Rabbit Arteries Research Articles

Superselective Arterial Hyaluronidase Thrombolysis Is Not an Effective Treatment for Hyaluronic Acid-Induced Retinal Artery Occlusion: Study in a Rabbit Model.

Worldwide application of hyaluronic acid has brought about severe complications, including central retinal arterial occlusion, which leads to a deleterious effect on vision. The current study explored the efficacy of superselective arterial hyaluronidase thrombolysis in rabbit retinal artery occlusion induced by hyaluronic acid. Occlusion of the internal/external ophthalmic artery in New Zealand White rabbits was induced with superselective injection of hyaluronic acid. Superselective subtraction angiography and fundus examination were conducted to confirm and evaluate the artery embolism. After 30 minutes of embolism, hyaluronidase was injected in the occluded artery through superselective arterial intubation. Compared with preoperative and contralateral eyes, the postoperative eyes showed the symptoms of central retinal arterial occlusion and embolization, confirmed by digital subtraction angiography. After intraarterial hyaluronidase thrombolysis, the embolization failed to dissolve as shown on funduscopic and angiographic examinations. Superselective ophthalmic artery intervention could accurately and successfully establish the animal models of retinal artery occlusion induced by hyaluronic acid. The precise occlusion site of the retinal artery and complete embolism were confirmed by ophthalmologic examinations. Intraarterial hyaluronidase thrombolysis might not be an effective method to treat retinal artery occlusion induced by hyaluronic acid.

Preclinical investigation of neoatherosclerosis in magnesium-based bioresorbable scaffolds versus thick-strut drug-eluting stents

Neoatherosclerosis is a frequent finding after implantation of permanent metallic stents. Bioresorbable scaffolds (BRS) are considered to reduce the incidence of neoatherosclerosis owing to their dissolution and consequent vascular restoration. The aim of this study was to evaluate the formation of neoatherosclerosis between magnesium-based BRS and thick-strut metallic drug-eluting stents (DES) in a rabbit model of neoatherosclerosis and in proportion to the effect of high-dose statin medication. Fully bioresorbable magnesium scaffolds (BRS, n=45) and thick-strut permanent metallic DES of equivalent geometry and design (n=45) were implanted into the iliac arteries of New Zealand White rabbits (n=45) following endothelial balloon injury and exposure to a cholesterol diet. Endothelialisation was assessed in 12 animals after 35 days using scanning electron microscopy (SEM), showing significantly enhanced re-endothelialisation above struts in the BRS (n=13) compared to DES (n=10). Eleven (11) animals were terminated for baseline assessment after 91 days while the remaining 22 animals were randomised to receive high-dose statin treatment (3 mg/kg) or placebo. BRS-treated vessels showed a significant reduction in foam cell infiltration as a sign of early neoatherosclerosis by histology and OCT when compared to thick-strut DES-treated vessels. Statin treatment resulted in significant reduction of foam cell infiltration in BRS and DES by histology. Our findings suggest reduced neoatherosclerosis formation in magnesium-based BRS relative to thick-strut DES. High-dose statin treatment may be a promising measure to reduce neoatherosclerosis progression, both on its own and in synergy with site-targeted device-based treatment.

Undercarboxylated osteocalcin is associated with vascular function in female older adults but does not influence vascular function in male rabbit carotid artery ex vivo.

