Pawel Gasior

Experimental evaluation of pharmacokinetic profile and biological effect of a novel paclitaxel microcrystalline balloon coating in the iliofemoral territory of swine.

New paclitaxel coated balloons (PCB) developments have been proposed to maintain therapeutic levels of drug in the tissue while decreasing particle release. In this series of studies, we evaluated the pharmacokinetic profile and biological effects after paclitaxel delivery via novel microcrystalline PCB coating (mcPCB, Pax®, Balton) in porcine iliofemoral arteries. Methods: Ten domestic swine were enrolled yielding 24 iliofemoral segments for evaluation. In the pharmacokinetic study, nine mcPCBs were dilated for 60 sec and animals sacrificed after 1 hr, 3 and 7 days. Studied segments were harvested and tissue paclitaxel concentration was analyzed utilizing HPLC. In the biological response evaluation, self‐expandable stents were implanted followed by post dilation with either mcPCB (n = 10) or POBA (n = 5). After 28 days, angiography was performed, animals were sacrificed and stented segments harvested for histopathological evaluation. Results: The 1‐hr, 3 and 7 days vessel paclitaxel concentrations were 152.9 ± 154.5, 36.5 ± 49.5, and 0.9 ± 0.7 ng/mg respectively. In the biological response study, stents in the mcPCB group presented lower angiographic measures of neointimal hyperplasia as expressed by late loss when compared to POBA (−0.43 ± 0.9 vs. 0.23 ± 1.2; P = 0.24) at 28 days. In the histopathological evaluation, percent area of stenosis (%AS) was reduced by 42% in the mcPCB group (P < 0.05). The healing process in mcPCB group was comparable to POBA with regard to fibrin deposition (0.7 vs. 0.7; P = ns), neointimal maturity (1.97 vs. 1.93; P = ns), inflammation score (0.92 vs. 1; P = ns) and endothelialization score (1.77 vs. 1.73; P = ns). The mcPCB group did however display a greater tendency of medial cell loss and mineralization (60% vs. 0; P = 0.08). Conclusions: Delivery of paclitaxel via a novel mcPCB resulted in low long‐term tissue retention of paclitaxel. However, this technological approach displayed reduced neointimal proliferation and favorable healing profile.

Extracellular Matrix Proteomics Reveals Interplay of Aggrecan and Aggrecanases in Vascular Remodeling of Stented Coronary Arteries

Background: Extracellular matrix (ECM) remodeling contributes to in-stent restenosis and thrombosis. Despite its important clinical implications, little is known about ECM changes post–stent implantation. Methods: Bare-metal and drug-eluting stents were implanted in pig coronary arteries with an overstretch under optical coherence tomography guidance. Stented segments were harvested 1, 3, 7, 14, and 28 days post-stenting for proteomics analysis of the media and neointima. Results: A total of 151 ECM and ECM-associated proteins were identified by mass spectrometry. After stent implantation, proteins involved in regulating calcification were upregulated in the neointima of drug-eluting stents. The earliest changes in the media were proteins involved in inflammation and thrombosis, followed by changes in regulatory ECM proteins. By day 28, basement membrane proteins were reduced in drug-eluting stents in comparison with bare-metal stents. In contrast, the large aggregating proteoglycan aggrecan was increased. Aggrecanases of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family contribute to the catabolism of vascular proteoglycans. An increase in ADAMTS-specific aggrecan fragments was accompanied by a notable shift from ADAMTS1 and ADAMTS5 to ADAMTS4 gene expression after stent implantation. Immunostaining in human stented coronary arteries confirmed the presence of aggrecan and aggrecan fragments, in particular, at the contacts of the stent struts with the artery. Further investigation of aggrecan presence in the human vasculature revealed that aggrecan and aggrecan cleavage were more abundant in human arteries than in human veins. In addition, aggrecan synthesis was induced on grafting a vein into the arterial circulation, suggesting an important role for aggrecan in vascular plasticity. Finally, lack of ADAMTS-5 activity in mice resulted in an accumulation of aggrecan and a dilation of the thoracic aorta, confirming that aggrecanase activity regulates aggrecan abundance in the arterial wall and contributes to vascular remodeling. Conclusions: Significant differences were identified by proteomics in the ECM of coronary arteries after bare-metal and drug-eluting stent implantation, most notably an upregulation of aggrecan, a major ECM component of cartilaginous tissues that confers resistance to compression. The accumulation of aggrecan coincided with a shift in ADAMTS gene expression. This study provides the first evidence implicating aggrecan and aggrecanases in the vascular injury response after stenting.

