Muscular Arteries Research Articles

Controlled and Synchronised Vascular Regeneration upon the Implantation of Iloprost- and Cationic Amphiphilic Drugs-Conjugated Tissue-Engineered Vascular Grafts into the Ovine Carotid Artery: A Proteomics-Empowered Study.

Implementation of small-diameter tissue-engineered vascular grafts (TEVGs) into clinical practice is still delayed due to the frequent complications, including thrombosis, aneurysms, neointimal hyperplasia, calcification, atherosclerosis, and infection. Here, we conjugated a vasodilator/platelet inhibitor, iloprost, and an antimicrobial cationic amphiphilic drug, 1,5-bis-(4-tetradecyl-1,4-diazoniabicyclo [2.2.2]octan-1-yl) pentane tetrabromide, to the luminal surface of electrospun poly(ε-caprolactone) (PCL) TEVGs for preventing thrombosis and infection, additionally enveloped such TEVGs into the PCL sheath to preclude aneurysms, and implanted PCLIlo/CAD TEVGs into the ovine carotid artery (n = 12) for 6 months. The primary patency was 50% (6/12 animals). TEVGs were completely replaced with the vascular tissue, free from aneurysms, calcification, atherosclerosis and infection, completely endothelialised, and had clearly distinguishable medial and adventitial layers. Comparative proteomic profiling of TEVGs and contralateral carotid arteries found that TEVGs lacked contractile vascular smooth muscle cell markers, basement membrane components, and proteins mediating antioxidant defense, concurrently showing the protein signatures of upregulated protein synthesis, folding and assembly, enhanced energy metabolism, and macrophage-driven inflammation. Collectively, these results suggested a synchronised replacement of PCL with a newly formed vascular tissue but insufficient compliance of PCLIlo/CAD TEVGs, demanding their testing in the muscular artery position or stimulation of vascular smooth muscle cell specification after the implantation.

Weakness of lower limb muscle in symptomatic peripheral artery disease with media sclerosis detected by ultrasound shear wave elastography.

Background: Symptomatic peripheral arterial disease (PAD) is difficult to non-invasively diagnose in the presence of calcified, media sclerotic arteries that are incompressible by blood pressure cuffs. Standard ankle-brachial index (ABI) measurements in these PAD patients are very often not helpful. Shear wave elastography (SWE) is a modern ultrasound technique to detect peripheral muscle stiffness changes i.e. muscle weakness during exercise. In a pilot study, we examined whether SWE could be a reproducible tool for diagnosing ischemic loss of muscle stiffness in patients with PAD and concomitant arterial media sclerosis. Patients and methods: N=13 consecutive patients with peripheral artery disease and media sclerosis were enrolled in the pilot study. All 13 patients were symptomatic in different stages of their PAD due to hemodynamically relevant arterial stenosis or occlusions of limb arteries as confirmed by oscillography, color-coded duplex sonography or angiography. Results: ABI measurements were invalid in all 13 patients. Mean SWE measurements of medial gastrocnemius muscles showed a significant transient muscle stiffness loss (weakness) at maximum exercise (active dorsal flexion of the foot, 103.4±25.9 kPa on the asymptomatic vs. 62.5±21.9 kPa on the symptomatic limb (p<0.001). Conclusions: SWE can reproducibly detect peripheral muscle weakness during exercise in the symptomatic leg of media sclerotic PAD patients. SWE of lower limb muscles may help to identify symptomatic PAD in patients presenting with invalid ABI measurements and unclear vascular status.

Association of serum klotho levels with different-staged vascular calcification status in patients with maintenance hemodialysis

BackgroundVascular calcification (VC) is suggested to be associated with serum klotho levels in patients with maintenance hemodialysis (MHD), whereas there is a lack of reports on the associations of VC status in whole arteries with serum klotho contents.MethodsOne hundred forty eligible patients with MHD and a total of age-and gender-matched normal controls (NCs) were recruited. We analyzed the VC statuses of large arteries and peripheral muscular arteries by calculating the sum of scores from each artery. The levels of serum klotho were determined by ELISA. In addition, the relationship between serum klotho and VC status was evaluated using correlation analysis and regression analysis.ResultsThe VC severity in MHD patients tended to be worse in comparison with NCs. Serum klotho level in patients with MHD was lower than that in the NC subjects (​P < 0.0001), which was correlated with VC scores as reflected by correlation analysis and regression analysis. Serum klotho concentrations exhibited a dynamic decline along with increased VC status stages. Subjects with higher levels of serum klotho had a higher prevalence of cardiovascular events.ConclusionOur study indicates serum klotho is strongly associated with VC status in a stage-dependent manner.