BackgroundThere are conflicting reports on the association of undercarboxylated osteocalcin (ucOC) in cardiovascular disease development, including endothelial function and hypertension. We tested whether ucOC is related to blood pressure and endothelial function in older adults, and if ucOC directly affects endothelial-mediated vasodilation in the carotid artery of rabbits.MethodsIn older adults, ucOC, blood pressure, pulse wave velocity (PWV) and brachial artery flow-mediated dilation (BAFMD) were measured (n = 38, 26 post-menopausal women and 12 men, mean age 73 ± 0.96). The vasoactivity of the carotid artery was assessed in male New Zealand White rabbits following a four-week normal or atherogenic diet using perfusion myography. An ucOC dose response curve (0.3–45 ng/ml) was generated following incubation of the arteries for 2-hours in either normal or high glucose conditions.ResultsucOC levels were higher in normotensive older adults compared to those with stage 2 hypertension (p < 0.05), particularly in women (p < 0.01). In all participants, higher ucOC was associated with lower PWV (p < 0.05), but not BAFMD (p > 0.05). In rabbits, ucOC at any dose did not alter vasoactivity of the carotid artery, either following a normal or an atherogenic diet (p > 0.05).ConclusionIncreased ucOC is associated with lower blood pressure and increased arterial stiffness, particularly in post-menopausal women. However, ucOC administration has no direct short-term effect on endothelial function in rabbit arteries. Future studies should explore whether treatment with ucOC, in vivo, has direct or indirect effects on blood vessel function.

All-Trans Retinoic Acid Prevented Vein Grafts Stenosis by Inhibiting Rb-E2F Mediated Cell Cycle Progression and KLF5-RARα Interaction in Human Vein Smooth Muscle Cells.

Vein graft failure (VGF) is an important limitation for coronary artery bypass graft (CABG) surgery. Inhibition of the excessive proliferation and migration of venous smooth muscle cells (SMCs) is an effective strategy to alleviate VGF during the CABG perioperative period. In the present study, we aimed to explore the role and potential mechanism of all-trans retinoic acid (ATRA) on preventing vein grafts stenosis. The autogenous vein grafts model was established in the right jugular artery of rabbits. Immunohistochemistry staining and western blot assays were used to detected the protein expression, while real-time PCR assay was applied for mRNAs expression detection. The interaction between proteins was identified by co-immunoprecipitation assay. The Cell Counting Kit-8 and wound-healing assays were used to investigate the role of ATRA on human umbilical vein smooth muscle cells (HUVSMCs) function. Cell cycle progression was identified by flow cytometry assay. Vein graft stenosis and SMCs hyperproliferation were confirmed in vein grafts by histological and Ki-67 immunohistochemistry assays. Treatment of ATRA (10mg/kg/day) significantly mitigated the stenosis extent of vein grafts, demonstrated by the decreased thickness of intima-media, and decreased Ki-67 expression. ATRA could repress the PDGF-bb-induced excessive proliferation and migration of HUVSMCs, which was mediated by Rb-E2F dependent cell cycle inhibition. Meanwhile, ATRA could reduce the interaction between KLF5 and RARα, thereby inhibiting the function of cis-elements of KLF5. KLF5-induced inducible nitric oxide synthase (iNOS) expression activation could be significantly inhibited by ATRA. These results suggested that ATRA treatment may represent an effective prevention and therapy avenue for VGF.

Development and Long-Term Follow-Up of an Experimental Model of Myocardial Infarction in Rabbits.

A chronic model of acute myocardial infarction was developed to study the mechanisms involved in adverse postinfarction ventricular remodeling. In an acute myocardial infarction (AMI), the left circumflex coronary artery of New Zealand White rabbits (n = 9) was occluded by ligature for 1 h, followed by reperfusion. A specific care protocol was applied before, during, and after the intervention, and the results were compared with those of a sham operated group (n = 7). After 5 weeks, programmed stimulation and high-resolution mapping were performed on isolated and perfused hearts using the Langendorff technique. The infarct size determined by 2,3,5-triphenyltetrazolium chloride inside of the area at risk (thioflavin-S) was then determined. The area at risk was similar in both groups (54.33% (experimental infarct group) vs. 58.59% (sham group), ns). The infarct size was 73.16% as a percentage of the risk area. The experimental infarct group had a higher inducibility of ventricular arrhythmias (100% vs. 43% in the sham group, p = 0.009). A reproducible chronic experimental model of myocardial infarction is presented in which the extent and characteristics of the lesions enable the study of the vulnerability to develop ventricular arrhythmias because of the remodeling process that occurs during cardiac tissue repair.

