Comparison of activation process of platelets and neutrophils after coronary stent implantation versus balloon angioplasty for stable angina pectoris

Circulating intermediate monocytes CD14++CD16+ are increased after elective percutaneous coronary intervention

AIM

Inflammation plays a central role in the pathogenesis of atherosclerosis and in the sequelae of percutaneous coronary intervention (PCI). Previous work demonstrated that intermediate monocytes (CD14++CD16+) are associated with adverse cardiovascular events, yet monocyte subset response following elective PCI has not been described. This article explores the changes in monocyte subset and humoral response after elective PCI.

METHODS

This prospective study included 30 patients without inflammatory diseases being referred for elective PCI. We included patients treated with drug coated balloons or 2nd generation drug eluting stents. Patients underwent blood tests at baseline (prior to PCI), four hours, two weeks and two months later. Analyses were performed in terms of monocyte subsets (classical CD14++CD16-, intermediate CD14++CD16+ and non-classical CD14+CD16++), gene expression of CD14+ leucocytes and humoral biomarkers.

RESULTS

Intermediate monocytes decreased significantly four hours after PCI, were recovered at two weeks, and increased significantly at two months post elective, uncomplicated PCI. They remain significantly elevated in the DES group but not in the DCB group. Gene expression analysis of CD14+ leucocytes showed IL18 had decreased expression at two weeks, CXCR4 and IL1β decreased at two months, while pentraxin 3 increased at two weeks and two months. In terms of humoral biomarkers, hsTnI remains elevated up to two weeks post PCI while IL6 and TNFα remain elevated till two months post PCI.

CONCLUSION

Intermediate monocytes increase significantly two months following elective, uncomplicated PCI. They remain significantly elevated in the DES group but not in the DCB group suggesting that the PCI strategy could be one of the ways to modulate the inflammatory response post PCI.

B, Kappelmayer J, Kőszegi Z, Csanádi Z, Szük T. Technically Challenging Percutaneous Interventions of Chronic Total Occlusions Are Associated with Enhanced Platelet Activation

Percutaneous coronary intervention (PCI) is a frequently performed treatment option for recanalization in patients with chronic total occlusion (CTO). As CTO-PCIs are often complicated and challenging for interventionalists, the stressful and damaging nature of the procedure can be remarkable, thus platelets can be easily activated. Our aim was to investigate the effect of CTO-PCI on platelet activation and the expression of selected circulating microRNAs (miR) of platelet and endothelium origin after CTO-PCI. In this study, 50 subjects after CTO-PCI were enrolled. Blood samples were obtained before PCI, at 2 days and 3-6 months after the procedure to measure the degree of platelet activation and the level of plasma miR-223, miR-181b, and miR-126. Patients were divided based on the characteristics of the intervention. Patients with higher Japanese CTO scores and longer duration of PCI showed significantly elevated platelet P-selectin positivity (p = 0.004 and p = 0.013, respectively) 2 days after the procedure compared to pre-PCI and increased concentration of soluble P-selectin 3-6 months after the intervention (higher Japanese CTO score: p = 0.028 and longer duration of PCI: p = 0.023) compared to baseline values. Shorter total stent length caused a significantly lower miR-181b expression at 3-6 months after the intervention (p = 0.031), while no difference was observed in miR-223 and miR-126. One stent thrombosis occurred during the follow-up period. Although these technically challenging CTO-PCIs may cause enhanced platelet activation right after the intervention and long-term endothelial cell dysfunction, these interventions are not associated with more adverse clinical events.

A novel noble metal stent coating reduces in vitro platelet activation and acute in vivo thrombosis formation: a blinded study

Inherent to any stenting procedure is the prescription of dual antiplatelet therapy (DAPT) to reduce the platelet response. Clinical guidelines recommend 6-12 months of DAPT, depending on stent type, clinical picture and patient factors. Our hypothesis is that a nanostructured noble metal coating has the potential to reduce protein deposition and platelet activation. These effects would reduce subsequent thrombo-inflammatory reactions, potentially mitigating the need for an extensive DAPT in the acute phase. Here, a noble metal nanostructure coating on stents is investigated. Twelve pigs underwent endovascular implantation of coated and non-coated stents for paired comparisons in a blinded study design. The non-coated control stent was placed at the contralateral corresponding artery. Volumetric analysis of angiographic data, performed by a treatment blinded assessor, demonstrated a significant thrombus reduction for one of the coatings compared to control. This effect was already seen one hour after implantation. This finding was supported by in vitro data showing a significant reduction of coagulation activation in the coated group. This novel coating shows promise as an implant material addition and could potentially decrease the need for DAPT in the early phases of stent implementation.

Paclitaxel exerts antiplatelet and antithrombotic activities: Additional benefit from use of paclitaxel-coated balloons and -eluting stents in coronary revascularization and prevention of in-stent restenosis

INTRODUCTION

Paclitaxel is a microtubule-stabilizing drug used to treat several types of cancer, including ovarian and breast cancer. Because of its antiproliferative effect on vascular smooth muscle cells, balloons and stents are coated with paclitaxel for use in coronary revascularization and prevention of in-stent restenosis (ISR). However, mechanisms underlying ISR are complicated. Platelet activation is one of the major causes of ISR after percutaneous coronary intervention. Although the antiplatelet activity of paclitaxel was noted in rabbit platelets, the effect of paclitaxel on platelets remains unclear. This study investigated whether paclitaxel exhibits antiplatelet activity in human platelets.

METHODS AND RESULTS

Paclitaxel inhibited platelet aggregation induced by collagen but not that induced by thrombin, arachidonic acid, or U46619, suggesting that paclitaxel is more sensitive to the inhibition of collagen-induced platelet activation. Moreover, paclitaxel blocked collagen receptor glycoprotein (GP) VI downstream signaling molecules, including Lyn, Fyn, PLCγ2, PKC, Akt, and MAPKs. However, paclitaxel did not directly bind to GPVI and cause GPVI shedding, as detected by surface plasmon resonance and flow cytometry, respectively, indicating that paclitaxel may interfere with GPVI downstream signaling molecules, such as Lyn and Fyn. Paclitaxel also prevented granule release and GPIIbIIIa activation induced by collagen and low convulxin doses. Moreover, paclitaxel attenuated pulmonary thrombosis and delayed platelet thrombus formation in mesenteric microvessels without significantly affecting hemostasis.

CONCLUSION

Paclitaxel exerts antiplatelet and antithrombotic effects. Thus, paclitaxel may provide additional benefits beyond its antiproliferative effect when used in drug-coated balloons and drug-eluting stents for coronary revascularization and prevention of ISR.

Serum sulfatide as a biomarker of carotid atherosclerosis in patients with rheumatoid arthritis

PURPOSE

Rheumatoid arthritis (RA) patients have accelerated atherosclerosis (AS) leading to excess cardiovascular morbidity and mortality, but traditional risk factors for cardiovascular disease (CVD) are invalid to explain the problem. Sulfatides, as major components of serum lipoproteins, are synthesized in the liver. These molecules are reported to play an important role in the development of AS, thrombogenesis, and inflammation. However, it is unclear whether sulfatides are responsible for such issue. To elucidate the possible association between serum sulfatide and the accelerated progress of AS, evaluated by carotid intima-media thickness (CIMT), and ascertain the related mechanism underlying the correlation in RA cases.

METHODS

We performed an observational study of 144 patients with RA and 120 sex and age-matched controls. Meanwhile, 107 patients (of the 144 RA patients enrolled at baseline) were invited to undergo a second measurement after 12 months. Serum sulfatide levels of all the enrolled subjects were quantified by mass spectrometry after they were converted into lysosulfatides (LS), and then calculated as the sum of the levels of seven LS molecular species. Serum oxidative stress marker, malondialdehyde (MDA) was detected by ELISA. We subsequently statistically analyzed the causalities between carotid AS and clinical parameters, and the association of serum sulfatide with other variables. Multivariable logistic regression analysis was finally employed by taking all factors to identify independent determinant for carotid atherosclerotic plaque and serum sulfatide level.

