Carotid Artery Jugular Vein Research Articles

A bio-instructive parylene-based conformal coating suppresses thrombosis and intimal hyperplasia of implantable vascular devices

Implantable vascular devices are widely used in clinical treatments for various vascular diseases. However, current approved clinical implantable vascular devices generally have high failure rates primarily due to their surface lacking inherent functional endothelium. Here, inspired by the pathological mechanisms of vascular device failure and physiological functions of native endothelium, we developed a new generation of bioactive parylene (poly(p-xylylene))-based conformal coating to address these challenges of the vascular devices. This coating used a polyethylene glycol (PEG) linker to introduce an endothelial progenitor cell (EPC) specific binding ligand LXW7 (cGRGDdvc) onto the vascular devices for preventing platelet adhesion and selectively capturing endogenous EPCs. Also, we confirmed the long-term stability and function of this coating in human serum. Using two vascular disease-related large animal models, a porcine carotid artery interposition model and a porcine carotid artery-jugular vein arteriovenous graft model, we demonstrated that this coating enabled rapid generation of self-renewable “living” endothelium on the blood contacting surface of the expanded polytetrafluoroethylene (ePTFE) grafts after implantation. We expect this easy-to-apply conformal coating will present a promising avenue to engineer surface properties of “off-the-shelf” implantable vascular devices for long-lasting performance in the clinical settings.

Pharmacological Effect of Panax notoginseng Saponins on Cerebral Ischemia in Animal Models.

Panax notoginseng saponins (PNS), bioactive compounds, are commonly used to treat ischemic heart and cerebral diseases in China and other Asian countries. Most previous studies of PNS have focused on the mechanisms underlying their treatment of ischemic cardiovascular diseases but not cerebral ischemic diseases. This study sought to explore the pharmacological mechanisms underlying the effectiveness of PNS in treating cerebral ischemic diseases. Different experimental cerebral ischemia models (including middle cerebral artery occlusion (MCAO) and the blockade of four arteries in rats, collagen-adrenaline-induced systemic intravascular thrombosis in mice, thrombosis of carotid artery-jugular vein blood flow in the bypass of rats, and hypoxia tolerance in mice) were used to investigate the mechanisms underlying the actions of PNS on cerebral ischemia. The results indicated that (1) PNS improved neurological function and reduced the cerebral ischemia infraction area in MCAO rats; (2) PNS improved motor coordination function in rats with complete cerebral ischemia (blockade of four arteries), decreased Ca2+ levels, and ameliorated energy metabolism in the brains of ischemia rats; (3) PNS reduced thrombosis in common carotid artery-jugular vein blood flow in the bypass of rats; (4) PNS provided significant promise in antistroke hemiplegia and hypoxia tolerance in mice. In conclusion, PNS showed antagonistic effects on ischemic stroke, and pharmacological mechanisms are likely to be associated with the reduction of cerebral pathological damage, thrombolysis, antihypoxia, and improvement in the intracellular Ca2+ overload and cerebral energy metabolism.

Abstract 482: Early Reduction of Blood Flow in Rabbit Jugular Vein-Carotid Artery Bypass Grafts is not Caused by Anastomotic Stenosis

Background: Obstructed arteries are often treated by surgical implantation of venous bypass grafts. Vein grafts can fail for many reasons, including thrombosis, atherosclerosis, or anastomotic stenoses (narrowings where the grafts connect to the artery). In a previous study aimed at developing a hyperlipidemic rabbit model of vein-graft atherosclerosis for testing gene therapy, vein grafts used to bypass carotid arteries were widely patent. However, vein graft blood flow decreased by a mean of 5.6 mL/minute (~23%) between 8 and 16 wks after grafting, with flow at 16 wks reduced to <60% of flow in an unoperated carotid artery. We hypothesized that decreased flow was caused by anastomotic stenoses, raising concern that this might lead to graft occlusion, precluding use of the model to test gene therapy for atherosclerosis. Methods: We designed an experiment to test whether anastomotic stenoses were present and—if so—whether the stenoses were the cause of decreased blood flow. In a new set of grafted veins, we harvested the anastomoses, embedded, sectioned and stained them, and measured percent stenosis using computer-assisted image analysis. Percent stenosis was calculated by dividing intimal area by the stenosis-free lumen area (calculated from the length of the IEL, assuming circular geometry in vivo). We measured stenoses in both anastomoses of 22 patent vein grafts, harvested from 14 hyperlipidemic rabbits (44 total anastomoses). Blood flow (mL/min) in each vein graft was measured with a flow meter at 4 wks after grafting and again at 16 wks (at harvest). Results: The mean blood flow at the 4 wks measurement was 51 mL/minute (range: 28 to 90) and 36 mL/minute (range: 21 to 53) at the harvest measurement. The calculated mean change in blood flow was –16 mL/minute (range: –55 to +14). The mean anastomotic stenosis was 39% (range: 2.3% to 89%). Using Spearman’s rank-order correlation test, we found that percentage stenosis did not correlate with the change in blood flow (r=0.059; P=0.8). Conclusions: Decreased blood flow in our vein graft model is likely not caused by anastomotic stenoses. Other explanations, such as decreased cardiac output or increased downstream vascular resistance (caused by cerebral atherosclerosis or microemboli) should be considered.