A novel mechanism of inhibiting in-stent restenosis with arsenic trioxide drug-eluting stent: Enhancing contractile phenotype of vascular smooth muscle cells via YAP pathway

ObjectiveArsenic trioxide (ATO or As2O3) has beneficial effects on suppressing neointimal hyperplasia and restenosis, but the mechanism is still unclear. The goal of this study is to further understand the mechanism of ATO's inhibitory effect on vascular smooth muscle cells (VSMCs). Methods and resultsThrough in vitro cell culture and in vivo stent implanting into the carotid arteries of rabbit, a synthetic-to-contractile phenotypic transition was induced and the proliferation of VSMCs was inhibited by ATO. F-actin filaments were clustered and the elasticity modulus was increased within the phenotypic modulation of VSMCs induced by ATO in vitro. Meanwhile, Yes-associated protein (YAP) nuclear translocation was inhibited by ATO both in vivo and in vitro. It was found that ROCK inhibitor or YAP inactivator could partially mask the phenotype modulation of ATO on VSMCs. ConclusionsThe interaction of YAP with the ROCK pathway through ATO seems to mediate the contractile phenotype of VSMCs. This provides an indication of the clinical therapeutic mechanism for the beneficial bioactive effect of ATO-drug eluting stent (AES) on in-stent restenosis (ISR).

Association Between Inflammatory Mediators and Pulmonary Blood Flow in a Rabbit Model of Acute Pulmonary Embolism Combined With Shock.

BackgroundThe pro-inflammatory cytokines were detected in pulmonary embolism (PE) and non-pulmonary embolism (non-PE) tissues to explore the role of inflammation responses and their relationship with the pulmonary blood flow in a rabbit model of acute pulmonary embolism combined with shock.Methods and ResultsNineteen rabbits were randomly divided into sham operation group (S group, n = 8) and massive PE (MPE group, n = 11). The MPE model was established by injecting the autologous blood clots into the main pulmonary artery of rabbit. Pulmonary angiography showed that the pulmonary circulation time was significantly prolonged in the MPE group, and pulmonary blood flow was attenuated at 120 min post PE. Hematoxylin–eosin (HE) staining revealed enhanced inflammatory cell infiltration around the pulmonary vessels in PE and non-PE tissues, and obvious edema on the perivascular region. Meanwhile, the expressions of inducible nitric oxide synthase (iNOS) and arginase 1 (Arg-1) in pulmonary vascular and alveolar tissues were significantly upregulated and the iNOS/Arg-1 ratio was significantly higher in the MPE group than in the S group. Moreover, the levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) were also significantly increased in PE and non-PE tissues, and interleukin-6 (IL-6) level was significantly increased in non-PE tissues in the MPE group as compared to the S group. Thromboxane A2 (TXA2) and alpha smooth muscle actin (α-SMA) levels were significantly higher in both PE and non-PE tissues in the MPE group than in the S group.ConclusionActivation of inflammation mediators in PE and non-PE tissues might be one of the crucial factors responsible for pulmonary vasculature constriction and pulmonary blood flow attenuation in this MPE model.

Glycyrrhizic Acid Attenuates Balloon-Induced Vascular Injury Through Inactivation of RAGE Signaling Pathways

Percutaneous coronary intervention is a well-established technique used to treat coronary artery disease, but the risk of coronary artery in-stent restenosis following percutaneous coronary intervention is still high. Previous studies revealed that high mobility group protein B1 (HMGB1) plays a critical role in neointima formation. In this study, we aimed to investigate the role of glycyrrhizic acid (GA), an HMGB1 inhibitor, in the process of neointima formation and the potential mechanisms. We investigated the role of GA in neointima formation through an iliac artery balloon injury model in rabbits. Proliferation, migration, and phenotype transformation of human vascular smooth muscle cells (VSMCs) were observed. Besides, inflammation and receptor for advanced glycosylation end products (RAGE) signaling pathways were studied. The results indicate that GA attenuated neointima formation and downregulated HMGB1 expression in injured artery in rabbits. HMGB1 promoted proliferation, migration, and phenotype transformation through the activation of RAGE signaling pathways in VSMCs, and blockade of HMGB1 by GA (1, 10, and 100 μM) could attenuate those processes and reduce proliferation of human VSMCs. In conclusion, the HMGB1 inhibitor GA might be useful to treat proliferative vascular diseases by downregulating RAGE signaling pathways. Our results indicate a new and promising therapeutic agent for restenosis.