RESULTS

A gradual declined trend in serum sulfatide levels was observed in control subjects, non-plaque group, and the plaque group (8.56 ± 1.37 nmol/mL, 5.63 ± 1.57 nmol/mL, 3.18 ± 1.32 nmol/mL, respectively, p < 0.01), along with an increased value of CIMT (0.63 ± 0.07 mm, 0.92 ± 0.14 mm, 1.43 ± 0.22 mm, respectively, p < 0.01). Meanwhile, a negative linear correlation between CIMT and serum sulfatide was further confirmed by Spearman's analysis (r = -0.622, p < 0.01). Eventually, multivariate logistic regression analysis identified serum MDA as the only independent factor for the abnormal level of serum sulfatide, and serum sulfatide was detected as a significant protective factor for the occurrence of carotid plaques in RA cases (p < 0.01), which was confirmed repeatedly by our cross-sectional and longitudinal studies.

CONCLUSION

Excessive abnormal levels of oxidative stress decreased serum sulfatide levels, followed by a high occurrence of AS in RA patients. Serum sulfatide level might be useful as a predictor (biomarker) for the progression of AS in RA cases.

Emerging Anti-Atherosclerotic Therapies

Cardiovascular disease (CAD) is the main cause of morbidity and deaths in the western world. The development of atherosclerosis underlying CAD development begins early in human life. There are numerous genetic and environmental risk factors accelerating its progression which then leads to the occurrence of acute events. Despite considerable progress in determining risk factors, there is still a lot of work ahead since identified determinants are responsible only for a part of overall CAD risk. Current therapies are insufficient to successfully reduce the risk of atherosclerosis development. Therefore, there is a need for effective preventive measures of clinical manifestations of atherosclerosis since the currently available drugs cannot prevent the occurrence of even 70% of clinical events. The shift of the target from lipid metabolism has opened the door to many new therapeutic targets. Currently, the majority of known targets for anti-atherosclerotic drugs focus also on inflammation (a common mediator of many risk factors), mechanisms of innate and adaptive immunity in atherosclerosis, molecule scavengers, etc. The therapeutic potential of cyclodextrins, protein kinase inhibitors, colchicine, inhibitors of p38 mitogen-activated protein kinase (MAPK), lipid dicarbonyl scavengers, a monoclonal antibody targeting interleukin-1β, and P-selectin inhibitors is still not fully confirmed and requires confirmation in large clinical trials. The preliminary results look promising.

A prediction model based on platelet parameters, lipid levels, and angiographic characteristics to predict in-stent restenosis in coronary artery disease patients implanted with drug-eluting stents

BACKGROUND

The present study was aimed to establish a prediction model for in-stent restenosis (ISR) in subjects who had undergone percutaneous coronary intervention (PCI) with drug-eluting stents (DESs).

MATERIALS AND METHODS

A retrospective cohort study was conducted. From September 2010 to September 2013, we included 968 subjects who had received coronary follow-up angiography after primary PCI. The logistic regression analysis, receiver operator characteristic (ROC) analysis, nomogram analysis, Hosmer-Lemeshow χ2 statistic, and calibration curve were applied to build and evaluate the prediction model.

RESULTS

Fifty-six patients (5.79%) occurred ISR. The platelet distribution width (PDW), total cholesterol (TC), systolic blood pressure (SBP), low-density lipoprotein cholesterol (LDL-C), and lesion vessels had significant differences between ISR and non-ISR groups (all P < 0.05). And these variables were independently associated with ISR (all P < 0.05). Furthermore, they were identified as predictors (all AUC > 0.5 and P < 0.05) to establish a prediction model. The prediction model showed a good value of area under curve (AUC) (95%CI): 0.72 (0.64-0.80), and its optimized cut-off was 6.39 with 71% sensitivity and 65% specificity to predict ISR.

CONCLUSION

The incidence of ISR is 5.79% in CAD patients with DES implantation in the Xinjiang population, China. The prediction model based on PDW, SBP, TC, LDL-C, and lesion vessels was an effective model to predict ISR in CAD patients with DESs implantation.

The Role of Biodegradable Poly-(L-lactide)-Based Polymers in Blood Cell Activation and Platelet-Monocyte Interaction

The main purpose of new stent technologies is to overcome unfavorable material-related incompatibilities by producing bio- and hemo-compatible polymers with anti-inflammatory and anti-thrombogenic properties. In this context, wettability is an important surface property, which has a major impact on the biological response of blood cells. However, the influence of local hemodynamic changes also influences blood cell activation. Therefore, we investigated biodegradable polymers with different wettability to identify possible aspects for a better prediction of blood compatibility. We applied shear rates of 100 s⁻¹ and 1500 s⁻¹ and assessed platelet and monocyte activation as well as the formation of CD62P+ monocyte-bound platelets via flow cytometry. Aggregation of circulating platelets induced by collagen was assessed by light transmission aggregometry. Via live cell imaging, leukocytes were tracked on biomaterial surfaces to assess their average velocity. Monocyte adhesion on biomaterials was determined by fluorescence microscopy. In response to low shear rates of 100 s⁻¹, activation of circulating platelets and monocytes as well as the formation of CD62P+ monocyte-bound platelets corresponded to the wettability of the underlying material with the most favorable conditions on more hydrophilic surfaces. Under high shear rates, however, blood compatibility cannot only be predicted by the concept of wettability. We assume that the mechanisms of blood cell-polymer interactions do not allow for a rule-of-thumb prediction of the blood compatibility of a material, which makes extensive in vitro testing mandatory.

A risk predictor of restenosis after superficial femoral artery stent implantation: relevance of mean platelet volume

Background

To investigate the relationship between an increase in the pre- and post-operative mean platelet volume (MPV) and superficial femoral artery in-stent restenosis (ISR) rate.

Methods and results

We recruited patients that underwent superficial femoral artery stenting for lower extremity arteriosclerosis obliterans at our hospital from March 2015 to March 2018. All patients gave venous blood three days before and following implantation. Doppler ultrasound, computed tomography angiography or digital subtraction angiography were used for regular follow-up examination. Logistic regression was used to identify predictors of ISR after superficial femoral artery stenting. We enrolled 173 patients, of which 34 (19.6%) were determined as having ISR for a mean of 8.9 ± 2.7 months (3–12 months). Neutrophil count, neutrophil ratio, lymphocyte ratio and platelet count pre-implantation, and platelet count and MPV after stent implantation, and the pre- and post-operative mean platelet volume difference (MPVD) and mean platelet volume difference ratio (MPVDR) were all statistically different when comparing the ISR and non-restenosis groups (p < 0.05). A positive correlation was found for post-operative MPV and presence of ISR (r = 0.58; P < 0.001). A MPVD not less than 1.5 fL was associated with an odds ratio of 9.17 (95% CI [3.76 to 22.35]; P < 0.001) for presence of ISR. A MPVDR of not less than 17.9% was associated with an odds ratio of 7.68 (95% CI [3.19 to 18.49]; P < 0.001) for occurrence of ISR.

Conclusions

An increase in pre- and post-operative MPV was correlated with the occurrence of superficial femoral artery ISR.

