Citations

In experimental hypercholesterolemia, endothelium-dependent relaxations decrease, as does endothelial immunoreactivity for nitric oxide (NO) synthase (NOS; eNOS) in coronary arteries. Systemic levels of NO also decrease with concomitant elevations in systemic circulating levels of endothelin (ET)-1. Chronic treatment of hypercholesterolemic pigs with ET-receptor antagonists increases circulating NO and improves endothelium-dependent relaxations. Mechanisms causing these increases are not known. Therefore, experiments were designed to test the hypothesis that chronic administration of ET-receptor antagonists to hypercholesterolemic pigs increases NO production through increases in NOS activity. Female juvenile pigs were fed a 2% cholesterol atherogenic diet and were randomly allocated to receive no treatment (controls), a selective ET A -receptor antagonist (ABT-624), or a combined ET A + ET B -receptor antagonist (RO-48-5695) daily for 12 wk. After 12 wk, endothelial cells from thoracic aorta were prepared for measurement of eNOS mRNA or eNOS activity. Total cholesterol, low-density-lipoprotein cholesterol, and concentrations of ET-1 were significantly higher in all three groups at 12 wk compared with baseline levels. Circulating plasma-oxidized products of NO (NOx) increased with ET-receptor blockade. NOS mRNA was similar among groups. Total and Ca-dependent NOS activity was significantly higher in aortic endothelial cells from the ET A + ET B -treated pigs compared with those treated with ET A antagonist alone. These results suggest that changes in systemic NOx after chronic inhibition of ET A + ET B receptors in hypercholesterolemia may result from posttranscriptional changes in NOS.

Transplantation of autologous mesenchymal stem cells (MSCs) may be a viable option for treatment of several diseases. MSCs efficacy depends on adequate function of their mitochondria, which might be impaired in a noxious milieu. We hypothesized that obesity compromises MSCs mitochondrial structure and function, possibly via micro‐RNA (miRNA)‐based mechanisms. MSCs were collected from swine abdominal adipose tissue after 16 weeks of Lean or Obese diet (n = 7 each). Mitochondrial structure was assessed by electron microscopy and function by membrane potential and cytochrome‐c oxidase (COX)‐IV activity. Oxidative stress was assessed by Mito‐SOX and dihydroethidium staining. Next‐generation sequencing (RNA‐seq) was performed to identify miRNAs expression in MSCs, and predicted mitochondrial target genes were then identified (MitoCarta). Compared to Lean‐MSCs, mitochondria from Obese‐MSCs were smaller and showed cristae remodeling and loss. Mitochondrial membrane potential and COX‐IV activity decreased in Obese‐MSCs, associated with increased mitochondrial oxidative stress. RNA‐seq generated reads for 413 miRNAs, of which 5 miRNAs were upregulated in Obese‐MSCs (fold change >2, p < 0.05) and found to target 43 specific mitochondrial genes. Obesity impairs MSC mitochondrial structure and function, possibly mediated partly through miRNA‐induced mitochondrial gene regulation, leading to increased oxidative stress. Importantly, these alterations may limit the therapeutic use of autologous MSCs in subjects with obesity.

AbstractAutologous transplantation of mesenchymal stem cells (MSCs) is a viable option for the treatment of several diseases. Evidence indicates that MSCs release extracellular vesicles (EVs) and that EVs shuttle miRNAs to damaged parenchymal cells to activate an endogenous repair program. We hypothesize that comorbidities may interfere with the packaging of cargo in MSC‐derived EVs. Therefore, we examined whether metabolic syndrome (MetS) modulates the miRNA content packed within MSC‐derived EVs. MSCs were collected from swine abdominal adipose tissue after 16 weeks of lean or obese diet (n = 7 each). Next‐generation RNA sequencing of miRNAs (miRNA‐seq) was performed to identify miRNAs enriched in MSC‐derived EVs and their predicted target genes. Functional pathway analysis of the top 50 target genes of the top 4 miRNAs enriched in each group was performed using gene ontology analysis. Lean‐ and MetS‐EVs were enriched in, respectively, 14 and 8 distinct miRNAs. Target genes of miRNAs enriched in MetS‐EVs were implicated in the development of MetS and its complications, including diabetes‐related pathways, validated transcriptional targets of AP1 family members Fra1 and Fra2, Class A/1 (Rhodopsin‐like receptors), and Peptide ligand‐binding receptors. In contrast, miRNAs enriched in Lean EVs target primarily EphrinA‐EPHA and the Rho family of GTPases. MetS alters the miRNA content of EVs derived from porcine adipose tissue MSCs. These alterations could impair the efficacy and limit the therapeutic use of autologous MSCs in subjects with MetS. Our findings may assist in developing adequate regenerative strategies to preserve the reparative potency of MSCs in individuals with MetS. © 2017 International Society for Advancement of Cytometry

Background Adenosine‐assisted transthoracic Doppler‐derived coronary flow reserve ( TDE ‐ CFR ) reflects coronary vascular function. The prognostic and incremental value of left anterior descending coronary artery TDE ‐ CFR above myocardial perfusion scintigraphy in patients with suspected myocardial ischemia has not yet been studied. Methods and Results Three hundred seventy‐one patients (mean age, 62.3±8.7 years; 46.8% males) referred to myocardial perfusion scintigraphy attributed to suspected myocardial ischemia were included in the study. The TDE ‐ CFR result was blinded to the referring physician. Patients were followed up regarding major cardiovascular events, defined as cardiovascular death, myocardial infarction, or acute revascularization during a median follow‐up time of 4.5 years. A TDE ‐ CFR value of ≤2.0 was considered reduced. Major cardiovascular events occurred during follow‐up in 60 patients (16.2%). A reduced TDE ‐ CFR was detected in 76 patients (20.5%). Patients with reduced TDE ‐ CFR had an event rate of 36.8% compared to 10.8% in patients with normal TDE ‐ CFR (unadjusted hazard ratio, 4.63; 95% CI, 2.78–7.69; P <0.001). In a multivariate model, TDE ‐ CFR remained a significant independent predictor of major cardiovascular events. The major cardiovascular events rate was 7.5% in patients without myocardial perfusion scintigraphy‐detected myocardial ischemia and normal TDE ‐ CFR (n=200), 24.2% in patients without ischemia but with reduced TDE ‐ CFR (n=33), and 46.5% in patients with both myocardial perfusion scintigraphy–detected myocardial ischemia and a reduced TDE ‐ CFR (n=43; P <0.001). Conclusions Coronary microvascular dysfunction, as determined by TDE ‐ CFR, is a strong independent predictor of cardiovascular events and adds incremental prognostic value compared with myocardial perfusion scintigraphy. The current study supports routine assessment of CFR in patients with suspected ischemic heart disease.