Effects of locally administered argatroban on restenosis after balloon angioplasty: experimental and clinical study

Nanoparticle eluting-angioplasty balloons to treat cardiovascular diseases

Nanoparticles (NPs) can be used to locally deliver anti-restenosis drugs when they are infused directly to the injured arteries after intervention procedures such as angioplasty. However, the efficacy of transferring NPs via infusion to the arterial wall is limited, at least partially, due to poor NP retention on the inner artery wall. To improve NP retention, angioplasty balloons coated with drug-loaded NPs were fabricated via either layer-by-layer (LbL) electrostatic coating or acrylic-based hydrogel (AAH) coating techniques. Three types of NPs, namely poly (lactide-co-glycolide) (PLGA), biodegradable photo-luminescent PLGA and urethane doped polyester were studied. The transfer efficacy of NPs from various coatings to the arterial wall were further evaluated to find the optimal coating conditions. The ex vivo NP transfer studies showed significantly more NPs being transferred to the rat arterial wall after the angioplasty procedure by the AAH coating (95% transfer efficiency) compared to that of the LbL technique (60%) and dip coating (20%) under flow conditions (10 dyn/cm²). Our results suggest that the AAH coating of drug-loaded NPs on the angioplasty balloon could potentially provide superior retention of drug-loaded NPs onto the arterial wall for a better local delivery of drug-loaded NPs to effectively treat arterial diseases.

Biodegradable polymer-based, argatroban-eluting, cobalt-chromium stent (JF-04) for treatment of native coronary lesions: final results of the first-in-man study and lessons learned

AIMS

The aim of the study was to investigate the six-month angiographic and nine-month clinical follow-up outcomes in a first-in-man study using the biodegradable polymer-based cobalt-chromium argatroban-eluting stent (JF-04) for treatment of native coronary atherosclerotic lesions.

METHODS AND RESULTS

A total of 31 patients with either stable or unstable angina, or silent myocardial ischaemia, exhibiting de novo coronary lesions were enrolled at seven Japanese sites. The lesions were treated with the JF-04 stent after predilatation. The primary endpoint was angiographic in-stent late loss six months after implantation. The secondary endpoints included angiographic restenosis and in-stent volume obstruction by intravascular ultrasound at six months and target vessel failure (TVF) at nine months. Procedural success was achieved in 100% of cases. At six months, angiographic in-stent late loss was 1.01±0.48 mm and binary restenosis was observed in nine cases (29.0%). Among these restenotic cases, most (n=8) demonstrated advanced angiographic restenosis patterns, including diffuse/proliferative restenosis and total occlusion. At nine months, TVF was observed in four cases (12.9%), exclusively attributed to target vessel revascularisation.

CONCLUSIONS

This argatroban-eluting stent failed to inhibit neointimal hyperplasia sufficiently, despite the theoretical benefits and promising clinical experience with local drug delivery.

Recombinant human thrombomodulin inhibits arterial neointimal hyperplasia after balloon injury

OBJECTIVE

Smooth muscle cell proliferation is a major pathophysiologic factor in injury-induced neointimal hyperplasia and recurrent stenosis. We have demonstrated that recombinant human thrombomodulin (rTM) inhibits thrombin-induced arterial smooth muscle cell proliferation in vitro. The purpose of this study was to investigate the effect of rTM on neointimal hyperplasia in vivo.

METHODS

A rabbit femoral artery balloon injury model was used. Bilateral superficial femoral arteries were deendothelialized with a 2F arterial embolectomy catheter. rTM (145 microg/kg; 2.0 microg/mL in circulation) or Tris-hydrochloride vehicle control was administered intravenously during the procedure, then either discontinued (group A) or administered twice daily for an additional 48 hours (group B). Rabbits were euthanized at 4 days and at 1, 2, and 4 weeks, and femoral artery specimens were prepared with in situ perfusion fixation and paraffin embedding. Luminal, intima, media, and whole artery areas were quantitated with digital imaging computerized planimetry. Intima-media and lumen-whole artery ratios were calculated. The injury-induced inflammatory reaction was also evaluated with light microscopy, scanning and transmission electron microscopy, and immunohistochemical and immunohistofluorescence staining.

RESULTS

In the buffer control group, neointimal hyperplasia after femoral artery balloon injury was evident at 2 weeks, and was pronounced at 4 weeks (P <.0001). Infusion of rTM significantly inhibited intimal hyperplasia at both 2 and 4 weeks (P <.0001). In group A, rTM reduced the intima-media ratio by 27% and 39% at 2 and 4 weeks, respectively. Extended administration of rTM (group B) resulted in inhibition of hyperplasia by 57% and 30% at 2 and 4 weeks, respectively, but failed to reach significance compared with the shorter exposure. rTM infusion significantly inhibited thrombosis (8.1-fold) compared with the buffer control group (P =.012). rTM had no significant effect on lumen area or lumen-whole artery ratio, but treated arteries demonstrated significantly less compensatory dilatation (P =.045), as measured by whole artery area in response to less intimal hyperplasia. rTM administration inhibited platelet adhesion and inhibition of neutrophil infiltration to a degree that approached statistical significance (P =.0675).