Flexible endoscopic micro-optical coherence tomography for three-dimensional imaging of the arterial microstructure

Micro-optical coherence tomography (µOCT) is a novel imaging approach enabling visualization of the microstructures of biological tissues at a cellular or sub-cellular level. However, it has been challenging to develop a miniaturized flexible endoscopic µOCT probe allowing helical luminal scanning. In this study, we built a flexible endoscopic µOCT probe with an outer diameter of 1.2 mm, which acquires three-dimensional images of the arterial microstructures via helical scanning with an axial and lateral resolutions of 1.83 µm and 3.38 µm in air, respectively. Furthermore, the depth of focus of the µOCT imaging probe was extended two-fold using a binary phase spatial filter. We demonstrated that the present endoscopic µOCT could image cellular level features of a rabbit artery with high-risk atheroma and a bioresorbable scaffold-implanted swine coronary artery. This highly-translatable endoscopic µOCT will be a useful tool for investigating coronary artery disease and stent biology.

Motility and function of smooth muscle cells in a silk small-caliber tubular scaffold after replacement of rabbit common carotid artery

Cell infiltration and proliferation are prerequisites for tissue regeneration and repair. The aim of the present study was to evaluate the motility and function of vascular smooth muscle cells (SMCs) in a silk-based small-caliber artificial blood vessel (SFTS) following implantation to replace the common carotid artery in rabbits. Hematoxylin and eosin (HE) staining showed a number of SMCs clearly distributed in the scaffold at 1month, which gradually increased up to 80-90% of autologous blood vessels at 3months and was 100% at 12months. Smooth muscle myosin heavy chain (SM-MHC) and α-smooth muscle actin (α-SMA) are specific markers of SMCs. Real-time PCR results showed that the gene expression level of α-SMA in SFTSs was significantly down-regulated within 6months, except in the early stage of implantation. The relative expression level of α-SMA at 12months was five times higher than that at 3months, indicating that SMCs phenotype transformed from synthetic to contractile. The SM-MHC+ and α-SMA+ SMCs were disorderly distributed in the scaffolds at 1month, but became ordered along the circumference 6months after grafting as shown by immunohistochemistry. Results indicated that the bionic SFTSs were able to induce in situ angiogenesis in defects.

Comparison of Aneurysm Patency and Mural Inflammation in an Arterial Rabbit Sidewall and Bifurcation Aneurysm Model under Consideration of Different Wall Conditions.

Background: Biological processes that lead to aneurysm formation, growth and rupture are insufficiently understood. Vessel wall inflammation and degeneration are suggested to be the driving factors. In this study, we aimed to investigate the natural course of vital (non-decellularized) and decellularized aneurysms in a rabbit sidewall and bifurcation model. Methods: Arterial pouches were sutured end-to-side on the carotid artery of New Zealand White rabbits (vital [n = 6] or decellularized [n = 6]), and into an end-to-side common carotid artery bifurcation (vital [n = 6] and decellularized [n = 6]). Patency was confirmed by fluorescence angiography. After 28 days, all animals underwent magnetic resonance and fluorescence angiography followed by aneurysm harvesting for macroscopic and histological evaluation. Results: None of the aneurysms ruptured during follow-up. All sidewall aneurysms thrombosed with histological inferior thrombus organization observed in decellularized compared to vital aneurysms. In the bifurcation model, half of all decellularized aneurysms thrombosed whereas the non-decellularized aneurysms remained patent with relevant increase in size compared to baseline. Conclusions: Poor thrombus organization in decellularized sidewall aneurysms confirmed the important role of mural cells in aneurysm healing after thrombus formation. Several factors such as restriction by neck tissue, small dimensions and hemodynamics may have prevented aneurysm growth despite pronounced inflammation in decellularized aneurysms. In the bifurcation model, rarefication of mural cells did not increase the risk of aneurysm growth but tendency to spontaneous thrombosis.