Platelets Activation in Patients Undergoing PTCA and Their Responsiveness After in vitro Stimulation

We evaluated expression of platelet activation markers in blood samples of 15 patients who underwent percutaneous transluminal coronary angioplasty (PTCA) by flow cytometry. Analysis was performed before the beginning of PTCA, during initial coronary angiography and after the end of PTCA or after a stent placement, respectively. We evaluated platelet-derived microparticles, platelet-leukocyte aggregates, platelet aggregates and a membrane expression of CD62P and CD63 molecules. Responsiveness of platelets to the activationin vitrowith thrombin-receptor activating protein – 6 (TRAP-6) was tested simultaneously. Statistically significant differences between patient samples were found only in the expression of the activation markers CD62P (before PTCA 0.22 %, during 0.39 %, after 0.67 %), CD63 (0.26 %/ 0.45 %/ 0.85 %) and platelet-leukocyte aggregates (13.57 %/ 18.39 %/ 23.63 %).In the same group the expression of all constitutive membrane markers was statistically significantly decreased: in patients undergoing PTCA was the expression of CD9:87.98 % (in comparison with control group 94.98 %), CD31: 87.10 % (92.78 %), CD36: 87.37 % (90.98 %), CD41: 88.09 % (95.62 %), CD42a: 88.54 % (94.98 %), CD42a: 88.31 % (94.13 %).

Platelet Distribution Width on Admission Predicts In-Stent Restenosis in Patients with Coronary Artery Disease and Type 2 Diabetes Mellitus Treated with Percutaneous Coronary Intervention

Background:

It is known that there is a definite association between platelet distribution width (PDW) and poor prognosis in patients with coronary artery disease (CAD) and type 2 diabetes mellitus (T2DM). However, there are no data available regarding the prognostic significance of PDW for in-stent restenosis (ISR) in patients with CAD and T2DM. We aimed to determine the value of PDW on admission that predicted ISR in patients with CAD and T2DM.

Methods:

Between January 2012 and December 2013, a total of 5232 consecutive patients diagnosed with CAD and T2DM undergoing percutaneous coronary intervention were admitted. Three years of retrospective follow-up was undertaken. A total of 438 patients with second angiography operations were included. ISR was defined as ≥50% luminal stenosis of the stent or peri-stent segments. Continuous data were presented as the mean ± standard deviation or median (P₂₅, P₇₅) and were compared by one-way analysis of variance or Kruskal-Wallis H-test. Categorical variables were presented as percentages and were compared by Chi-square test or Fisher's exact test. The association between PDW and ISR was calculated by logistic regression analysis. A two-sided value of P < 0.05 was considered statistically significant. Statistical analyses were performed by SPSS version 22.0 for windows.

Results:

Fifty-nine patients with ISR, accounting for 13.5% of the total, were included. ISR was significantly more frequent in patients with higher PDW quartiles compared with lower quartiles. We observed that PDW had a strong relationship with mean platelet volume (r = 0.647, 95% confidence interval [CI]: 0.535–0.750, P < 0.0001). The receiver-operating characteristic curves showed that the PDW cutoff value for predicting ISR rate was 13.65 fl with sensitivity of 59.3% and specificity of 72.4% (area under curve [AUC] = 0.701, 95% CI: 0.625–0.777, P < 0.001). Multivariate analysis showed that the risk of ISR increased approximately 30% when PDW increased one unit (odds ratio [OR]: 1.289, 95% CI: 1.110–1.498, P = 0.001). Patients with higher PDW, defined as more than 13.65 fl, had a 4-fold higher risk of ISR compared with lower PDW (OR: 4.241, 95% CI: 1.879–9.572, P = 0.001). Furthermore, when patients were divided by PDW quartiles values, PDW was able to predict ISR (Q2: OR = 0.762, 95% CI: 0.189–3.062, P = 0.762; Q3: OR = 2.782, 95% CI: 0.865–8.954, P = 0.086; and Q4: OR = 3.849, 95% CI: 1.225–12.097, P = 0.021, respectively; P for trend <0.0001).

Conclusion:

PDW is an independent predictor of ISR in patients with CAD and T2DM.

Myeloid-related protein-8/14 in acute coronary syndrome

BACKGROUND

The alarmin family member myeloid-related protein (MRP)-14 (S100A9), which has been identified by platelet transcriptional profiling as an acute myocardial infarction gene, regulates vascular inflammation and thrombosis. Elevated plasma levels of MRP-8/14 (S100A8/A9) heterodimer predict first and recurrent cardiovascular events. The aim of this study was to elucidate pathophysiological roles of MRP-8/14 in acute coronary syndrome (ACS).

METHODS AND RESULTS

In 38 consecutive ACS patients, the MRP-8/14 level in coronary artery blood obtained at thrombus aspiration was higher in 23 patients, in whom aspirated thrombus was confirmed, compared to the 15 patients, in whom it was absent [4.86 (1.95, 8.29) vs 2.94 (1.31, 4.44), P=0.017]. The MRP-8/14 level was correlated with myeloperoxidase (MPO) level (R²=0.52), but not with soluble P-selectin level (R²=0.0002) in the coronary artery blood. Immunohistochemistry of the aspirated thrombus exhibited that expression of MRP8/14 was co-localized with leukocytes positive for activated Mac-1. Finally, in cultured human umbilical vein endothelial cells, MRP-8/14 increased tissue factor expression.

CONCLUSIONS

Our findings indicate that MRP-8/14 concentration increases in coronary artery blood in association with thrombus formation in ACS, co-localizes with leukocytes, and is associated with leukocyte activation. MRP-8/14 is positioned as a unique biomarker at the interface of inflammation and thrombosis in ACS.

Long-term serial changes in platelet activation indices following sirolimus elution and bare metal stent implantation in patients with stable coronary artery disease

BACKGROUND

Platelet activation is crucial in the development of stent thrombosis following percutaneous coronary intervention (PCI). We carried out a long-term assessment of multiple factors implicated in the thrombotic process and monitored markers of platelet activation after the implantation of sirolimus-eluting stents (SES) in patients with stable coronary artery disease (CAD). Additionally, we compared these findings with those after bare-metal stent (BMS) implantation.

METHODS

A cohort of 47 consecutive patients, aged <70 years, with severe stenosis (>70% narrowing of the lumen) of one major epicardial coronary artery and stable CAD underwent successful elective PCI. Patients were randomly allocated to SES (n = 25) or BMS (n = 22). Venous blood was obtained 24 hours before and 24 hours, 48 hours, 1 month, and 6 months after PCI for measurements of plasma levels of sP-selectin, von Willebrand Factor (vWF), fibrinogen, d-dimer, sCD40, factor VIII, b-thromboglobulin (b-TG) and platelet factor 4 (PF-4).

RESULTS

There were no significant differences between the two groups in levels of fibrinogen or d-dimers in peripheral blood. However, we observed a significant kinetic effect (p<0.001) and stent-effect (p<0.015) on vWF levels and a significant kinetic effect (p = 0.012) on factor VIII, sP-selectin (p = 0.04), b-TG (p<0.001), and PF4 (p = 0.016). A trend towards a significant stent effect on sCD40 was also detected (p = 0.06).

CONCLUSIONS

SES and BMS did not show significant differences in relationship to markers of platelet activation and coagulation in patients with stable CAD. Although some markers showed an increase after stent implantation, they returned to the initial levels 6 months later.

Evaluation of Platelet and Leukocyte Functions in Effort Angina Patients Using High Shear Conditions in Small-Sized Collagen Bead Columns

This study used a small-sized collagen bead column system to investigate platelet functions under high shear stress in 28 patients with effort angina and 15 healthy controls. Soluble P-selectin and soluble L-selectin were also evaluated. Patients underwent stent insertion, followed by treatment with aspirin (100 mg/day) and ticlopidine (200 mg/day). High-shear-dependent platelet function was measured using small-sized collagen beads. The retention rate of platelets from patients with angina was higher than that in healthy controls (10.9% ± 3.9% versus 5.6% ± 1.7%, P < .01). Soluble P-selectin and soluble L-selectin levels of patients with angina significantly increased after passage through the columns. Levels of soluble P-selectin and L-selectin in healthy controls did not exhibit significant changes with passage through the columns. These results suggested that high shear stress caused abnormal activation of leukocytes or adhesive proteins in patients with effort angina, and ticlopidine failed to suppress hyperaggregability of platelets in these patients.

