.05) but not of smooth muscle cells. Protein array and ELISA analysis of isolated primary endothelial cells and ex vivo stimulated carotid segments revealed that MALP-2 stimulated the release of multiple growth factors and cytokines predominantly from endothelial cells. MALP-2 induced a strong activation of the mitogen-activated protein kinase cascade in endothelial cells, which was attenuated in smooth muscle cells. Furthermore, MALP-2 significantly enhanced circulating monocytes and hematopoietic progenitor cells., Conclusions: The toll-like receptor 2/6 agonist MALP-2 promotes reendothelialization and inhibits neointima formation after experimental vascular injury via enhanced proliferation and migration of endothelial cells. Thus, MALP-2 represents a novel therapeutic option to accelerate reendothelialization after vascular injury.