[Pulmonary hypertension associated with left heart disease (group 2)]

Pulmonary hypertension associated with left heart disease (PH-LHD) corresponds to group two of pulmonary hypertension according to clinical classification. Haemodynamically, this group includes isolated post-capillary pulmonary hypertension (IpcPH) and combined post- and pre-capillary pulmonary hypertension (CpcPH). PH-LHD is defined by an mPAP > 20 mmHg and a PAWP > 15 mmHg, pulmonary vascular resistance (PVR) with a cut-off value of 2 Wood Units (WU) is used to differentiate between IpcPH and CpcPH. A PVR greater than 5 WU indicates a dominant precapillary component. PH-LHD is the most common form of pulmonary hypertension, the leading cause being left heart failure with preserved (HFpEF) or reduced ejection fraction (HFmrEF, HFrEF), valvular heart disease and, less commonly, congenital heart disease. The presence of pulmonary hypertension is associated with increased symptom burden and poorer outcome across the spectrum of left heart disease. Differentiating between group 1 pulmonary hypertension with cardiac comorbidities and PH-LHD, especially due to HFpEF, is a particular challenge. Therapeutically, no general recommendation for the use of PDE5 inhibitors in HFpEF-associated CpcPH can be made at this time. There is currently no reliable rationale for the use of PAH drugs in IpcPH, nor is therapy with endothelin receptor antagonists or prostacyclin analogues recommended for all forms of PH-LHD.

The significance of vasodilator-stimulated phosphoprotein for risk stratification of stent thrombosis

Low-response to the P2Y12 adenosine diphosphate (ADP)-receptor antagonist clopidogrel was suggested to correspond to a higher incidence of stent thrombosis (ST). This prospective observational study assessed the capability of two platelet function assays, e.g. direct measurement of the phosphorylation status of vasodilator-stimulated phosphoprotein (VASP) and ADP-induced platelet aggregation for definition of the individual risk to develop ST. Ninety-nine patients with an elevated high risk to develop ST were enrolled. All patients received a dual antiplatelet therapy consisting of 100 mg aspirin and 75 mg clopidogrel during an observation period of six months. Flow cytometry of VASP phosphorylation and densitometrically-determined measurement of ADP-induced platelet aggregation was performed 72–96 hours after stent implantation. These data were related to angiographically confirmed ST. Nine patients suffered from angiographically confirmed ST (9.1%). The meanVASP-platelet reactivity indices (VASP-PRI) and values for ADP-induced platelet aggregation in the ST group were significantly higher (60.8 ± 13.0 and 60.9 ± 13.1, respectively) compared to patients without ST (41.3 ± 14.0 and 50.8 ± 14.4, P<0.001 vs. 0.048, respectively). There was a fair correlation between both methods using non-linear regression analysis (r=0.332). In a multivariate analysis, VASP was the only independent predictor of ST and was superior to previously identified angiographic parameters. Receiver- operator characteristic (ROC) curve analysis revealed a cut-off value for VASP-PRI of <48% to be associated with low risk of ST. In conclusion, determination ofVASP phosphorylation is superior to conventional platelet aggregometry and angiographic parameters for assessing the risk of ST. Patients with a VASP-PRI >48% seem to have a significantly increased risk.

[Pulmonary hypertension associated with left heart disease: recommendations of the Cologne Consensus Conference 2016]

The 2015 European Guidelines on Diagnosis and Treatment of Pulmonary Hypertension are also valid for Germany. While the guidelines contain detailed recommendations regarding pulmonary arterial hypertension (PAH), they contain only a relatively short paragraph on other, much more common forms of PH such as PH due to left heart disease. Despite the lack of data, targeted PAH treatments are increasingly being used for PH associated with left heart disease. This development is of concern because of limited ressources and the need to base treatments on scientific evidence. On the other hand, PH is a frequent problem that is highly relevant for morbidity and mortality in patients with left heart disease, representing an unmet need of targeted PH therapies. It that sense, the practical implementation of the European Guidelines in Germany requires the consideration of several specific issues and already existing novel data. This requires a detailed commentary to the guidelines, and in some aspects an update already appears necessary. In June 2016, a Consensus Conference organized by the PH working groups of the German Society of Cardiology (DGK), the German Society of Respiratory Medicine (DGP) and the German Society of Pediatric Cardiology (DGPK) was held in Cologne, Germany. This conference aimed to solve practical and controversial issues surrounding the implementation of the European Guidelines in Germany. To this end, several working groups were initiated, one of which was specifically dedicated to PH associated with left heart disease. This article summarizes the results and recommendations of this working group.

Development and characterization of a coronary polylactic acid stent prototype generated by selective laser melting

In-stent restenosis is still an important issue and stent thrombosis is an unresolved risk after coronary intervention. Biodegradable stents would provide initial scaffolding of the stenosed segment and disappear subsequently. The additive manufacturing technology Selective Laser Melting (SLM) enables rapid, parallel, and raw material saving generation of complex 3- dimensional structures with extensive geometric freedom and is currently in use in orthopedic or dental applications. Here, SLM process parameters were adapted for poly-L-lactid acid (PLLA) and PLLA-co-poly-ε-caprolactone (PCL) powders to generate degradable coronary stent prototypes. Biocompatibility of both polymers was evidenced by assessment of cell morphology and of metabolic and adhesive activity at direct and indirect contact with human coronary artery smooth muscle cells, umbilical vein endothelial cells, and endothelial progenitor cells. γ-sterilization was demonstrated to guarantee safety of SLM-processed parts. From PLLA and PCL, stent prototypes were successfully generated and post-processing by spray- and dip-coating proved to thoroughly smoothen stent surfaces. In conclusion, for the first time, biodegradable polymers and the SLM technique were combined for the manufacturing of customized biodegradable coronary artery stent prototypes. SLM is advocated for the development of biodegradable coronary PLLA and PCL stents, potentially optimized for future bifurcation applications.

Pulmonary hypertension: Hemodynamic evaluation. Updated Recommendations of the Cologne Consensus Conference 2011

The 2009 European Guidelines on Diagnosis and Treatment of Pulmonary Hypertension have been adopted for Germany. The guidelines contain detailed recommendations for the diagnosis of pulmonary hypertension. However, the practical implementation of the European Guidelines in Germany requires the consideration of several country-specific issues and already existing novel data. This requires a detailed commentary to the guidelines, and in some aspects an update already appears necessary. In June 2010, a Consensus Conference organized by the PH working groups of the German Society of Cardiology (DGK), the German Society of Respiratory Medicine (DGP) and the German Society of Pediatric Cardiology (DGPK) was held in Cologne, Germany. This conference aimed to solve practical and controversial issues surrounding the implementation of the European Guidelines in Germany. To this end, a number of working groups was initiated, one of which was specifically dedicated to the invasive hemodynamic evaluation of pulmonary hypertension. This manuscript describes in detail the results and recommendations of the working group which were last updated in October 2011.