First-in-Man Study With Inclacumab, a Human Monoclonal Antibody Against P-selectin

Inclacumab, a novel monoclonal antibody against P-selectin in development for the treatment and prevention of atherosclerotic cardiovascular diseases, was administered in an ascending single-dose study as intravenous infusion to evaluate safety, pharmacokinetics, and pharmacodynamics. Fifty-six healthy subjects were enrolled in this randomized, double-blind placebo-controlled study. Each dose level (0.03-20 mg/kg) was investigated in separate groups of 8 subjects (6 on inclacumab, 2 on placebo). Platelet-leukocyte aggregates, free/total soluble P-selectin concentration ratio, drug concentrations, bleeding time, platelet aggregation, antibody formation, and routine laboratory parameters were measured frequently until 32 weeks. Pharmacokinetic profiles were indicative of target-mediated drug disposition. Platelet-leukocyte aggregate inhibition and soluble P-selectin occupancy showed dose dependency and were strongly correlated to inclacumab plasma concentrations, with IC50 of 740 and 4600 ng/mL, respectively. Inclacumab was well tolerated by the majority of subjects and did neither affect bleeding time nor platelet aggregation. These findings allowed the investigation of the potential beneficial therapeutic use of inclacumab in patient study.

Absence of pharmacodynamic interaction between inclacumab and heparin in healthy smokers

Inclacumab is a novel monoclonal antibody directed against P-selectin in development for the prevention and treatment of atherosclerotic cardiovascular diseases. It is likely to be used concomitantly with heparin in patients undergoing percutaneous coronary intervention. Coadministration of both drugs may potentially increase the bleeding risk associated with heparin. This crossover study evaluated the potential pharmacodynamic interaction between inclacumab and unfractionated heparin in 18 healthy smokers. Owing to the long elimination of inclacumab (half-life of approximately 18 days), a 2-period, one-sequence study design was used. Subjects received an intravenous bolus injection of unfractionated heparin (5000 IU) on days 1 and 8 and an intravenous infusion of inclacumab (20 mg/kg) on day 8. Blood samples were collected on days 1 and 8 for pharmacodynamic effects of unfractionated heparin (anti-FXa and anti-FIIa activities, activated partial thromboplastin time and tissue factor pathway inhibitor) and over 6 months for pharmacokinetics of inclacumab. Sixteen subjects were eligible for pharmacodynamic analysis. Inclacumab had no clinically significant pharmacodynamic interaction with unfractionated heparin. With the exception of the minor but statistically significant increase of the maximum effect [Emax] of anti-FIIa activity, pharmacodynamic parameters (areas under the effect curve [AUElast] and Emax of anti-FXa) were almost similar on days 1 and 8. The 90% confidence intervals of geometric mean ratios of day 8 to day 1 for AUElast and Emax were however all contained within bioequivalence boundaries. The data demonstrate that the anticoagulant effect of unfractionated heparin was not affected by the administration of inclacumab.

Association between serum sulfatide and carotid intima media thickness in patients with familial hypercholesterolemia

There is a positive association between sulfatide and atherosclerosis in an animal model for human familial hypercholesterolemia. Carotid intima-media thickness (IMT) is thought to be a marker of atherosclerosis in humans. We investigated the relationship between sulfatide and carotid IMT in heterozygous familial hypercholesterolemia (FH) patients. Thirty-five genetically-verified heterozygous patients with FH and 34 healthy controls were recruited into our study. We measured serum sulfatide levels, the carotid IMT, and conventional cardiovascular risk factors including obesity parameters, blood pressure, fasting blood glucose, and lipid profiles. Subjects with heterozygous FH had significantly elevated serum sulfatide, elevated total cholesterol, low-density lipoprotein cholesterol, and increased carotid IMT compared with control subjects. In patients with FH, univariate analysis showed that serum sulfatide was significantly correlated with carotid IMT. Multiple linear regression analysis indicated that serum sulfatide was the only independent predictor of carotid IMT in patients with FH. Patients with heterozygous FH had significantly higher carotid IMT and the level of serum sulfatide was independently associated with atherosclerotic progression. (R: 0.720, R(2): 0.503, p < 0.001).

Development of glycoprotein IIb–IIIa antagonists: translation of pharmacodynamic effects into clinical benefit

This article will review the development of glycoprotein IIb-IIIa antagonists, with particular emphasis on the characteristics and pharmacodynamic studies of each agent that is available for clinical use. Abciximab is a Fab fragment of the 7E3 antibody that has high affinity and a slow rate of dissociation from glycoprotein IIb-IIIa. In contrast, the small molecules eptifibatide and tirofiban, have a much more rapid rate of dissociation, with an off time of 10 to 15 s. Accordingly, the circulating pool of abciximab is predominantly associated with platelets, whereas maintenance of a consistent concentration of tirofiban and eptifibatide in the blood is critical in order to achieve and sustain their inhibitory effects. The affinity of abciximab and tirofiban for glycoprotein IIb-IIIa are substantially greater than that of eptifibatide, necessitating maintenance of greater molar concentrations of eptifibatide in blood in order to achieve effective inhibition of the binding of fibrinogen to the activated conformer of glycoprotein IIb-IIIa.

Effects of the P-selectin antagonist inclacumab on myocardial damage after percutaneous coronary intervention for non-ST-segment elevation myocardial infarction: results of the SELECT-ACS trial

OBJECTIVES

The study aimed to evaluate inclacumab for the reduction of myocardial damage during a percutaneous coronary intervention (PCI) in patients with non-ST-segment elevation myocardial infarction.

BACKGROUND

P-selectin is an adhesion molecule involved in interactions between endothelial cells, platelets, and leukocytes. Inclacumab is a recombinant monoclonal antibody against P-selectin, with potential anti-inflammatory, antithrombotic, and antiatherogenic properties.

METHODS

Patients (N = 544) with non-ST-segment elevation myocardial infarction scheduled for coronary angiography and possible ad hoc PCI were randomized to receive 1 pre-procedural infusion of inclacumab 5 or 20 mg/kg or placebo. The primary endpoint, evaluated in patients who underwent PCI, received study medication, and had available efficacy data (n = 322), was the change in troponin I from baseline at 16 and 24 h after PCI.

RESULTS

There was no effect of inclacumab 5 mg/kg. Placebo-adjusted geometric mean percent changes in troponin I with inclacumab 20 mg/kg were -24.4% at 24 h (p = 0.05) and -22.4% at 16 h (p = 0.07). Peak troponin I was reduced by 23.8% (p = 0.05) and area under the curve over 24 h by 33.9% (p = 0.08). Creatine kinase-myocardial band yielded similar results, with changes of -17.4% at 24 h (p = 0.06) and -16.3% at 16 h (p = 0.09). The incidence of creatine kinase-myocardial band increases >3 times the upper limit of normal within 24 h was 18.3% and 8.9% in the placebo and inclacumab 20-mg/kg groups, respectively (p = 0.05). Placebo-adjusted changes in soluble P-selectin level were -9.5% (p = 0.25) and -22.0% (p < 0.01) with inclacumab 5 and 20 mg/kg. There was no significant difference in adverse events between groups.

