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Tirofiban is a fibrinogen receptor antagonist, generated using the tripeptide Arg-Gly-Asp (RGD) as a template. RGD activates integrin receptors and integrin-mediated signals are necessary for normal cells to promote survival and stimulate cell cycle progression. We investigated whether tirofiban activated growth-stimulatory signals in endothelium. For this study human umbilical vein endothelial cells (HUVEC) and human aortic endothelial cells (HAEC) were used. Analysis of cell proliferation, by cell counts, showed that the number of endothelial cells doubled after 72 h of culture in the absence of tirofiban, while they were tripled and even quadrupled, in the presence of increasing doses of the drug. Moreover, tirofiban-stimulated cells had a greater ability to migrate through the transwell filters of Boyden chamber, compared to unstimulated cells. The scratch assay, which mimics cell migration during wound healing, showed that tirofiban stimulated HUVECs to migrate into the leading hedge of the scratch. Western blot showed that tirofiban increased the expression levels of VEGF and the downstream effectors Erk and cyclin D. An inhibitor of VEGFR2 counteracted tirofiban-induced-proliferation, suggesting a role for VEGF in such effect. Our study shows that tirofiban stimulates the migration and proliferation of endothelial cells suggesting that it can promote endothelial repair. Ex vivo cultures of arterial rings confirmed the growth stimulatory effect of tirofiban on endothelium. Thus, the benefits of tirofiban in those with acute coronary syndromes undergoing PTCA may be due to rapid endothelization of damaged vessel, besides antiplatelet effects.

Although considered promising for use in drug-eluting stents (DES), tacrolimus failed clinically. Tacrolimus inhibits growth factor production but can also act as a growth factor on vascular smooth muscle cells (VSMC). This unexpected proliferative stimulus could reverse the beneficial effects of the drug on restenosis. We hypothesized that tacrolimus' association with statins, which lower cholesterol and impair cell proliferation, could restore tacrolimus' beneficial effect by abrogating the aberrant proliferative stimulus. Additionally, since maintenance of endothelial function represents a challenge for new-generation DES, we investigated the combined effect of tacrolimus and atorvastatin on endothelial cells. Human VSMC and umbilical vein endothelial cells (HUVEC) were incubated with 100 nM tacrolimus and increasing doses of atorvastatin (0–3.0 μM). Atorvastatin plus tacrolimus dose-dependently inhibited VSMC proliferation. The percentage of cells incorporating 5-bromo-2′-deoxyuridine (BrdU) in their DNA was 49 ± 14% under basal conditions, 62 ± 15% ( P = 0.01) with tacrolimus, 40 ± 22% with 3 μM atorvastatin, and 30 ± 7% ( P < 0.05) with 3 μM atorvastatin plus tacrolimus. Atorvastatin downregulated β-catenin, Erk1 and Erk2, and cyclin B in tacrolimus-stimulated VSMC. In contrast, atorvastatin plus tacrolimus did not affect proliferation of endothelial cells. The percentage of HUVEC incorporating BrdU in their DNA was 47 ± 8% under basal conditions, 58 ± 6% ( P = 0.01) with tacrolimus, 45 ± 4% with 3 μM atorvastatin, and 49 ± 1% with 3 μM atorvastatin plus tacrolimus. Both agents stimulated endoglin production by HUVEC. Taken together, these results suggest that, when combined with tacrolimus, atorvastatin exerts a dose-dependent antiproliferative effect on VSMC. In contrast, atorvastatin acts in concert with tacrolimus in HUVEC to stimulate production of endoglin, a factor that has an important role in endothelial repair. Our study supports the conclusion that prevention of postcoronary in-stent restenosis and late thrombosis may benefit of concomitant association of tacrolimus and high doses of atorvastatin.

BACKGROUND: Despite significant improvements in stent platform, currently available bare-metal stents (BMS) are still associated with restenosis. Thin-strut design cobalt-chromium alloys hold the promise of improving results of BMS, especially when implanted with direct technique. We performed an observational study to appraise outcomes of the novel Skylor™ stent, stratifying outcomes according to stenting technique. METHODS and RESULTS: We included all consecutive patients undergoing coronary stenting with Skylor™ at 2 centers between 2006 and 2009. The primary end-point was the long-term rate of major adverse cardiac events (MACE, i.e. death, myocardial infarction (MI), coronary artery bypass grafting (CABG) or target vessel revascularization (TVR)). As pre-specified analysis, we compared patients undergoing direct stenting versus those stent implantation following predilation. A total of 1020 patients were included (1292 Skylor™ stents), with procedural success obtained in 99%. Comparing patients undergoing direct stenting (66%) versus pre-dilation (34%) at 16±7 months of follow-up, MACE had occurred in, respectively, 8% versus 14% (p=0.001), with death in 1% versus 2% (p=0.380), MI in 1% versus 2% (p=0.032), CABG in 0.2% versus 2% (p=0.012), and TVR in 6% versus 9% [p=0.071]. Even at multivariable analysis with propensity adjustment, direct stenting was associated with significantly fewer MACE [hazard ratio 0.60 [0.38-0.93], p=0.024]. CONCLUSIONS: This observational study suggests the presence of a beneficial synergy between direct coronary stenting technique and use of the novel thin-strut cobalt-chromium Skylor™ stent in real-world patients undergoing PCI.

To evaluate the influence of the severity of regional myocardial dysfunction and of the length of follow-up on the identification of myocardial viability with rest-redistribution Tl single photon emission computed tomography (SPECT) and low-dose dobutamine echocardiography (LDDE).Twenty-six patients with chronic coronary artery disease and wall motion abnormalities, candidates for revascularization, were included in this study. All patients underwent, in the same week, Tl SPECT and LDDE for pre-revascularization evaluation of myocardial viability. Reversibility of regional dysfunction was assessed by two-dimensional echocardiography, 40+/-20 days (early follow-up) and 12+/-5 months (late follow-up) after revascularization.In a/dyskinetic segments, Tl SPECT showed similar values of sensitivity (78% vs. 71%, P=NS) and slightly higher values of specificity (43% vs. 18%, P0.01) compared to hypokinetic segments, in predicting functional recovery at early follow-up. No significant changes were observed in the diagnostic accuracy of Tl SPECT at late follow-up. On the contrary, LDDE provided significantly lower values of sensitivity (56% vs. 94%, P0.05) and higher values of specificity (73% vs. 9%, P0.01) in a/dyskinetic compared to hypokinetic segments. Specificity of LDDE in a/dyskinetic segments significantly increased from early (73%) to late follow-up (95%; P0.05). Similarly, positive predictive value in a/dyskinetic segments significantly increased from early (69%) to late follow-up (96%; P0.05).The severity of regional dysfunction and the length of follow-up significantly influence the diagnostic accuracy of LDDE but not of rest-redistribution Tl SPECT in the identification of myocardial viability.