Introduction of a high-throughput double-stent animal model for the evaluation of biodegradable vascular stents

Current stent system efficacy for the treatment of coronary artery disease is hampered by in-stent restenosis (ISR) rates of up to 20% in certain high-risk settings and by the risk of stent thrombosis, which is characterized by a high mortality rate. In theory, biodegradable vascular devices exhibit crucial advantages. Most absorbable implant materials are based on poly-L-lactic acid (PLLA) owing to its mechanical properties; however, PLLA might induce an inflammatory reaction in the vessel wall. Evaluation of biodegradable implant efficacy includes a long-term examination of tissue response; therefore, a simple in vivo tool for thorough biocompatibility and biodegradation evaluation would facilitate future stent system development. Rats have been used for the study of in vivo degradation processes, and stent implantation into the abdominal aorta of rats is a proven model for stent evaluation. Here, we report the transformation of the porcine double-stent animal model into the high-throughput rat abdominal aorta model. As genetic manipulation of rats was introduced recently, this novel method presents a powerful tool for future in vivo biodegradable candidate stent biocompatibility and biodegradation characterization in a reliable simple model of coronary ISR.

Effect of statin therapy before Q-wave myocardial infarction on myocardial perfusion

Recent studies emphasized the non-lipid-lowering effects of hydroxymethylglutaryl coenzyme A reductase inhibitors on endothelial function, inflammation, and platelet activation in patients with stable atherosclerosis. This study sought to evaluate the impact of statin pretreatment in patients with acute myocardial infarction (AMI) on level of systemic inflammation and myocardial perfusion. A total of 253 consecutive patients undergoing primary angioplasty on a native vessel within 12 hours of AMI were divided into a group with statin pretreatment (n = 86) and control patients (n = 167). Angiographic myocardial blush grade (MBG) after revascularization of the infarct-related artery was determined to evaluate myocardial perfusion. Statin pretreatment was associated with a lower frequency of increased C-reactive protein (>or=5 mg/L) on admission compared with the control group (48% vs 64%; p = 0.019). The frequency of normal perfusion (MBG 3) was higher in the statin-pretreatment group than the control group (45% vs 26%, respectively; p <0.001). Statin pretreatment was an independent predictor of normal myocardial perfusion (MBG 3; odds ratio 2.53, 95% confidence interval 1.15 to 9.53, p = 0.022) in addition to age <or=70 years and C-reactive protein <5 mg/L. In conclusion, statin pretreatment in patients with AMI was associated with decreased systemic inflammation and better perfusion after primary angioplasty of the infarct-related artery.

The significance of vasodilator-stimulated phosphoprotein for risk stratification of stent thrombosis

Low-response to the P2Y12 adenosine diphosphate (ADP)-receptor antagonist clopidogrel was suggested to correspond to a higher incidence of stent thrombosis (ST). This prospective observational study assessed the capability of two platelet function assays, e.g. direct measurement of the phosphorylation status of vasodilator-stimulated phosphoprotein (VASP) and ADP-induced platelet aggregation for definition of the individual risk to develop ST. Ninety-nine patients with an elevated high risk to develop ST were enrolled. All patients received a dual antiplatelet therapy consisting of 100 mg aspirin and 75 mg clopidogrel during an observation period of six months. Flow cytometry of VASP phosphorylation and densitometrically-determined measurement of ADP-induced platelet aggregation was performed 72-96 hours after stent implantation. These data were related to angiographically confirmed ST. Nine patients suffered from angiographically confirmed ST (9.1%). The meanVASP-platelet reactivity indices (VASP-PRI) and values for ADP-induced platelet aggregation in the ST group were significantly higher (60.8 +/- 13.0 and 60.9 +/- 13.1, respectively) compared to patients without ST (41.3 +/- 14.0 and 50.8 +/- 14.4, P < 0.001 vs. 0.048, respectively). There was a fair correlation between both methods using non-linear regression analysis (r = 0.332). In a multivariate analysis, VASP was the only independent predictor of ST and was superior to previously identified angiographic parameters. Receiver- operator characteristic (ROC) curve analysis revealed a cut-off value for VASP-PRI of <48% to be associated with low risk of ST. In conclusion, determination of VASP phosphorylation is superior to conventional platelet aggregometry and angiographic parameters for assessing the risk of ST. Patients with a VASP-PRI >48% seem to have a significantly increased risk.

Impact of the metabolic syndrome on angiographic and clinical events after coronary intervention using bare-metal or sirolimus-eluting stents

Patients with metabolic syndrome (MS) are at increased risk for cardiovascular events. Although the number of patients with MS requiring coronary revascularization is increasing rapidly, the impact of MS on clinical events and restenosis in patients who undergo stent placement is not well defined. Seven hundred thirty-four consecutive patients with 734 de novo coronary lesions (<50 mm lesion length, reference vessel diameter <3.5 mm) were enrolled in this study. Four hundred thirty-seven patients were treated with bare-metal stents, and 297 patients were treated with sirolimus-eluting stents. Patients with bifurcation lesions, left main lesions, and ST-segment-elevation myocardial infarctions were excluded from the study. Patients were categorized into 3 groups: those with (1) diabetes mellitus (DM), (2) MS without DM, and (3) no MS and no DM. MS was defined according to American Heart Association and National Heart, Lung, and Blood Institute criteria (the presence of > or =3 of the following criteria: obesity, hypertension, hypertriglyceridemia, low high-density lipoprotein cholesterol, and increased fasting glucose). Clinical follow-up was performed for > or =1 year (mean 27.5 +/- 18.1 months). One hundred sixty-four patients (22%) had DM, 180 patients (25%) had MS without DM, and 390 patients (53%) had no MS and no DM. Baseline clinical and angiographic parameters were comparable among the 3 groups, including lesion length and reference vessel diameter. In patients treated with bare-metal stents, the rates of major adverse cardiac events (MACEs) at 12 months were 14% in patients without DM or MS, 18% in those with MS but no DM, and 33% in those with DM (p = 0.046). In patients treated with sirolimus-eluting stents, the MACE rates were 3% in patients without DM or MS, 4% in those with MS, and 13% in those with DM (p = 0.034). DM (odds ratio 2.14, 95% confidence interval 1.48 to 3.07, p <0.001) and bare-metal stent (odds ratio 2.51, 95% confidence interval 1.49 to 4.22, p <0.001) implantation were independent predictors of MACEs during follow-up, whereas MS was not predictive. Similarly, MS was not a predictor of target lesion revascularization. In conclusion, patients with MS did not have an increased risk for target lesion revascularization or a greater MACE rate compared with control patients during a 12 month follow-up period after bare-metal or drug-eluting stent placement. In contrast, DM is associated with significantly increased event rates.