CONCLUSIONS

Inclacumab appears to reduce myocardial damage after PCI in patients with non-ST-segment elevation myocardial infarction. (A Study of RO4905417 in Patients With Non ST-Elevation Myocardial Infarction [Non-STEMI] Undergoing Percutaneous Coronary Intervention; NCT01327183).

Do statins have a role in reduction/prevention of post-PCI restenosis?

The pathophysiology of post-PCI restenosis involves neointimal formation that consists of three phases: thrombosis (within 24 h), recruitment (3-8 days), and proliferation, which starts on day 8 of PCI. Various factors suggested to be predictors/risks for restenosis include C-reactive protein (CRP), inflammatory mediators (cytokines and adhesion molecules), oxygen radicals, advanced glycation end products (AGEs) and their receptors (RAGE), and soluble RAGE (sRAGE). The earlier noted factors produce thrombogenesis, vascular smooth muscle cell proliferation, and extracellular matrix formation. Statins have pleiotropic effects. Besides lowering serum cholesterol, they have various other biological effects including antiinflammatory, antithrombotic, CRP-lowering, antioxidant, antimitotic, and inhibition of smooth muscle cell proliferation. They inhibit matrix metalloproteinase and cyclooxygenase-2, lower AGEs, decrease expression of RAGE and increase levels of serum sRAGE. They also increase the synthesis of nitric oxide (NO) by increasing endothelial NO synthase expression and activity. Preprocedural statin therapy is known to reduce peri- and post-PCI myonecrosis and reduce the need for repeat revascularization. There is evidence that statin-eluting stents inhibit in-stent restenosis in animal models. It is concluded that because of the above attributes of statins, they are suitable candidates for reduction of post-PCI restenosis and post-PCI myonecrosis. The future directions for the use of statins in reduction of post-PCI restenosis and myonecrosis have been discussed.

Vascular inflammation and repair: implications for re-endothelialization, restenosis, and stent thrombosis

The cellular and molecular processes that control vascular injury responses after percutaneous coronary intervention involve a complex interplay among vascular cells and progenitor cells that control arterial remodeling, neointimal proliferation, and re-endothelialization. Drug-eluting stents (DES) improve the efficacy of percutaneous coronary intervention by modulating vascular inflammation and preventing neointimal proliferation and restenosis. Although positive effects of DES reduce inflammation and restenosis, negative effects delay re-endothelialization and impair endothelial function. Delayed re-endothelialization and impaired endothelial function are linked to stent thrombosis and adverse clinical outcomes after DES use. Compared with bare-metal stents, DES also differentially modulate mobilization, homing, and differentiation of vascular progenitor cells involved in re-endothelialization and neointimal proliferation. The effects of DES on vascular inflammation and repair directly impact clinical outcomes with these devices and dictate requirements for extended-duration dual antiplatelet therapy.

Free radical functionalization of surfaces to prevent adverse responses to biomedical devices

Immobilizing a protein, that is fully compatible with the patient, on the surface of a biomedical device should make it possible to avoid adverse responses such as inflammation, rejection, or excessive fibrosis. A surface that strongly binds and does not denature the compatible protein is required. Hydrophilic surfaces do not induce denaturation of immobilized protein but exhibit a low binding affinity for protein. Here, we describe an energetic ion-assisted plasma process that can make any surface hydrophilic and at the same time enable it to covalently immobilize functional biological molecules. We show that the modification creates free radicals that migrate to the surface from a reservoir beneath. When they reach the surface, the radicals form covalent bonds with biomolecules. The kinetics and number densities of protein molecules in solution and free radicals in the reservoir control the time required to form a full protein monolayer that is covalently bound. The shelf life of the covalent binding capability is governed by the initial density of free radicals and the depth of the reservoir. We show that the high reactivity of the radicals renders the binding universal across all biological macromolecules. Because the free radical reservoir can be created on any solid material, this approach can be used in medical applications ranging from cardiovascular stents to heart-lung machines.

Expression of inflammatory and apoptosis factors following coronary stent implantation in coronary heart disease patients

We investigated the changes in characteristics of neutrophil CD11b, monocyte CD11b, platelet CD62P, endothelin (ET), and neutrophil CD178 in patients with coronary heart disease (CHD) before and after primary coronary stenting. A total of 41 patients with CHD who underwent coronary stenting and 40 control subjects were enrolled in the study. In CHD patients, peripheral blood samples were taken 24 h before and 30 min, 24 h, and 72 h after successful coronary stenting. All markers were significantly elevated in patients with CHD compared with controls (P<0.05). Time-course studies revealed that the expressions of neutrophil CD11b, monocyte CD11b, platelet CD62P, and ET were lower at 30 min post-operation (PO) compared with that at 24 h before operation (BO) (P<0.05). All levels significantly increased from 30 min PO to 24 h PO (P<0.05) and decreased thereafter until 72 h PO (P>0.05). Time course changes in neutrophil CD11b levels after coronary stenting were significantly higher in patients with unstable angina pectoris than in patients with stable angina pectoris (P<0.05). CD11b levels were related to CD62P in patients with CHD (P<0.05). Neutrophil CD11b and monocyte CD11b levels were significantly increased in patients with CHD who underwent coronary stenting compared with controls (P<0.05). Results show that CD11b levels increased, meanwhile, the levels of CD62P and ET increased in CHD patients after coronary stenting. In addition, neutrophil CD178 levels of apoptosis factor in patients, which is important for regression of inflammation, remained high for a period of time after coronary stenting.

The effect of hormone therapy and tibolone on serum CD40L and ADAM-8 in healthy post-menopausal women

BACKGROUND/AIM

The role of neutrophils and platelets in atherothrombotic disease is well established. The aim of our study was to investigate the effect of HT and tibolone on the soluble markers of neutrophil and platelet activation, "a disentigrin and metalloproteinase domain" (ADAM-8) and CD40 ligand (CD40L) respectively, in healthy post-menopausal women.

SUBJECTS AND METHODS

One hundred and six healthy post-menopausal women were randomly allocated to: estradiol plus drospirenone (E₂/DSP), E₂ hemihydrate 1 mg plus norethisterone acetate (E₂/NETA) 0.5 mg, and tibolone 2.5 mg. Serum ADAM-8 and CD40L were measured at baseline and at 6 months.

RESULTS

Baseline values of ADAM-8 and CD40L were similar between groups. No significant correlation was revealed between ADAM-8 or CD40L and parameters related to cardiovascular risk factors in each group. No significant changes were observed between baseline values and values at 6 months (E₂/DSP group: ADAM-8: 267.4±71.3 pg/ml vs 270.7±42.8 pg/ml, p=0.86, CD40L: 6.43±3.13 vs 6.79±2.70 ng/ml, p=0.67), (E₂/NETA group: ADAM-8: 308.3±64.3 vs 294.7±57.7 pg/ml, p=0.40, CD40L: 9.68±2.81 vs 8.59±5.13 ng/ml, p=0.51), (tibolone group: ADAM-8: 307.5±87.5 vs 289±48.1 pg/ml, p=0.48, CD40L: 9.46±4.30 vs 9.26±4.60 ng/ml, p=0.99).

CONCLUSIONS

Our study has not revealed an association between estrogen plus progestin treatment or tibolone on serum ADAM-8 and CD40L levels in healthy post-menopausal women. Larger prospective studies are needed to further investigate the effect of low-dose HT or tibolone on serum markers of neutrophil and platelet activation.

