Benjamin Seguy

Hypoxia Preconditioned Mesenchymal Stem Cells Improve Vascular and Skeletal Muscle Fiber Regeneration After Ischemia Through a Wnt4-dependent Pathway

Mesenchymal stem cells (MSC) are multipotent postnatal stem cells, involved in the treatment of ischemic vascular diseases. We investigate the ability of MSC, exposed to short-term hypoxic conditions, to participate in vascular and tissue regeneration in an in vivo model of hindlimb ischemia. Transplantation of hypoxic preconditioned murine MSC (HypMSC) enhanced skeletal muscle regeneration at day 7, improved blood flow and vascular formation compared to injected nonpreconditioned MSC (NormMSC). These observed effects were correlated with an increase in HypMSC engraftment and a putative role in necrotic skeletal muscle fiber clearance. Moreover, HypMSC transplantation resulted in a large increase in Wnt4 (wingless-related MMTV integration site 4) expression and we demonstrate its functional significance on MSC proliferation and migration, endothelial cell (EC) migration, as well as myoblast differentiation. Furthermore, suppression of Wnt4 expression in HypMSC, abrogated the hypoxia-induced vascular regenerative properties of these cells in the mouse hindlimb ischemia model. Our data suggest that hypoxic preconditioning plays a critical role in the functional capabilities of MSC, shifting MSC location in situ to enhance ischemic tissue recovery, facilitating vascular cell mobilization, and skeletal muscle fiber regeneration via a paracrine Wnt-dependent mechanism.Mesenchymal stem cells (MSC) are multipotent postnatal stem cells, involved in the treatment of ischemic vascular diseases. We investigate the ability of MSC, exposed to short-term hypoxic conditions, to participate in vascular and tissue regeneration in an in vivo model of hindlimb ischemia. Transplantation of hypoxic preconditioned murine MSC (HypMSC) enhanced skeletal muscle regeneration at day 7, improved blood flow and vascular formation compared to injected nonpreconditioned MSC (NormMSC). These observed effects were correlated with an increase in HypMSC engraftment and a putative role in necrotic skeletal muscle fiber clearance. Moreover, HypMSC transplantation resulted in a large increase in Wnt4 (wingless-related MMTV integration site 4) expression and we demonstrate its functional significance on MSC proliferation and migration, endothelial cell (EC) migration, as well as myoblast differentiation. Furthermore, suppression of Wnt4 expression in HypMSC, abrogated the hypoxia-induced vascular regenerative properties of these cells in the mouse hindlimb ischemia model. Our data suggest that hypoxic preconditioning plays a critical role in the functional capabilities of MSC, shifting MSC location in situ to enhance ischemic tissue recovery, facilitating vascular cell mobilization, and skeletal muscle fiber regeneration via a paracrine Wnt-dependent mechanism.

Mapping 3-Dimensional Neovessel Organization Steps Using Micro-Computed Tomography in a Murine Model of Hindlimb Ischemia–Brief Report

Objectives—Studying the mechanisms of neovascularization and evaluating the effects of proangiogenic strategies require accurate analysis of the neovascular network. We sought to evaluate the contribution of the microcomputed tomography (mCT) providing high-resolution 3-dimensional (3D) structural data, to a better comprehension of the well-studied mouse hindlimb postischemic neovascularization. Methods and Results—We showed a predominant arteriogenesis process in the thigh and a predominant angiogenesis-related process in the tibiofibular region, in response to ischemia during the first 15 days. After 15 days, mCT quantitative analysis reveals a remodeling of arterial neovessels and a regression depending on the restoration of the blood flow. We provided also new mCT data on the rapid and potent angiogenic effects of mesenchymal stem cell therapy on vessel formation and organization. We discussed the contribution of this technique compared with or in addition to data generated by the more conventional approaches. Conclusion—This study demonstrated that optimized mCT is a robust method for providing new insights into the 3D understanding of postischemic vessel formation.

