Endovascular irradiation with the liquid beta-emitter Rhenium-188 to reduce restenosis after experimental wall injury

The effect of locally delivered c-myc antisense oligonucleotides combined with intravascular brachytherapy of 188Re liquid-filled balloon therapy on vascular smooth muscle cell proliferation in rabbit iliac arteries after injury with a balloon catheter

Poststenting restenosis is a significant clinical problem that involves vascular smooth muscle cell (VSMC) proliferation. We primarily investigated the effect of c-myc antisense oligodeoxynucleotides (ASODNs) combined with 188Re radiation therapy on VSMC proliferation in rabbit common iliac arteries injured by the porous balloon catheter to explore the therapeutic potential of the combined therapy for the prevention of restenosis. The iliac arteries in rabbits were injured with balloon catheters, and radiation therapy was carried out with a 2.5 mm balloon catheter filled with 188Re (8 or 15 Gy), and ASODNs (300 microg) were applied to the adventitia introduced using a pluronic gel releasing system and a lipofectin delivery system. After 3 weeks, the animals were killed and defined segments of arteries were sectioned. The histological sections were stained using alpha-actin immunohistochemistry staining. The positive alpha-actin ratios were calculated and analyzed statistically among groups. In contrast to the rate of alpha-actin positive cell staining in the control group, the rate of alpha-actin positive cell staining did not decrease (P > 0.05) in the 188Re-irradiated group (8 Gy). However, in the ASODN-treated group, the 188Re-irradiated group (15 Gy), and the combined ASODN - 188Reirradiated groups (8 or 15 Gy), the ratios had markedly decreased (P < 0.01). The effect of the combined group (ASODNs + 188Re (15 Gy)) provided the lowest level of alpha-actin positive cell staining (P < 0.01). The ASODNs (300 microg) effectively decreased VSMC poliferation. The effect of the 188Re radiation on the VSMCs depended on the dosage. The ASODNs (300 microg) and combined 188Re irradiation effectively lowered VSMC proliferation, and the effect was better than that achieved with any other treatment.

Rhenium-188 Mercaptoacetyltriglycine–filled Balloon Dilation in the Treatment of Recurrent Urethral Strictures: Initial Experience with Five Patients

PURPOSE

To evaluate the efficacy of beta-irradiation therapy with use of a rhenium-188 mercaptoacetyltriglycine ((188)Re-MAG(3))-filled balloon for the prevention of restenosis in urethral strictures refractory to repetitive surgical or interventional procedures.

MATERIALS AND METHODS

Five male patients with traumatic (n = 4) or postoperative anastomotic (n = 1) recurrent urethral strictures were included. One to four sessions of 20-30 Gy beta-irradiation at a 1-mm tissue depth with (188)Re-MAG(3)-filled balloon dilation were undertaken in each patient.

RESULTS

No procedural complications or toxicities were noted. During the mean follow-up period of 16.2 months, the stricture did not recur in two patients, whereas three patients required additional interventional procedures. In two of these patients, the treatment intervals between the required sessions were significantly prolonged. For the entire group, the mean treatment interval was prolonged from 2.2 months before (188)Re-MAG(3)-filled balloon dilation to 10.7 months after therapy.

CONCLUSION

(188)Re-MAG(3)-filled balloon dilation shows promise in preventing or delaying stricture recurrence in patients with recurrent urethral strictures.

Effects of irradiation using a radioisotope-filled balloon on tissue hyperplasia caused by stent placement in a canine urethral model

PURPOSE

To evaluate 20 Gy and 40 Gy of intraluminal beta-irradiation using a 188Re-7mercaptoacetyltriglycine (MAG3)-filled balloon catheter to reduce tissue hyperplasia caused by covered stent placement for 12 weeks of follow-up in a canine urethral model.

MATERIAL AND METHODS

Ten dogs underwent 188Re-MAG3-filled balloon dilatation immediately after stent placement; 20 Gy at 1-mm tissue depth in group I (n = 5) and 40 Gy in group II (n = 5), whereas 5 dogs (group III) underwent conventional balloon dilatation only.

RESULTS

There were no significant differences among the three groups for percentage diameter of stenosis, although this was highest in group III. There was a tendency toward lower mean thickness of the epithelial layer and the papillary projection for out-stent area, and thickness of the papillary projection and degree of inflammatory cells for instent area in groups I and II compared with group III. Thickness of the papillary projection in out-stent area was significantly different among the three groups (P = 0.031). It was significantly less thick in group I than in group III (P < 0.05), whereas group II was not significantly different from group III.

