Granulocyte colony-stimulating factor (G-CSF), alone or in combination with stem cell factor (SCF), can improve hemodynamic cardiac function after myocardial infarction. Apart from impairing the pump function, myocardial infarction causes an enhanced vulnerability to ventricular arrhythmias. Therefore, we investigated the electrophysiological effects of G-CSF/SCF and the underlying cellular events in a murine infarction model.G-CSF/SCF improved cardiac output after myocardial infarction. Although G-CSF/SCF led to a twofold increased, potentially proarrhythmic homing of bone marrow (BM)-derived cells to the area of infarction, <1% of these cells adopted a cardial phenotype. Inducibility of ventricular tachycardias during programmed stimulation was reduced 5 wk after G-CSF/SCF treatment. G-CSF/SCF increased cardiomyocyte diameter, arteriogenesis, and expression of connexin43 in the border zone of the infarction. An enhanced expression of the G-CSF receptor demonstrated in cardiomyocytes and other cell types of the infarcted myocardium indicates a sensitization of the heart to direct influences of this cytokine. In addition to paracrine effects potentially caused by the increased homing of BM-derived cells, these might contribute to the therapeutic effects of G-CSF.

To identify proteins involved in cardiac regeneration, a proteomics approach was applied. A total of 26 proteins, which displayed aberrant expression in mouse hearts infarcted through ligation of the left anterior descending coronary artery, were identified. These included the intermediate filament protein nestin, which was up-regulated in the infarct border zone. Corresponding changes were observed for its mRNA. Nestin mRNA was also up-regulated in hearts from 17 of 19 patients with end-stage heart failure, including 4 with acute myocardial infarction in comparison with 8 donor hearts. Immunofluorescence confocal laser scanning microscopy revealed that nestin is expressed, on the one hand, in small proportions of cardiomyocytes, endothelial cells, smooth muscle cells, neuronal cells, and fibroblasts. On the other hand, it was found to be coexpressed with the stem cell markers c-kit, Sca-1, Mdr-1, and Abcg2 in small interstitial cells. In infarcted hearts from chimeric mice transplanted with bone marrow from enhanced green fluorescent protein (EGFP) transgenic mice, less than 1% of nestin-positive cells coexpressed EGFP, although EGFP-positive cells were abundant in these. Consequently, enhanced expression of nestin in the injured myocardium might reflect spontaneous regenerative processes supposedly based on the differentiation of resident cardiac stem cells into diverse cardiac cell types.

ObjectiveRegulatory T cells (Tregs) are considered atheroprotective, and low levels have been associated with the acute coronary syndrome (ACS), particularly non‐ST elevation (NSTE)‐ACS. However, the functional properties as well as homeostasis of Tregs are mainly unknown in coronary artery disease (CAD). Here, we investigated the composition and functional properties of naïve (n) and memory (m)Tregs in patients with NSTE‐ACS and in patients 6–12 months post‐ACS.MethodsBased on the expression of CD25, FOXP3, CD127, CD45RA, CD39 and CTLA‐4, Treg subsets were defined by flow cytometry in whole blood or isolated CD4+ T cells. The functional properties of nTregs and mTregs were examined in terms of proliferative capacity and modulation of cytokine secretion. To understand the potential consequences of Treg defects, we also investigated correlations with lipopolysaccharide (LPS)‐induced cytokine secretion and ultrasound‐defined carotid atherosclerosis.ResultsBoth NSTE‐ACS and post‐ACS patients exhibited reduced levels of nTregs (P < 0.001) compared with healthy control subjects, but without compensatory increases in mTregs. Both nTregs and mTregs from patients showed significantly lower replicative rates and impaired capacity to modulate T‐cell proliferation and secretion of interferon‐gamma and IL‐10. The Treg defect was also associated with LPS‐induced cytokine secretion and increased burden of carotid atherosclerosis.ConclusionOur results demonstrate a functional and homeostatic Treg defect in patients with NSTE‐ACS and also in stabilized patients 6–12 months after ACS. Moreover, this defect was associated with a subclinical proinflammatory and atherogenic state. We believe that the failure to preserve Treg function and homeostasis reflects a need for immune‐restoring strategies in CAD.

