Transcriptional profiling of CD133(+) cells in coronary artery disease and effects of exercise on gene expression.

BACKGROUND AIMS: Bone marrow (BM)-derived progenitor cells are under investigation for cardiovascular repair but may be altered by disease. Our aim was to identify differences in gene expression in CD133(+) cells of patients with coronary artery disease (CAD) and healthy controls, and determine whether exercise modifies gene expression. METHODS: CD133(+) cells were flow-sorted from 10 CAD patients and four controls, and total RNA was isolated for microarray-based gene expression profiling. Genes that were found to be differentially regulated in patients were analyzed further to investigate whether exercise had any normalizing effect on CD133(+) cells in CAD patients following 3 months of an exercise program. RESULTS: Improvement in effort tolerance and increases in the number of CD133(+) cells were observed in CAD patients after 3 months of exercise. Gene expression analysis of the CD133(+) cells identified 82 differentially expressed genes (2-fold cut-off, 25% false-discovery rate and % present calls) in patients compared with controls, of which 59 were found to be up-regulated and 23 down-regulated. These genes were found to be involved in carbohydrate metabolism, cell cycle, cellular development and signaling, and molecular transport. Following completion of the exercise program, gene expression patterns resembled those of controls in seven of 10 patients. CONCLUSIONS: Alterations in gene expression of BM-derived CD133(+) progenitor cells were found in CAD patients, which in part may be normalized by exercise.

Targeted antagonism of CXCR4 mobilizes progenitor cells under investigation for cardiovascular disease.

BACKGROUND AIMS: Bone marrow (BM)-derived cells may repair cardiovascular injury but populations of interest circulate in small numbers. Cytokines such as granulocyte-colony-stimulating factor mobilize cells under investigation for this purpose, including CD133+ but require injections over multiple days and may promote inflammation. The purpose of this study was to evaluate the effects of a novel CXCR4 inhibitor (plerixafor), previously shown to mobilize CD34+ stem cells, on CD133+ mobilization and markers of inflammation. METHODS: Healthy subjects received a single subcutaneous injection of plerixafor in escalating doses: 240 mcg/kg (n = 3), 320 mcg/kg (n = 5) and 400 mcg/kg (n = 7). CD133+ and CD133+/VEGFR-2+ cells were measured by flow cytometry at baseline, then 4-6 h following plerixafor injection. Markers of inflammation in serum were measured at baseline, then again 10 h following injection of the 400 mcg/kg dose. RESULTS: Across all doses, white blood cells increased on average three-fold from baseline values. CD133+ cells increased on average 24-fold (from 616 +/- 141 cells/mL to 14 713 +/- 4423 cells/mL, P = 0.0064) without clear evidence of a dose effect. CD133+/VEGFR-2+ cells ranged from 0 to 20 cells/mL at baseline and from 0 to 124 cells/mL following plerixafor administration, although the rarity of these cells precluded a statistical analysis of this population. C-reactive protein and serum amyloid type A were not increased after the 400 mcg/kg dose. Pro-inflammatory cytokine levels were undetectable before and after plerixafor, except for macrophage inflammatory protein-1 beta, which increased slightly but significantly after the 400 mcg/kg dose of plerixafor (P = 0.0156). CONCLUSIONS: CD133+ cells are mobilized into the circulation following a single injection of the CXCR4 antagonist plerixafor, without clear evidence for systemic activation of inflammation. This effect may be of importance in cell-based approaches for treating cardiovascular diseases.

Relation of endothelial function to cardiovascular risk in women with sedentary occupations and without known cardiovascular disease.