Three-month evaluation of strut healing using a novel optical coherence tomography analytical method following bioresorbable polymer everolimus-eluting stent implantation in humans: the TIMELESS study

Aims Bioresorbable polymer drug-eluting stent technologies have been considered to have the potential to enhance vascular healing by reducing polymer exposure to the vessel wall, potentially allowing the earlier discontinuation of dual antiplatelet therapy. At present, the early vascular healing response to this type of technologies is still unclear. Patients and methods The TIMELESS study is a multicenter, prospective, single-arm study that enrolled real-world patients undergoing percutaneous coronary intervention. All patients underwent Synergy stent implantation, which consists of a platinum–chromium platform coated with an ultra-thin abluminal bioabsorbable poly-D,L-lactide-co-glycolide polymer-eluting everolimus. Results A total of 37 patients were included in the study. The majority of the patients underwent percutaneous coronary intervention because of acute coronary syndromes. At 3 months, angiographic follow-up showed a percentage diameter of stenosis of 8.1±7.5% and an angiographic late loss of 0.03±0.24 mm. In all analyzed struts, less than 1% of struts were definitely uncovered or covered with fibrin, 12.5% (5.0–18.5%) showed evidence of partial coverage, and the remaining (∼85%) were fully covered. No stent thrombosis was observed up to 12 months of clinical follow-up. Conclusion In a real-world population, the implantation of a bioresorbable polymer drug-eluting stent resulted in almost complete strut coverage throughout the entire stent length at 3 months. The clinical implications for antiplatelet therapy and outcomes should be investigated further.

Four-year polymer biocompatibility and vascular healing profile of a novel ultrahigh molecular weight amorphous PLLA bioresorbable vascular scaffold: an OCT study in healthy porcine coronary arteries

AIMS The vascular healing profile of polymers used in bioresorbable vascular scaffolds (BRS) has not been fully characterised in the absence of antiproliferative drugs. In this study, we aimed to compare the polymer biocompatibility profile and vascular healing response of a novel ultrahigh molecular weight amorphous PLLA BRS (FORTITUDE®; Amaranth Medical, Mountain View, CA, USA) against bare metal stent (BMS) controls in porcine coronary arteries. METHODS AND RESULTS Following device implantation, optical coherence tomography (OCT) evaluation was performed at 0 and 28 days, and at one, two, three and four years. A second group of animals underwent histomorphometric evaluation at 28 and 90 days. At four years, both lumen (BRS 13.19±1.50 mm2 vs. BMS 7.69±2.41 mm2) and scaffold areas (BRS 15.62±1.95 mm2 vs. BMS 8.65±2.37 mm2) were significantly greater for BRS than BMS controls. The degree of neointimal proliferation was comparable between groups. Histology up to 90 days showed comparable healing and inflammation profiles for both devices. CONCLUSIONS At four years, the novel PLLA BRS elicited a vascular healing response comparable to BMS in healthy pigs. Expansive vascular remodelling was evident only in the BRS group, a biological phenomenon that appears to be independent of the presence of antiproliferative drugs.

Comparative Characterization of Biomechanical Behavior and Healing Profile of a Novel Ultra-High-Molecular-Weight Amorphous Poly-l-Lactic Acid Sirolimus-Eluting Bioresorbable Coronary Scaffold

Background—Clinically available bioresorbable scaffolds (BRS) rely on polymer crystallinity to achieve mechanical strength resulting in limited overexpansion capabilities and structural integrity when exposed to high-loading conditions. We aimed to evaluate the biomechanical behavior and vascular healing profile of a novel, sirolimus-eluting, high-molecular-weight, amorphous poly-L-lactic acid–based BRS (Amaranth BRS). Methods and Results—In vitro biomechanical testing was performed under static and cyclic conditions. A total of 99 devices (65 Amaranth BRS versus 34 Absorb bioresorbable vascular scaffold [BVS]) were implanted in 99 coronary arteries of 37 swine for pharmacokinetics and healing evaluation at various time points. In the Absorb BVS, the number of fractures per scaffold seen on light microscopy was 6.0 (5.0–10.5) when overexpanded 1.0 mm above nominal values (≈34%). No fractures were observed in the Amaranth BRS group at 1.3 mm above nominal values (≈48% overexpansion). The number of fractures was higher in the Absorb BVS on accelerated cycle testing over time (at 24K cycles=5.0 [5.0–9.0] Absorb BVS versus 0.0 [0.0–0.5] Amaranth BRS). Approximately 90% of sirolimus was found to be eluted by 90 days. Optical coherence tomography analysis demonstrated lower percentages of late scaffold recoil in the Amaranth BRS at 3 months (Amaranth BRS=−10±16.1% versus Absorb BVS=10.7±13.2%; P=0.004). Histopathology analysis revealed comparable levels of vascular healing and inflammatory responses between both BRSs up to 6 months. Conclusions—New-generation high-molecular-weight amorphous poly-L-lactic acid scaffolds have the potential to improve the clinical performance of BRS and provide the ideal platform for the future miniaturization of the technology.