Evaluation of aortocoronary bypass stents with cardiac MDCT compared with conventional catheter angiography

OBJECTIVE

The objective of our study was to determine the accuracy of 16-MDCT for evaluation of stent patency and in-stent stenosis in venous coronary bypass grafts.

SUBJECTS AND METHODS

Fourteen patients who had previous stent placements in stenosed venous coronary bypass grafts underwent contrast-enhanced MDCT of the heart (collimation, 16 x 0.75 mm; 120 kV; 550 mAs(eff)) and invasive coronary angiography. A total of 20 stents were evaluated: Vessel and stent diameters proximal to, distal to, and at various sites inside the stent were measured on both techniques, and Bland-Altman plots and correlations were calculated. Image noise and image quality were also assessed applying a Student's t test for data comparison of image noise.

RESULTS

All 20 bypass stents were correctly classified as patent. Vessel diameters outside the stent showed an excellent correlation (r = 0.90) and in-stent diameters showed a good correlation (r = 0.72), with lower values for MDCT due to blooming artifacts. All significant in-stent stenoses were correctly classified.

CONCLUSION

In patients suspected of bypass in-stent stenosis, 16-MDCT may be considered as a valuable alternative to conventional angiography for evaluating bypass patency and in-stent stenosis.

Polymer-based paclitaxel-eluting stents are superior to nonpolymer-based paclitaxel-eluting stents in the treatment of de novo coronary lesions

Although polymer coating of coronary stents enables sufficient loading and release of incorporated drugs, it has also been associated with potentially negative effects. This study compared the clinical, angiographic, and intravascular ultrasound (IVUS) outcomes of patients treated with polymer- versus nonpolymer-based paclitaxel-eluting stents (PESs). Sixty-five consecutive patients (70 de novo lesions) treated with polymer-based PESs (TAXUS, 1 microg/mm2 of paclitaxel; Boston Scientific Corp.) and 65 consecutive patients (65 de novo lesions) treated with nonpolymer-based PESs (V-Flex Plus, 2.7 microg/mm2 of paclitaxel; Cook, Inc.) were enrolled in the study. Six-month angiographic follow-up was performed on 54 lesions of the polymer-based PES group and 51 lesions of the nonpolymer-based PES group. IVUS at angiographic follow-up was performed in 61 of the first 70 included lesions. At 6-month IVUS follow-up, mean intimal hyperplasia cross-sectional area was 2.36 +/- 1.60 mm2 in the nonpolymer-based PES group versus 0.62 +/- 0.41 mm2 in the polymer-based PES group (p = 0.003). Implantation of polymer-based PESs resulted in significantly lower in-stent late lumen loss (0.22 +/- 0.27 vs 0.74 +/- 0.61 mm, respectively, p <0.001). In-stent binary restenosis rate was 5% versus 20%, respectively (p <0.001). Target lesion revascularization rate was 9% after implantation of polymer-based PES versus 18% (p = 0.128) after implantation of nonpolymer-based PES, and the major adverse cardiac event rate was 9% versus 23%, respectively (p = 0.032). In conclusion, polymer-based PESs result in superior angiographic and IVUS follow-up findings compared with nonpolymer-based PESs.

Reduced numbers of circulating endothelial progenitor cells in patients with coronary artery disease associated with long-term statin treatment

While statin treatment may transiently mobilize endothelial progenitor cells (EPCs), the dose-dependent effects of a continuous statin therapy on EPCs in patients with chronic coronary artery disease (CAD) have not been analyzed. In 209 patients with angiographically documented CAD, 144 of which received 10-40 mg/day of statins for >8 weeks, the EPC number was determined by flow cytometry directly (CD34(+)/KDR(+), n=58) and after in vitro-culture (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine-labeled Ac-LDL (DiI-Ac-LDL(+))/lectin(+), n=209). EPC function was assessed by the formation of colony forming units (CFUs). Univariate analysis revealed that the dose of continuous statin therapy inversely correlated with the EPC number. Treatment with 40 mg/day significantly reduced EPC counts. Multivariate analysis unveiled the statin dose and extent of CAD as independent predictors of reduced EPC numbers. Conversely, obesity predicted increased counts, while CFU development was not detectable in all patients and augmented in females and smokers but not in statin-treated patients. Compared with matched controls, statin-treated patients showed significantly reduced absolute and relative EPC counts. In a prospective analysis, initiation of statin therapy significantly diminished the number of circulating and isolated EPCs after 3 but not after 1 month(s). Thus, the statin dose during chronic and continuous treatment independently predicts reduced numbers of circulating as well as isolated EPCs in patients with CAD.

A Novel Drug-Eluting Stent Coated With an Integrin-Binding Cyclic Arg-Gly-Asp Peptide Inhibits Neointimal Hyperplasia by Recruiting Endothelial Progenitor Cells

OBJECTIVES

Novel stents loaded with an integrin-binding cyclic Arg-Gly-Asp peptide (cRGD) were analyzed for their potential to limit coronary neointima formation and to accelerate endothelialization by attracting endothelial progenitor cells (EPCs).

BACKGROUND

Re-endothelialization is important for healing after arterial injury.

METHODS

Effects of cRGD on EPC number, recruitment in flow, and invasion were analyzed in vitro. A durable polymer coating containing 67 microg cRGD per stent was developed for Guidant Tetra stents. Twelve cRGD-loaded polymer, 12 unloaded polymer, and 12 bare metal stents were deployed in porcine coronary arteries. Quantification of cRGD in peri-stent tissue was established by high-performance liquid chromatography (HPLC) and mass spectrometry (MS). Histomorphometry and immunostaining were performed after 4 and 12 weeks. Recruitment of labeled porcine EPCs was assessed 7 days after intracoronary infusion.

RESULTS

The cRGD clearly supported the outgrowth, recruitment, and migration of EPCs in vitro. At 4 weeks, there was no difference for mean neointimal area and percent area stenosis in the cRGD-loaded, polymer, or bare metal stent group. At 12 weeks, neointimal area (2.2 +/- 0.3 mm2) and percent area stenosis (33 +/- 5%) were significantly reduced compared with polymer stents (3.8 +/- 0.4 mm2, 54 +/- 6%; p = 0.010) or bare metal stents (3.8 +/- 0.3 mm2, 53 +/- 3%; p < 0.001). The HPLC/MS confirmed cRGD tissue levels of 1 to 3 mug/stent at 4 weeks, whereas cRGD was not detectable at 12 weeks. Staining for CD34 and scanning electron microscopy indicated enhanced endothelial coverage on cRGD-loaded stents at 4 weeks associated with a significant increase in the early recruitment of infused EPCs.

CONCLUSIONS

Stent coating with cRGD may be useful for reducing in-stent restenosis by accelerating endothelialization.

