Bioactive Sphingolipids, Complement Cascade, and Free Hemoglobin Levels in Stable Coronary Artery Disease and Acute Myocardial Infarction.

BACKGROUND: Acute myocardial infarction (AMI) and coronary artery bypass graft (CABG) surgery are associated with a pathogen-free inflammatory response (sterile inflammation). Complement cascade (CC) and bioactive sphingolipids (BS) are postulated to be involved in this process. AIM: The aim of this study was to evaluate plasma levels of CC cleavage fragments (C3a, C5a, and C5b9), sphingosine (SP), sphingosine-1-phosphate (S1P), and free hemoglobin (fHb) in AMI patients treated with primary percutaneous coronary intervention (pPCI) and stable coronary artery disease (SCAD) undergoing CABG. PATIENTS AND METHODS: The study enrolled 37 subjects (27 male) including 22 AMI patients, 7 CABG patients, and 8 healthy individuals as the control group (CTRL). In the AMI group, blood samples were collected at 5 time points (admission to hospital, 6, 12, 24, and 48 hours post pPCI) and 4 time points in the CABG group (6, 12, 24, and 48 hours post operation). SP and S1P concentrations were measured by high-performance liquid chromatography (HPLC). Analysis of C3a, C5a, and C5b9 levels was carried out using high-sensitivity ELISA and free hemoglobin by spectrophotometry. RESULTS: The plasma levels of CC cleavage fragments (C3a and C5b9) were significantly higher, while those of SP and S1P were lower in patients undergoing CABG surgery in comparison to the AMI group. In both groups, levels of CC factors showed no significant changes within 48 hours of follow-up. Conversely, SP and S1P levels gradually decreased throughout 48 hours in the AMI group but remained stable after CABG. Moreover, the fHb concentration was significantly higher after 24 and 48 hours post pPCI compared to the corresponding postoperative time points. Additionally, the fHb concentrations increased between 12 and 48 hours after PCI in patients with AMI. CONCLUSIONS: Inflammatory response after AMI and CABG differed regarding the release of sphingolipids, free hemoglobin, and complement cascade cleavage fragments.

Circulating microRNAs (miR-423-5p, miR-208a and miR-1) in acute myocardial infarction and stable coronary heart disease.

AIM: The microRNAs (miRs) are small non-coding RNAs which regulate expression of multiple genes involved in atherogenesis. MicroRNA are also present in circulation. The aims of this study were: 1) assessment of expression level of miR-1, miR-208a and miR-423-5p in plasma in patients with STEMI, stable CAD and healthy individuals; 2) evaluation of correlation between plasma miRs and left ventricle ejection fraction, end- systolic and end-diastolic diameters and troponin release in patients with STEMI. METHODS: Study group consisted of 26 patients: 1) acute MI group (N.=17); 2) stable CAD group (N.=4); and 3) subjects with no history of CAD (control group, N.=5). Expression of miR-423-5p, miR-208 and miR-1 was measured in plasma before PCI, 6, 12 and 24 hours later. Expression level ofmiRs was measured using TaqMan® MicroRNA Assays. Expression was assessed by Pfaffl method, and miR-39 was used for normalization of the results. RESULTS: In stable CAD in comparison to control group the expression level of miR-1, miR-208a and miR-423-5p did not show significant differences. Also there was no significant increase of number of miR copies at 6, 12 and 24 hours after PCI. There was a significantly higher number of miR-423-5p copies in patients with acute MI before the pPCI. After 6, 12 and 24 hours post-procedure the expression level was similar to the control group and significantly lower than the baseline level. Conversely, the expression level of miR-1 and miR-208a were not significantly different than in the control group. In patients with acute MI there were no significant correlations between the expression level of miRs and any of the echocardiographic parameters of LV as well as level of troponin I at any time-point of the follow-up. CONCLUSION: Early in acute myocardial infarction the expression of miR-423-5p in plasma is significantly increased with subsequent normalization within 6 hours. Potentially it is an early marker of myocardial necrosis.

Circulating endothelial progenitor cells are inversely correlated with in-stent restenosis in patients with non-ST-segment elevation acute coronary syndromes treated with EPC-capture stents (JACK-EPC trial).