Traumatic extracranial internal carotid-jugular fistula leading to serious injury: a case report in forensic assessment

Traumatic carotid artery jugular vein fistula is a rare entity that is not usually detected during the acute injury phase. We presented 1 cases of traumatic carotid–jugular fistula. A 52 years old man that was referred to us because of an expanding neck hematoma. There was a 1×1 cm ulcer with a clot in zone II right neck and a thrill was palpated. We clamped the proximal and distal site of injury (Arteriovenous fistula), then divided the fistula and primarily repaired the artery (transversely) and the vein with 7-0 prolene suture. We placed two hemovac drains and then repaired the subcutaneous and skin and covered the site with gauze and then the patient was transferred to ICU. He was extubated the next day and physical exam was completely normal without any neurologic deficit. Carotid–jugular fistula should always be treated early to avoid the complications associated with the injury.

Traumatic Common Carotid-jugular Fistula In A 6-year-old Child: Rare Cause Of Pulsatile Neck Mass

Background: Traumatic common carotid artery-jugular vein fistula is an uncommon clinical entity that may follow penetrating neck injury. It is rarely seen in children. It usually presents with a pulsatile neck mass following a history of trauma to the neck. It may present with pulsatile mass, thrill on palpation and murmurs on auscultation. There may be a neurologic deficit, which may vary from hemiparesis to hemiplegia. We present a case of traumatic arteriovenous fistula that presented as pulsatile anterior neck swelling in a school child. Case Presentation: A 6 year old male child, presented with a 3 days history of penetrating gunshot injury to the right side of the neck, as a result of accidental discharge from a gun during a marriage ceremony. The patient said to have bled profusely from the site of injury and had transient loss of consciousness. Examination revealed a healing wound and a slight swelling on the right side of the neck just anterior to the anterior border of the sternocleidomastoid muscle. The mass was pulsatile, with palpable thrill and bruit on auscultation. Colour doppler ultrasound demonstrated an abnormal connection with abnormal blood flow from the right common carotid artery to the right internal jugular vein. He was successfully treated surgically by neck exploration, excision of the fistula, and repair of defects in both vessels. Conclusions: Traumatic carotid-jugular fistula following gunshot injury is rarely seen in children. Guns should not be used or left unattended to in crowds so as to forestall future occurrence of accidental discharge that could lead to avoidable injuries. We recommended strict adherence to the rules and regulations guarding the use of firearms by civilians.

The Screening for Long Non-coding RNAs Related to Vein Graft Failure in Rat External Jugular Vein-Carotid Bypass Models

This study was designed to show the time-dependent changes in the expression profiles of long non-coding RNAs (lncRNAs) in rat vein grafts by using the high-throughput sequencing technique, and subsequently figure out lncRNAs related to vein graft failure. The whole SD rats were randomly classified into four groups according to different sampling time points (0, 7, 14 and 28 days after surgery, respectively; n=3 per group). The day 0 group was set as a control, and the other three groups were set as experimental groups (the model of external jugular vein-carotid artery bypass was prepared in the experimental group). We identified the differentially expressed lncRNAs of the vein graft sample at different sampling time points with high-throughput sequencing, and verified these results using the technique of real-time quantitative PCR (RT-qPCR). Meanwhile, we used Gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis to screen lncRNAs which may play roles in the restenosis process of vein grafts. The function of lncRNA-mRNA pairs was predicted. We subsequently used RT-qPCR to verify these lncRNAs. A total of 2 572 sustained differentially expressed lncRNAs were identified in our study. We showed the top ten differentially expressed lncRNAs at each post-operative time point. Through GO analysis and KEGG pathway analysis, we revealed the sustained differentially expressed genes which may be involved in VGF-related biological process, cellular component, molecular function and biological pathways. Finally, we screened 15 pairs of lncRNA-mRNA, including MRAK083052- Nrp1, which may play roles in mediating the restenosis of vein graft. And the results of RT-qPCR were consistent with the results of the high-throughput sequencing. The present study investigated the time-dependent changes in the expression profiles of lncRNAs in vein grafts. We also screened 15 pairs of lncRNA-mRNA which may paly roles in vein graft failure.