Comparison of hypoxia-induced pulmonary hypertension rat models caused by different hypoxia protocols

Background and aim: Pulmonary hypertension (PH) is a serious and even fatal disorder with limited treatment strategies. The hypoxia-induced pulmonary hypertension (HPH) rat model is commonly used in this field. While the HPH rat model has strong predictability and repeatability, the model is a chronic model, making it time-consuming, costly, and complicated and limiting the progress of the experiments. Currently, there is no uniform international standard for the HPH model. Our study aimed to find a relatively effective and efficient HPH modeling protocol. Methods: We established HPH rat models with different total hypoxia periods and different daily hypoxia times, and assessed different hypoxia modeling modes in multiple dimensions, such as haemodynamics, right ventricular (RV) hypertrophy, pulmonary arterial remodeling, muscularization, inflammation, and collagen deposition. Results: Longer daily hypoxia time resulted in higher mean pulmonary arterial pressure (mPAP)/right ventricular systolic pressure (RVSP) and more obvious RV hypertrophy, as well as more severe pulmonary arterial remodeling and muscularization, regardless of the total period of hypoxia (3- or 4-week). Moreover, pulmonary perivascular macrophages and collagen deposition showed daily hypoxia time-dependent increases, both in 3- and 4-week hypoxia groups. Conclusion: Our findings showed that the 3-week continuous hypoxia mode was a relatively efficient way to reduce the time needed to induce significant disease phenotypes, which offered methodological evidence for future studies in building HPH models.

Abstract 11484: Upregulation of Dynamin 2 Increases Mitochondrial Fission and Cell Proliferation in Pulmonary Arterial Hypertension

Introduction: The obstructive vasculopathy in pulmonary arterial hypertension (PAH) results in part from acquired mitochondrial changes in pulmonary arterial smooth muscle cells (PASMC), including increased mitotic fission. Mitotic fission, mitochondrial division which is coordinated with mitosis to equitably distribute mitochondria to daughter cells, is mediated by activation of dynamin-related protein 1 (Drp1). To complete mitochondrial fission, Drp1 requires assistance from the GTPase dynamin 2 (DNM2). Hypothesis: Pathological increase in DNM2 expression drives mitochondrial fission and proliferation of PAH PASMC. Methods: Immunoblots of human PASMC and immunohistochemistry and immunofluorescence of lung sections from human (n=5/group) and monocrotaline (MCT) rats with PAH (n=4-5/group) were used to assess the expression of DNM2. The effect of manipulating DNM2 on cell proliferation, cell cycle and apoptosis were assessed by flow cytometry. Mitochondrial fission was quantified using confocal imaging. Results: DNM2 protein expression is increased in human PAH PASMC. DNM2 is also increased in the media of small pulmonary arteries of PAH patients and MCT-PAH rats. Silencing DNM2 inhibited mitochondrial fission and reduced proliferation causing cell cycle arrest in G1/G0 phase. Silencing DNM2 in PAH PASMC also induced apoptosis. Conversely, augmenting DNM2 in normal PASMC induced mitochondrial fission and accelerated cell proliferation. miR-124-3p, a putative negative regulator of DNM2, is decreased in PAH PASMC. Augmenting miR-124-3p decreased DNM2 expression, inhibited proliferation and induced apoptosis in PAH PASMC. Conclusion: In health, DNM2 regulates mitochondrial fission whilst in disease, epigenetic upregulation of DNM2 increases mitotic fission, which drives pathologic proliferation and apoptosis resistance. The miR-124-3p-DNM2 pathway offers novel PAH therapeutic targets.