Impact of Fluoropolymer-Based Paclitaxel Delivery on Neointimal Proliferation and Vascular Healing: A Comparative Peripheral Drug-Eluting Stent Study in the Familial Hypercholesterolemic Swine Model of Femoral Restenosis

Background— A polymer-free peripheral paclitaxel-eluting stent (PES, Zilver PTX, Cook, IN) has shown to improve vessel patency after superficial femoral angioplasty. A new-generation fluoropolymer-based PES (FP-PES; Eluvia, Boston Scientific, MA) displaying more controlled and sustained paclitaxel delivery promise to improve the clinical outcomes of first-generation PES. We sought to compare the biological effect of paclitaxel delivered by 2 different stent-coating technologies (fluoropolymer-based versus polymer-free) on neointimal proliferation and healing response in the familial hypercholesterolemic swine model of femoral restenosis. Methods and Results— The biological efficacy of clinically available FP-PES (n=12) and PES (n=12) was compared against a bare metal stent control (n=12; Innova, Boston Scientific, MA) after implantation in the femoral arteries of 18 familial hypercholesterolemic swine. Longitudinal quantitative vascular angiography and optical coherence tomography were performed at baseline and at 30 and 90 days. Histological evaluation was performed at 90 days. Ninety-day quantitative vascular angiography results showed a lower percent diameter stenosis for FP-PES (38.78% [31.27–47.66]) compared with PES (54.16% [42.60–61.97]) and bare metal stent (74.52% [47.23–100.00]; P<0.001). Ninety-day optical coherence tomography results demonstrated significantly lower neointimal area in FP-PES (8.01 mm2 [7.65–9.21]) compared with PES (10.95 mm2 [9.64–12.46]) and bare metal stent (13.83 mm2 [11.53–17.03]; P<0.001). Histological evaluation showed larger lumen areas and evidence of higher biological activity (smooth muscle cell loss and fibrin deposition) in the FP-PES compared with PES and bare metal stent. Conclusions— In the familial hypercholesterolemic swine model of femoral restenosis, the implantation of an FP-PES resulted in lower levels of neointimal proliferation and sustained biological effect ⩽90 days compared with a polymer-free stent-based approach.

First in human evaluation of the vascular biocompatibility and biomechanical performance of a novel ultra high molecular weight amorphous PLLA bioresorbable scaffold in the absence of anti‐proliferative drugs: Two‐year imaging results in humans

In this first‐in‐human study, we prospectively studied the vascular compatibility and mechanical performance of a novel bare ultra‐high molecular weight amorphous PLLA bioresorbable scaffold (BRS, FORTITUDE®, Amaranth Medical, Mountain View, California) up to two years after implantation using multimodality imaging techniques.

Biological effect of microengineered grooved stents on strut healing: a randomised OCT-based comparative study in humans

Objective To evaluate the biological effect of microengineered stent grooves (MSG) on early strut healing in humans by performing optical coherence tomography (OCT) analysis 3 weeks following the implantation. Background In the experimental setting, MSG accelerate endothelial cell migration and reduce neointimal proliferation compared with bare metal stent (BMS). Methods A total of 37 patients undergoing percutaneous coronary intervention with de novo coronary lesions were randomly assigned to either MSG (n=19) or an identical BMS controls (n=18). All patients underwent OCT imaging at 3 weeks. A total of 7959 struts were included in the final analysis. Results At 3 weeks following stent implantation, almost all struts analysed (~97%) had evidence of tissue coverage. The percentage of partially covered struts was comparable between both groups. However, the percentage of fully embedded struts was higher in the BMS group (81.22%, 49.75–95.52) compared with the MSG group (74.21%, 58.85–86.38). The stent-level analysis demonstrated reduction in neointimal formation (neointimal hyperplasia area and volume reduction of ~14% and ~19%, respectively) in the MSG versus the BMS group. In the strut-level analysis, an even greater reduction (~22% in neointimal thickness) was seen in the MSG group. Layered neointimal was present in ~6% of the OCT frames in the BMS group while it was not present in the MSG group. Conclusions MSG induced a more homogeneous and predictable pattern of surface healing in the early stages following stent implantation. The biological effect of MSG on stent healing has the potential to improve the safety profile of current generation drug-eluting stents. Classifications BMS, OCT, clinical trials.

Bioresorbable polymer-coated thin strut sirolimus-eluting stent vs durable polymer-coated everolimus-eluting stent in daily clinical practice: Propensity matched one-year results from interventional cardiology network registry

We sought to determine the 1‐year clinical follow‐up in patients treated with the thin strut (71 μm) bioabsorbable polymer‐coated sirolimus‐eluting stent (BP‐SES) vs durable coating everolimus eluting stent (DP‐EES) in daily clinical routine.

Novel ultrahigh molecular weight amorphous PLLA bioresorbable coronary scaffold upsized up to 0.8 mm beyond nominal diameter: An OCT and histopathology study in porcine coronary artery model

The aim of the study was to evaluate the biomechanical properties and healing pattern of novel sirolimus‐eluting, ultrahigh molecular weight amorphous poly‐L‐lactic acid bioresorbable scaffolds (S‐BRS) that have been postdilated by 0.55 and 0.8 mm beyond the nominal diameters within the pressure‐diameter compliance chart range.