Modeling of Hypervolemia in Pulmonary Circulation in Rats Changes the Structure of NO-Mediated Relaxation of Pulmonary Arteries.

We analyzed the contribution of soluble guanylate cyclase-dependent pathway into NO-mediated relaxation of pulmonary arteries under conditions of high pulmonary blood flow modeled by creation of carotid artery-jugular vein shunt in rats. Inhibitor of soluble guanylate cyclase suppressed NO-donor induced relaxation was lower in rats with shunt, but dilatation in response to phosphodiesterase V inhibitor did not differ in the sham-operated and shunt groups. Thus, the structure of NO-mediated vasodilatation of pulmonary arteries under conditions of hypervolemia of pulmonary circulation was shifted to soluble guanylate cyclase-independent pathways, whereas intracellular soluble guanylate cyclase-dependent mechanisms of dilatation were in general unchanged.

Cardiac thermal pulse at the neck-skin surface as a measure of stenosis in the carotid artery

In this study, a cardiac thermal pulse evaluation-based carotid artery stenosis detection method is proposed. It is postulated that the presence of stenosis in the carotid artery results in a thermal lag in skin temperature at the neck skin surface that can be quantified to the degree of stenosis. A finite volume method-based transient bioheat transfer study was performed on a carotid artery-jugular vein 3-Dimensional (3D) geometry model encapsulated by the neck tissue. As the transient physiological blood flow in the carotid artery thermally interacts with the blood perfusion in the neck tissue, a thermal fluctuation or cardiac thermal pulse is resulted in the top-neck skin localized surface temperature contours. Two tissue blood perfusion models, constant (temperature-independent) and varying (temperature-dependent), were used to comparatively study the cardiac thermal pulse characterized by their signal noise. For 0% stenosis case, compared to the constant perfusion model, the average instantaneous noise for the varying perfusion model was found to be significantly lower (0.02 ± 0.01 versus 0.05 ± 0.01, p < 0.01). Furthermore, varying degrees of stenosis (25%, 50%, and 75%) were introduced in the carotid artery to study their effect on the cardiac thermal pulse. It was observed that there is a successive shift in the phase of the cardiac thermal pulse with an increase in the degree of stenosis in the carotid artery. This study demonstrates the potential of a cardiac thermal pulse evaluation-based indirect screening tool for carotid artery stenosis.

Atorvastatin Reduces In Vivo Fibrin Deposition and Macrophage Accumulation, and Improves Primary Patency Duration and Maturation of Murine Arteriovenous Fistula.

Arteriovenous fistulas placed surgically for dialysis vascular access have a high primary failure rate resulting from excessive inward remodeling, medial fibrosis, and thrombosis. No clinically established pharmacologic or perisurgical therapies currently address this unmet need. Statins' induction of multiple anti-inflammatory and antithrombotic effects suggests that these drugs might reduce arteriovenous fistula failure. Yet, the in vivo physiologic and molecular effects of statins on fistula patency and maturation remain poorly understood. We randomized 108 C57Bl/6J mice to receive daily atorvastatin 1.14 mg/kg or PBS (control) starting 7 days before end-to-side carotid artery-jugular vein fistula creation and for up to 42 days after fistula creation. We then assessed longitudinally the effects of statin therapy on primary murine fistula patency and maturation. We concomitantly analyzed the in vivo arteriovenous fistula thrombogenic and inflammatory macrophage response to statin therapy, using the fibrin-targeted, near-infrared fluorescence molecular imaging agent FTP11-CyAm7 and dextranated, macrophage-avid nanoparticles CLIO-VT680. In vivo molecular-structural imaging demonstrated that atorvastatin significantly reduced fibrin deposition at day 7 and macrophage accumulation at days 7 and 14, findings supported by histopathologic and gene-expression analyses. Structurally, atorvastatin promoted favorable venous limb outward remodeling, preserved arteriovenous fistula blood flow, and prolonged primary arteriovenous fistula patency through day 42 (P<0.05 versus control for all measures). These findings provide new in vivo evidence that statins improve experimental arteriovenous fistula patency and maturation, indicating that additional clinical evaluation of statin therapy in patients on dialysis undergoing arteriovenous fistula placement is warranted.