Lethal Aorto-Right Ventricular Defect After Transcatheter Aortic Valve Implantation in a Patient With Radiation-Induced Porcelain Aorta: Notes of Caution

A 47-year-old man with severe radiation-induced aortic stenosis was rejected for cardiac surgery because of porcelain aorta. We successfully implanted an Edwards SAPIEN valve (Edwards Lifesciences, Irvine, CA), but the patient was readmitted 3 weeks later for heart failure with a continuous murmur on auscultation. Echocardiography showed a small defect between the aorta and the infundibulum of the right ventricle, which was also confirmed with aortography and computed tomography. Medical therapy was optimized; however, he died unexpectedly a few weeks later. We concluded that irradiated tissues are particularly fragile and require specific attention during transcatheter aortic valve implantation. Furthermore, this case suggests that a more aggressive closure should have been applied.

Planar cell polarity genes frizzled4 and frizzled6 exert patterning influence on arterial vessel morphogenesis

Quantitative analysis of the vascular network anatomy is critical for the understanding of the vasculature structure and function. In this study, we have combined microcomputed tomography (microCT) and computational analysis to provide quantitative three-dimensional geometrical and topological characterization of the normal kidney vasculature, and to investigate how 2 core genes of the Wnt/planar cell polarity, Frizzled4 and Frizzled6, affect vascular network morphogenesis. Experiments were performed on frizzled4 (Fzd4-/-) and frizzled6 (Fzd6-/-) deleted mice and littermate controls (WT) perfused with a contrast medium after euthanasia and exsanguination. The kidneys were scanned with a high-resolution (16 μm) microCT imaging system, followed by 3D reconstruction of the arterial vasculature. Computational treatment includes decomposition of 3D networks based on Diameter-Defined Strahler Order (DDSO). We have calculated quantitative (i) Global scale parameters, such as the volume of the vasculature and its fractal dimension (ii) Structural parameters depending on the DDSO hierarchical levels such as hierarchical ordering, diameter, length and branching angles of the vessel segments, and (iii) Functional parameters such as estimated resistance to blood flow alongside the vascular tree and average density of terminal arterioles. In normal kidneys, fractal dimension was 2.07±0.11 (n = 7), and was significantly lower in Fzd4-/- (1.71±0.04; n = 4), and Fzd6-/- (1.54±0.09; n = 3) kidneys. The DDSO number was 5 in WT and Fzd4-/-, and only 4 in Fzd6-/-. Scaling characteristics such as diameter and length of vessel segments were altered in mutants, whereas bifurcation angles were not different from WT. Fzd4 and Fzd6 deletion increased vessel resistance, calculated using the Hagen-Poiseuille equation, for each DDSO, and decreased the density and the homogeneity of the distal vessel segments. Our results show that our methodology is suitable for 3D quantitative characterization of vascular networks, and that Fzd4 and Fzd6 genes have a deep patterning effect on arterial vessel morphogenesis that may determine its functional efficiency.

0430 : Predictors of long-term clinical outcomes in acute coronary syndrome treated with everolimus-eluting stent

Background Everolimus-eluting stent (EES) improves long-term prognosis in patients with acute coronary syndrome (ACS) and is currently recommended over bare metal stent (BMS) in this population. Nevertheless, predictors of long-term outcomes in ACS patients treated with EES have not been evaluated in routine practice. Methods We retrospectively included patients treated with EES for ACS between June 2012 and December 2013 in our institution. Baseline clinical, biological and procedural characteristics were collected and all patients completed at least one-year follow-up. The primary endpoint was defined as the composite of target-vessel revascularization (TVR), target-vessel myocardial infarction (MI), or cardiac death at one year. Results of 447 patients included, 67 patients (15.1%) reached the primary endpoint at one year. In a multivariate analysis using Cox regression model, cardiogenic shock (HR 6.74; 95% CI [5-18.6]; p Conclusion in ACS patients treated with EES, cardiogenic shock and baseline anemia were the most robust predictors of long-term adverse clinical outcomes. The author hereby declares no conflict of interest

063 A single pre-hospital enoxaparine protocole for all STEMI admitted to ICU: One year experience and one year follow-up in Haut Lévêque cardiological hospital

Background: Clopidogrel and low-dose aspirin have become the mainstay oral antiplatelet regimen to prevent recurrent ischaemic events after acute coronary syndromes or stent placement. The frequent genetic functional variant 681 G>A (*2) of cytochrome P450 2C19 (CYP2C19) is an important contributor to the wide variability between individuals of the antiplatelet effect of clopidogrel. We assessed whether the CYP2C19*2 polymorphism affected long-term prognosis of patients who were chronically treated with clopidogrel.