Preventing serious sequelae after an acute coronary syndrome: the consequences of thrombosis versus bleeding with antiplatelet therapy

Acute coronary syndrome (ACS) is associated with a persistent prothrombotic state, placing patients at high risk of subsequent ischemic events. Guidelines recommend the use of dual antiplatelet therapy with aspirin + a thienopyridine (clopidogrel) for at least a year after ACS in most patients, except those who undergo coronary artery bypass grafting. Clinical studies demonstrate that this strategy significantly reduces the risk of ischemic events at the expense of a small increase in the risk of bleeding. Physicians must balance the risk of bleeding against the benefit of ischemia prevention, bearing in mind that ischemic events are generally more common than major bleeding and often associated with more catastrophic consequences or ongoing morbidity. The relationship between bleeding and mortality is complicated by the fact that many risk factors for bleeding are also those for mortality and that bleeding may lead to discontinuation of antiplatelet therapy, thereby increasing the risk for an ischemic event. Data suggest that physicians tend to overestimate the risk of bleeding and underestimate the risk of ischemia. Careful patient selection and thorough patient education are the keys to managing antiplatelet therapy after ACS, especially as newer more potent antiplatelet agents, such as prasugrel, become available.

Activation of matrix metalloproteinase-9 is associated with mobilization of bone marrow-derived cells after coronary stent implantation

BACKGROUND

After stent-related vascular injury, an inflammatory response triggers the mobilization of bone marrow-derived stem cells, including both endothelial and smooth muscle progenitors, leading to re-endothelialization as well as restenosis. It has been postulated that neutrophil-released matrix metalloproteinase-9 (MMP-9) induces stem cell mobilization.

AIM

To elucidate the mechanistic link between inflammation and stem cell mobilization after coronary stenting.

METHODS

In 31 patients undergoing coronary stenting, we serially measured activated Mac-1 on the surface of neutrophils and active MMP-9 levels in the coronary sinus blood plasma, and the number of circulating CD34-positive cells in the peripheral blood.

RESULTS

After bare-metal stent implantation (n=21), significant increases in the numbers of CD34-positive cells (maximum on post-procedure day 7, P<0.001), activated Mac-1 (at 48 h, P<0.001), and active MMP-9 levels (at 24h, P<0.001) were observed. However, these changes were absent after sirolimus-eluting stent implantation (n=10). In overall patients, the numbers of CD34-positive cells on day 7 (R=0.58, P<0.01) and activated Mac-1 at 48 h (R=0.58, P<0.01) were both correlated with active MMP-9 levels at 24h. Stimulation of activated Mac-1 on the surface of isolated human neutrophils produced active MMP-9 release in vitro.

CONCLUSIONS

These results suggest that stent-induced activation of Mac-1 on the surface of neutrophils might trigger their MMP-9 release, possibly leading to the mobilization of bone marrow-derived stem cells. These reactions were substantially inhibited by sirolimus-eluting stents.

[Imaging of coronary stents using multislice computed tomography]

Coronary artery stenting has become the most important form of coronary revascularization. With the introduction of drug-eluting stents (DES) the rate of restenosis has declined but due to the delayed formation of intimal tissue the incidence of late (>30 days after stent placement) and very late thrombosis of the stents is higher for DES. Visualization of the stent lumen is possible with multislice computed tomography (MSCT) but blooming artifacts hamper the delineation of the stent lumen. The severity of these artifacts and thus the width of the visible stent lumen depends on several factors, such as the thickness of the stent struts, the design of the stent and the underlying material itself. The most important factor influencing the extent of blooming artifacts is the convolution kernel selected for image reconstruction. Dedicated, edge-enhancing kernels offer superior lumen visualization compared to the soft or medium kernels used for coronary artery imaging. The trade-off using edge-enhancing kernels is an increase in image noise.Despite all efforts undertaken to enhance stent lumen visualization, stent imaging is still a challenge in MSCT. In the majority of stents currently used, sufficient lumen visualization is only possible in stents with a diameter larger than 3 mm. A position of the stent in the proximal segments of the coronary artery tree facilitates delineation of the stent lumen not only because of the relatively little motion but also because of the lesser extent of blooming artifacts obscuring the stent lumen if the stent is oriented perpendicular to the z-axis of the scanner.

Platelet-derived chemokine RANTES may be a sign of restenosis after percutaneous coronary intervention in patients with stable angina pectoris

Inflammation plays a pathogenic role in the development of restenosis after percutaneous coronary intervention (PCI). We measured and compared the ratio of elevated levels of regulated on activation normally T-cell expressed and secreted (RANTES), monocytic chemotactic peptide-1 (MCP-1), soluble (s) P-selectin and sL-selectin after PCI. Plasma levels of chemokines and soluble markers were measured before, 1, 3 and 7 days after PCI in 52 patients (43 males and nine females, aged 63 +/- 10 years) who underwent PCI and who had repeated angiograms at a 6-month follow-up. Restenosis occurred in 16 (31%) patients. A significant and time-dependent increase in sL-selectin was observed in the restenosis group. However, there were no significant differences in MCP-1 levels with or without restenosis. sP-selectin levels in the restenosis group exhibited a transient elevation at 3 days after PCI. RANTES levels were no different at baseline between patients with or without restenosis. However, a significant and time-dependent decrease in RANTES levels were observed in the non-restenosis group, and patients with restenosis compared with patients without restenosis had a statistically significant ratio of elevated levels of RANTES. These findings suggest that restenosis development after PCI in patients with effort angina pectoris may involve leukocyte activation at an early period after PCI. In addition, platelet-derived chemokine RANTES may be a sign of restenosis after PCI in patients with stable angina pectoris.

Optimal management of platelet function after coronary stenting

Coronary stenting elicits vessel wall damage, and subsequent activation of platelets is implicated as a major component of complications such as acute, subacute, and late stent thrombosis. As such, dual antiplatelet therapy using aspirin and clopidogrel has become a routine adjunct to coronary stenting. Use of aspirin and clopidogrel with or without glycoprotein IIb/IIIa inhibitors after coronary stenting reduces the complication rate and improves long-term outcomes. Dual antiplatelet therapy using aspirin and clopidogrel is recommended for at least 4 weeks with bare metal stents, and for 3 to 6 months with drug-eluting stents for prevention of major adverse cardiac events. After coronary stenting, 1 year of dual antiplatelet therapy is recommended for prevention of future cardiac events. However, despite the use of antiplatelet agents, stent thrombosis occurs in approximately 1% of patients, with an increased likelihood of occurrence in high-risk patients or a lesion subset of patients. Although the incidence of stent thrombosis is low, stent thrombosis usually presents as acute coronary syndrome and the mortality rate is up to 45%. Thus, considering the widespread use of stents, a considerable number of people are inadequately protected from thrombotic events despite current standard antiplatelet therapy using aspirin and clopidogrel. A concern with clopidogrel is the loading time and loading dose required to achieve and maintain optimal inhibition of platelet aggregation. The current recommendation for ensuring maximum antiplatelet activity is administration of a 300-mg loading dose of clopidogrel initiated at least 6 hours prior to percutaneous coronary intervention (PCI), and ideally the day before. If this is not possible, a loading dose of 600 mg of clopidogrel should be administered at least 2 hours before PCI. Recently, new combinations of antiplatelet agents (ie, triple therapy using aspirin, clopidogrel, and cilostazol) and new drugs with potent antiplatelet effects (ie, Prasugrel , Cangrelor , and AZD6140) have been evaluated in clinical trials; such treatments may help reduce the number of cardiac events after coronary stenting.

Interleukin-8 as an independent predictor of long-term clinical outcome in patients with coronary artery disease

BACKGROUND

Accumulating evidence suggests that inflammation plays an essential role in the pathogenesis of atherosclerosis and that circulating inflammatory markers predict future cardiovascular events. However, previous studies evaluated the predictive value of only a single cytokine at a time.

AIMS

This study was designed to simultaneously measure plasma levels of multiple cytokines in patients with coronary artery disease and to evaluate their ability to predict long-term prognosis.