Association of C-reactive protein and myocardial perfusion in patients with ST-elevation acute myocardial infarction

This study sought to evaluate the relation between C-reactive protein (CRP) on admission of patients with acute myocardial infarction (AMI) and myocardial perfusion as defined by postintervention angiographic myocardial blush grade (MBG) and their impact on subsequent mortality. The patient population comprised 191 consecutive patients with AMI undergoing PTCA within 12h of symptom onset on a native vessel. Patients were divided based on the CRP level on admission (Rolf Greiner BioChemica, Germany, cutpoint for the assay CRP: 5mg/l) into a group with elevated CRP (>or=5mg/l) and a group with normal CRP. Angiographic myocardial blush grade (MBG) after revascularization of the infarct-related artery was determined to evaluate myocardial reperfusion. Revascularization of the infarct-related artery was successful in 176 (92.6%) patients. The frequency of impaired perfusion (MBG 0-2) was higher in the elevated CRP group than in the normal CRP group (74.5% versus 59.7%, respectively, p=0.046). Elevated CRP on admission was an independent predictor of impaired myocardial perfusion (MBG 0-2, OR 1.92, 95% CI 1.02-4.01, p=0.042) in addition to age >70 years. Elevated CRP (OR 2.64, 95% CI 1.26-5.53, p=0.009) and MBG 0-2 (OR 4.58; 95% 1.73-12.20, p=0.002) were independent predictors of mortality during a 22.4+/-15.3 months follow-up in addition to heart rate on admission >100 beats/min (OR 3.07; 95% CI 1.30-7.25, p=0.009). In sequential Cox models, the predictive power of clinical data and MBG for mortality (model chi-squared 18.3) was strengthened by the inclusion of CRP levels (model chi-squared 24.3). In conclusion, there is a relation between elevated admission CRP and impaired reperfusion in the myocardium subtended to the infarct-related artery. The combination of clinical data, myocardial reperfusion levels after primary angioplasty for AMI and admission CRP increases the predictive value for subsequent survival.

Three-year follow-up after intracoronary beta-radiation therapy for in-stent restenosis

BACKGROUND

Most studies that proved intracoronary radiation therapy (IRT) to be highly effective to reduce recurrent restenosis after treatment of in-stent restenosis (ISR) have looked at time periods up to 12 months. Whether the beneficial effect from radiation is sustained during long-term follow-up remains a concern. This study sought to evaluate the effectiveness of IRT using a beta-emitter during a 3-year follow-up period.

METHODS

One hundred twenty-eight consecutive symptomatic patients (mean age, 63 +/- 11 years) with 134 in-stent restenotic lesions were treated for ISR with IRT (noncentred beta-emitter, Novoste; radiation dosis 21.1 +/- 3.1 Gy). Six-month angiographic follow-up was obtained in 104 patients (81%) with 105 lesions (78%). All patients underwent 36-month clinical follow-up.

RESULTS

Six-month angiographic restenosis rate was 22% in stent (29% in lesion) with an in-stent late loss of 0.49 +/- 0.62 mm. Target lesion resvascularization (TLR) at 6-month follow-up was performed in 23 cases (18%). MACE (death, myocardial infarction, and target vessel revascularisation) was observed in 24 patients (19%). At 36-month follow-up, TLR increased to 36 cases (28%) and MACE was observed in 47 patients (37%). In a multivariate analysis, minimal lumen diameter before treatment of ISR using IRT was the only predictor of recurrent TLR at 36 months (OR = 0.131; 95% CI, 0.068-0.254; p = 0.002). In a subgroup of patients (N = 15) without restenosis at 6-month angiography but with clinically driven recurrent late angiography (mean, 18 +/- 7 months); in-lesion late loss increased from 0.47 +/- 0.54 mm at 6 months to 1.27 +/- 0.76 mm at repeated angiography (p = 0.005).

CONCLUSION

There is a considerable number of delayed recurrent restenosis post IRT for ISR. This is due to ongoing late loss more than 6-month post IRT. The minimal lumen diameter before IRT predicts the need for recurrent TLR at 36 months.

A rare but life-threatening complication of ventriculo-atrial shunt

Insertion of ventriculoperitoneal and ventriculoatrial shunts is routinely performed. Infarction pneumonia and atrial thrombus formation are described as very rare complications of ventriculoatrial shunts. We present the case of a female patient with ventriculoatrial shunt insertion as long term treatment for aequeductal stenosis who presented with recurrent episodes of dyspnoea, chest pain, and unilateral pleural effusion. Diagnostic evaluation revealed a positive D-dimer test, bilateral basal infiltrates and pleural effusion. Transesophageal echocardiography established the diagnosis of a thrombus in the right atrium. Laboratory testing for thrombophilia revealed a homozygous factor V Leiden mutation. In the following, a shunt revision was performed.

Superiority of sirolimus eluting stent compared with intracoronary beta radiation for treatment of in-stent restenosis: a matched comparison

OBJECTIVE

To compare acute and follow up clinical and angiographic results after treatment of in-stent restenosis (ISR) by sirolimus eluting stents (SES) with results obtained after intracoronary radiation therapy (IRT).

DESIGN

Matched pair analysis.

METHODS

62 consecutive ISR lesions (< 30 mm lesion length, reference diameter < 3.5 mm) in 62 patients were treated with SES. From a database of 174 lesions (n = 141 patients) treated for ISR by intracoronary beta radiation, 62 lesions (62 patients) were pair matched with the SES group for diabetes mellitus, lesion length, vessel size, and pattern of ISR. Six month angiographic and 12 month clinical follow up results were obtained.

RESULTS

Baseline clinical and angiographic characteristics were similar between the groups (not significant). SES implantation resulted in significantly lower postprocedural in-lesion diameter stenosis than did IRT (mean (SD) 14.2 (9.5)% v 21.1 (10.6)%, p = 0.001), significantly higher minimum lumen diameter at follow up (1.91 (0.58) v 1.55 (0.72) mm, p = 0.005), and a higher net gain (1.16 (0.55) v 0.77 (0.70) mm, p = 0.002). Angiographic binary in-lesion restenosis rate at six months was 11% in the SES group and 29% in the IRT group (p = 0.046). In 16 ISR lesions SES were used after failed IRT and in 46 lesions for first time ISR. In-lesion late loss was higher after use of SES for failed IRT than after use of SES for first time ISR (0.61 (0.67) mm v 0.24 (0.41) mm, p = 0.018). In a multivariate analysis prior failed IRT was the only independent predictor for recurrent restenosis after SES for ISR (p = 0.052, odds ratio 5.8). Six patients (10%) in the SES group and 17 patients (27%) in the IRT group underwent target lesion revascularisation during the 12 months of follow up (p = 0.022).

CONCLUSIONS

In this non-randomised matched cohort SES achieved acute and follow up results superior to IRT for treatment of ISR even if cases of failed IRT are included. Failed IRT is a predictor of impaired SES effectiveness.