The placental growth factor attenuates intimal hyperplasia in vein grafts by improving endothelial dysfunction

Saphenous vein grafts (SVG) patency is limited by intimal hyperplasia (IH) caused by endothelial dysfunction. This study aimed to explore the effect of placental growth factor (PlGF) on the endothelial function of SVG. In rat models of external jugular vein-carotid artery graft treated with PlGF or saline hydrogel, PlGF inhibited vein graft IH (day 28: 12.0 ± 1.9 vs. 61.7 ± 13.1 μm, P < 0.001), promoted microvessel proliferation (day 14: 33.3% 3+ vs. 50.0% 2+, P = 0.03), and increased nitric oxide (NO) production (P < 0.05 on days 1/3/5) and NO synthase (NOS) expression by immunohistochemistry. In human umbilical vein endothelial cells (HUVECs) cultured under hypoxia and treated or not with PlGF, PlGF restored the survival (50 ng/ml PlGF, 48 h: 91.7 ± 0.6% vs. 84.9 ± 0.5%, P < 0.01), migration (by Matrigel assay), and tube formation ability (junctions, tubules, and tubule total length; all P < 0.01) of HUVECs after hypoxia. PlGF increased NO production through increased eNOS expression (P < 0.05), without changes in iNOS expression. The mRNA expression of eNOS decreased after the addition of the PI3K inhibitor LY294002 (P < 0.05). PlGF promoted the protein expression of eNOS by up-regulating AKT, and the AKT and eNOS protein levels were decreased after adding LY294002 (all P < 0.05). In conclusion, PlGF is a candidate for the inhibition of IH in SVG after coronary artery bypass graft. The effects of PlGF are mediated by the upregulation of the eNOS mRNA and protein through the PI3K/AKT signaling pathway. PlGF promotes the secretion of NO by endothelial cells and thereby reduces the occurrence and development of IH.

Right ventricular remodeling in response to volume overload in fetal sheep.

The fetal myocardium is known to be sensitive to hemodynamic load, responding to systolic overload with cellular hypertrophy, proliferation, and accelerated maturation. However, the fetal cardiac growth response to primary volume overload is unknown. We hypothesized that increased venous return would stimulate fetal cardiomyocyte proliferation and terminal differentiation, particularly in the right ventricle (RV). Vascular catheters and pulmonary artery flow probes were implanted in 16 late-gestation fetal sheep: a right carotid artery-jugular vein (AV) fistula was surgically created in nine fetuses, and sham operations were performed on seven fetuses. Instrumented fetuses were studied for 1 wk before hearts were dissected for component analysis or cardiomyocyte dispersion for cellular measurements. Within 1 day of AV fistula creation, RV output was 20% higher in experimental than sham fetuses ( P < 0.0001). Circulating atrial natriuretic peptide levels were elevated fivefold in fetuses with an AV fistula ( P < 0.002). On the terminal day, RV-to-body weight ratios were 35% higher in the AV fistula group ( P < 0.05). Both left ventricular and RV cardiomyocytes grew longer in fetuses with an AV fistula ( P < 0.02). Cell cycle activity was depressed by >50% [significant in left ventricle ( P < 0.02), but not RV ( P < 0.054)]. Rates of terminal differentiation were unchanged. Based on these studies, we speculate that atrial natriuretic peptide suppressed fetal cardiomyocyte cell cycle activity. Unlike systolic overload, fetal diastolic load appears to drive myocyte enlargement, but not cardiomyocyte proliferation or maturation. These changes could predispose to RV dysfunction later in life. NEW & NOTEWORTHY Adaptation of the fetal heart to changes in cardiac load allows the fetus to maintain adequate blood flow to its systemic and placental circulations, which is necessary for the well-being of the fetus. Addition of arterial-venous fistula flow to existing venous return increased right ventricular stroke volume and output. The fetal heart compensated by cardiomyocyte elongation without accelerated cellular maturation, while cardiomyocyte proliferation decreased. Even transient volume overload in utero alters myocardial structure and cardiomyocyte endowment.