Our purpose was to determine predictors of endothelial function and potential association with cardiovascular risk in women with sedentary occupations, in whom obesity-associated risk factors may contribute to excess morbidity and mortality. Ninety consecutive women (age range 22 to 63 years, 22 overweight (body mass index [BMI] > or =25 to 29.9 kg/m(2)) and 42 obese (BMI > or = 30 kg/m(2)), had vital signs, lipids, insulin, glucose, high-sensitivity C-reactive protein, and sex hormones measured. Endothelial function was determined using brachial artery flow-mediated dilation after 5 minutes of forearm ischemia. Treadmill stress testing was performed with gas exchange analysis at peak exercise (peak oxygen consumption [Vo(2)]) to assess cardiorespiratory fitness. Brachial artery reactivity was negatively associated with Framingham risk score (r = -0.3542, p = 0.0007). Univariate predictors of endothelial function included peak Vo(2) (r = 0.4483, p <0.0001), age (r = -0.3420, p = 0.0010), BMI (r = -0.3065, p = 0.0035), and high-sensitivity C-reactive protein (r = -0.2220, p = 0.0400). Using multiple linear regression analysis with stepwise modeling, peak Vo(2) (p = 0.0003) was the best independent predictor of brachial artery reactivity, with age as the only other variable reaching statistical significance (p = 0.0436) in this model. In conclusion, endothelial function was significantly associated with cardiovascular risk in women with sedentary occupations, who were commonly overweight or obese. Even in the absence of routine exercise, cardiorespiratory fitness, rather than conventional risk factors or body mass, is the dominant predictor of endothelial function and suggests a modifiable approach to risk.

Predictors of endothelial function in employees with sedentary occupations in a worksite exercise program.

A sedentary workforce may be at increased risk for future cardiovascular disease. Exercise at the work site has been advocated, but effects on endothelium as a biomarker of risk and relation to weight loss, lipid changes, or circulating endothelial progenitor cells (EPCs) have not been reported. Seventy-two office and laboratory employees (58 women; average age 45 years, range 22 to 62; 26 with body mass index values >30 kg/m(2)) completed 3 months of participation in the National Heart, Lung, and Blood Institute's Keep the Beat program, with the determination of vital signs, laboratory data, and peak oxygen consumption (VO(2)) during treadmill exercise. Brachial artery endothelium was tested by flow-mediated dilation (FMD), which at baseline was inversely associated with Framingham risk score (r = -0.3689, p <0.0001). EPCs were quantified by colony assay. With exercise averaging 98 +/- 47 minutes each workweek, there was improvement in FMD (from 7.8 +/- 3.4% to 8.5 +/- 3.0%, p = 0.0096) and peak VO(2) (+1.2 +/- 3.1 ml O(2)/kg/min, p = 0.0028), with reductions in diastolic blood pressure (-2 +/- 8 mm Hg, p = 0.0478), total cholesterol (-8 +/- 25 mg/dl, p = 0.0131), and low-density lipoprotein cholesterol (-7 +/- 19 mg/dl, p = 0.0044) but with a marginal reduction in weight (-0.5 +/- 2.1 kg, p = 0.0565). By multiple regression modeling, lower baseline FMD, greater age, reductions in total and low-density lipoprotein cholesterol and diastolic blood pressure, and increases in EPC colonies and peak VO(2) were jointly statistically significant predictors of change in FMD and accounted for 47% of the variability in FMD improvement with program participation. Results were similar when modeling was performed for women only. In contrast, neither adiposity at baseline nor change in weight was a predictor of improved endothelial function. In conclusion, daily exercise achievable at their work sites by employees with sedentary occupations improves endothelial function, even with the absence of weight loss, which may decrease cardiovascular risk, if sustained.

Primary PCI for ST-segment elevation myocardial infarction in a patient treated with subcutaneous enoxaparin utilizing point-of-care Enox test.

The superiority of enoxaparin compared with unfractionated heparin in the medical management of patients with non-ST elevation acute coronary syndromes (NSTE ACS) has been demonstrated in clinical trials. Further, enoxaparin has been shown to be safe and effective during PCI, including in combination with glycoprotein IIb/IIIa inhibitors. Whether enoxaparin is superior to unfractionated heparin in patients with NSTE ACS under-going early invasive strategy is currently being tested in a large clinical trial. Data on the use of enoxaparin in patients undergoing primary angioplasty for ST-segment elevation myocardial infarction are limited. Unlike patients who present to the catheterization laboratory after several doses of enoxaparin where in a steady state anticoagulation might have been achieved, patients who present early after administration of a single dose of subcutaneous enoxaparin may not have an adequate level of anticoagulation for PCI. The ability to monitor activity of enoxaparin in such patients using a point-of-care test might be useful. This report describes a patient with ST-segment elevation myocardial infarction who presented for primary angioplasty 75 minutes after administration of subcutaneous enoxaparin. The Rapidpoint Enox test measured 135 seconds and the patient's corresponding serum anti-Xa level was 0.12 IU/mL indicating a suboptimal level of anticoagulation for PCI. Procedural success was attained using additional 0.3-mg/kg intravenous enoxaparin.

