Drug Distribution and Basic Pharmacology of Paclitaxel/Resveratrol-Coated Balloon Catheters

Purpose

To experimentally investigate a new homogenously paclitaxel/resveratrol-coated balloon catheter in terms of transport of the coating to the treated tissue and local effects including histology and functional tests.

Methods

Adherence of the coating to the balloon was explored by in vitro simulation of its passage to the lesion. Paclitaxel and resveratrol transfer to the vessel wall was investigated in porcine coronary and peripheral arteries. Matrix-assisted laser desorption/ionization (MALDI) was used for direct microscopic visualization of paclitaxel in arterial tissue. Inhibition of neointimal proliferation and tolerance of complete coating and resveratrol-only coating was investigated in pigs 4 weeks after treatment, and the effect of resveratrol on inflammation and healing after 3 and 7 days.

Results

Drug loss on the way to the lesion was < 10% of dose, while 65 ± 13% was detected at the site of balloon inflation. After treatment similar proportions of drug were detected in coronary and peripheral arteries, i.e., 7.4 ± 4.6% of dose or 125 ± 74 ng/mg tissue. MALDI showed circumferential deposition. Inhibition of neointimal proliferation by paclitaxel/resveratrol coating was significant (p = 0.001) whereas resveratrol-only coating did not inhibit neointimal proliferation. During the first week after treatment of peripheral arteries with resveratrol-only balloons, we observed nominally less inflammation and fibrin deposition along with a significant macrophage reduction and more pronounced re-endothelialization. No safety issues emerged including left ventricular ejection fraction for detection of potential distal embolization after high-dose treatment of coronary arteries.

Conclusions

Paclitaxel/resveratrol-coated balloons were effective and safe in animal studies. Beyond acting as excipient resveratrol may contribute to vascular healing.

Treatment of chronic total occlusions in native coronary arteries by drug-coated balloons without stenting - A feasibility and safety study

BACKGROUND

Chronic total occlusions remain one of the biggest challenges for interventional cardiologists and the high risk of restenosis and stent thrombosis is still a major problem. Drug-coated balloons showed favorable results for the treatment of in-stent restenosis and other lesion types. The aim of this study was to evaluate the feasibility and outcome of a drug-coated balloon only approach for chronic total occlusion.

METHODS

We included 34 patients with a native chronic total occlusion treated only by drug-coated balloons. A visual residual stenosis of 30% or less without major dissection was considered a satisfactory percutaneous intervention result according to the German Consensus Group recommendations for drug-coated balloon use. We collected clinical and procedural data. Angiograms were conducted during the procedure and at follow-up. Quantitative coronary analysis was performed and mean and minimal lumen diameter and late luminal changes were assessed.

RESULTS

The recanalization was considered satisfactory in 79.4% (n=27). Restenosis occurred in 11.8% (n=4) and reocclusion in 5.9% (n=2). Out of the 27 patients with a satisfactory initial result, 3.7% (n=1) had reocclusion and 3.7% (n=1) had restenosis. In the subgroup without satisfactory result (n=7), restenosis occurred in 3 patients (42.9%) and reocclusion in 1 patient (14.3%). A luminal increase was found in 67.6% (n=23) and mean late luminal gain was 0.11±0.49mm. Angina class improved significantly (p<0.001). There was no death or myocardial infarction.

CONCLUSIONS

Drug-coated balloon angioplasty without stenting is a feasible and well-tolerated treatment method for chronic total occlusions if the predilatation result is good.

Treatment of a coronary bifurcation lesion with drug-coated balloons: lumen enlargement and plaque modification after 6 months

We report a male with a coronary bifurcation lesion in the mid circumflex artery (CX). After predilatation, the lesion was treated with two drug-coated balloons (DCB). Primary success in the posterolateral branch was good; however the CX lesion had a residual stenosis including a non-flow-limiting type A dissection. After 6 months, angiography showed slight lumen enlargement in both branches of the bifurcation. Intravascular ultrasound identified about 35 % atherosclerotic plaque load within the inner area of the bifurcation but more than 50 % concentric atherosclerotic plaque burden in the vessel areas proximal and distal to the DCB-treated area.

Do pharmacokinetics explain persistent restenosis inhibition by a single dose of paclitaxel?

BACKGROUND

The purpose of this study was to investigate the elimination of paclitaxel from the arterial wall after a single short administration with a coated balloon.

METHODS AND RESULTS

Slightly oversized paclitaxel-coated balloons (dose 3 or 9 μg/mm(2)) without or with premounted stents were inflated in nonatherosclerotic coronary arteries of either young domestic pigs or adult Goettingen minipigs. The paclitaxel content of plasma, arterial segments, and residual hearts (without treated arteries) was measured for up to 180 days using high-performance liquid chromatography/ultraviolet detection or mass spectrometry. Angiograms were evaluated for lumen narrowing. The paclitaxel concentration in plasma remained <10 ng/mL. In arteries of domestic pigs and minipigs treated with paclitaxel-coated balloons with premounted stents, 10%±5% or 21%±8% of dose, respectively, was initially detected and decreased to 3.5%±3.1% of dose (domestic pig) by Day 7. Within 6 months it fell with a half-life of 1.9 months to 0.40%±0.35%. After 3 months the concentration in the arterial wall was 17±11 μmol/L. Without a stent, drug transfer to the vessel wall was somewhat reduced and elimination faster. Immediately after treatment up to 26%±4% of dose was detected in the residual whole hearts. It dropped with a half-life of 45 days to 1.5%±0.6% of dose (0.3 μmol/L) within 6 months.