Inadvertent carotid-jugular conduit: An uncommon yet dreaded jugular venous catheterization complication

Carotid-jugular fistula is one of the uncommon complications of internal jugular vein catheterization. It can have serious consequences such as infection, embolization, and high output cardiac failure and requires invasive repair. We describe a case of a common carotid artery-jugular vein arteriovenous fistula following the insertion of a double-lumen catheter for hemodialysis access.

Umbilical cannulation optimizes circuit flows in premature lambs supported by the EXTra-uterine Environment for Neonatal Development (EXTEND).

Bronchopulmonary dysplasia is a disease of extreme prematurity that occurs when the immature lung is exposed to gas ventilation. We designed a novel 'artificial womb' system for supporting extreme premature lambs (called EXTEND) that obviates gas ventilation by providing oxygen via a pumpless arteriovenous circuit with the lamb submerged in sterile artificial amniotic fluid. In the present study, we compare different arteriovenous cannulation strategies on EXTEND, including carotid artery/jugular vein (CA/JV), carotid artery/umbilical vein (CA/UV) and umbilical artery/umbilical vein (UA/UV). Compared to CA/JV and CA/UV cannulation, UA/UV cannulation provided significantly higher, physiological blood flows to the oxygenator, minimized flow interruptions and supported significantly longer circuit runs (up to 4weeks). Physiological circuit blood flow in UA/UV lambs made possible normal levels of oxygen delivery, which is a critical step toward the clinical application of artificial womb technology. EXTEND (EXTra-uterine Environment for Neonatal Development) is a novel system that promotes physiological development by maintaining the premature lamb in a sterile fluid environment and providing gas exchange via a pumpless arteriovenous oxygenator circuit. During the development of EXTEND, different cannulation strategies evolved with the aim of improving circuit flow. The present study examines how different cannulation strategies affect EXTEND circuit haemodynamics in extreme premature lambs. Seventeen premature lambs were cannulated at gestational ages 105-117days (term 145-150days) and supported on EXTEND for up to 4weeks. Experimental groups were distinguished by cannulation strategy: carotid artery outflow and jugular vein inflow (CA/JV; n=4), carotid artery outflow and umbilical vein inflow (CA/UV; n=5) and double umbilical artery outflow and umbilical vein inflow (UA/UV; n=8). Circuit flows and pressures were measured continuously. As we transitioned from CA/JV to CA/UV to UA/UV cannulation, mean duration of circuit run and weight-adjusted circuit flows increased (P<0.001) and the frequency of flow interruptions declined (P<0.05). Umbilical vessels generally accommodated larger-bore cannulas, and cannula calibre was directly correlated with circuit pressures and indirectly correlated with flow:pressure ratio (a measure of post-membrane resistance). We conclude that UA/UV cannulation in fetal lambs on EXTEND optimizes circuit flow dynamics and flow stability and also supports circuit flows that closely approximate normal placental flow.

Time characteristics of apoptosis and proliferate in rabbit remodeling process of vein grafting

