Örs Petneházy

Optimization of drug-eluting balloon use for safety and efficacy: Evaluation of the 2nd generation paclitaxel-eluting DIOR-balloon in porcine coronary arteries

Objectives: The aim of this preclinical study was to optimize the use of drug‐eluting balloon (DEB) DIOR2nd generation by measurements of tissue and plasma paclitaxel concentrations in porcine coronary artery overstretch and prove efficacy in inhibition of neointimal growth without complementary use of stent. Background: The usually recommended DEB 60 sec inflation time causes prolonged ischemia and arterial injury. Methods: Tissue, plasma, and balloon surface concentrations of paclitaxel were measured in pigs 45 min and 12 hr after balloon inflation times of 15, 20, 30, 45, and 60 sec. Extent of neointimal hyperplasia was compared using DIOR2nd generation or noncoated balloon at two‐week follow‐up. Paclitaxel was replaced by fluorescent paclitaxel derivative in DEB and DES to demonstrate the distribution of the drug in arterial wall. Results: DIOR2nd generation DEB provided 29 ± 3 μM/L, 52 ± 6 μM/L, 196 ± 44 μM/L, 202 ± 36 μM/L, and 184 ± 59 μM/L paclitaxel to the vessel wall after 15, 20, 30, 45, and 60 sec of dilation, reaching plateau at 30 sec inflation time. Paclitaxel penetrated up to 2 mm tissue deepness. Measurable plasma paclitaxel level (45 ± 28 ng/mL) was found only after 60 sec balloon inflation time. At follow‐up, the dilated arterial segment neointimal area and maximal neointimal thickness were significantly smaller with DIOR vs. uncoated balloon use. Fluorescence images of DIOR showed a homogenous distribution of the drug on the vessel, in contrast with DES. Conclusion: Using the DIOR2nd generation DEB, a maximal balloon inflation time of 30–45 sec is optimal, reducing effectively the neointimal hyperplasia.

Attainment of local drug delivery with paclitaxel-eluting balloon in porcine coronary arteries.

ObjectiveOur purpose was to confirm the local drug delivery of a paclitaxel-eluting balloon by percutaneous intervention of single arterial segments or bifurcations of porcine coronary arteries. MethodsEight domestic pigs were subjected to 2×30 s Dior balloon dilatation of the mid left anterior descending, left circumflex and proximal right coronary arteries. Bifurcation intervention was performed in six arteries. The dilated, and the distal and proximal reference segments were prepared for tissue paclitaxel concentration measurement. Tissue samples were harvested at mean 1.5, 12, 24 and 48 h after balloon dilatation and plasma samples were taken at various time points. ResultsThe tissue paclitaxel concentration of the single dilated segment was at 1.5 h postdilatation 1.82±1.60 μmol/l, which decreased significantly to 0.73±0.27 (P=0.032), 0.62±0.34 and 0.44±0.31 μmol/l at 12, 24 and 48 h. The bifurcation intervention resulted in 5.10±1.80 μmol/l tissue paclitaxel amount in the main branch, which at 12 h had diminished to 1.41±1.23 μmol/l (P=0.004). The bifurcation side contained 7.00±4.80 μmol/l paclitaxel at 1.5 h postdilatation, which lowered to 2.72±0.40 μmol/l (P=0.034). The mean paclitaxel concentration of the reference segments decreased gradually from 0.84±0.99 to 0.34±0.36 μmol/l (P=0.09), 0.28±0.16 and 0.19±0.18 μmol/l tissue at 1.5, 12, 24 and 48 h postdilatation, respectively. No paclitaxel was found in the peripheral blood at any time point. ConclusionShort exposure of the coronary artery to paclitaxel with a coated balloon is sufficient for the attainment of an adequate tissue concentration of paclitaxel, which is known to be efficient in inhibiting neointimal growth.

Time Course of Endothelium-Dependent and -Independent Coronary Vasomotor Response to Coronary Balloons and Stents : Comparison of Plain and Drug-Eluting Balloons and Stents