A study on the primary and secondary nucleation of ice by power ultrasound

Several different investigations have been carried out to study the primary and secondary nucleation of ice by sonocrystallisation. Firstly, the primary nucleation of discrete ice crystals in a supercooled sucrose solution has been observed. For increasing concentrations of sucrose solutions from 0 to 45 wt%, the nucleation temperature consistently occurs at a higher nucleation temperature in the presence of ultrasound. The nucleation temperature also increases as the power output and duty cycle of a commercial ultrasonic horn are increased. Snap shot images of the bubble clouds obtained from the ultrasonic horn also show that the number of bubbles appears to increase as the ultrasonic output is increased. This suggests that the nucleation of ice is related to the power output and number of cavitation bubbles. The effect of a single bubble on the sonocrystallisation of ice is discussed. High-speed movies (1120 fps) have shown that the crystallisation appears to occur in the immediate vicinity of the single bubble. In most cases, many crystals are observed and it is not known whether a single ice crystal is being fragmented by the bubble or whether many crystals are being initiated. The bubble appears to undergo a dancing regime, frequently splitting and rejoining and also emitting some small microbubbles. A study on the secondary nucleation of ice in sucrose solutions has been carried out using a unique ultrasonic cold stage device. Images taken using a microscope system show that the pre-existing ice dendrite crystals can be broken up into smaller fragments by an ultrasonic field. Cavitation bubbles appear to be important during the fragmentation process, possibly melting any ice crystals in their path. Flow patterns around cavitation bubbles have also been observed, and these may be responsible for the fragmentation of ice crystals.

Sirolimus- and paclitaxel-eluting stents in comparison with balloon angioplasty for treatment of in-stent restenosis

This study evaluated the acute and follow-up effectiveness of sirolimus-eluting stents (SESs) and nonpolymer-based paclitaxel-eluting stents (PESs) in comparison will balloon angioplasty for treatment of complex in-stent restenosis (ISR) lesions. Drug-eluting stents have been demonstrated to be highly effective for treatment of de novo lesions. The use of drug-eluting stents for treatment of complex ISR is less well defined. Eighty one lesions with in-stent restenosis (lesion length < 30 mm in a native coronary artery) were treated with either PTCA alone (n = 26 lesions in 25 patients), PES (n = 27 lesions in 24 patients; Achieve, Cook; 3,1 mug paclitaxel/mm(2) nonpolymer-based coating), SES (n = 28 lesions in 28 patients; Cypher, Cordis; 140 mug sirolimus/cm(2) metal surface area). Nine-month MACE rates were 32%, 8%, and 14% (all due to repeated revascularization procedures, except one death in the SES group) in the PTCA, PES, and SES group, respectively. Postintervention minimal lumen diameter in stent was significantly greater in the SES and the PES group in comparison with the PTCA group (2.37 +/- 0.26, 2.54 +/- 0.42, 1.78 +/- 0.23 mm; P < 0.001). At 6-month angiographic follow-up, late loss in stent was 0.77 +/- 0.45, 0.43 +/- 0.53, and 0.29 +/- 0.52 mm for the PTCA, PES, and SES group, respectively (P = 0.005). In-lesion restenosis rate was 61% for the PTCA group, 20% for the PES group, and 13% for the SES group (P = 0.042). The implantation of SES as well as nonpolymer PES proved to be effective for treatment of ISR. The combination of improved acute gain and reduced late loss results in a significantly improved angiographic follow-up result in comparison with PTCA.

Intravascular ultrasonic comparative analysis of degree of intimal hyperplasia produced by four different stents in the coronary arteries

Intravascular ultrasound studies were performed at angiographic follow-up on 121 native coronary lesions treated with 1 bare metal stent (n = 50), high-dose dexamethasone-eluting stents (n = 18), non-polymer-based paclitaxel-eluting stents (n = 18), or sirolimus-eluting stents (n = 35). Paclitaxel- and sirolimus-eluting stents reduced mean intimal hyperplasia thickness compared with bare metal stents by 49% and 90% (p = 0.048 and p <0.001), respectively, whereas mean intimal hyperplasia thickness treated with dexamethasone-eluting stents was similar to those lesions treated with bare metal stents.

Long-term assessment of a novel biodegradable paclitaxel-eluting coronary polylactide stent

AIM

The aim of this study was to assess technical feasibility, biocompatibility, and impact on coronary stenosis of a new biodegradable paclitaxel-loaded polylactide stent. Due to high rates of in-stent restenosis and permanent nature of metal stent implants, synthetic polymers have been proposed as surrogate materials for stents and local delivery systems for drugs. Paclitaxel was shown to inhibit vascular smooth muscle cell proliferation and migration.

METHODS AND RESULTS

A novel biodegradable double-helical stent was manufactured using controlled expansion of saturated polymers (CESP) for the moulding of a bioresorbable poly(D,L)-lactic acid (PDLLA). A modified balloon catheter for stent deployment was developed according to the mechanical stent properties. Twelve paclitaxel-loaded (170 microg) polylactide stents, 12 unloaded polylactide stents, and 12 316L bare metal stents were deployed in porcine coronary arteries of 36 animals. Six pigs of each group were sacrificed after 3 weeks and 3 months, respectively, for every setting. Drug release kinetics as well as histomorphometrical and histopathological analyses were performed. A slow paclitaxel release kinetic for more than 2 months and therapeutic tissue concentrations were demonstrated. Coronary stenosis after implantation of paclitaxel-loaded stents (30+/-5% or 49+/-4%) was significantly inhibited compared to unloaded PDLLA stents (65+/-10%, P=0.021 or 71+/-4%, P=0.004) and metal stents (53+/-6% or 68+/-8%, P=0.029 and P=0.020) after 3 weeks or 3 months. Early complete endothelialisation was shown. Nevertheless, a local inflammatory response to the polylactide as a result of the polymer resorption process was observed.

CONCLUSIONS

This novel polylactide stent showed sufficient mechanic stability, and by incorporation of paclitaxel, a significant potential to reduce restenosis development after vascular intervention was seen.

Downregulation of N-cadherin in the neointima stimulates migration of smooth muscle cells by RhoA deactivation

OBJECTIVE

The aim of the study was to analyze whether cadherin- and Rho-family GTPases-mediated dynamic rearrangement of cell-cell adhesion play an important role during human arterial smooth muscle cell (haSMC) migration.

METHODS

Expression patterns of N-cadherin and beta-catenin were analyzed in a domestic pig restenosis model after 14, 28, and 90 days as well as in quiescent and migratory haSMCs in vitro. N-cadherin expression was upregulated by transient sense; downregulation was induced by antisense transfection. For functional inhibition, antibody GC-4 was used. Cell migration was quantified using Boyden chamber assays. Regulation of RhoA GTPase was tested by assessment of RhoA activity.