Objective Research transplanted vein remodeling time characteristic of the level of apoptosis and proliferation in the process. Methods Pure New Zealand big-eared white rabbit to 42 health to establish the rabbit model of external jugular vein carotid artery bypass grafting. It divided into 7 groups, respectively in the preoperative and postoperative day 1, 3, 7, 14, 28 days and 90 days after remove transplanted vein, and the degree of stenosis, proliferating cell nuclear antigen (PCNA) protein levels, apoptosis, and transmission electron microscopy (SEM) and other related testing. Results (1) Morphological observation: Intimal thickness was found to have decreased slightly 1 day after surgery [(1.5±0.3) μm], compared with normal control group [(4.6±0.8) μm], with significant difference (t=8.778, P=0.000), group 3rd days postoperatively [(4.6±0.7) μm], compared with normal control group differences insignificant (t=0.027, P=0.979), postoperative 7th days group [(19.0±2.8) μm, t=-12.114, P=0.000], 14th days after surgery group [(36.2±5.8) μm, t=-13.229, P=0.000], 28th days after group [(67.2±4.6) μm, t=-32.842, P=0.000], in 90th days group [(95.0±6.8) μm, t=-32.322, P=0.000], were higher than normal vein group, with significant difference; Membrane + outer membrane thickness: normal vein group was (6.6±0.8) μm, postoperative 1rd day group (8.8±1.2) μm (t=-3.737, P=0.005), group 3rd days postoperatively (16.2±2.1) μm (t=-10.471, P=0.000), in 7th days group (46.2±6.1) μm (t=-15.755, P=0.000), 14th days after surgery group (64.0±6.1) μm (t=-22.871, P=0.000), 28th days after group (126.1±6.4) μm (t=-45.409, P=0.000), 90th days after group (132.4±11.0) μm (t=-27.951, P=0.000), were higher than in normal control group, significant difference; (2) Western blotting analysis: The grayscale ratio of the band of interest to the internal reference band demonstrated that PCNA expression had decreased 1 day after surgery (33.4±3.7)%, for the normal control group (42.2±2.6)%, with significant difference (t=4.770, P=0.000), group 3 days postoperatively (56.3±3.8)% (t=8.778, P=0.000), higher than the control group, with significant difference, set up to 7 days after peak (79.7±8.3)% (t=-10.564, P=0.000), significantly higher than control group, postoperative 1 day, 3 days group, with significant difference, and gradually declining thereafter, for the 14 days after surgery (72.8±3.1)% (t=-18.537, P=0.000), 28 days after surgery (60.6±5.4)% (t=-7.527, P=0.000), and 90 days after surgery (48.0±3.8)% (t=-3.083, P=0.013), all higher than normal control group, with significant difference, and no unit of measure; (3) Immunohistochemistry: The percentage of PCNA-positive cells in control group was (6.25±0.90)%, which decreased slightly to (4.96±0.70)%1 day following surgery (t=2.755, P=0.021). By the 7th day, this value had peaked (32.70±3.10)% (t=-20.101, P=0.000), and gradually decreased after this point, no unit of measure. (4) TdT-mediated dUTP nick end labeling (TUNEL) apoptosis assay: A small number of apoptotic cells were observed in control group vein samples (1.36±0.20)%. The rate of apoptosiswas higheston the1st day following surgery (18.61±1.50)% (t=-27.873, P=0.000), and had decreasedby 3rd day (7.16±0.50)% (t=-26.251, P=0.000), reaching its lowest level on the 7th day (1.98±0.40)% (t=-3.402, P=0.011) and subsequently remaininglow. The percentage of apoptotic cells on days 14, 28, and 90 after surgery were (4.37±0.70)% (t=-10.122, P=0.000), (6.18±0.90)% (t=-12.839, P=0.000) and (6.56±1.20)% (t=-10.497, P=0.000), respectively, no unit of measure. Conclusion 1 day after venous transplantation to 3 days postoperatively, apoptosis level is higher; 7 days after proliferation level is higher. Key words: Proliferating cell nuclear antigen; Vein grafts; Restenosis

Rapamycin reduced pulmonary vascular remodelling by inhibiting cell proliferation via Akt/mTOR signalling pathway down-regulation in the carotid artery-jugular vein shunt pulmonary hypertension rat model.

Pulmonary arterial hypertension (PAH) is a common complication of congenital heart disease. However, effective treatments for PAH are rare. This study aimed to investigate the inhibitory effects of rapamycin on PAH in the carotid artery-jugular vein (CA-JV) shunt PAH rat model as well as the mechanism underlying these effects. Twenty-four Sprague-Dawley rats were randomized into the following 3 groups: a control group, a CA-JV shunt group and a treatment group. Rapamycin (2 mg/kg/day) was administered to the treatment group, and placebo was administered to the CA-JV shunt group. Haemodynamic evaluations, pulmonary tissue samplings for morphometry and immunofluorescence and western blot analyses were performed to evaluate the effects of rapamycin on PAH. Rapamycin attenuated the increase of right ventricular systolic pressure (RVSP) and the right ventricular (RV) hypertrophy (RVSP: CA-JV vs CA-JV + rapamycin, P = 0.017; RV: CA-JV vs CA-JV + rapamycin, P = 0.022), as well as the intrapulmonary vessel thickening (thickness index: CA-JV vs CA-JV + rapamycin, P = 0.028; area index: CA-JV vs CA-JV + rapamycin, P = 0.014), induced by overcirculation of the pulmonary vasculature in the CA-JV shunt-induced PAH rat model. Rapamycin decreased the expression level of the indicated cell proliferation marker (α-smooth muscle actin) in the lung vessel and mechanistic target of rapamycin (mTOR) pathway components (p-mTOR: CA-JV vs CA-JV + rapamycin, P = 0.004; p-Raptor: CA-JV vs CA-JV + rapamycin, P = 0.000; p-S6K1: CA-JV vs CA-JV + rapamycin, P = 0.000; p-Akt: CA-JV vs CA-JV + rapamycin, P = 0.001; p-Rheb: CA-JV vs CA-JV + rapamycin, P = 0.000) in pulmonary tissue. Rapamycin reduced pulmonary vascular remodelling by inhibiting cell proliferation via Akt/mTOR signalling pathway down-regulation in the CA-JV shunt-induced PAH model in rats. Thus, rapamycin may be a novel candidate drug for the treatment of PAH.

