Zsolt Petrasi

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.

Differential effect of ischaemic preconditioning on mobilisation and recruitment of haematopoietic and mesenchymal stem cells in porcine myocardial ischaemia-reperfusion

Effects of ischaemic preconditioning (IP) on the mobilisation and recruitment of haematopoietic (HSCs) and mesenchymal stem (MSC) cells were determined in porcine coronary occlusion/reperfusion. Thirty-three pigs underwent percutaneous occlusion of the left anterior descending coronary artery (LAD) for 90 minutes (min), followed by 120 min reperfusion. IP was performed in 16 of the 33 pigs by two cycles of 5 min balloon occlusion/reperfusion prior to the 90 min occlusion (group IP vs. group C). Peripheral blood and myocardial tissue concentration of bone marrow origin HSCs (characterised by coexpression of CD31+, CD90+, CD45+) and MSCs (characterised by coexpression of CD44+, CD90+, CD45-) were measured by flow cytometry in the early phase of IP. Plasma/serum levels of stem cell mobilisation factors (stromal cell-derived factor-1a [SDF-1a], vascular endothelial growth factor [VEGF], tumour necrosis factor a[TNF-a] and interleukin-8 [IL-8]) were measured. IP led to a significant increase in circulating HSCs as compared with the group C (475 +/- 233 vs. 281 +/- 264 /ml, p=0.032) in the early phase of IP. In contrast, a rapid and prolonged decrease in level of circulating MSCs was observed in group IP as compared with group C (19 +/- 12 vs. 32 +/- 17 /ml, p=0.015). The recruitment of HSCs and MSCs in infarct and border zone was significantly greater in IP group, indicating a faster homing of MSCs as compared with the rate of mobilisation. Rapid increase in VEGF, TNF-a and IL-8 levels was induced by IP, which, however, was not correlated with the levels of circulating SCs. In conclusion, IP resulted in differential mobilisation and recruitment of HSCs and MSCs in the early phase of cardioprotection.

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.

Protective effect of ischaemic preconditioning on ischaemia/reperfusion-induced microvascular obstruction determined by on-line measurements of coronary pressure and blood flow in pigs

We investigated the protective effect of ischaemic preconditioning (IP) on the maintenance of coronary patency using on-line measurements of coronary pressures and blood flow in a closed-chest reperfused acute myocardial infarction (MI) model in pigs. Catheter-based 90-min occlusion followed by 60-min reperfusion of the left anterior descending coronary artery (LAD) was performed in anesthetised pigs (MI group). IP was applied (IP group) through two cycles of 5-min occlusion and 5-min reperfusion of the LAD before MI induction. Coronary patency was determined by measurements of coronary wedge pressure, collateral fractional flow reserve (FFRcoll), collateral pressure index (CPI) and absolute coronary blood flow (CBF). Inducible and constitutive nitric oxide synthase (iNOS/cNOS) activities and expressions were determined in the myocardium. Plasma levels of myeloperoxidase (MPO, index of activated leukocytes) and mean platelet volume (MPV, index of activated platelets) were measured. IP resulted in significantly lower levels of MPO (0.52 ± 0.19 vs. 1.05 ± 0.24 U/l, p<0.001) and MPV (9.1 ± 0.6 vs. 9.6 ± 1.0 fl, p=0.04), higher FFRcoll (0.17 ± 0.05 vs. 0.04 ± 0.05, p<0.001), CPI (0.13 ± 0.05 vs. 0.02 ± 0.05, p<0.001) and CBF (70.7 ± 4.2 vs. 50.8 ± 4.8 m/min, p<0.001) post-reperfusion as compared with the MI group. IP resulted in significantly higher cNOS activity and eNOS expression. Significant negative correlation was found between MPO and measures of coronary patency (FFRcoll, CPI and CBF) and cNOS activity. Moreover, cNOS activity correlated significantly with FFRcoll, CPI and CBF. In conclusion, IP attenuates the release of MPO and platelet activation, thereby contributing to the maintenance of vessel patency at microvascular level after reperfusion of the infarct-related artery.

Imaging the migration of therapeutically delivered cardiac stem cells.

the initial results of human clinical studies demonstrated the safety and potential benefit of autologous bone marrow cells in improving left ventricular function after acute myocardial infarction (AMI). However, a fundamental problem in developing stem cell (SC)–based therapies has been the

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.

Platelet activation and high tissue factor level predict acute stent thrombosis in pig coronary arteries: Prothrombogenic response of drug-eluting or bare stent implantation within the first 24 hours

Increased thrombogenicity of drug-eluting stents (DESs) has recently been reported. The aim of the present study was to investigate the prothrombogenic effect of DESs and Bare stents, and determine factors predictive of acute stent thrombosis (AST) in preclinical experiments using new stent design or coating. Circulating pre- and post-stenting parameters of platelet activation (mean platelet volume, MPV; platelet distribution width, platelet large cell ratio), thrombin activation (thrombin-antithrombin complex, TAT and prothrombin fragments, F1+2), tissue factor antigen (TF-ag) and -activity (TF-act) and plasminogen activator inhibitor-1 (PAI-1) were measured in 141 consecutive pigs. Stent implantations were performed after pretreatment with aspirin and clopidogrel with unfractionated heparin anticoagulation. Nineteen pigs (groups AST-DES, n = 12; and AST-Bare, n = 7) died mean 6.3 +/- 2.9 h after stent implantation from AST. The remaining 122 control (C) pigs (groups C-DES, n = 76, and C-Bare, n = 46) survived the 1-month follow-up. Non-significantly elevated levels of post-stent F1+2 and TAT were measured in AST groups. Post-stenting MPV was increased significantly in the groups ASTDES and AST-Bare as compared with the groups C-DES and C-Bare (11.73 +/- 1.12 and 11.6 +/- 0.68 vs. 8.85 +/- 0.78 and 9.04 +/- 0.81 fL; p < 0.001), similarly to TF-ag (189.1 +/- 87.5 and 127 +/- 34.9 vs. 42.5 +/- 24.6 and 35.3 +/- 37.6 pg/ml; p < 0.001, respectively), Tfact (3.23 +/- 0.95 and 2.73 +/- 1.68 vs. 1.43 +/- 1.12 and 1.61 +/- 1.31 pM; p < 0.01, respectively) and PAI-1 (99.1 +/- 15.8 and 99 +/- 14.7 vs.53.4 +/- 40.2 and 46.9 +/- 42.4 ng/ml;p < 0.01, respectively). Multivariate analysis revealed elevated post-stenting plasma levels of TF-ag (p = 0.016) and MPV (p = 0.001) as independent risk factors for developing AST within the first 24 h in a porcine coronary stent model.

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.