Inhibition of JAK2/STAT3/SOCS3 signaling attenuates atherosclerosis in rabbit

BackgroundPrevious studies have indicated that the JAK/STAT signaling pathway is involved in modulating arterial adventitia inflammation response. In this study, we designed experiments to further investigate the effect of JAK2/STAT3/SOCS3 signaling in rabbit atherosclerosis process.MethodsAtherosclerosis was induced in the abdominal arteries of rabbits by balloon injury of the aorta supplemented by the atherogenic diet. Simultaneously, in the process of atherosclerosis, animals underwent either ruxolitinib treatment or not for 12 weeks. At the end of the experimental period, all rabbits were sacrificed. The plaque areas in abdominal artery, the lipid burden of plaque and the calcium burden of plaque were detected by H&E staining, Oil Red O staining and Alizarin Red staining, respectively. In addition, rabbit plasma lipids and inflammatory cytokines were measured by biochemical test kits or ELISA kits. Finally, the expression and phosphorylation levels of JAK2/STAT3/SOCS3 pathway-related proteins were detected by RT-qPCR, western blot and immunohistochemistry assays.ResultsH&E staining and CT scan analysis showed that rabbit atherosclerosis model was constructed successfully. Ruxolitinib, an inhibitor of the Janus kinase 2 (JAK2), substantially reduced the area of atherosclerotic plaques in rabbits treated with high fat diet and balloon injury of the aorta. Moreover, ruxolitinib significantly decreased IL-6, IL-1β, IFN-γ and TNF-α, but increased IL-10 and IL-17 levels in plasma of atherosclerotic rabbits. Additionally, ruxolitinib reduced plasma TC, TG and LDL-C contents and AIP value, while enhanced HDL-C level in atherosclerotic rabbits. Furthermore, we found that JAK2 and STAT3 phosphorylation were up-regulated in rabbits with atherosclerosis when compared with those of the control group, followed by the expression of SOCS3 was also increased due to the activation of JAK2 and STAT3. Interestingly, ruxolitinib could inactivate JAK2 and STAT3 pathway and decrease SOCS3 expression.ConclusionTaken together, the inhibition of JAK2/STAT3/SOCS3 signaling pathway may be a novel method for the clinical treatment of artery atherosclerosis.

Abstract No. 690 Magnetic resonance imaging–visible and triggered-degradable nanocomposite microsphere for on-demand temporary embolic agents

Temporary embolization of vessels plays a critical role in many angiographic procedures. However, predictability and reproducibility of vessel recanalization is limited, and in these situations permanent occlusion may be undesirable. The purpose of this study is to evaluate the feasibility of MRI visible and triggered degradable nanocomposite microspheres for a temporary embolic agent. Microspheres composed by superparamagnetic iron oxide nanocluster and alginate were fabricated with spray atomization and coagulation with CaCl2 solution. Size and morphology of the fabricated microspheres with different precursor concentrations and various distance between nozzle and spray were characterized by optical microscope and scanning electron microscope. MR T2 contrast effect of microspheres was measured with 7 T MRI. Triggered degradation of microspheres using various concentration of chelating agents (EDTA) was investigated. In vivo, hepatic arteries of New Zealand white rabbits (n = 3) were occluded by the intra-artery (IA) infused microspheres. Recanalization with a chelating agent were subsequently examined by angiography. The occlusion and recanalization of hepatic arteries were re-confirmed with a perfusion MR in Magnevist contrast-enhanced 3 T MR scans. Uniform-sized microspheres composed by 2%w/v sodium alginate and 5%w/w iron oxide were fabricated with 20 psi spray pressure. Iron oxide contributed to significant MR T2 contrast effect of the microspheres. Chelating agents (∼30 mM) rapidly dissolved the calcium crosslinked microspheres in both water and serum. In vivo angiography demonstrated fast recanalization of embolized right hepatic artery with the chelating agent. Finally, contrast-enhanced MRI showed the occlusion by microspheres and recanalization upon IA infusion of chelating agents. H&E and Prussian blue staining displayed dissolved microspheres in the tumor regions. Nanocomposite microspheres by a simple spray method demonstrated MRI visibility and fast triggered degradation in vitro and in vivo. Further studies will characterize this new on-demand temporary embolic agent.