RESULTS

In vivo analysis of N-cadherin expression in a porcine restenosis model revealed downregulation in the neointima after 14 days. After 28 days, N-cadherin expression was slightly restored, while after 90 days, no difference between medial and neointimal expression was detectable. beta-Catenin levels remained unchanged during the whole period. According to the in vivo situation, N-cadherin was significantly downregulated in migratory haSMCs compared to quiescent cells in vitro. After N-cadherin overexpression, haSMC migration was reduced by 87% (P<0.001). By contrast, inhibition of N-cadherin in quiescent haSMCs by GC-4 increased the migratory potential by 87% (P<0.01). In haSMCs overexpressing N-cadherin, a significant upregulation of RhoA activity was demonstrated, while RhoA activity was blocked by GC-4.

CONCLUSIONS

These results indicate that the regulation of haSMC attachment by N-cadherins is essential for haSMC migration. Modification of N-cadherin expression and activity induces RhoA signaling with relevance for the reorganization of the actin cytoskeleton.

Evaluation of a high-dose dexamethasone-eluting stent

This study evaluated the safety and efficacy of a dexamethasone-eluting stent with a special high dexamethasone-loading dose for treatment of de novo coronary lesions in 30 patients. Eight patients had in-stent restenosis (restenosis rate 31%) at 6-month follow-up, and the in-stent late lumen loss was 0.96 +/- 0.63 mm due to an average intimal hyperplasia area obstruction of 32 +/- 21%, indicating that high-dose dexamethasone-loaded stents do not significantly reduce neointimal proliferation.

A high power ultrasonic array based test cell

This paper describes the use of finite element (FE) analysis as a tool in the design process for laboratory based ultrasonic test cells. The system was designed to incorporate an array of ultrasonic transducers to provide a pressure focus in the centre of the cell and importantly, operate both above and below the cavitation threshold of the load medium. Furthermore, the cell incorporates a coolant jacket to accommodate temperature control of the load material associated with the process. A 2D FE model corresponding to a slice through the operational plane of the cell was developed and used to investigate the influence of cell wall material and thickness, transducer configuration, rotation of a metallic stirrer blade and heat transfer fluid on the cell acoustic response. Importantly, experimentally measured pressure field maps demonstrate good correlation with the FE predicted fields. A final manufactured test cell is shown to produce a highly focussed region of cavitation. Finally, the importance in accurately representing the acoustic properties of the constituent materials used in such FE models is demonstrated through an illustrated example.

Treatment of In-Stent restenosis using a stent with non-polymer-based paclitaxel elution

Treatment of in-stent restenosis remains a therapeutic challenge. Twenty-seven lesions with in-stent restenosis were treated with non-polymer-based paclitaxel-eluting stents. At 6-month follow-up, in-stent late loss was 0.44 +/- 0.54 mm and the restenosis rate was 20%, indicating effective treatment for reduction of recurrent restenosis.

Coronary Artery Stents in Multislice Computed Tomography

RATIONALE AND OBJECTIVE

The aim of this study was to systematically compare the ability to assess the coronary artery lumen in the presence of coronary artery stents in multislice spiral CT (MSCT).

METHODS

Ten different coronary artery stents were examined with 4- and 16-detector row MSCT scanners. For image reconstruction, a standard and a dedicated convolution kernel for coronary artery stent visualization were used. Images were analyzed regarding lumen visibility, intraluminal attenuation, and artifacts outside the stent lumen. Results were compared using repeated-measure analysis of variance.

RESULTS

Depending on stent type, scanner hardware, and convolution kernel, artificial lumen narrowing ranged from 20% to 100%. The convolution kernel had the most significant influence on the visibility of the stent lumen. Artificial lumen narrowing and intraluminal attenuation changes decreased significantly using the dedicated convolution kernel. In general, most severe artifacts were caused by gold or gold-coated stents.

CONCLUSIONS

Independent of the scanner hardware or dedicated convolution kernels, routine evaluation of most coronary artery stents is not yet feasible using MSCT.

Usefulness of myocardial blush grade early and late after primary coronary angioplasty for acute myocardial infarction in predicting left ventricular function

This study sought to analyze the evolution of myocardial perfusion during follow-up after primary angioplasty for acute myocardial infarction (AMI) and relate it to final left ventricular (LV) function. In 101 patients with a first AMI, angiographic myocardial blush grade (MBG) was analyzed immediately after intervention and at follow-up 7.5 +/- 5.6 months later. Cine ventriculography was performed at follow-up angiography to define LV function. Five patients had occluded stents or flow-limiting restenosis. In the remaining patients, myocardial perfusion at follow-up, as defined by MBG, was persistently abnormal in 19 patients (20%), had become normalized from previously abnormal MBG in 30 patients (31%), remained normal in 40 patients (42%), and deteriorated from normal to abnormal in 7 patients (7%). Patients with improvement of abnormal blush determined immediately after intervention to normal blush at follow-up (n = 30) compared with patients with persistently abnormal blush (n = 19) had a better LV ejection fraction at follow-up (53.7 +/- 11.1 vs. 37.4 +/- 9.7%, p <0.001). Evolution of MBG had a better predictive value for LV ejection fraction at follow-up than acute MBG only. Multivariate analysis proved evolution of MBG from AMI to follow-up to be an independent predictor of LV function (R(2) = 0.177, p <0.001) in addition to the initial size of jeopardized myocardium as defined by the sum of ST-segment elevation (R(2) = 0.138, p = 0.001) and infarct location (R(2) = 0.044, p = 0.033). In conclusion, tissue reperfusion after angioplasty for AMI is characterized by frequent improvement over time, as indicated by repeated MBG analysis. Patients with recovery of perfusion have better, final LV function.

Expression patterns of integrins on quiescent and invasive smooth muscle cells and impact on cell locomotion

Migration and invasion of human arterial smooth muscle cells (haSMCs) are essential steps during the development of atherosclerosis, restenosis, and transplant vasculopathy. The molecular mechanisms leading to these processes are only incompletely understood. Due to their contact to the surrounding extracellular matrix, integrins have been shown to be essentially involved in cell locomotion. Therefore, the function of integrins during this process was analyzed in an in vitro model which was based on the defined quiescent and invasive phenotypes of human haSMCs induced by cell culture conditions. Flow-cytometric analysis of integrin expression between both phenotypes showed a strong upregulation of alpha 5 beta 1 (13.1x) and a modest upregulation of alpha vs beta 3 (3.4x) and alpha IIb (3.0x) in invasive haSMCs in comparison to quiescent ones. Other integrins analyzed (alpha 2, alpha 3, alpha 4, beta 1) did not show differential regulation. Functional inhibition of alpha 5 beta 1 reduced cell migration (-29%+/-8), invasion (-49%+/-16), collagen contraction (-125%), and attachment to fibronectin. Although, there was a clear discrepancy between alpha 5 beta 1 and alpha vs beta 3 expression levels, inhibition of alpha vs beta 3 (-45%+/-9) reduced haSMC invasion equally. Interestingly, alpha vs beta 3 unlike alpha 5 beta 1 blockade caused a significant stimulation of collagen contraction (+52% vs 154%) with possible implications on vascular remodeling. In conclusion, alpha 5 beta 1 blockade or combined alpha 5 beta 1/alpha v beta 3 blockade by specific antibodies or selective RGD peptides together with local drug delivery strategies could be a promising strategy for the therapy of restenotic lesions or atheromatous plaques.