AIM: Aim of the study was to evaluate the association between circulating endothelial progenitor cells (EPCs) and angiographic outcomes after implantation of GenousTM stent in patients with non-ST-segment elevation acute coronary syndromes (ACS) (NSTE-ACS) undergoing urgent percutaneous coronary intervention (PCI). METHODS: Sixty patients treated with EPC-capture stent (N.=30) or bare metal stents (BMS) (N.=30) receiving 80 mg atorvastatin and dual antiplatelet therapy (DAT) for 12 months. Restenosis was assessed after 6 months by quantitative coronary angiography (QCA) and major acute coronary events (MACE) evaluated after 6 and 12 months. INCLUSION CRITERIA: de novo lesion >70% in native vessel, diameter 2.5-4 mm, lesion length <30 mm. EXCLUSION CRITERIA: diabetes, previous revascularization, significant left main stenosis, chronic total occlusions (CTO) and multivessel disease. RESULTS: Majority of patients in EPC-capture stent and BMS groups presented with NSTEMI (73.3% and 70%, respectively). Mean stent length was 20.1±8 and 19.9±10 mm, diameter 3±0.97 and 3.1±0.88 mm in respective groups. The binary restenosis was significantly lower in GenousTM (13 vs. 26.6%, P=0.04). Risk of MACE after 6 and 12 months were comparable in both groups. There was no stent thrombosis. Numbers of circulating EPCs were significantly approximately 2-fold higher during the ACS than after 6 months. Mobilization of EPCs during acute ischemia was significantly lower in patients who developed restenosis after 6 months (3 vs. 4.5 cells/µL, P=0.002) and it was negatively correlated with late-loss after 6 months (R=-0.42; P<0.03). CONCLUSION: Use of GenousTM stents in NSTE-ACS is associated with lower restenosis rate than BMS at 6 months. There was no ST through 1 year. The number of circulating EPCs is inversely correlated with in-stent late loss (LL).

Stem cell therapy for cardiovascular disease: the demise of alchemy and rise of pharmacology.

Regenerative medicine holds great promise as a way of addressing the limitations of current treatments of ischaemic disease. In preclinical models, transplantation of different types of stem cells or progenitor cells results in improved recovery from ischaemia. Furthermore, experimental studies indicate that cell therapy influences a spectrum of processes, including neovascularization and cardiomyogenesis as well as inflammation, apoptosis and interstitial fibrosis. Thus, distinct strategies might be required for specific regenerative needs. Nonetheless, clinical studies have so far investigated a relatively small number of options, focusing mainly on the use of bone marrow-derived cells. Rapid clinical translation resulted in a number of small clinical trials that do not have sufficient power to address the therapeutic potential of the new approach. Moreover, full exploitation has been hindered so far by the absence of a solid theoretical framework and inadequate development plans. This article reviews the current knowledge on cell therapy and proposes a model theory for interpretation of experimental and clinical outcomes from a pharmacological perspective. Eventually, with an increased association between cell therapy and traditional pharmacotherapy, we will soon need to adopt a unified theory for understanding how the two practices additively interact for a patient's benefit.

Pivotal role of paracrine effects in stem cell therapies in regenerative medicine: can we translate stem cell-secreted paracrine factors and microvesicles into better therapeutic strategies?

Although regenerative medicine is searching for pluripotent stem cells that could be employed for therapy, various types of more differentiated adult stem and progenitor cells are in meantime being employed in clinical trials to regenerate damaged organs (for example, heart, kidney or neural tissues). It is striking that, for a variety of these cells, the currently observed final outcomes of cellular therapies are often similar. This fact and the lack of convincing documentation for donor-recipient chimerism in treated tissues in most of the studies indicates that a mechanism other than transdifferentiation of cells infused systemically into peripheral blood or injected directly into damaged organs may have an important role. In this review, we will discuss the role of (i) growth factors, cytokines, chemokines and bioactive lipids and (ii) microvesicles (MVs) released from cells employed as cellular therapeutics in regenerative medicine. In particular, stem cells are a rich source of these soluble factors and MVs released from their surface may deliver RNA and microRNA into damaged organs. Based on these phenomena, we suggest that paracrine effects make major contributions in most of the currently reported positive results in clinical trials employing adult stem cells. We will also present possibilities for how these paracrine mechanisms could be exploited in regenerative medicine to achieve better therapeutic outcomes. This approach may yield critical improvements in current cell therapies before true pluripotent stem cells isolated in sufficient quantities from adult tissues and successfully expanded ex vivo will be employed in the clinic.

Mobilization of stem and progenitor cells in cardiovascular diseases.

Circulating bone marrow (BM)-derived stem and progenitor cells (SPCs) participate in turnover of vascular endothelium and myocardial repair after acute coronary syndromes. Acute myocardial infarction (MI) produces a generalized inflammatory reaction, including mobilization of SPCs, increased local production of chemoattractants in the ischemic myocardium, as well as neural and humoral signals activating the SPC egress from the BM. Several types of circulating BM cells were identified in the peripheral blood, including hematopoietic stem cells, endothelial progenitor cells, mesenchymal stromal cells, circulating angiogenic cells and pluripotent very small embryonic-like cells; however, the contribution of circulating cells to the myocardial and endothelial repair is still unknown. The number and function of these cells is impaired in patients with diabetes and other cardiovascular risk factors, but can be improved by physical exercise and use of statins. The mobilization of SPCs in acute coronary syndromes and stable coronary artery disease seems to predict the clinical outcomes in selected groups of patients. Interpretation of the findings has to incorporate other factors that modulate the process of mobilization, such as coexisting diseases, age and medications. This review discusses the mobilization of SPCs in acute ischemia (MI, stroke), as well as in stable cardiovascular disease, and highlights the possibility of using the SPC as a marker of cardiovascular risk.