Technical Development of the Sutureless ELANA Clip Anastomosis Device

Abstract A cranial bypass can be a last resort procedure for patients suffering from complex neurovascular pathology. Since the clinically proven excimer laser-assisted nonocclusive anastomosis (ELANA) technique has become available, it is no longer necessary to temporarily close the recipient artery to facilitate an anastomosis. Aiming to simplify and shorten the operation time of the ELANA technique, a sutureless ELANA, the so-called SELANA slide (SEsl) was developed, but it failed during clinical study. We developed an improved device, the SELANA clip (SEcl).We describe the SEcl design and the first in vitro test results. The SEsl design was optimized with a clip at the backside, creating the SEcl which facilitates smooth and friction-free insertion in the recipient artery. Subsequently, the laser catheter was optimized by adding a grid and conus to provide an improved vacuum and flat reaction surface during lasing. We aimed to compare the SEcl to the current ELANA regarding application time difference, anastomosis success (“flap retrieval”) and technical difficulties. Hereto 32 ELANA and 32 SEcl anastomoses were performed on pressurized rabbit arteries in the ELANA practice system. Mean application time difference was 14.0 min (95%CI 13.0–15.0). The flap retrieval rate of the ELANA anastomoses was 94% (30/32) and 100% (32/32) for the SEcl technique. During the experiments no technical difficulties were encountered. The SEcl is technical feasible with promising simplicity and application times. However, extensive in vivo short-term and long-term experiments are indispensable before clinical application.

Nesiritide protects endothelial function after balloon-induced trauma in the iliac artery in rabbits

To assess the effect of nesiritide on the endothelial function of iliac arteries following endothelia trauma. Right iliac artery trauma was created with a balloon catheter. Ten rabbits were treated with a 4-week subcutaneous injection of nesiritide at a fixed daily dose of 0.1mg/kg. Ten rabbits received daily normal saline injection. Plasma endothelin 1 (ET-1), nitric oxide (NO), and Von Willebrand Factor (vWF) were measured before and after the therapies. Tissue proliferating cell nuclear antigen (PCNA) was measured after the treatment. After the treatment, in the therapeutic group, the area under internal elastic membrane and the residual lumen area were higher than in the normal saline group (P <0.05). The plasma levels of ET-1 (91.6±6.8 vs 114.9±6.3 ng/L, P =0.001), vWF (134.6±10.8% vs 188.8±10.4%, P =0.001) and the ratio of PCNA positive expression (11.7±4.2% vs 36.2±11.4%, P =0.005) in the therapeutic group was lower than in the normal saline group, while the plasma levels of NO was higher (89.7±9.3 vs 43.5±5.3 µmol/L, P =0.001). Nesiritide inhibited remodeling of rabbit iliac artery following endothelial trauma. The inhibition of vascular remodeling may be related to the alleviated endothelial dysfunction and reduced expression of tissue proliferating cell nuclear antigen.

THE DESIGN OF THE ARTERIOVENOUS VASCULAR LOOP DOES NOT AFFECT ITS PATENCY: EXPERIMENTAL STUDY.

ABSTRACTObjective:To evaluate the effect of the design of a femoral vascular loop with anastomosis in the femoral artery of rabbits on the presence of flow (patency) after seven days.Methods:A total of 39 rabbits underwent arteriovenous microanastomosis using the microsurgical technique. Two loop designs were used: one circular and the other angled. The parameters evaluated were presence or absence of flow, signs of hemolysis and hemodynamic changes.Results:After seven days, flow was present in 68% of the angled loops and 75% of the circular loops (p > 0.05). There was a significant intragroup decrease in pCO2 and a significant increase in pH. For the other parameters evaluated, no significant differences between the two loop models were found.Conclusions:A reproducible vascular loop model was shown. There was no significant difference between the two vascular loop models about the presence of flow after seven days. Level of Evidence V, Animal experimental study.