Abstract 10336: Phase 3 Anticancer Agent, RRx-001, Ameliorates Hypoxia-Induced Pulmonary Hypertension

Introduction: The hallmark features of pulmonary artery hypertension (PAH), for which hypoxia is a trigger, are vascular remodeling, elevated pulmonary blood pressure, oxidative stress, and right ventricular hypertrophy. RRx-001 is a minimally toxic Phase 3 anticancer agent with anti-oxidative, anti-inflammatory, nitric oxide-donating, and anti-proliferative properties. This study aimed to investigate the effect of RRx-001 on intermittent hypoxia-induced PAH in rats. Hypothesis: RRx-001 attenuates PAH Methods: Male Wistar rats (180-220 g) were divided into four groups (n=6 per group): normoxic control, hypoxic with vehicle treatment (2 weeks breathing an atmosphere containing 10% oxygen), hypoxic treated with oral endothelin-1 receptor inhibitor, bosentan, 50 mg/kg per day for 2 weeks during hypoxia and one intravenous dose of 5mg/kg RRx-001 given the day before the start of the hypoxia. After sacrifice, hearts and lungs were removed and harvested for analyses. Results: RRx-001 and bosentan, separately, significantly attenuated hypoxia-induced increases in right ventricular systolic pressure and right ventricular hypertrophy in PAH rats vs. vehicle. RRx-001 and bosentan, separately, also significantly decreased the thickening of pulmonary artery media and decreased the muscularization of pulmonary arterioles in PAH rats and the wall thickness/external diameter ratio of the pulmonary arteries vs. vehicle. Conclusions: RRx-001 significantly reduced right ventricular systolic pressure and pulmonary remodeling in a rat model of PAH, which potentially makes it a new therapeutic option for this dread disease. As a next step, combination of RRx-001 and bosentan will be attempted.

Analysis of characteristics of the location of lower extremity deep vein thrombosis and the site of pulmonary embolism in hospitalized patients

To investigate the characteristics and relationship between the location of lower extremity deep vein thrombosis (DVT) and the site of pulmonary embolism in hospitalized patients. The data of patients with lower extremity DVT diagnosed by ultrasound examination and pulmonary embolism diagnosed by CT pulmonary angiography from December 2017 to December 2021 were analyzed retrospectively. According to the location of lower extremity DVT, the patients were divided into mixed DVT, proximal DVT, and distal DVT which was further divided into anterior/posterior tibial vein or peroneal vein thrombosis and calf muscular venous thrombosis. Mixed DVT was referred to the presence of both proximal and distal DVT. According to the involved site of pulmonary artery, pulmonary embolism was divided into three types: main pulmonary artery, left or right pulmonary artery trunk embolism, lobar pulmonary artery embolism and segmental pulmonary artery embolism. The location of lower extremity DVT, the site of pulmonary embolism, the clinical manifestation (shortness of breath, chest tightness, chest pain, hemoptysis, cough, lower limb swelling, lower limb pain, syncope, fever) and risk factors (fracture/trauma, tumor, diabetes, hypertension, atrial fibrillation, infection, surgery, autoimmune diseases, paralysis, pregnancy) of venous thromboembolism (VTE), and the level of D-dimer were analyzed. A total of 209 patients were enrolled finally, including 127 patients with left lower extremity DVT (60.8%) and 82 with right lower extremity DVT (39.2%). Mixed DVT accounted for 39.2%, proximal DVT accounted for 17.3%, and distal DVT accounted for 43.5% (anterior/posterior tibial vein and peroneal vein thrombosis accounted for 14.8%, calf muscular venous thrombosis accounted for 28.7%). The incidences of main pulmonary artery embolism, left or right pulmonary artery trunk embolism in the mixed DVT and proximal DVT were significantly higher than those in the anterior/posterior tibial vein or peroneal vein thrombosis and calf muscular venous thrombosis [41.5% (34/82), 38.8% (14/36) vs. 16.2% (5/31), 10.0% (6/60)], with statistically significant differences (all P < 0.05). The incidences of pulmonary segmental artery embolism in the anterior/posterior tibial vein or peroneal vein thrombosis were higher than those in the mixed DVT and proximal DVT [41.9% (13/31) vs. 26.8% (22/82), 30.6% (11/36)], but the difference was not statistically significant (both P > 0.05). The incidences of pulmonary segmental artery embolism in the calf muscular venous thrombosis were significantly higher than those in the mixed DVT and the proximal DVT [66.7% (40/60) vs. 26.8% (22/82), 30.6% (11/36)], and the difference was statistically significant (both P < 0.05). The levels of D-dimer in patients with calf muscular venous thrombosis combined with main pulmonary artery embolism, left or right pulmonary artery trunk embolism were significantly higher than those in patients with calf muscular venous thrombosis combined pulmonary segmental artery embolism (mg/L: 6.08±3.12 vs. 3.66±2.66, P < 0.05). There were no significant differences in D-dimer levels in other patients with DVT combined with pulmonary embolism in different sites. In terms of the clinical manifestations of VTE, the incidences of lower limb swelling in the mixed DVT and proximal DVT were significantly higher than those in the anterior/posterior tibial vein or peroneal vein thrombosis and calf muscular venous thrombosis [54.9% (45/82), vs. 29.0% (9/31), 15.0% (9/60), both P < 0.05], the incidences of lower limb swelling in the proximal DVT were significantly higher than those in the calf muscular venous thrombosis [41.7% (15/63) vs. 15.0% (9/60), P < 0.05], there were no significant difference in the other clinical manifestations among the DVT groups. There was no significant difference in the incidence of VTE risk factors among the groups. The DVT of inpatients mostly occurred in the left lower limb, and the incidence of distal DVT was higher than that of proximal DVT. Mixed DVT and proximal DVT combined with pulmonary embolism mostly occurred in the main pulmonary artery, left or right pulmonary artery trunk, while distal DVT combined with pulmonary embolism mostly occurred in the pulmonary segmental artery. The levels of D-dimer in patients with lower extremity DVT combined with main pulmonary artery or left and right pulmonary artery trunk embolism were higher than those in patients with pulmonary lobe and segmental artery embolism. The incidence of lower extremity swelling in patients with mixed DVT and proximal DVT was higher than that in patients with distal DVT.