Decrease of vascular smooth muscle cell locomotion by abciximab, but not tirofiban: a possible role of different affinity to alpha v beta 3 integrins

AIM

The EPISTENT and EPIC studies demonstrated a reduction of clinically driven re-interventions after percutaneous transluminal coronary angioplasty (PTCA) and stent implantation in patients treated with abciximab, while for tirofiban no similar effects could be demonstrated. This may be explained by the different effects on the migratory and invasive potential of vascular smooth muscle cells (VSMCs) by integrin alpha v beta 3 blockade. Therefore, the objective of this study was to compare the effectiveness of abciximab and tirofiban to affect VSMC migration and invasion.

METHODS

Vascular smooth muscle cells were treated with abciximab (0.1-1 microg/ml), tirofiban (0.1-1 microg/ml), and the alpha v beta 3 specific antibody LM609 (1-5 microg/ml), that was used as a positive control during the assay (treatment) over 24 h before the assay (pre-treatment), or before and during the assay (combined treatment). Sodium 3'-[1-(phenylaminocarbonyl)-3,4-tetrazolium]-bis (4-methoxyy-6-nitro) benzene sulfonic acid (XTT)-assay and cell counting measured the influence of the substances on VSMC proliferation. Using a Boyden Chamber model, the capability of VSMCs for migration and invasion was tested with different chemo-attractants and barriers.

RESULTS

Any influence of the platelet glycoprotein (GP) IIb/IIIa receptor (integrin alpha IIb beta 3) antagonists on VSMC proliferation could be excluded. After combined treatment, abciximab demonstrated a dose-dependent inhibition of migration (IC50 = 33 microg/ml) and invasion (IC50 = 0.5 microg/ml) of VSMCs. Administration during the assay without pre-treatment inhibited migration similarly (IC50 = 32 microg/ml) but invasion to a significant lower extent (IC50 = 44 microg/ml). Administration of tirofiban during the assay with or without pre-treatment had no inhibitory effect on VSMC migration and invasion. Pre-treatment alone with one of the substances also did not alter VSMC migration or invasion.

CONCLUSION

Abciximab administration in physiological concentrations was capable of significantly inhibiting the migratory and invasive potential of VSMCs, while for tirofiban no similar effect could be demonstrated.

Rotational atherectomy for the treatment of in-stent restenosis

Restenosis after coronary stent implantation remains the major limitation of this treatment modality. At present, re-dilatation is considered the therapeutic option of choice for focal lesions, however, long restenotic lesions (>10 mm) do not respond favourably. Despite the emerging concept of intracoronary radiation, encouraging acute procedural results are also reported for different debulking techniques (Excimer laser angioplasty, directional coronary atherectomy, and rotational atherectomy, or rotablation). Rotablation has been studied most extensively with acute and long- term results published in a total of more than 850 patients. Experimental and first clinical data indicate favourable results for the rotablator as compared to balloon angioplasty alone for the treatment of in-stent restenosis. Data from the first 2 randomized clinical trials (ROSTER-, and ARTIST-trial) have now been published with conflicting results: The european multicenter ARTIST-trial including 300 patients could not prove a benefit for the rotablator as compared to re-dilatation in patients with diffuse stent restenosis. On the contrary, the monocenter ROSTER-trial, which has been presented as an abstract until today, suggests a clinical benefit of patients treated by the rotablator if they were studied with intracoronary ultrasound prior to randomization. Currently, rotablation for the treatment of restenosis cannot be considered as the first line treatment modality in patients with in-stent restenosis. As a result of unsatisfying angiographic and clinical long-term results by the use of a variety of treatment modalities in diffuse stent restenosis, prevention of this iatrogenic entity has become mandatory.

Characterization of differential gene expression in quiescent and invasive human arterial smooth muscle cells

Proliferation, migration and invasion of smooth muscle cells (SMCs) are essential pathogenic processes in the development of a broad spectrum of cardiovascular disorders, like arteriosclerosis, restenosis after percutaneous transluminal angioplasty and stent implantation as well as transplant vessel disease. As an in vitro model mimicking these processes, the Boyden chamber was employed to characterize the diverging migratory and invasive potentials of proliferating and nonproliferating human arterial SMCs (haSMCs). Using this model, differential gene expression of both phenotypes was analyzed by a cDNA array system (Clontech human cardiovascular array). With these arrays, 558 cardiovascular-associated genes could be compared. Further, gene expression was exactly quantified by real-time RT-PCR. Protein expression was analyzed by ELISA and Western blotting. In total, 47 genes were differentially expressed more than 1.5 times. Most of the differentially regulated genes in this study were associated with the extracellular matrix (ECM) and cell motility. In detail, the respective groups were matrix-organizing proteins, ECM proteins, cell adhesion proteins, extracellular communication and cytoskeleton motility proteins. Genes known to be differentially regulated during haSMC migration and invasion, like TIMP 2, TIMP 3, and MMP 3, were confirmed by the array data. Reduced expression of several cytoskeletal proteins, like vimentin, fibronectin, cytokeratins and beta1 integrin, was shown in the invasive phenotype. Further, angio-associated protein, alpha E-catenin and atrial brain natriuretic peptide receptor were downregulated whereas TFPI 2 was strongly upregulated in invasive haSMCs. In conclusion, several relevant potential candidate genes for the quiescent and the invasive SMC phenotype were identified and genes already known to be differentially regulated by previous analysis were confirmed.

Upregulation of the cytoskeletal-associated protein Moesin in the neointima of coronary arteries after balloon angioplasty: a new marker of smooth muscle cell migration?

Migrating cells like coronary smooth muscle cells in restenosis change their cell shape and form cellular protrusions called filopodia. A prerequisite for filopodia formation is the rearrangement of the actin cytoskeleton. An essential role of the 78-kDa protein Moesin is described for Rho- and Rac-dependent assembly of actin filaments. In vivo Moesin is not observed in mature smooth muscle cells. The objective of this study was to demonstrate that Moesin is upregulated in migrating coronary smooth muscle cells during restenosis development. In vivo expression of Moesin was upregulated in neointimal coronary smooth muscle cells of dilated porcine coronary arteries compared to the undilated left circumflex coronary artery of the same swine. Concordant to these results Moesin expression was upregulated in migrating and invading human arterial smooth muscle cells in vitro analyzed by FACS, Western blotting and RT-PCR. In addition, the invasive potential of Moesin-positive Mel Im cells transfected with Moesin sense DNA increased by 28% as compared to mock-transfected control, whereas antisense transfected cells had a decreased invasive potential of 32%. Transfection of Moesin-negative HepG2 with Moesin sense cDNA increased the invasive potential by 43%. Finally, transfection of human arterial smooth muscle cells with Moesin sense cDNA caused an increased invasive potential of 30%. Transfection of haSMCs with antisense cDNA decreased the invasive potential by 37% in comparison to mock-transfected control. These results demonstrate for the first time an upregulation of Moesin expression in coronary smooth muscle cells of the neointima after arterial injury. The increased migrative and invasive potential of cells transfected with Moesin confirmed the functional role of Moesin in cell migration. This indicates an important role of Moesin during restenosis development.

