Impact of Stent Surface on Thrombogenicity and Vascular Healing

Abstract

Flat disks and strips were fabricated from platinum chromium (PtCr; Carpenter Technology, Reading PA) and were cut from sheets by electric discharge machining. Final dimensions of disks were 1.70 cm (0.680 inches) in diameter, and final dimensions of strips were 8.89 cm (3.5 inches)×0.782 cm (0.308 inches)×0.079 cm (0.031 inches).Background-Emerging drug-eluting stent technologies are evolving toward the elimination of polymeric component used as the method for modulating drug delivery. Although this technological approach seems to be biologically appealing, the impact of durable polymers and metallic stent surfaces on vascular healing remains unclear. In the present study, we aimed to compare the independent effect of a durable polymer and a metallic stent surface on thrombogenicity and endothelial cell coverage using different in vitro and in vivo experimental models. Methods and Results-Platinum chromium (PtCr) and polyvinylidene fluoride-co-hexafluoropropene (PVDF-HFP)-coated surfaces were evaluated in this study. Thrombogenicity was assessed by exposing all surfaces to human blood under shear flow conditions. The inflammatory potential of the material was evaluated by measuring cytokine release from THP-1 cells exposed to all surfaces for 24 hours. Endothelial cell coverage was evaluated by detection of CD31 after the stents were exposed to human coronary artery endothelial cells for ≤14 days. Platelet adhesion (P<0.01) and activation (P=0.03) on PVDF-HFP were greater than on PtCr. In vivo, PVDF-HFP revealed more neointimal area (P<0.01) and residual parastrut fibrin (P=0.01) at 30 days compared with PtCr. PtCr displayed higher endothelialization rates and higher vascular endothelial-cadherin expression at 7 and 14 days (P=0.02) compared with PVDF-HFP. Conclusions-Thrombogenicity and vascular healing differ among metallic and polymeric stent surfaces. PVDF-HFP exhibits higher degrees of platelet activation-adhesion and thrombus accumulation in vivo compared with PtCr. PtCr displayed higher degrees of endothelial surface coverage compared with PVDF-HFP surfaces. (Circ Cardiovasc Interv. 2013;6:370-377.)

Thrombogenicity and Early Vascular Healing Response in Metallic Biodegradable Polymer-Based and Fully Bioabsorbable Drug-Eluting Stents

“…In a previous study, Eppihimer et al determined acute thrombus formation in a closed loop system, in which stents made of PtCr were exposed to human blood under physiological shear rates in the presence or absence of polyvinylidene fluoride-co-hexafluoropropene (PVDF-HFP) polymer coating. 15 In that study, PtCr stents exhibited significantly less thrombus formation when compared with their PVDF-HFP coated counterparts, 15 which may partly explain the favorable outcomes of the thin-strut EES made from a PtCr alloy in the current study. Although studies by Kolandaivelu and Eppihimer used customized stent designs to specifically address the comparative influence of stent components on vascular healing, we sought to characterize the integrated performance of clinically used devices rather than to decipher the effect of individual stent components.…”

“…Durable PVDF-HFP polymer surfaces are associated with lower endothelial cell coverage and maturity in the early phase after stent placement when compared with bare PtCr metallic stent surfaces used in the thin-strut biodegradable polymer EES. 15 However, these findings were observed in the absence of drug and may not be applicable to commercially available DES. In another experimental study, endothelialization of 2 durable polymers, poly(ethylene-co-vinylacetate) and poly(butyl methacrylate) was reduced, whereas enhanced endothelial coverage was observed in biodegradable polymers, namely PLLA, poly(3-hydroxybutyrate), poly(4-hydroxybutyrate), and a polymeric blend of PLLA/poly(4-hydroxybutyrate), tested in in vitro cultures using human umbilical endothelial cells.…”

Antiplatelet therapy before cardiac surgery

“…The antiproliferative properties of the eluted drugs were [23]. The need to increase the intensity and specificity, as well as to prolong the duration, of DAPT was the direct consequence and the right choice to protect patients from deleterious acute stent thrombosis [24].…”

Dose-dependent vascular response following delivery of sirolimus via fast releasing, biodegradable polymer stent matrix: an experimental study in the porcine coronary model of restenosis

“…The optimisation of vascular response and clinical outcome of DES technologies is dependent upon multiple factors. The utilisation of biodegradable and biocompatible polymers has shown theoretical advantages in vitro and in the experimental setting [12]; however, the clinical benefit, especially when compared with second-generation durable polymer counterparts, is inconclusive [13). It seems that the type of drug, and specifically modification of the release profile, plays more pronounced role.…”