CONCLUSIONS

After a single local administration with coated balloons, paclitaxel stays in the vessel wall of pigs long enough to explain persistent inhibition of neointimal proliferation. The pharmacokinetics of paclitaxel does, however, not exclude other reasons for sustained efficacy such as early blocking of processes initiating excessive and prolonged neointimal proliferation.

Paclitaxel and sirolimus differentially affect growth and motility of endothelial progenitor cells and coronary artery smooth muscle cells

AIMS

EPC and hCASMC play an important role in the pathogenesis of restenosis and stent thrombosis. Drug-coated balloon catheters exert a local, short-term application of antiproliferative agents. This study investigates the time-dependent influence on growth and motility of paclitaxel and sirolimus alone and combined with the coating additive iopromide on EPC and hCASMC.

METHODS AND RESULTS

Treatment of cultured human EPC and hCASMC with paclitaxel and sirolimus 1.5 and 15 µM for three seconds, three minutes and 24 hours, alone or combined with iopromide 0.197 M, resulted in a concentration- and time- dependent inhibition of proliferation and of migration. Paclitaxel and sirolimus increase apoptosis in either cell type. However, the effects of paclitaxel and sirolimus differed between the cell types: short-term exposure with paclitaxel leads to stronger inhibition of cell-density and apoptosis of hCASMC compared to EPC. In comparison to paclitaxel, short-term incubation with sirolimus showed a more effective inhibition of cell-density and migration as well as increased apoptosis in EPC in contrast to hCASMC. The effects of paclitaxel and sirolimus were increased in combination with iopromide. Interestingly, the antiproliferative effect of the paclitaxel-iopromide formulation on hCASMC was more potent compared to its effect on EPC. Endothelialisation in a porcine coronary stent model was similar with drug-coated balloons and uncoated controls, whereas it was delayed with drug-eluting stents.

CONCLUSION

After short-term application, paclitaxel and sirolimus show differential, cell-specific effects on EPC and hCASMC. Iopromide used as a coating agent intensifies these effects.

Long-Term Follow-Up of Early Versus Delayed Invasive Approach After Fibrinolysis in Acute Myocardial Infarction

Background—

Optimal reperfusion strategy in ST-elevation myocardial infarction is controversial. Failure of fibrinolytic therapy is related to limited efficacy, high reocclusion rates, reinfarction, and systemic bleeding complications. Data on the impact of percutaneous coronary intervention (PCI) after fibrinolysis are conflicting. The Southwest German Interventional Study in Acute Myocardial Infarction (SIAM III) evaluated the effects of transfer for early PCI in acute ST-elevation–myocardial infarction compared with a delayed PCI strategy.

Methods and Results—

SIAM III was a multicenter, randomized, prospective, controlled trial in patients with ST-elevation–myocardial infarction receiving fibrinolysis <12 hours after onset of symptoms. All patients received reteplase, aspirin in combination with ticlopidine, and heparin. Patients of the early PCI group were transferred within 6 hours after fibrinolysis for PCI. The delayed PCI group received elective PCI 2 weeks after fibrinolysis. In total, 197 patients were included; 163 were treated by PCI. The primary end point was the composite of death, reinfarction, target lesion revascularization, and ischemic events. During a mean follow-up time of 7.9±3.4 years (maximum, 11.2 years), early PCI was associated with a significant reduction of the primary end point (hazard ratio, 0.61 [95% confidence interval, 0.42 to 0.88]; P =0.008). Long-term survival was higher in the early PCI group ( P =0.057). Ischemic events were significantly reduced after early PCI ( P =0.003).

Conclusions—

Early PCI after fibrinolysis improves long-term event-free survival compared with a delayed PCI treatment strategy.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01124890.

Contemporary issues in cardiac pacing

This article addresses current pacing practices and issues. Pacing, sensing, sensing amplifiers, and pacing leads are discussed. Cardiac resynchronization is reviewed. Issues of ventricular pacing avoidance, pacemaker lead infections, ionizing radiation effects on pacing and pacing issues after deterioration and expiration of the patient are considered.