Activation of IP and EP(3) receptors alters cAMP-dependent cell migration

Migration of vascular smooth cells from the media to the intima essentially contributes to neointima formation after percutaneous transluminal angioplasty and stent implantation. The stable prostacyclin mimetic iloprost has been shown to inhibit neointima formation in experimental restenosis, but it is currently unknown whether this may be caused by an antimigratory effect. Hence, the present study analyses (i) the influence of G(s)-coupled prostacyclin (IP) receptors on cell migration and (ii) verifies whether EP(3) receptors with opposite (i.e., G(i)) coupling may conversely stimulate cell migration. In a modified Boyden chamber model, it was shown that iloprost dose-dependently inhibits the migration of primary human arterial smooth muscle cells, which constitutively express the IP receptor. On the other hand, human arterial smooth muscle cell migration was stimulated by the EP(3) receptor agonist M&B 28.767. To independently study the effects of these receptors, IP or EP(3) receptors were stably overexpressed in chinese hamster ovary cells (CHO-IP and CHO-EP(3)). Chemotaxis of CHO cells transfected with G(s)-coupled IP receptors was concentration-dependently inhibited by iloprost (2-100 nM), while there was no effect of iloprost on mock-transfected CHO. By contrast, CHO-cells that overexpressed EP(3) receptors showed a significant, concentration dependent (1-100 nM) increase of cell migration in presence of the selective EP(3) agonist M&B 28.767. It is concluded that the prostacyclin mimetic iloprost inhibits vascular cell migration, which probably depends on a G(s)-mediated increase of intracellular cAMP. EP(3) receptors conversely stimulate CHO migration.

Efficient transfection method for primary cells

Transfection of primary cells and stem cells is a problem in the laboratory routine and further in tissue engineering and gene therapy. Most methods working effectively for cell lines in culture fail to transfect primary cells. Here we describe the use of the Nucleofector technology developed by amaxa biosystems. We were able to transfect primary human melanocytes, human coronary smooth muscle cells, human chondrocytes, and human mesenchymal stem cells with high efficiencies (28.9-45.3%). All primary cell types failed to be transfected satisfactorily by methods based on liposome-mediated transfection in our hands. The viability of the transfected cells varied between 11.2% and 75% in comparison to untreated cells. Only 200,000 cells per transfection sample were needed. In summary, this method presents an effective and fast mean for transfection of primary and stem cells demonstrated by four cell types which are only transfected with low efficiency by other methods.

Abciximab inhibits the migration and invasion potential of human coronary artery smooth muscle cells

In the EPIC trial, high-risk patients received the integrin receptor antagonist abciximab v placebo during and for 12 h following percutaneous coronary intervention with a significant 23% decrease of repeat revascularisation at 6 months. However, EPILOG and CAPTURE trials could not confirm these promising long-term results. Recently presented data from the EPISTENT trial suggested a beneficial effect of abciximab on restenosis in patients with diabetes. Based on these divergent results the aim of this study was to test whether alpha v beta 3 receptor blockade by abciximab could cause inhibition of human coronary smooth muscle cell (hcSMC) proliferation, migration, and invasion which represent crucial steps during restenosis development. In contrast to quiescent hcSMCs, proliferating cells were capable to migrate towards chemoattractive stimuli and even capable to invade through a basement membrane equivalent. Abciximab and LM609, an alpha v beta 3 specific inhibiting antibody, caused only a modest dose-dependent inhibition of hcSMC proliferation. On the contrary, the chemotactic and invasive potential of hcSMCs was significantly inhibited by abciximab administration 24 h prior to and during migration. (IC(50)=33.0 microg/ml for chemotaxis and IC(50)=0.5 microg/ml for invasion). For LM609 similar results were obtained. Administration of the drugs just during migration without pretreatment inhibited migration equally but invasion to a lower extent (abciximab: IC(50)=32.6 microg/ml for chemotaxis and IC(50)=44.9 microg/ml for invasion; LM609 IC(50)=3.1 microg/ml for chemotaxis and IC(50)=2.0 microg/ml for invasion). The attachment to the extracellular matrix proteins collagen I, collagen IV, laminin and vitronectin was not influenced. Pretreatment for 24 h with abciximab or LM609 did not cause a downregulation of the alpha v beta 3-integrin receptor. The results of this study indicate that the alpha v beta 3 antagonist abciximab is a potent inhibitor of hcSMC migration and invasion which could explain the observed lower reintervention rate after PTCA and stent implantation.

Development of a new biodegradable intravascular polymer stent with simultaneous incorporation of bioactive substances

OBJECTIVE

Due to the thrombogenicity and permanent implant nature of metallic stents, bioresorable synthetic polymers have been proposed for stents and local drug delivery systems. Bioresorbable polyesters like poly(D,L-lactide) demonstrated excellent biocompatibility in various tissues. This paper describes a novel method for the molding of these polymers. The specific CESP-process (Controlled Expansion of Saturated Polymers) is characterised by the use of the plasticizer carbon dioxide and allows the incorporation of bioactive substances at physiologic temperatures into the polymer bulk and the production of complex designed implants.

METHODS

The CESP-process is characterised by the exposure of an amorphous polymer to an inert gas at high pressure with a significant lower glass transition point. The plasticizing effect makes it possible to process polylactides at a temperature close to room temperature. The low process temperature constitutes a key advantage for thermally sensitive polymers and allows the incorporation of thermally sensitive pharmaceutical additives. To obtain some preliminary information on the biocompatibility, in vitro cell toxicity testing as well as drug release assessment was performed.

RESULTS

Different polymer sheets were produced using the CESP-process. Cytotoxicity was not observed in any molded polymer material. According to the mechanical and biocompatibility results Poly(D,L-lactide) (P-DL-LA) was investigated in the CESP-process. Finite element analysis was used to test the possible geometry of an adequate stent. A helical design was chosen and a stent-prototype was produced using the CESP-process. Peroxidase activity as an incorporated marker enzyme could be measured over 6 weeks. Different drug release profiles were obtained due to various pore sizes of the polymer.

CONCLUSIONS

The new CESP-process can be used to process biodegradable polymers and to mold different stent geometries without inducing cytotoxic effects to the material. Furthermore, this procedure permits the simultaneous incorporation of bioactive substances during the molding process. Drug release kinetics can be regulated by different pore sizes of the material.