Inhibitory Effect of TLR4 Gene Silencing on Intimal Hyperplasia of Vein Grafting.

The present study aimed to explore the regulating effect of Toll-like receptor 4 (TLR4) on intimal hyperplasia in rat vein grafts. Rat models of external jugular vein carotid artery bypass grafting were established. Afterward, TLR4 small interfering RNA (siRNA) recombinant plasmids were constructed, which were transfected into rat vein graft bypass to study the effect of TLR4 silencing on intimal hyperplasia and to explore the underlying mechanisms. Real-time polymerase chain reaction and Western blot were used to detect the expression levels of TLR4 and inflammatory factors in TLR4 siRNA-transfected vein graft bypass. The intimal thickness was evaluated using hematoxylin-eosin staining. Compared with the scramble siRNA group, the intimal thickness of vein grafting was decreased significantly, while the inflammatory factors including interleukin (IL) 1β, IL-6, and tumor necrosis factor α in grafted vein were dramatically downregulated in the TLR4 siRNA group. These results showed that local silencing of TLR4 in the vein grafts could inhibit intimal hyperplasia by downregulating the expression of inflammatory factors in the vein grafts, suggesting that TLR4 can be used as a new target for therapy of vascular intimal hyperplasia.

Hemodynamics and right-ventricle functional characteristics of a swine carotid artery-jugular vein shunt model of pulmonary arterial hypertension: An 18-month experimental study.

The continuous changes in pulmonary hemodynamic properties and right ventricular (RV) function in pulmonary arterial hypertension (PAH) have not been fully characterized in large animal model of PAH induced by a carotid artery-jugular vein shunt. A minipig model of PAH was induced by a surgical anastomosis between the left common carotid artery and the left jugular vein. The model was validated by catheter examination and pathologic analyses, and the hemodynamic features and right-ventricle functional characteristics of the model were continuously observed by Doppler echocardiography. Of the 45 minipigs who received the surgery, 27 survived and were validated as models of PAH, reflected by mean pulmonary artery pressure ≥25 mmHg, and typical pathologic changes of pulmonary arterial remodeling and RV fibrosis. Non-invasive indices of pulmonary hemodynamics (pulmonary artery accelerating time and its ratio to RV ventricular ejection time) were temporarily increased, then reduced later, similar to changes in tricuspid annular displacement. The Tei index of the RV was elevated, indicating a progressive impairment in RV function. Surgical anastomosis between carotid artery and jugular vein in a minipig is effective to establish PAH, and non-invasive hemodynamic and right-ventricle functional indices measured by Doppler echocardiography may be used as early indicators of PAH.

Simvastatin attenuates pulmonary vascular remodelling by down-regulating matrix metalloproteinase-1 and -9 expression in a carotid artery-jugular vein shunt pulmonary hypertension model in rats

It remains controversial as to whether simvastatin has a beneficial effect on pulmonary artery hypertension. This study aimed to explore the efficacy of simvastatin on haemodynamic changes, pulmonary vascular remodelling and expression of matrix metalloproteinase-1 and -9 (MMP-1,9) in a carotid artery-jugular vein (CA-JV) shunt pulmonary artery hypertension (PAH) model in rats. Thirty-six Sprague-Dawley rats were randomized into three groups: Control group, CA-JV group, and Treatment group. A pre-tricuspid systemic-pulmonary shunt from the left common carotid artery to the external jugular vein was established on the CA-JV and Treatment groups, but only ligations of both vessels were performed in Control group. Simvastatin (4 mg/kg/d) was administered to the Treatment group, and placebo to the CA-JV group. Twelve weeks later, the animals underwent a haemodynamic evaluation, followed by pulmonary tissue sampling for morphometry, quantitative real-time PCR and Western blot analysis. By week 12, rats in the CA-JV group had higher right ventricular systolic pressure (RVSP), medial area/total area (MA/TA) and percentage of fibrous tissue (F%) than those in the Control group. These changes were associated with up-regulation of MMP-1,9 mRNA and increased expression of MMP-1,9 proteins. Pretreatment with simvastatin decreased the shunt-induced RVSP, MA/TA and F% in pulmonary arteries. In addition, lung MMP-1,9 mRNA and proteins levels decreased toward normal levels in simvastatin-treated rats. Simvastatin ameliorated the structural and functional derangements of pulmonary arterioles caused by the CA-JV shunt, partly associated with the suppression of up-regulated MMP-1, as well as MMP-9. Simvastatin may play a role in the treatment of systemic-pulmonary shunt-induced PAH diseases, such as congenital heart disease.