The Comparative Effects of Ticagrelor and Clopidogrel on Arterial Injury and In-Stent Restenosis and Thrombosis of Carotid Artery in Atherosclerotic Rabbits

Introduction - Carotid artery angioplasty and stenting (CAS) is expanding as a method to treat carotid artery disease worldwide. Until now a combination of aspirin and clopidogrel has been used pre and post CAS. Ticagrelor, a P2Y (12) inhibitor, has an important role in coronary artery angioplasty. There is lack of evidence about the impact of ticagrelor on carotid artery disease and CAS. Our aim was the comparative evaluation of ticagrelor and clopidogrel on carotid balloon-injury and in-stent restenosis (ISR) and thrombosis in rabbits. Methods - After a pharmacokinetic study to standardise the appropriate dose of ticagrelor, we enrolled 48 New Zealand White rabbits. They were fed a high-cholesterol diet for 8 weeks prior to and up to 4 weeks following interventions in the right carotid artery (RCA). Aspirin was administered orally (10mg/kg/day) to all rabbits, beginning 7 days before the procedures and continued until euthanasia (4 weeks later). At 8th week of age, all rabbits were randomly assigned into the following equivalent (N=12) groups: A1) Balloon injury and clopidogrel (30 mg/kg/day), A2) Balloon injury and ticagrelor (21mg/kg bd), B3) Balloon injury and CAS and clopidogrel (30 mg/kg/day), B4) Balloon injury and CAS and ticagrelor (21mg/kg bd). During CAS a balloon expandable 2,25x8 mm bare metal stent was implanted in the RCA. Before euthanasia optical coherence tomography (OCT) and angiography were carried out to evaluate the patency of both carotid arteries. Blood samples to measure platelet aggregation and lipid profile were obtainedas well. Rabbits were then immediately euthanized and both carotid arteries (right-RCA and left-LCA) were excised for histological analysis. Results - Among groups, no significant differences were seen regarding balloon injury, stent implantation success rates and platelet aggregation measurements (p>0.05). All groups had similar lipid levels (total cholesterol, triglycerides) and weight by the end of the study. Notably, 3 rabbits in the B3 group appeared with thrombotic total occlusion of the carotid stents and were excluded from morphometric analysis. None such episode was observed after CAS in ticagrelor-treated rabbits. In balloon injury rabbits, the OCT-calculated neointimal areas in RCAs were: A1: 4.20±0.96mm2, A2: 3.78±1.31mm2, p=0.781, while the mid-stent neointimal areas were: B1: 1.74±0.51mm2 and B2: 1.45±0.62mm2, p=0.654. The histological findings in balloon-injured rabbits were in agreement with those from OCT analysis, since the percentage of intima/(media + intima)(%) in RCA did not differ between groups: A1 (68.48±12.31%) vs A2 (64.22±13.22%) (p=0.812). Importantly the atherosclerotic lesions in non-injured LCAs did not differ between all groups (p>0.1). Conclusion - In atherosclerotic rabbits undergoing carotid artery balloon injury with or without stent implantation, clopidogrel and ticagrelor seemed to be equally effective in terms of neointimal formation and ISR prevention. . Importantly, ticagrelor treatment prevented thrombotic stent occlusions compared to clopidogrel treatment. Further studies are needed to clarify the impact of P2Y(12) inhibitors on carotid in-stent restenosis and thrombosis in humans.

