Abstract-Recent studies provide increasing evidence that postnatal neovascularization involves bone marrow-derived circulating endothelial progenitor cells (EPCs).

Background-Experimental studies suggest that transplantation of blood-derived or bone marrow-derived progenitor cells beneficially affects postinfarction remodeling. The safety and feasibility of autologous progenitor cell transplantation in patients with ischemic heart disease is unknown. Methods and Results-We randomly allocated 20 patients with reperfused acute myocardial infarction (AMI) to receive intracoronary infusion of either bone marrow-derived (nϭ9) or circulating blood-derived progenitor cells (nϭ11) into the infarct artery 4.3Ϯ1.5 days after AMI. Transplantation of progenitor cells was associated with a significant increase in global left ventricular ejection fraction from 51.6Ϯ9.6% to 60.1Ϯ8.6% (Pϭ0.003), improved regional wall motion in the infarct zone (Ϫ1.5Ϯ0.2 to Ϫ0.5Ϯ0.7 SD/chord; PϽ0.001), and profoundly reduced end-systolic left ventricular volumes (56.1Ϯ20 mL to 42.2Ϯ15.1 mL; Pϭ0.01) at 4-month follow-up. In contrast, in a nonrandomized matched reference group, left ventricular ejection fraction only slightly increased from 51Ϯ10% to 53.5Ϯ7.9%, and end-systolic volumes remained unchanged. Echocardiography revealed a profound enhancement of regional contractile function (wall motion score index 1.4Ϯ0.2 at baseline versus 1.19Ϯ0.2 at follow-up; PϽ0.001). At 4 months, coronary blood flow reserve was significantly (PϽ0.001) increased in the infarct artery. Quantitative F-18-fluorodeoxyglucose-positron emission tomography analysis revealed a significant (PϽ0.01) increase in myocardial viability in the infarct zone. There were no differences for any measured parameter between blood-derived or bone marrow-derived progenitor cells. No signs of an inflammatory response or malignant arrhythmias were observed. Conclusions-In

Abstract-The activity of the endothelial nitric oxide synthase (eNOS) can be regulated independently of an increase in Ca 2ϩ by the phosphorylation of Ser 1177 but results only in a low nitric oxide (NO) output. In the present study, we assessed whether the agonist-induced (Ca 2ϩ -dependent, high-output) activation of eNOS is associated with changes in the phosphorylation of

Physiological levels of shear stress alter the genetic programm of cultured endothelial cells and are associated with reduced cellular turnover rates and formation of atherosclerotic lesions in vivo. To test the hypothesis that shear stress (15 dynes/cm2) interferes with programmed cell death, apoptosis was induced in human umbilical venous cells (HUVEC) by tumor necrosis factor-α (TNF-α). Apoptosis was quantified by ELISA specific for histone-associated DNA-fragments and confirmed by demonstrating the specific pattern of internucleosomal DNA-fragmentation. TNF-α (300 U/ml) mediated increase of DNA-fragmentation was completely abrogated by shear stress (446 ± 121% versus 57 ± 11%, P <0.05). This anti-apoptotic activity of shear stress decreased after pharmacological inhibition of endogenous nitric oxide (NO)-synthase by NG-monomethyl-l-arginine and was completely reproduced by exogenous NO-donors.The activation of interleukin-1β–converting enzyme (ICE)-like and cysteine protease protein (CPP)-32-like cysteine proteases was required to mediate TNF-α–induced apoptosis of HUVEC. Endothelial-derived nitric oxide (NO) as well as exogenous NO donors inhibited TNF-α–induced cysteine protease activation. Inhibition of CPP-32 enzyme activity was due to specific S-nitrosylation of Cys 163, a functionally essential amino acid conserved among ICE/CPP-32–like proteases. Thus, we propose that shear stress-mediated NO formation interferes with cell death signal transduction and may contribute to endothelial cell integrity by inhibition of apoptosis.

Thus, elevated CRP serum levels indicative of a systemic inflammatory response are associated with a blunted systemic endothelial vasodilator function. The identification of elevated CRP levels as a transient independent risk factor for endothelial dysfunction might provide an important clue to link a systemic marker of inflammation to atherosclerotic disease progression.

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Abstract-Fluid shear stress alters the morphology and function of the endothelium by activating several kinases.Furthermore, shear stress potently inhibits apoptosis of endothelial cells. Since activation of Akt kinase has been shown to prevent cell death, we investigated the effects of shear stress on Akt phosphorylation. To test the hypothesis that shear stress interacts with the Akt kinase pathway, human umbilical venous endothelial cells were exposed to laminar shear stress (15 dyne/cm 2 ). Western blotting with specific antibodies against the phosphorylated Akt demonstrated a time-dependent stimulation of Akt phosphorylation by shear stress with a maximal increase up to 6-fold after 1 hour of shear stress exposure. The stimulation of Akt phosphorylation by shear stress thereby seemed to be mediated by the phosphoinositide 3-OH kinase (PI3K), as evidenced by the significant inhibition of shear stress-induced Akt phosphorylation by the PI3K inhibitors wortmannin (20 nmol/L) and Ly294002 (10 mol/L). In addition, pharmacological inhibition of PI3K reduced the antiapoptotic effect of shear stress against growth factor depletion-induced apoptosis. Most important, overexpression of a dominant-negative Akt mutant significantly inhibited the apoptosissuppressive effect of shear stress against serum depletion-induced apoptosis, thus indicating the direct involvement of shear stress-induced Akt phosphorylation for inhibition of endothelial cell apoptosis. These results define a novel shear stress-stimulated signal transduction pathway, namely, activation of the serine/threonine kinase Akt, which may contribute to the profound changes in endothelial morphology and function by shear stress. (Circ Res. 1998;83:334-341.)

Key Points Question What is the clinical significance of clonal hematopoiesis of indeterminate potential (CHIP) for chronic heart failure (CHF) owing to ischemic origin? Findings In this cohort study, CHIP had a high prevalence in 200 investigated patients with CHF. While no clinical baseline characteristics associated with CHF were different between CHIP carriers and non-CHIP carriers, except for the mean age, harboring mutations in the most prevalent driver genes associated with CHIP, namely DNMT3A and TET2 , was associated with a significant and profound increase in death and rehospitalization for heart failure. Meaning Clonal hematopoiesis of indeterminate potential is presented as a newly identified risk factor for impaired long-term survival and increased disease progression in patients with CHF that may be well targetable as a valuable approach to precision medicine in patients with CHF carrying specific mutations encoding for clonal hematopoiesis.