CONCLUSION

188Re-MAG3-filled balloon dilatation has the potential to reduce tissue hyperplasia after 12 weeks of follow-up in a canine urethral model. The use of 20 Gy compared to 40 Gy did not show significant differences.

Beta radiation in the treatment of in-stent restenosis of an in situ saphenous vein bypass graft A case report

We describe a case of instent restenosis in a femoral-distal saphenous vein bypass graft successfully treated with brachytherapy. A 45-year-old insulin-requiring diabetic woman underwent an in-situ femoral-anterior tibial bypass graft for a non-healing ischemic ulcer. Despite a technically successful percutaneous transluminal angioplasty and endovascular stenting of a retained valve within the threatened graft, the wound failed to heal. At the 1-month follow-up, instent restenosis was documented and successful cutting balloon angioplasty, complemented by adjunctive beta-irradiation was successfully performed. Clinical and hemodynamic success was achieved, with prompt ulcer healing and intermediate-term graft patency maintained on surveillance duplex ultrasound follow-up. We review the literature on radiation therapy in the management of peripheral arterial disease and discuss therapeutic options in the management of restenosis.

Cigarette smoke metal-catalyzed protein oxidation leads to vascular endothelial cell contraction by depolymerization of microtubules

Smoking is a significant risk factor for development of atherosclerosis. However, the pathophysiology of smoking-mediated vessel wall damage is not understood. With tools ranging from analytical chemistry to cell biology, we show that cigarette smoke contains metals that catalyze the direct oxidation of cellular proteins by smoke oxidants. Oxidation of cellular proteins causes a loss of microtubule function, culminating in microtubule depolymerization and proteasome-dependent degradation of alpha-tubulin. As a consequence of the microtubule collapse, cytoskeletal structures as well as intermediate filaments break down, leading finally to a contraction of vascular endothelial cells. We observed a smoke extract-induced, calpain-dependent degradation of the intracellular form of platelet-endothelial cell adhesion molecule 1/CD31, as well as a release of P-selectin/CD62P, IL-6, and IL-8 from endothelial cells into the supernatant. Increased levels of soluble CD62P and IL-6 are well known to be associated with smoking in humans. Increased permeability of the vascular endothelium is a crucial event in atherogenesis. This work highlights the compounds and mechanisms by which cigarette smoke induces leakiness of the vascular endothelium.

Regional Radiochemotherapy Using In Situ Hydrogel

PURPOSE

To evaluate the feasibility of regional radiochemotherapy of mammary tumors using in situ hydrogel loaded with cisplatin (CDDP) and rhenium-188 ((188)Re).

METHODS

Sodium alginate (SA) and calcium chloride were used to create a hydrogel for delivery of CDDP and (188)Re. In vitro studies were performed to evaluate cytotoxic effects of (188)Re-hydrogel and sustained-release ability of the CDDP-hydrogel. Tumor-bearing rats were injected with (188)Re-hydrogel (0.5-1 mCi/rat), (188)Re-perrhenate (0.5-1 mCi/rat, intratumoral, I.T.), CDDP-hydrogel (3 mg/kg), and (188)Re-hydrogel loaded with CDDP (3 mg/kg body weight, 0.5-1 mCi/rat), respectively, and groups receiving (188)Re were imaged at 24 and 48 h postinjection. Tumor volume, body weight, imaging, and kidney function were assessed as required for each group.

RESULTS

Successful formation of the hydrogel was demonstrated by cytotoxic effects of (188)Re-hydrogel and slow release of CDDP-hydrogel in vitro. Tumor volume measurements showed significant delay in tumor growth in treated vs. control groups with minimal variation in normal kidney function for the CDDP-hydrogel group. Scintigraphic images indicated localization of (188)Re-hydrogel in the tumor site up to 48 h postinjection.

CONCLUSIONS

Our data demonstrate the feasibility of using hydrogel for delivery of chemotherapeutics and radiation locally. This technique may have applications involving other contrast modalities as well as treatment in cases where tumors are inoperable.

Intracoronary beta-irradiation with a rhenium-188-filled balloon catheter: a randomized trial in patients with de novo and restenotic lesions

BACKGROUND

Restenosis requiring reintervention is the main limitation of coronary angioplasty. Intracoronary irradiation reduces neointimal proliferation. We studied the efficacy of a self-centering liquid rhenium-188-filled balloon catheter for coronary beta-brachytherapy.