3D cellular-resolution imaging in arteries using few-mode interferometry

Cross-sectional visualisation of the cellular and subcellular structures of human atherosclerosis in vivo is significant, as this disease is fundamentally caused by abnormal processes that occur at this scale in a depth-dependent manner. However, due to the inherent resolution-depth of focus tradeoff of conventional focusing optics, today’s highest-resolution intravascular imaging technique, namely, optical coherence tomography (OCT), is unable to provide cross-sectional images at this resolution through a coronary catheter. Here, we introduce an intravascular imaging system and catheter based on few-mode interferometry, which overcomes the depth of focus limitation of conventional high-numerical-aperture objectives and enables three-dimensional cellular-resolution intravascular imaging in vivo by a submillimetre diameter, flexible catheter. Images of diseased cadaver human coronary arteries and living rabbit arteries were acquired with this device, showing clearly resolved cellular and subcellular structures within the artery wall, such as individual crystals, smooth muscle cells, and inflammatory cells. The capability of this technology to enable cellular-resolution, cross-sectional intravascular imaging will make it possible to study and diagnose human coronary disease with much greater precision in the future.

The Role of Cardiac Ganglia in the Prevention of Coronary Atherosclerosis: An Analytical Examination of Cholesterol-fed Rabbits

Background:The heart is innervated by the autonomic nervous system, which contributes to the control of the heart’s rhythm and coronary circulation. It has been suggested that the cardiac fibers of the vagus nerve play important roles in controlling circulatory functions and in protecting against atherosclerotic pathologies in coronary arteries.Aims:To investigate the presence of atherosclerotic differences in the coronary arteries of cholesterol-fed rabbits by measuring the density of cardiac ganglia neurons.Study Design:Animal experiment.Methods:This study was conducted using 45 male rabbits. Over a period of 16 weeks, they were kept on an atherogenic diet of water ad libitum and high fat (8.6%) containing saturated fatty acids with 205 mg/kg of cholesterol (1%) per day. Then, their hearts were removed and examined by histopathological methods. Atherosclerotic plaques of the main coronary arteries were examined using the Cavalieri method. Atherosclerosis index values (AIVs) were estimated as the wall surface area/plaque surface area, and the results were analyzed with the Kruskal-Wallis and Mann-Whitney U tests.Results:While the average atherosclerosis index value was estimated to be ≤8% in 21 animals, the atherosclerosis index value was 9-20% in animals with minor plaque detection (n=11) and ≥20% in animals with major plaque detection (n=10). Increased atherosclerosis index values were more common in animals with low neuron densities than in animals with high neuron densities (p<0.017).Conclusion:The low neuron density of the cardiac ganglia in cholesterol-fed rabbits is associated with an increased atherosclerotic plaque incidence and volume.

Adventitial Collagen Crosslink Reduces Intimal Hyperplasia in a Rabbit Arteriovenous Graft Model

BackgroundIntimal hyperplasia (IH) is the initial lesion of vein graft failure after coronary artery bypass grafting. The weak venous wall is likely one of the primary reasons for IH after exposure to the arterial environment. We investigate whether adventitial collagen cross-link by glutaraldehyde (GA) reinforces the venous wall and then reduces IH. Materials and methodsAdventitial collagen cross-link by 0.3% GA was performed on the rabbit jugular veins. The degree of cross-link was accessed by tensile test. The jugular vein with or without cross-link was implanted into the carotid artery of rabbit. Vein dilatation at the immediate anastomosis and pathological remodeling of vein graft after 4 wk was assessed. ResultsTensile test indicated that the mechanical property of 3-min cross-linked veins more closely resembled that of the carotid artery. In rabbit arteriovenous graft models, 3-min adventitial collagen cross-link limited overdistension (diameter: 3.24 mm versus 4.65 mm, P < 0.01) at the immediate anastomosis and reduced IH (intima thickness: 78.83 μm versus 140.19 μm, P < 0.01) of vein grafts 4 wk after implantation in the cross-link group as compared with the graft group (without cross-link). Compared with the cross-link group, the expression of proliferating cell nuclear antigen and vascular cell adhesion molecule–1 increased significantly at both the mRNA and protein levels within the graft group (P < 0.01), but the expression of smooth muscle-22α decreased significantly (P < 0.01). ConclusionsAdventitial collagen cross-link by GA increased the vessel stiffness and remarkably reduced IH in a rabbit arteriovenous graft model.