OBJECTIVES This study sought to determine the time dependency of the endothelium-dependent and -independent vascular responses after percutaneous coronary intervention (PCI) with drug-eluting (DEB) or plain balloons, bare-metal (BMS), and drug-eluting (DES) stents, or controls. BACKGROUND Long-term endothelial dysfunction after DES implantation is associated with delayed healing and late thrombosis. METHODS Domestic pigs underwent PCI using DEB or plain balloon, BMS, or DES. The dilated and stented segments, and the proximal reference segments of stents and control arteries were explanted at 5-h, 24-h, 1-week, and 1-month follow-up (FUP). Endothelin-induced vasoconstriction and endothelium-dependent and -independent vasodilation of the arterial segments were determined in vitro and were related to histological results. RESULTS DES- and BMS-treated arteries showed proneness to vasoconstriction 5 h post-PCI. The endothelium-dependent vasodilation was profoundly (p < 0.05) impaired early after PCI (9.8 ± 3.7%, 13.4 ± 9.2%, 5.7 ± 5.3%, and 7.6 ± 4.7% using plain balloon, DEB, BMS, and DES, respectively), as compared with controls (49.6 ± 9.5%), with slow recovery. In contrast to DES, the endothelium-related vasodilation of vessels treated with plain balloon, DEB, and BMS was increased at 1 month, suggesting enhanced endogenous nitric oxide production of the neointima. The endothelium-independent (vascular smooth muscle-related) vasodilation decreased significantly at 1 day, with slow normalization during FUP. All PCI-treated vessels exhibited imbalance between vasoconstriction-vasodilation, which was more pronounced in DES- and BMS-treated vessels. No correlation between histological parameters and vasomotor function was found, indicating complex interactions between the healing neoendothelium and smooth muscle post-PCI. CONCLUSIONS Coronary arteries treated with plain balloon, DEB, BMS, and DES showed time-dependent loss of endothelial-dependent and -independent vasomotor function, with imbalanced contraction/dilation capacity.

Implantation of paclitaxel-eluting stent impairs the vascular compliance of arteries in porcine coronary stenting model.

BACKGROUND The impaired compliance of large and medium-sized muscular arteries has been shown to correlate with the risk of adverse cardiovascular events. We assessed coronary artery distensibility using simultaneous intracoronary ultrasound and pressure wire measurements in porcine coronary arteries after implantation of paclitaxel-eluting (PES) and bare metal stents (BMS) and compared this with the histopathology of the arterial wall injury. METHODS PES and BMS were implanted into porcine left coronary arteries under general anesthesia. At 1-month follow-up (FUP) the endothelium-dependent and endothelium-independent vascular compliances were measured after intracoronary infusion of 10(-6)M acetylcholine for 2.5min, and intracoronary bolus of 100microg nitroglycerine, respectively. The arterial stiffness index, distensibility and reflexion index were calculated in stented arteries (n=25 PES and n=25 BMS), and correlated with histopathologic and histomorphometric changes of the vessel wall. RESULTS In spite of smaller neointimal area, the fibrin deposition, medial thickening, vascular wall inflammation scores and arterial remodeling index were elevated and endothelialization was impaired in arteries with PES. Arteries with PES exhibited significantly worse endothelium-dependent vascular compliance: the stiffness (p<0.001) and reflexion index (p<0.001) were significantly higher and the distensibility index (p<0.001) lower as compared with the arteries with BMS. The endothelium-independent vascular reaction was similarly impaired in arteries with PES, as the stiffness index (p<0.001) and the distensibility index (p<0.001) differed significantly between the PES and BMS groups. Incomplete endothelialization (r=0.617, p<0.001) was significantly associated with the endothelium-dependent increased vascular stiffness. The increased fibrin score (r=0.646, p<0.001), vessel wall inflammation (r=0.657, p<0.001) and medial thickening (r=0.672, p<0.001) correlated significantly with the endothelium-independent stiffness index. CONCLUSIONS Implantation of PES impairs the coronary artery wall structure and the endothelium-dependent and independent vessel wall dynamics more than does the implantation of BMS.

Long-acting beneficial effect of percutaneously intramyocardially delivered secretome of apoptotic peripheral blood cells on porcine chronic ischemic left ventricular dysfunction

The quantity of cells with paracrine effects for use in myocardial regeneration therapy is limited. This study investigated the effects of catheter-based endomyocardial delivery of secretome of 2.5 × 10(9) apoptotic peripheral blood mononuclear cells (APOSEC) on porcine chronic post-myocardial infarction (MI) left ventricular (LV) dysfunction and on gene expression. Closed-chest reperfused MI was induced in pigs by 90-min occlusion followed by reperfusion of the mid-LAD (day 0). At day 30, animals were randomized to receive porcine APOSEC (n = 8) or medium solution (control; n = 8) injected intramyocardially into the MI border zone using 3D NOGA guidance. At day 60, cardiac MRI with late enhancement and diagnostic NOGA (myocardial viability) were performed. Gene expression profiling of the infarct core, border zone, and normal myocardium was performed using microarray analysis and confirmed by quantitative real-time PCR. Injection of APOSEC significantly decreased infarct size (p < 0.05) and improved cardiac index and myocardial viability compared to controls. A trend towards higher LV ejection fraction was observed in APOSEC vs. controls (45.4 ± 5.9% vs. 37.4 ± 8.9%, p = 0.052). Transcriptome analysis revealed significant downregulation of caspase-1, tumor necrosis factor and other inflammatory genes in APOSEC-affected areas. rtPCR showed higher expression of myogenic factor Mefc2 (p < 0.05) and downregulated caspase genes (p < 0.05) in APOSEC-treated pigs. In conclusion, overexpression of MEF2c and repression of caspase was related to decreased infarct size and improved cardiac function in secretome-treated animals. Altered gene expression 1-month post-APOSEC treatment proved the long-acting effects of cell-free therapy with paracrine factors.