Preventing intimal thickening of vein grafts in vein artery bypass using STAT-3 siRNA

BackgroundProliferation and migration of vascular smooth muscle cells (VSMCs) play a key role in neointimal formation which leads to restenosis of vein graft in venous bypass. STAT-3 is a transcription factor associated with cell proliferation. We hypothesized that silencing of STAT-3 by siRNA will inhibit proliferation of VSMCs and attenuate intimal thickening.MethodsRat VSMCs were isolated and cultured in vitro by applying tissue piece inoculation methods. VSMCs were transfected with STAT 3 siRNA using lipofectamine 2000. In vitro proliferation of VSMC was quantified by the MTT assay, while in vivo assessment was performed in a venous transplantation model. In vivo delivery of STAT-3 siRNA plasmid or scramble plasmid was performed by admixing with liposomes 2000 and transfected into the vein graft by bioprotein gel applied onto the adventitia. Rat jugular vein-carotid artery bypass was performed. On day 3 and7 after grafting, the vein grafts were extracted, and analyzed morphologically by haematoxylin eosin (H&E), and assessed by immunohistochemistry for expression of Ki-67 and proliferating cell nuclear antigen (PCNA). Western-blot and reverse transcriptase polymerase chain reaction (RT-PCR) were used to detect the protein and mRNA expression in vivo and in vitro. Cell apoptosis in vein grafts was detected by TUNEL assay.ResultsMTT assay shows that the proliferation of VSMCs in the STAT-3 siRNA treated group was inhibited. On day 7 after operation, a reduced number of Ki-67 and PCNA positive cells were observed in the neointima of the vein graft in the STAT-3 siRNA treated group as compared to the scramble control. The PCNA index in the control group (31.3 ± 4.7) was higher than that in the STAT-3 siRNA treated group (23.3 ± 2.8) (P < 0.05) on 7d. The neointima in the experimental group(0.45 ± 0.04 μm) was thinner than that in the control group(0.86 ± 0.05 μm) (P < 0.05).Compared with the control group, the protein and mRNA levels in the experimental group in vivo and in vitro decreased significantly. Down regulation of STAT-3 with siRNA resulted in a reduced expression of Bcl-2 and cyclin D1. However, apoptotic cells were not obviously found in all grafts on day 3 and 7 post surgery.ConclusionsThe STAT-3 siRNA can inhibit the proliferation of VSMCs in vivo and in vitro and attenuate neointimal formation.

Fibrosis of pulmonary vascular remodeling in carotid artery-jugular vein shunt pulmonary artery hypertension model of rats

The aim of the present study was to observe the changes of hemodynamics, stereology in pulmonary vascular remodeling and messenger RNA (mRNA) expressions of transforming growth factor beta 1, and receptors in carotid artery-jugular vein (CA-JV) shunt pulmonary artery hypertension model of rats. Thirty-six Sprague-Dawley rats were randomized into three groups: CA-JV group, monocrotaline (MCT) administration group, and control group. Left CA-JV shunts were established in CA-JV group. Dorsal subcutaneous injections of MCT (60 mg kg(-1)) were received in MCT group. Ligations of left common carotid artery and external jugular vein were performed in control group. Right ventricular systolic pressure (RVSP) measurement, histological evaluation of the pulmonary tissue, and mRNA levels of transforming growth factor beta 1 (TGFß1), receptor 1 and receptor 2, were investigated after 6 weeks on MCT group, and after 12 weeks on both control and CA-JV groups. Compared with control group, RVSP, percentage of fibrous tissue (F%) in pulmonary arterioles, mRNA levels of TGFß1, and receptors of CA-JVand MCT groups increased significantly. Severe hemodynamics change was found in MCT groups. On the other hand, CA-JV group demonstrated more obvious fibrogenesis and TGFß1 signals' upregulation in two pulmonary artery hypertension (PAH) models. CA-JV shunt model of rats was a well-established PAH animal model simulating congenital heart disease with systemic-pulmonary shunt.