Paclitaxel delivered into the adventitia of pig femoral arteries effectively attenuates neointima formation after angioplasty without compromising re-endothelialization. Adventitial drug delivery may therefore be an alternative to drug-eluting stents for the prevention of restenosis.

Currently available drug-eluting stents have been shown to reduce the prevalence of in-stent restenosis. However, their use is limited by their enormous cost and unwanted side effects associated with both drugs, sirolimus and paclitaxel, presently used to coat most of the stents clinically available. Due to their lack of selectivity with respect to targeted cell types these drugs do not only inhibit vascular smooth muscle cell proliferation underlying neointima formation, they also compromise endothelial repair increasing the risk for subacute thrombosis following implantation of drug-eluting stents. Accordingly, there is need for new cost-effective agents capable to inhibit restenosis without clinically relevant, unwanted side effects. In the present paper a selection of the most important patent applications published within the last 3 years and claiming the use of homologous cellular and extracellular agents as therapeutics or targets to prevent restenosis are reviewed. Such agents include c-Jun, the focal adhesion kinase (FAK) and its inhibitor FAK-related non-kinase (FRNK), estrogen receptors, variants of vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2) as well as some so far poorly characterized factors supposedly involved in the control of cell proliferation, inflammation and apoptosis. Such agents promise to be cost-effective and, in some cases, potentially devoid of unwanted side effects. Clinical long-term studies have yet to support such notions.

No abstract

Background: There is evidence for a protective role of regulatory T cells (Tregs) in atherosclerosis. A few studies have analysed Tregs in patients with coronary artery disease (CAD) although with contradictory results. Our aim was to characterize naïve(n) Tregs and memory(m) Tregs in patients with CAD. Methods: Phenotypic analysis of circulating Tregs (including activation markers CTLA4 and Helios) was performed in 21 patients with CAD (all statin-treated) and 24 controls by flow cytometry. CD4+ T cells were enriched by negative selection followed by positive selection using anti-CD4, anti-CD25, anti-CD127, and anti-CD45RA. The fractions of CD4+CD25highCD127lowCD45RA- (mTregs) and CD4+CD25highCD127lowCD45RA+ (nTregs) were analysed for FoxP3 expression. In suppression assays, nTregs and mTregs were cocultured with T responder cells (CD4+CD25-CD127+) at ratios of 1:1, 1:4 and 1:10 for 18 h. Proliferation was evaluated by using a BrdU assay. Results: Total Tregs were reduced in patients compared with controls, 3.8 (3.2-4.7) % vs 4.8 (4.0-5.4) %), p=0.011. Patients also had lower proportions of nTregs, 1.0 (1.0-1.3) % vs 1.4 (1.1-2.0) %, p=0.015, compared with controls while the difference in mTregs did not reach significance, 2.6 (2.0-3.3) % vs 3.0 (2.3-3.2) %. The expression of FoxP3+ in nTregs tended to be reduced in patients compared with controls (77 % vs 88 %, p=0.06) while its expression in mTregs was significantly decreased in patients compared with controls (83 % vs 90 %, p=0.015). The expression of CTLA4 and Helios was significantly higher in mTregs than nTregs in vivo but did not differ between patients and controls. However, the ability of Tregs, in particular nTregs, to inhibit responder CD4+CD25- T cell proliferation at a 1:1 ratio was significantly reduced in patients, p<0.001. Conclusion: The proportions of Tregs as well as FoxP3 expression in Tregs were reduced in CAD patients. Moreover, the suppressive capacity of nTregs was markedly impaired in patients although the expression of activation markers on Tregs in vivo did not seem to reflect the suppressive capacity ex vivo. The data highlight the presence of immune perturbations in CAD and call for further studies to evaluate clinical consequences involving immune dysfunction.

No abstract