METHODS

The study enrolled 158 consecutive patients with angiographically identified stable coronary artery disease. Using the Luminex micro-beads array system, we simultaneously measured plasma levels of the following 10 cytokines: interleukin (IL)-1beta, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, tumor necrosis factor (TNF)-alpha, granulocyte-macrophage colony stimulating factor (GM-CSF) and gamma-interferon (IFN-gamma).

RESULTS

None of the 10 cytokine levels as well as high-sensitive C reactive protein (hs-CRP) was correlated with the severity of coronary artery disease. During a 7-year follow-up period, cardiovascular events occurred in 56 patients (35%). Multi-vessel disease, diabetes, and high levels of all of the 10 measured cytokines and hs-CRP were significant predictors of cardiovascular events in univariate analysis. However, multivariate analysis using multi-vessel disease, diabetes and the levels of all of 10 cytokines and hs-CRP showed that the only independent predictor was IL-8 (RR, 2.98; 95%CI, 1.64-7.24; P=0.0001).

CONCLUSION

IL-8 was the only cytokine that predicted cardiovascular events independent of the other 9 cytokines and hs-CRP. Since IL-8 is a neutrophil chemokine, these results suggest that neutrophil activation may be related to the occurrence of cardiovascular events.

High P-selectin expression and low CD36 occupancy on circulating platelets are strong predictors of restenosis after coronary stenting in patients with coronary artery disease

Recent studies have shown that circulating platelets play an important role in the development of restenosis early after coronary stent implantation. We investigated P-selectin expression and CD36 blockade on platelets by flow cytometry in 48 consecutive patients who underwent coronary stenting. P-selectin expression was significantly higher 1 day after stenting in patients who had restenosis (n = 15) than in those who had no restenosis (n = 28), and the odds ratio for restenosis in patients with high P-selectin levels (MFI > 6.5) was 11.67 (P < 0.001) as compared with patients who had intermediate and low P-selectin levels. CD36 blockade was assessed with the use of two anti-CD36 antibodies, OKM5 and GS95 (our new anti-CD36 antibody), the binding of which indicates total CD36 amount and free CD36 unoccupied by lipid-related ligands, respectively. Binding of OKM5 to platelets was similar before and after stenting in both groups. CD36 blockade on platelets was seen 1 day after stenting in the non-restenosis group, and the odds ratio for restenosis in patients without CD36 blockade [GS95 binding ratio >0.8 as compared with binding before stenting] on day 1 was 28.60 (P < 0.001). P-selectin expression and unoccupied CD36 on platelets shortly after stenting may be strong predictors of post-stent restenosis.

Mobilization of CD34-positive bone marrow-derived cells after coronary stent implantation: impact on restenosis

BACKGROUND

Recently, accumulating evidence has indicated that bone marrow-derived stem cells are capable of differentiating into vascular cells. It has been hypothesized that the inflammatory response after vascular injury triggers the mobilization of endothelial and smooth muscle progenitor cells from bone marrow.

METHODS AND RESULTS

We measured circulating CD34-positive mononuclear cells, activation of integrin Mac-1 on the surface of neutrophils, and plasma granulocyte-colony stimulating factor levels in 40 patients undergoing coronary stenting. After bare-metal stenting, CD34-positive cells increased, reaching a maximum on day 7 after stenting. The maximum change compared with baseline before stenting was more striking in patients with restenosis than without restenosis (332+/-108% versus 148+/-49%; P<0.05). In contrast, CD34-positive cells decreased after sirolimus-eluting stenting (72+/-21% on day 7). The change in CD34-positive cells on day 7 relative to baseline was closely correlated with that in activated Mac-1 at 48 hours (R=0.52, P<0.01) and that in granulocyte-colony stimulating factor levels at 24 hours (R=0.42, P<0.05). Cell culture assay on day 7 showed that mononuclear cells differentiated into CD31-positive endothelium-like cells after bare-metal stenting. In patients with restenosis, mononuclear cells differentiating into alpha-smooth muscle actin-positive smooth muscle-like cells also were observed. Implantation of sirolimus-eluting stents suppressed both types of differentiation.

CONCLUSIONS

Stent implantation may induce differentiation of bone marrow cells into endothelial or smooth muscle cells. Endothelial cells may participate in reendothelialization, a protective reaction against vascular injury, whereas smooth muscle cells may participate in neointimal thickening and restenosis. Sirolimus-eluting stents appear to inhibit the mobilization and differentiation of bone marrow cells.

Increased circulating platelet-derived microparticles are associated with stent-induced vascular inflammation

Inflammation as well as platelet activation at the site of local vessel-wall injury plays an essential role in the mechanism of restenosis after Percutaneous coronary intervention (PCI). Platelet-derived microparticles (PDMPs) released from activated platelets are thought to play a role in the inflammatory process, possibly interacting with leukocyte integrin Mac-1. We serially measured circulating PDMPs, high-sensitive C-reactive protein (hs-CRP) and activated Mac-1 on the surface of neutrophils in 61 patients undergoing coronary stenting. PDMPs, hs-CRP and Mac-1 increased after coronary stenting in a time-dependent manner with the maximum response at 48 h in coronary sinus blood (PDMPs: 10.3+/-8.9-32.8+/-13.8 U/ml; P<0.001, hs-CRP: 0.27+/-0.23-1.46+/-0.99 mg/dl; P<0.001, activated Mac-1, 134+/-19% relative increase, P<0.001). PDMPs were correlated with hs-CRP (R=0.58, P<0.001) and the relative increase in Mac-1 (R=0.69, P<0.001) 48 h after coronary stenting. Multiple regression analysis showed that each of PDMPs (R=0.40, P<0.05), hs-CRP (R=0.33, P<0.05) and Mac-1 (R=0.48, P<0.01) was an independent predictor of the late lumen loss. Coronary stenting enhanced circulating PDMPs in association with an inflammatory response in the injured vessel wall. PDMPs may be a useful marker for evaluation of stent-induced inflammatory status and a powerful predictor of restenosis equivalent to activated Mac-1.

Comparison of changes in circulating platelet-derived microparticles and platelet surface P-selectin expression after coronary stent implantation

Platelet-derived microparticles (PDMPs) are released from activated platelets and may participate in the inflammatory process in response to vessel wall injury. This study was designed to compare the clinical significance of circulating PDMPs with that of P-selectin on the platelet membrane surface. In 20 patients with stable angina undergoing coronary stent implantation, circulating PDMPs were serially measured by enzyme-linked immunosorbent assay, and P-selectin expression on the surface of platelets was simultaneously analyzed by flow cytometry. PDMPs increased 24-48 h after coronary stenting in the coronary sinus (8.7 +/- 8.9 to 31.8 +/- 19.8 U/ml, P < 0.001) with a maximum at 48 h. In contrast, the mean channel fluorescence intensity for P-selectin increased 15 min after coronary stenting in the coronary sinus (19.5 +/- 5.6 to 25.2 +/- 7.5, P < 0.01) and remained elevated for 48 h; the changes were less striking in peripheral blood. The relative increase in PDMPs was not correlated with the increase in P-selectin expression at 15 min or 24 h after coronary stenting, but was correlated at 48 h (R = 0.48, P < 0.05). Both circulating PDMPs and P-selectin expression were enhanced in association with stent-induced platelet activation; however, the time course of changes in these two platelet activation markers was different. Therefore, the clinical relevance of circulating PDMPs may differ from that of P-selectin expression on the platelet membrane surface.

Iliac Anastomotic Stenting With a Biodegradable Poly-L-Lactide Stent: A Preliminary Study After 1 and 6 Weeks

PURPOSE

To assess the technical feasibility, thrombogenicity, and biocompatibility of a new biodegradable poly-L-lactic acid (PLLA) anastomotic stent.