METHODS AND RESULTS

After successful coronary angioplasty with or without stenting, 225 patients (71% de novo lesions) were randomly assigned to receive 22.5 Gy intravascular beta-irradiation in 0.5-mm tissue depth (n=113) or to receive no additional intervention (n=112). Clinical and procedural data did not differ between the groups except a higher rate of stenting in the control group (63%) compared with the rhenium-188 group (45%, P<0.02). After 6 months of follow-up, late loss was significantly lower in the irradiated group compared with the control group, both of the target lesion (0.11+/-0.54 versus 0.69+/-0.81 mm, P<0.0001) and of the total segment (0.22+/-0.67 versus 0.70+/-0.82 mm, P<0.0001). This was also evident in the subgroup of patients with de novo lesions and independent from stenting. Binary restenosis rates were significantly lower at the target lesion (6.3% versus 27.5%, P<0.0001) and of the total segment (12.6% versus 28.6%, P<0.007) after rhenium-188 brachytherapy compared with the control group. Target vessel revascularization rate was significantly lower in the rhenium-188 (6.3%) compared with the control group (19.8%, P=0.006).

CONCLUSIONS

Intracoronary beta-brachytherapy with a rhenium-188 liquid-filled balloon is safe and efficiently reduces restenosis and revascularization rates after coronary angioplasty.

[Brachytherapy for coronary restenosis: state of art in 2003]

Based on therapeutic approach for benign diseases, vascular brachytherapy decreases smooth vascular muscle cells proliferation and multiplication which lead to the formation of the neo-intima. The radioactive positive action affects arterial recoil due to post angioplasty vessel injury. Randomised studies has shown good angiographic results up to 6 months of follow-up, with 50% in-stent restenosis rate decrease and on the analysed segment as well. Decrease on Mace and TLR show statistically significance. Results don't correlate with emitter and bêta emitters had been introduced in France recently. Vascular brachytherapy is actually indicated for in-stent restenosis, there is no evidence to perform this treatment for de novo lesion. Geographic miss, source centering, late thrombosis and pullback procedure may interfere with treatment quality. IVUS allows best target volume determination to a higher quality level. Internationals guidelines such as Eva-Gec-Estro recommendations could increase treatment safety and enable development of an optimal technique.

Dosimetry study of Re-188 liquid balloon for intravascular brachytherapy using polymer gel dosimeters and laser-beam optical CT scanner

Angioplasty balloons inflated with a solution of the beta-emitter Re-188 have been used for intravascular brachytherapy to prevent restenosis. Coronary stents are in extensive clinical use for the treatment of de novo atherosclerotic stenoses. In this study, the effect of an interposed stent on the dose distribution has been measured for Re-188 balloon sources using the proprietary BANG polymer gel dosimeters and He-Ne laser-beam optical CT scanner. In polymer gels, after ionizing radiation is absorbed, free-radical chain-polymerization of soluble acrylic monomers occurs to form an insoluble polymer. The BANG polymer gel dosimeters used in these measurements allow high resolution, precise, and accurate three-dimensional determination of dosimetry from a given source. Re-188 liquid balloons, with or without an interposed metallic stent, were positioned inside thin walled tubes placed in such a polymer dosimeter to deliver a prescribed dose (e.g., 15 Gy at 0.5 mm). After removing the balloon source, each irradiated sample was mounted in the optical scanner for scanning, utilizing a single compressed He-Ne laser beam and a single photodiode. In the absence of a stent, doses at points along the balloon axis, at radial distance 0.5 mm from the balloon surface and at least 2.5 mm from the balloon ends, are within 90% of the maximum dose. This uniformity of axial dose is independent of the balloon diameter and length. Dose rate and dose uniformity for intravascular brachytherapy with Re-188 balloon are altered by the presence of stent. The dose reduction by the stent is rather constant (13%-15%) at different radial distances. However, dose inhomogeneity caused by the stent decreases rapidly with radial distance.

Peripheral vascular brachytherapy

Ongoing advances in peripheral endovascular technology have been met with disappointing results because of restenosis within the treated vessel. In particular, stent balloon angioplasty of peripheral vessels has yet to achieve patency rates that approximate conventional treatment in the long term. Recent advances in stent, balloon, and wire construction include the incorporation of radioactive substances in an attempt to ameliorate the inflammatory response provoked by typical endovascular manipulation, a technique termed vascular brachytherapy. gamma- and beta-isotopes and external beam radiation target the very cell population whose activity results in the development of neointimal hyperplasia. Although most clinical research examining the efficacy of vascular brachytherapy has emerged from the coronary artery literature, the use of vascular brachytherapy also has been examined in the peripheral arterial tree and has shown promising results. Current data indicate that vascular brachytherapy is a safe and accessible adjunctive endovascular maneuver that may improve the short-term patency rate of peripheral endovascular applications. The effects on long-term patency rates remain indeterminate compared to conventional therapy.