Drug-Eluting Introducer Sheath Prevents Local Peripheral Complications : Pre-Clinical Evaluation of Nitric Oxide–Coated Sheath

OBJECTIVES This study evaluated the protective effect of nitric oxide-coating of introducer sheath on the local complications in juvenile porcine femoral arteries with similar size to human radial arteries. BACKGROUND Insertion of an introducer sheath induces vasospasm and transient or permanent vessel occlusion of radial arteries. METHODS Nitric oxide-coated or control introducer sheaths with or without spasmolytic cocktail (control + C-sheath) were inserted into porcine femoral arteries, followed by percutaneous coronary intervention (PCI). The diameter of the femoral artery at the puncture site, distally and proximally, was measured by quantitative angiography. Histopathological and histomorphometric parameters of the femoral arteries were analyzed 1 h or 1 week after PCI. RESULTS Insertion of femoral sheath led to mild or severe spasms, with significantly higher vessel diameter at the access site (2.69 ± 0.81 mm vs. 1.77 ± 0.77 mm and 1.85 ± 0.66 mm, p < 0.001), and proximal and distal to it, during PCI in the nitric oxide-sheath group versus the control-sheath and control + C-sheath groups, respectively. Immediately following PCI, significantly less luminal thrombosis (12% vs. 33% and 31% of all analyzed segments, p < 0.001) was observed in the nitric oxide-sheath arteries. At 1 week, lower intimal inflammation score (0.43 ± 11 vs. 1.03 ± 0.35 and 1.04 ± 0.32, p < 0.05), less luminal thrombosis (8% vs. 21% and 30% p < 0.05), and smaller intimal hyperplasia (0.31 ± 0.31 mm(2) vs. 0.47 ± 1.00 mm(2) and 0.86 ± 0.82 mm(2), p < 0.05) were observed in NO-sheath arteries at the injury site. CONCLUSIONS Nitric oxide coating on the introducer sheath prevents local complications during PCI and results in less vascular thrombosis and inflammation at the access site, contributing to patency of the access vessel with similar size to the radial artery.

Evaluation of experimental myocardial infarction models via electromechanical mapping and magnetic resonance imaging.

The diagnostic characteristics of electromechanical mapping (EMM) were evaluated in porcine myocardial infarction (MI) models with the parallel application of cardiac magnetic resonance imaging (cMRI) from the aspect of different pathophysiology and localization. Balloon occlusion in the left anterior descending coronary artery (LAD balloon group) or coil deployment in the LAD (LAD coil group) or circumflex artery (Cx coil group) was applied percutaneously in 16 domestic pigs. Regional left ventricular viability data were captured via cMRI and EMM. The unipolar voltage (UV) value was significantly decreased in segments containing transmural and subendocardial late enhancement compared with viable segments in the LAD balloon, LAD coil, and Cx coil groups. Receiver operating characteristic analysis revealed area under the curve values of 0.809 and 0.691 in the LAD infarct territory, and 0.864 and 0.855 in the Cx infarct territory for the UV compared with cMRI viability results as transmural late enhancement or viable tissue and subendocardial late enhancement or viable tissue, respectively. In conclusion, the UV value detected the presence of scar tissue with differential transmural extent and which represented proper diagnostic features both in the reperfused and nonreperfused models. This data could provide additional benefit in the clinical use of EMM for diagnostic purposes.

Preclinical randomised safety, efficacy and physiologic study of the silicon dioxide inert-coated Axetis and bare metal stent: short-, mid- and long-term outcome.

AIMS To evaluate the short-, mid- and long-term safety, efficacy and vascular physiology of Axetis silicon dioxide (SiO2, abrading the micropores) inert-coated stent implantation in a randomised preclinical setting. METHODS AND RESULTS Coronary arteries of domestic pigs were randomised to receive either Axetis or BMS (same design) stents with one-, three- and six-month follow-up (FUP), controlled by coronary angiography, optical coherence tomography (OCT), intravascular ultrasound (IVUS) and histology (n=32). The time-dependent vasomotor reaction of coronary arteries to stenting was measured using modified myography (n=12). Complete endothelialisation of the Axetis stent was confirmed by OCT, IVUS and histology at one-month FUP. Histopathology revealed continuous healing of the vessel wall with a gradual reduction of inflammation and fibrin score during the six-month FUP in both stent types. Significantly smaller neointimal area and %area stenosis were measured in Axetis stents compared with BMS at each FUP time point. Vascular reactivity measurements showed significantly better endothelium-dependent vasodilation of stented arteries with Axetis implantation. CONCLUSIONS Implantation of the Axetis SiO2-coated stent resulted in a significantly better safety, efficacy and vessel physiology profile compared with BMS of the same design with a continuous decrease in vessel inflammation during the six-month FUP.