METHODS

A polytetrafluoroethylene bifurcated graft was implanted in 17 pigs through a midline abdominal incision. After transverse graft incision, 17 316L stainless steel stents and 17 PLLA stents were randomly implanted at both iliac anastomotic sites and deployed with a 6-mm balloon under direct vision without angiography. Intended follow-up was 1 week in 6 pigs receiving oral acetylsalicylic acid (ASA) and in 7 pigs receiving ASA/clopidogrel; 4 pigs receiving ASA/clopidogrel were followed for 6 weeks. At the end of the study, the segments containing the stents were surgically explanted and processed for histology to measure the mean luminal diameter, intimal thickness, and the vascular injury and inflammation scores.

RESULTS

Initial technical success of stent placement was achieved in all animals without rupture of the suture. Two pigs died (unrelated to the stent) at 3 days after operation (1 in groups A and B). At 1 week, all PLLA stents showed thrombotic occlusion with the use of ASA alone. In contrast, all PLLA stents remained patent with concurrent administration of ASA/clopidogrel. All metal stents were patent regardless of the antiplatelet regimen. The mean luminal diameter of patent PLLA stents (4.13+/-0.17 mm) was comparable to metal stents (4.27+/-0.35 mm, p=0.78) at 1 week, but significantly diminished at 6 weeks (3.21+/-0.44 versus 4.19+/-0.18 mm, p=0.005). Histological analysis showed no signs of excessive recoil. PLLA stents induced a higher inflammation score (1.79+/-0.56) and more intimal hyperplasia (0.34+/-0.11 mm) compared to metal stents [1.27+/-0.44 mm (p<0.001) and 0.18+/-0.04 mm (p=0.006), respectively] at 6 weeks. Vascular injury was comparable between PLLA and metal stents.

CONCLUSION

Biodegradable PLLA stents showed higher thrombogenicity and reduced patency compared to metal stents during early follow-up. Although ASA and clopidogrel prevented thrombotic occlusion, the increased inflammatory response and neointima formation remain major concerns of PLLA stents. A solution to this problem might be the incorporation of anti-inflammatory drugs into the PLLA stent.

Cellular, molecular and immunological mechanisms in the pathophysiology of vein graft intimal hyperplasia

Coronary artery disease, leading to myocardial infarction and ischaemia, affects millions of persons and is one of the leading causes of morbidity and mortality worldwide. Invasive techniques such as coronary artery bypass grafting are used to alleviate the sequelae of arterial occlusion. Unfortunately, restenosis or occlusion of the grafted conduit occurs over a time frame of months to years with a gradual reduction in patency, especially in vein grafts. The events leading to intimal hyperplasia (IH) formation involve numerous cellular and molecular components. Various cellular elements of the vessel wall are involved as are leucocyte-endothelial interactions that trigger the coagulation cascade leading to localized thrombus formation. Subsequent phenotypic modification of the medial smooth muscle cells and their intimal migration is the basis of the lesion formation that is thought to be propagated by an immune-mediated reaction. Despite intense scrutiny, the pathophysiology of IH remains an enigma. Although several growth factors, cytokines and numerous other biomolecules have been implicated and their relationship to prohyperplasia pathways such as the phosphatidyl-inositol 3-kinase (PI3K)-Akt pathway has been established, many pieces of the puzzle are still missing. An in-depth understanding of early vein graft adaptation and progression is necessary to improve the long-term prognosis and develop more effective therapeutic measures. In this review, we have critically evaluated and summarized the literature to elucidate and interlink the numerous established and emerging factors that play a key role in the development of IH leading to vein graft restenosis.

Restenosis following implantation of bare metal coronary stents: pathophysiology and pathways involved in the vascular response to injury

This review summarizes the restenotic process that occurs after the implantation of bare metal coronary stents. The pathology of in-stent restenosis is distinct from that seen after balloon angioplasty and is characterized by neointimal proliferation and extracellular matrix deposition. The degree of neointimal proliferation is proportional to the amount of injury, the intensity of the inflammatory infiltrate and the association of stent struts with lipid-filled plaque. In-stent restenosis also appears to be associated with systemic markers of inflammation. Shear stress has an important influence on restenosis as does the presence and adhesiveness of vascular progenitor cells. Clinical predictors (e.g., artery size, stent length, diabetes, and gender) may affect the incidence of restenosis seen after stent placement. A number of catheter-based interventions have been used to treat in-stent restenosis. Although preliminary data suggest that the use of drug-eluting stents may be effective, only intracoronary radiation has shown consistent efficacy in randomized trials.

Long-term care after percutaneous coronary intervention: focus on the role of antiplatelet therapy

Arterial wall injury caused by percutaneous coronary intervention (PCI) triggers transient platelet activation and mural thrombosis; these effects are superimposed on the preexisting platelet hyperreactivity associated with underlying atherothrombosis. Platelet activation has been implicated in the major complications of PCI: acute and subacute thrombosis and restenosis. Antithrombotic and anticoagulant therapy minimizes thrombotic complications after PCI. Aspirin plus a thienopyridine (ticlopidine or clopidogrel) is more effective than aspirin plus heparin and extended warfarin therapy in preventing periprocedural ischemic events and subsequent stent thrombosis and results in less major and minor bleeding. Dual antiplatelet therapy with aspirin and clopidogrel (the preferred thienopyridine because of its superior hematologic safety) is recommended for at least 4 weeks to prevent subacute stent thrombosis with bare-metal stents and 3 to 6 months to prevent late-stent thrombosis with drug-eluting stents. Coronary atherothrombosis is a diffuse vascular disease, and reduction of the risk of future ischemic events requires strategies that extend beyond the focal treatment of stenotic lesions. Optimal long-term care after PCI requires aggressive systemic pharmacotherapy (antiplatelet agents, statins, beta-blockers, and angiotensin-converting enzyme Inhibitors) in conjunction with therapeutic lifestyle changes (smoking cessation, weight reduction, dietary measures, and exercise). In this context, dual antiplatelet therapy (aspirin plus clopidogrel) is recommended for at least 12 months after PCI for prophylaxis of future atherothrombotic events.

The Role of Coagulation and Inflammation After Angioplasty in Patients with Peripheral Arterial Disease

PURPOSE

Restenosis remains a frequent complication after angioplasty in peripheral arterial disease. Inflammation plays a critical role in the vascular response to injury. Effective medical treatment to improve patency after angioplasty is still elusive. The aims of this prospective clinical study were to investigate changes in blood coagulation and inflammatory markers after angioplasty and their significance for restenosis.

METHODS

Thirty-four patients with peripheral arterial disease underwent angioplasty of the iliac and superficial femoral arteries. Ten patients undergoing diagnostic angiography were included in the study as controls. Plasma levels of tissue factor, prothrombin fragment 1 + 2, D-dimer, P-selectin, C-reactive protein (CRP), and fibrinogen were analyzed before and after angioplasty. Patients were followed up with angiography after 6 months to assess restenosis.

RESULTS

CRP was elevated the day after angioplasty (6.6 mg/l, p = 0.0001) and tended to peak after 1 week (11 mg/l, p = 0.09). There was a significant increase of D-dimer and P-selectin 1-4 hr after angioplasty (0.4 mg/l, p = 0.001 and 68 ng/ml, p = 0.05, respectively). None of the biochemical markers was a statistically significant predictor of restenosis.

CONCLUSION

We have observed a much more prolonged inflammatory response than previously noted, but only minor changes in coagulation activity after angioplasty. The biochemical markers, before and after angioplasty, were not related to restenosis. Further studies are needed to delineate the molecular mechanisms behind these observations and their involvement in thrombosis and restenosis. If these pathways are further defined, improved treatment strategies, including antithrombotic treatments and statins, could be tailored to modulate postprocedural inflammation.