CONCLUSIONS

Systemic intravenous administration of rTM significantly decreases neointimal hyperplasia and improves patency in the rabbit femoral artery after balloon injury. In addition to exhibiting antithrombotic and antiproliferative effects, rTM may also invoke an anti-inflammatory mechanism, and may alter vascular remodeling in a multidimensional role to inhibit recurrent stenosis after arterial injury.

Inhibition of Intimal Hyperplasia by Direct Thrombin Inhibitors in an Animal Vein Bypass Model

Many functions of the coagulation system have nonthrombotic effects. The indirect thrombin inhibitor heparin has been previously shown to be effective in limiting intimal hyperplasia (IH). We sought to study the effect of thrombin on IH by using two direct thrombin inhibitors (DTIs), argatroban and lepirudin. Sprague-Dawley rats underwent interposition vein grafting to the carotid artery. Vein grafts were treated with either saline (n = 6) or one of the two DTIs (n = 6 for both). At 30 days, the rats were sacrificed and vessels were perfusion fixed. Sections of the proximal carotid artery, graft, and both anastomoses were stained with both hematoxlyin/eosin and von Gieson's elastin stain. Sections were examined and compared for luminal area and intima-to-media (IM) ratio. The vessels treated with DTIs had less (p < 0.05) IH (IM ratio for proximal anastomosis: control 1.036 +/- 0.857, lepirudin 0.373 +/- 0.21, argatroban 0.182 +/- 0.118) and better lumen preservation than the control vessels (lumen area of proximal anastomosis: control 1.69 +/- 0.9, lepirudin 2.45 +/- 0.74, argatroban 2.81 +/- 0.78). There were no thromboses in the DTI-treated vessels. Dilatation of the graft segment was noted in the argatroban group. Thus, DTIs are effective at reducing IH in a small-animal model, suggesting that inhibition of thrombin has a protective role in IH. In addition, a difference of action between DTIs is suggested by the dilatation seen only in the argatroban-treated graft sections.

No Difference Among Modern Contrast Media's Effect on Neointimal Proliferation and Restenosis After Coronary Stenting in Pigs

RATIONALE AND OBJECTIVES

Recent clinical trials indicate that the choice of radiographic contrast media (CM) may influence the late outcome of coronary interventions. This might be explained by the different effects of various CM on neointimal proliferation.

METHODS

The effect of a 1-hour incubation of bovine aortic smooth muscle cells in ioxaglate or iopromide solution on in vitro cell division was tested. Furthermore, in 12 pigs randomized into 3 groups (iopromide, ioxaglate, and iosimenol; a novel nonionic dimer), coronary angiography was performed followed by implantation of stents. After 28 days, restenosis was assessed by quantitative angiography and histomorphometry.

RESULTS

Compared with saline, CM did no change cell counts up to 15 days after incubation. Baseline parameters in the pigs indicated no difference between the test groups. After 28 days, the test groups showed no significant differences in the parameters characterizing in-stent restenosis.

CONCLUSIONS

Under the experimental conditions iopromide, ioxaglate, and iosimenol had no or very similar direct or otherwise mediated effect on cell proliferation and restenosis.

Argatroban, specific thrombin inhibitor, induced phenotype change of cultured rabbit vascular smooth muscle cells

To investigate whether argatroban ((2R,4R)-4-methyl-1-[N(2)-((RS)-3-methyl-1,2,3,4-tetrahydro-8-quinolinesulfonyl)-L-arginyl]-2-piperidinecarboxylic acid hydrate, a selective thrombin inhibitor, exerts a direct action on phenotype conversion of vascular smooth muscle cells, cultured rabbit aortic vascular smooth muscle cells were employed. Myosin heavy chain isoforms (SM1, SM2, and SMemb) mRNA expressions were evaluated by in situ hybridization and reverse transcription-polymerase chain reaction (RT-PCR). After the cells were incubated in serum-free medium containing argatroban (10 and 50 microg/ml) and platelet-derived growth factor (PDGF)-BB (10 and 50 ng/ml) for 3 h, total RNA was extracted. In situ hybridization demonstrated that myosin heavy-chain isoform mRNAs were homogenously expressed in argatroban- and PDGF-BB-treated cells. RT-PCR revealed that SM1/SM2 mRNA expressions were not changed with argatroban, while SMemb mRNA expression was increased to 1.6-fold with a statistical significance (P<0.05). Treatment with argatroban (10 and 50 microg/ml) at 24 h did not change SM1/SM2 mRNA expressions. Although SMemb mRNA expression was slightly increased, there was no statistical significance. Other phenotype markers including plasminogen activator inhibitor-1 (PAI-1) and beta-actin mRNAs were also significantly increased by argatroban. In conclusion, argatroban can directly induce phenotype conversion of vascular smooth muscle cells with the resultant up-regulation of SMemb, PAI-1, and beta-actin mRNAs.