Representative examples of histological and immunohistochemical cross-section (CHE, MAC2, SMA).

<p>A–D) Elastase treated aortae after 7 weeks: (A) Cholinesterase (CHE) staining (x100) shows absence of neutrophils, (B) MAC2 (x100) staining shows absence of macrophages, (C) alpha-Smooth Muscle Actin (SMA) staining (x100) shows abundant content of smooth muscle cells, (D) DAPI staining. E–H) Control grafted aortae after 7 weeks: (E) Cholinesterase (CHE) staining (x100) shows absence of neutrophils (F), MAC2 (x100) staining shows no accumulation of macrophages, (G) alpha-Smooth Muscle Actin (SMA) staining (x100) shows minimal loss of smooth muscle cell actin, (H) DAPI staining.</p

Schematic presentation of the main steps of the procedure.

<p>(A, D) Step 1: Mouse jugular catheter introduced through an aortotomy and secured with a silk tie. (B, E) Step 2: Aorta filled with saline containing type I porcine pancreatic elastase. (C, F, G) Step 3: Aortic transplantation using sleeve technique/F: Proximal anastomosis, G: Distal anastomosis/. (H) Aorta after transplantation.</p

Parameters measured by high resolution ultrasound.

<p>Indicated parameters were measured in control grafted mice and mice transplanted with elastase-pretreated aortae at 4 and 7 weeks after surgery. * p≤0,05; ** p ≤0,01; *** p ≤0,001 <i>versus</i> controls.</p

Representative examples of histological cross-section (EVG, SIR).

<p>A,B) Elastase treated aortae after 7 weeks: (A) Elastic van Gieson (EVG) staining (×100, ×200) reveals destruction of medial elastin layer, neointima formation, but no existence of pseudoaneurysms. (B) Sirius Red Staining (SIR) (x100) shows substantial collagen content. C,D) Control grafted aortae after 7 weeks: (C) Elastic van Gieson (EVG) staining (x100) shows no destruction of the medial elastin layer, no existence of aneurysms or no neoitimal formation, (D) Sirius Red Staining (SIR) (x100) shows only low collagen content.</p

Anterior δa/Dd and posterior δp/Dd wall displacement ratio.

<p>(A) Anterior and (B) posterior wall displacement ratios were measured in control grafted mice and mice transplanted with elastase-pretreated aortae at 4 and 7 weeks after surgery using high resolution ultrasound. *p<0,05, ***p<0,001.</p

Circulating NOS3 Modulates Left Ventricular Remodeling following Reperfused Myocardial Infarction

<div><p>Purpose</p><p>Nitric oxide (NO) is constitutively produced and released from the endothelium and several blood cell types by the isoform 3 of the NO synthase (NOS3). We have shown that NO protects against myocardial ischemia/reperfusion (I/R) injury and that depletion of circulating NOS3 increases within 24h of ischemia/reperfusion the size of myocardial infarction (MI) in chimeric mice devoid of circulating NOS3. In the current study we hypothesized that circulating NOS3 also affects remodeling of the left ventricle following reperfused MI.</p><p>Methods</p><p>To analyze the role of circulating NOS3 we transplanted bone marrow of NOS3^−/− and wild type (WT) mice into WT mice, producing chimerae expressing NOS3 only in vascular endothelium (BC−/EC+) or in both, blood cells and vascular endothelium (BC+/EC+). Both groups underwent 60 min of coronary occlusion in a closed-chest model of reperfused MI. During the 3 weeks post MI, structural and functional LV remodeling was serially assessed (24h, 4d, 1w, 2w and 3w) by echocardiography. At 72 hours post MI, gene expression of several extracellular matrix (ECM) modifying molecules was determined by quantitative RT-PCR analysis. At 3 weeks post MI, hemodynamics were obtained by pressure catheter, scar size and collagen content were quantified post mortem by Gomori’s One-step trichrome staining.</p><p>Results</p><p>Three weeks post MI, LV end-systolic (53.2±5.9μl;***p≤0.001;n = 5) and end-diastolic volumes (82.7±5.6μl;*p<0.05;n = 5) were significantly increased in BC−/EC+, along with decreased LV developed pressure (67.5±1.8mmHg;n = 18;***p≤0.001) and increased scar size/left ventricle (19.5±1.5%;n = 13;**p≤0.01) compared to BC+/EC+ (ESV:35.6±2.2μl; EDV:69.1±2.6μl n = 8; LVDP:83.2±3.2mmHg;n = 24;scar size/LV13.8±0.7%;n = 16). Myocardial scar of BC−/EC+ was characterized by increased total collagen content (20.2±0.8%;n = 13;***p≤0.001) compared to BC+/EC+ (15.9±0.5;n = 16), and increased collagen type I and III subtypes.</p><p>Conclusion</p><p>Circulating NOS3 ameliorates maladaptive left ventricular remodeling following reperfused myocardial infarction.</p></div

BC−/EC+ exhibited increased end-systolic and end-diastolic volume and decreased left ventricular function 3 weeks post MI.

<p>BC−/EC+ exhibited an increase in end-systolic (<b>A</b>) and end-diastolic volume (<b>B</b>), a significantly more pronounced decrease in stroke volume (<b>C</b>) (BC+/EC+ n = 8 and BC−/EC+ n = 5; two-way ANOVA and Bonferroni’s post hoc test or student’s t-test; * p<0.05, ** p≤ 0.01 BC+/EC+ vs. BC−/EC+; # p<0.05, ## p≤ 0.01, ### p≤ 0.001 BC+/EC+ at different time points; $p<0.05,$$p≤ 0.01,$ $$ p≤ 0.001 BC−/EC+ at different time points), and decreased left ventricular developed pressure (<b>D</b>) 3 weeks post MI compared to BC+/EC+ (BC+/EC+ n = 24 and BC−/EC+ n = 18; student‘s t-test; ***p≤0.001).</p

Flow chart of the presented study.

<p>In a closed chest model, animals were subjected to reperfused myocardial infarction. After 60 min of ischemia, animals were divided into two different groups: 1) 72 h post MI 2) 3 weeks post MI. Further analysis followed as depicted.</p