50th Anniversary of the first successful permanent pacemaker implantation in the United States: historical review and future directions.

June 2010 marks the 50th anniversary of the first successful human cardiac pacemaker implantation in the United States. On June 6, 1960, in Buffalo, New York, Dr. William Chardack implanted a pacemaker, designed and built by Wilson Greatbatch, an electrical engineer and inventor, in a 77-year old man with complete atrioventricular block, extending the patient's life by 18 months. This landmark event ushered in a new era of implantable cardiac pacemakers with batteries and leads of high reliability and increasing durability. Over the past half century, the field of electrophysiology and implantable devices for the management of cardiac conduction disturbances has evolved dramatically. Today's pacemakers include increasingly complex features such as telemetry monitoring, auto programmability, and hemodynamic sensors. New-generation leads present a sophisticated design with improved geometry and steroid-eluting tips to reduce chronic inflammation, maintaining a low pacing threshold and high sensing capability. The lithium iodide battery remains the mainstay of implantable pacemaker systems, exhibiting a multiple-year lifespan, slow terminal decay, and a reduced size and cost of production. Although Greatbatch's first successful pacemaker implantation remains a seminal scientific contribution to modern cardiovascular disease management, emerging developments in this field may challenge its preeminence. Important challenges such as imaging compatibility, lead durability, and infection prevention are being addressed. Novel concepts such as leadless and biologic pacing are under active investigation. In conclusion, Greatbatch's historic achievement 50 years ago reminds us that technologic progress is timeless, as efforts to enhance clinical outcomes and the quality of life continue unimpeded into the 21st century.

Overexpression of cardiac connexin45 increases susceptibility to ventricular tachyarrhythmias in vivo.

Electrophysiological remodeling involving gap junctions has been demonstrated in failing hearts and may contribute to intercellular uncoupling, delayed conduction, enhanced arrhythmias, and vulnerability to sudden death in patients with heart failure. Recently, we showed that failing human hearts exhibit marked increases in connexin45 (Cx45) expression in addition to previously documented decreases in connexin43 (Cx43) expression. Each of these changes results in reduced gap junction coupling. The objective of the present study was to examine functional consequences of increased Cx45 in cardiac gap junctions. Transgenic mice with cardiac-selective overexpression of the developmentally downregulated cardiac connexin, connexin45 (Cx45OE mice) were subjected to in vivo electrophysiology studies in which an intracardiac catheter was used to induce ventricular arrhythmias in anesthetized mice, and in which ambulatory ECG monitoring was used to detect spontaneous arrhythmias in unanesthetized mice. Hearts were analyzed by TaqMan RT-PCR, immunostaining, immunoblotting, and echocardiography. Lucifer yellow and neurobiotin dye transfer was used to assess coupling in transgenic and control myocyte cultures. Cx45 mRNA was two orders of magnitude greater in Cx45OE mice. Cx45-immunoreactive signal at gap junctions increased twofold and total Cx45 protein by immunoblotting increased 25% in Cx45OE mice compared with nontransgenic littermate controls. Functionally, Cx45OE mice exhibited more inducible ventricular tachycardia than controls but did not exhibit any other functional or structural derangements as assessed by echocardiography. Ventricular myocytes isolated from Cx45OE mice exhibited diminished intercellular transfer of Lucifer yellow dye and increased transfer of neurobiotin, consistent with altered cell-to-cell communication. Thus increased myocardial expression of Cx45 results in remodeling of intercellular coupling and greater susceptibility to ventricular arrhythmias in vivo.