Sulci of the canine brain: a review of terminology

Over the last decades there have been several publications of anatomical and neurological textbooks, which include descriptions about the dogs’ brain. However, the terminology used is inconsistent, partly due to individual differences in neocortical gyration and partly due to the common practice of adapting terms from human and murine anatomy. In order to identify such incongruences, in Study 1, we reviewed the existing literature and identified the common terms used as well as any discrepancies between textbooks. Three main forms of inconsistencies were found; a) the use of terms that are not included in the Nomina Anatomica Veterinaria (NAV), b) the inclusion of structures that are listed as not canine-specific, and c) the use of similar names to identify potentially different anatomical structures. To address these issues, in Study 2 we investigated the consistency in appearance of the cerebral sulci, performing a macroscopical examination on 79 canine brains obtained through the Canine Brain and Tissue Bank (CBTB). We then evaluated whether sulci on the frontal regions of brachycephalic breeds differed from those of mesocephalic and dolichocephalic groups, as frontal and olfactory regions are subjected to the most extreme modifications following the shortening of the skull. The statistical analysis showed no difference across the skull length types regarding the occurrence of these sulci, although furrows on the lateral side of the brain proved to be more stable than those on the medial side. In Study 3, we summarized the findings in accordance with the NAV to produce a definitive index of the terms that we recommend be used for each identified sulci. Such an index is beneficial for educational, clinical use, and research (e.g. neuroscience) purposes. The dog is emerging as a pioneering and exceptional model in comparative neuroscience, and therefore the implications for canine neuroscience research should not be underestimated.

Matrix Metalloproteinase-2 Impairs Homing of Intracoronary Delivered Mesenchymal Stem Cells in a Porcine Reperfused Myocardial Infarction: Comparison With Intramyocardial Cell Delivery

Background Intracoronary (IC) injection of mesenchymal stem cells (MSCs) results in a prompt decrease of absolute myocardial blood flow (AMF) with late and incomplete recovery of myocardial tissue perfusion. Here, we investigated the effect of decreased AMF on oxidative stress marker matrix metalloproteinase-2 (MMP-2) and its influence on the fate and homing and paracrine character of MSCs after IC or intramyocardial cell delivery in a closed-chest reperfused myocardial infarction (MI) model in pigs. Methods Porcine MSCs were transiently transfected with Ad-Luc and Ad-green fluorescent protein (GFP). One week after MI, the GFP-Luc-MSCs were injected either IC (group IC, 11.00 ± 1.07 × 106) or intramyocardially (group IM, 9.88 ± 1.44 × 106). AMF was measured before, immediately after, and 24 h post GFP-Luc-MSC delivery. In vitro bioluminescence signal was used to identify tissue samples containing GFP-Luc-MSCs. Myocardial tissue MMP-2 and CXCR4 receptor expression (index of homing signal) were measured in bioluminescence positive and negative infarcted and border, and non-ischemic myocardial areas 1-day post cell transfer. At 7-day follow-up, myocardial homing (cadherin, CXCR4, and stromal derived factor-1alpha) and angiogenic [fibroblast growth factor 2 (FGF2) and VEGF] were quantified by ELISA of homogenized myocardial tissues from the bioluminescence positive and negative infarcted and border, and non-ischemic myocardium. Biodistribution of the implanted cells was quantified by using Luciferase assay and confirmed by fluorescence immunochemistry. Global left ventricular ejection fraction (LVEF) was measured at baseline and 1-month post cell therapy using magnet resonance image. Results AMF decreased immediately after IC cell delivery, while no change in tissue perfusion was found in the IM group (42.6 ± 11.7 vs. 56.9 ± 16.7 ml/min, p = 0.018). IC delivery led to a significant increase in myocardial MMP-2 64 kD expression (448 ± 88 vs. 315 ± 54 intensity × mm2, p = 0.021), and decreased expression of CXCR4 (592 ± 50 vs. 714 ± 54 pg/tissue/ml, p = 0.006), with significant exponential decay between MMP-2 and CXCR4 (r = 0.679, p < 0.001). FGF2 and VEGF of the bioluminescence infarcted and border zone of homogenized tissues were significantly elevated in the IM goups as compared to IC group. LVEF increase was significantly higher in IM group (0.8 ± 8.4 vs 5.3 ± 5.2%, p = 0.046) at the 1-month follow up. Conclusion Intracoronary stem cell delivery decreased AMF, with consequent increase in myocardial expression of MMP-2 and reduced CXCR4 expression with lower level of myocardial homing and angiogenic factor release as compared to IM cell delivery.