Paclitaxel-coated balloons - Survey of preclinical data

Restenosis following interventions in the coronary or peripheral arteries develops over weeks to months. In coronary arteries the restenosis rate has been markedly reduced since the advent of drug-eluting stents. Non-stent-based methods for local drug delivery enable restenosis inhibition without the need for stent implantation, does not permanently change the structure of the vessel, are repeatable, and seems to be applicable where drug-eluting stents provide insufficient protection. Preclinical data indicate that short exposure of the vessel wall to a lipophilic inhibitor of cell proliferation is sufficient for preventing restenosis. Initial evidence to this effect emerged from an investigation of paclitaxel embedded in a matrix that enhances the solubility and release of the agent from the balloon coating as well as its transfer to the vessel wall. Further corroborating data from preclinical and clinical studies demonstrating a reduction in late lumen loss and lower restenosis rates led to the market introduction of a variety of paclitaxel-coated angioplasty balloons. The effectiveness of restenosis inhibition is not determined by the active agent alone. Other factors that are crucial for the effectiveness and safety of drug-coated angioplasty balloons are the formulation containing the agent and the coating technique. In this review we first outline the development of paclitaxel-coated balloons to then provide an overview of the preclinical results obtained with different paclitaxel-coated balloons and finally compare these with the outcome in patients. The article concludes with a short outlook on initial results with a zotarolimus-coated angioplasty balloon.

The PPAR-γ agonist pioglitazone increases neoangiogenesis and prevents apoptosis of endothelial progenitor cells

PPAR-gamma agonists (thiazolidinediones, TZDs) may improve endothelial function independently of insulin sensitizing. Bone marrow-derived endothelial progenitor cells (EPC) contribute to neoangiogenesis. Mice were treated with pioglitazone, 20mg/kg/day for 10 days. Treatment with TZD upregulated circulating Sca-1/VEGFR-2 positive EPC in the blood (235+/-60%) and the bone marrow (166+/-30%), cultured spleen-derived DiLDL/lectin positive EPC increased to 231+/-21% (n=24 per group). Upregulation of EPC was persistent after 20 days. TZD increased SDF-1-induced migratory capacity per number of EPC by 246+/-73% and increased expression of telomere repeat-binding factor 2 by 320+/-50%. In vivo neoangiogenesis was increased two-fold (214+/-42%, 20 days). The NOS inhibitor L-NAME did not inhibit the TZD-induced upregulation of EPC. EPC from TZD-treated animals showed reduced in vivo apoptosis (65+/-2.8% of vehicle). In cultured human EPC, pre-treatment with pioglitazone prevented H(2)O(2)-induced apoptosis. Inhibition of EPC apoptosis by TZD was abolished in the presence of wortmannin but not by LNMA. In summary, TZD upregulates both number and functional capacity of endothelial progenitor cells. Pioglitazone prevents apoptosis of EPC in mice as well as in human EPC in a PI3K-dependent but NO-independent manner. Reduction of EPC apoptosis by TZD may be a potentially beneficial mechanism for patients with vascular diseases.

Role of integrin-linked kinase in vascular smooth muscle cells: Regulation by statins and angiotensin II

Our goal was to characterize the role of integrin-linked kinase (ILK) in vascular smooth muscle cells (VSMC), which play a crucial role in atherogenesis. Transfection of VSMC with wild-type and dominant-negative ILK cDNA constructs revealed that ILK mediates migration and proliferation of VSMC but has no effect on VSMC survival. The pro-atherogenic mediator angiotensin II increases ILK protein expression and kinase activity while statin treatment down-regulates ILK in VSMC. Functionally, ILK is necessary for angiotensin II-mediated VSMC migration and proliferation. In VSMC transduced with dominant-negative ILK, statins mediate an additive inhibition of VSMC migration and proliferation, while transfection with wild-type ILK is sufficient to overcome the inhibitory effects of statin treatment on VSMC migration and proliferation. In vivo, ILK is expressed in VSMC of aortic sections from wild-type mice where it is down-regulated following statin treatment and up-regulated following induction of atherosclerosis in apoE-/- mice. These data identify ILK as a novel target in VSMC for anti-atherosclerotic therapy.

17Beta-estradiol inhibits monocyte adhesion via down-regulation of Rac1 GTPase

Estrogens confer atheroprotective effects that remain poorly understood. We hypothesised that estrogens directly target monocytes, and investigated the pathways via which estrogens might impact on monocyte adhesion. In an in vitro model of the vasculature (parallel plate laminar flow chamber, 2 dynes/cm2), 17beta-estradiol (24 h, 0.1-1 microM) potently inhibits monocyte adhesion. In parallel, 17beta-estradiol down-regulates Rac1 GTPase activity in monocytes. Transfection of monocytic cells with dominant-negative Rac1N17 significantly decreases adhesion to human endothelial cells, while constitutively-active Rac1L61 augments adhesion. As determined by pull-down assays, Rac1 is rapidly activated by the chemokine stromal-derived factor-1 (SDF-1) in human monocytes (100 nM, 30 s). Within the same time period, SDF-1 mediates both ICAM-1/beta2- and VCAM-1/beta1-integrin-dependent monocyte adhesion, which is significantly decreased in cells overexpressing dominant-negative Rac1N17. Inhibitor studies revealed that Rac1-triggered monocyte adhesion is dependent upon actin rearrangement, while production of reactive oxygen species via Rac1 is not involved. Estrogen directly inhibits monocyte adhesion via down-regulation of Rac1, which is both necessary and sufficient to enhance monocyte adhesion under physiological flow conditions. These studies extend current knowledge about the mechanisms responsible for the vascular recruitment of pro-inflammatory cells, and potentially open up new avenues for the therapy of atherosclerosis.