Effects of local delivery of trapidil on neointima formation in a rabbit angioplasty model

Rationale and study design of the OISTER trial: optical coherence tomography evaluation of stent struts re-endothelialization in patients with non-ST-elevation acute coronary syndromes--a comparison of the intrEpide tRapidil eluting stent vs. taxus drug-eluting stent implantation

BACKGROUND

Drug-eluting stents (DES) have been designed to prevent restenosis, but long-term clinical outcome may be offset by an increased risk of stent thrombosis, which is associated with suboptimal stent implantation or delayed re-endothelialization. DES implantation has also been associated with local persistent endothelial dysfunction. Conversely, Trapidil is a potent anti-inflammatory, vasodilatator and antiproliferative drug and several studies have shown anti-restenotic effects, suggesting substantial clinical benefits through the use of Trapidil-eluting DES.

STUDY DESIGN

This is a longitudinal, single-blind, double-arm, randomized multicenter study. Forty patients with non-ST-elevation acute coronary syndromes who present at the index procedure with multivessel coronary disease in the major epicardial coronary arteries will be enrolled. Patients should present a culprit lesion with stenosis 70% or more associated with another stenosis 70% or more in another coronary artery. Patients will be randomized in a 1: 1 fashion to receive either an Intrepide trapidil-eluting stent or a Taxus paclitaxel-eluting stent on the culprit lesion. After 90 days, the nonculprit lesion will be treated with the stent of the opposite randomization arm and optical coherence tomography (OCT) analysis of the index stented segment will be performed. Follow-up angiography, combined with vasomotor analysis of endothelial function by rapid atrial pacing, will be done at 12 months after the index procedure on both stents. To further characterize the status of the endothelium, serum measurement of vascular endothelial growth factor gradient between the aorta and 15 mm distal to the implanted stent will be performed at 12 months. The primary endpoint of the study is to compare stent struts re-endothelialization at 90 days by OCT. The secondary endpoint is to compare angiographic outcome and coronary endothelial function 12 months after the index procedure and to compare clinical outcome at 1 and 2 years between trapidil-eluting DES versus paclitaxel-eluting DES.

CONCLUSION

We hypothesize that the utilization of trapidil-eluting DES in the setting of acute coronary syndromes will be characterized by a greater early re-endothelialization associated with an antiproliferative effect offering a similar efficacy with a better safety profile compared with first-generation DES.

Pharmacological treatment for prevention of restenosis

Coronary artery disease (CAD) is the leading cause of mortality and morbidity among adults in the Western world. Coronary artery bypass grafting and percutaneous coronary interventions (PCI) have gained widespread acceptance for the treatment of symptomatic CAD. There has been an explosive growth worldwide in the utilisation of PCI, such as balloon angioplasty and stenting, which now accounts for over 50% of coronary revascularisation. Despite the popularity of PCI, the problem of recurrent narrowing of the dilated artery (restenosis) continues to vex investigators. In recent years, significant advances have occurred in the understanding of restenosis. Two processes seem to contribute to restenosis: remodelling (vessel size changes) and intimal hyperplasia (vascular smooth muscle cell [VSMC] proliferation and extracellular matrix [ECM] deposition). Despite considerable efforts, pharmacological approaches to decrease restenosis have been largely unsuccessful and the only currently applied modality to reduce the restenosis rate is stenting. However, stenting only prevents remodelling and does not inhibit intimal hyperplasia. Several potential targets for inhibiting restenosis are currently under investigation including platelet activation, the coagulation cascade, VSMC proliferation and migration, and ECM synthesis. In addition, new approaches for local drug therapy, such as drug eluting stents, are currently being evaluated in preclinical and clinical studies. In this article, we critically review the current status of drugs that are being evaluated for restenosis at various stages of development (in vitro, preclinical animal models and human trials).

Effects of triazolopyrimidine on lipid peroxidation and nitric oxide levels in the corticosteroid-impaired healing of rat tracheal anastomoses

Corticosteroids are used to reduce the oedema and prevent scar tissue formation of the upper airways by their ability to inhibit influx of inflammatory cells, limit capillary permeability and block collagen synthesis in the early stages of wound healing. Triazolopyrimidine (Trapidil) is an antiplatelet agent that acts in part as a phosphodiesterase inhibitor and as a competitive inhibitor of the platelet-derived growth factor (PDGF) receptor. Trapidil, with its vasodilator and NO releasing effect may have some potential to diminish the tissue injury. This study was carried out to evaluate the effects of trapidil (triazolopyrimidine) on lipid peroxidation and nitric oxide in the corticosteroid-impaired healing of tracheal anastomoses. Thirty-four adult Wistar rats were divided into five groups. The animals underwent tracheal transection and primary anastomoses. The groups were assigned as follows: group I, control, (GI, n = 6); group II, sham, (GII, n = 6); group III, dexamethasone, 0.1 mg kg(-1) twice daily intramuscularly, (GIII, n = 8); group IV, trapidil, 6 mg kg(-1) twice daily intraperitoneally (GIV, n = 7); group V, dexamethasone, 0.1 mg kg(-1) plus trapidil, 6 mg kg(-1) twice daily (GV, n = 7), for 1 week. After 1 week, anastomotic healing was assessed by measurement of bursting pressure, evaluation of histopathology, measurement of MDA and nitrite/nitrate levels. In GIII, GIV and GV bursting pressures resulted in significantly reduced anastomotic strength compared to the controls (p < 0.001 for all groups). The difference between bursting pressures of GIII and GIV was not found to be statistically significant (p = 0.966). In regard to fibroblast proliferation and collagen content, a significant difference was found between GIII and GI (p < 0.01), A significant difference was also found when GIV and GV were compared to GIII (p < 0.01). MDA and nitrite/nitrate levels were found to be higher in GIII when compared to all other groups. MDA levels of GIV and GV rats were found to be lower than GIII (p < 0.001, for both groups). The nitrite/nitrate levels of GIV and GV rats were found to be lower than GIII (p < 0.05), and higher than GI (p < 0.001). Trapidil may be useful for its preventive effects on lipid peroxidation and possible increases in NO in cases with corticosteroid-impaired healing of trachea anastomoses.