Towards a better understanding of arterial calcification disease progression in CKD: investigation of early pathological alterations.

Cardiovascular disease remains the leading cause of death in chronic kidney disease (CKD) patients, especially in those undergoing dialysis and kidney transplant surgery. CKD patients are at high risk of developing arterial media calcifications (AMC) and arterial stiffness. We hypothesized that investigation of disease progression at an early stage could provide novel insights in understanding AMC etiology. An adenine diet was administered to male Wistar rats to induce AMC. Rats were sacrificed after 2, 4 and 8 weeks. AMC was measured by assessment of aortic calcium and visualized using histology. Arterial stiffness was measured in vivo by ultrasound and ex vivo by applying cyclic stretch of physiological magnitude on isolated arterial segments, allowing us to generate the corresponding pressure-diameter loops. Further, ex vivo arterial reactivity was assessed in organ baths at 2 and 4 weeks to investigate early alterations in biomechanics/cellular functionality. CKD rats showed a time-dependent increase in aortic calcium which was confirmed on histology. Accordingly, ex vivo arterial stiffness progressively worsened. Pressure-diameter loops showed a gradual loss of arterial compliance in CKD rats. Additionally, viscoelastic properties of isolated arterial segments were altered in CKD rats. Furthermore, after 2 and 4 weeks of adenine treatment, a progressive loss in basal, nitric oxide (NO) levels was observed, which was linked to an increased vessel tonus and translates into an increasing viscous modulus. Our observations indicate that AMC-related vascular alterations develop early after CKD induction prior to media calcifications being present. Preventive action, related to restoration of NO bioavailability, might combat AMC development.

Vascular Aging and Arterial Stiffness.

ResumoO envelhecimento biológico é reflexo da interação entre genética, idade cronológica e fatores externos; é a base para novos conceitos em envelhecimento vascular, cuja progressão é determinada pela diferença entre idade biológica e cronológica. Do ponto de vista estrutural, os efeitos do envelhecimento vascular são mais evidentes na camada média das grandes artérias elásticas e resultam em aumento da rigidez arterial, da dilatação do lúmen e da espessura da parede. Esses efeitos são descritos no continuum de envelhecimento cardiovascular (proposto por Dzau em 2010) em que as etapas progressivas de lesões da microvasculatura de coração, rins e cérebro, têm início a partir do processo de envelhecimento. O aumento da rigidez arterial pode ser verificado de forma não invasiva por vários métodos. Os eventos cardiovasculares têm sido tradicionalmente previstos utilizando escores que combinam fatores de risco convencionais para aterosclerose. No continuum cardiovascular clássico (Dzau, 2006), é desafiador avaliar o peso exato da contribuição de cada fator de risco; entretanto, por refletir o dano precoce e cumulativo desses fatores de riscos cardiovascular, a rigidez arterial reflete o verdadeiro dano à parede arterial. Este artigo fornece uma visão geral dos mecanismos da fisiopatogenia, alterações estruturais das artérias e consequências hemodinâmicas do envelhecimento arterial; métodos não invasivos para a avaliação da rigidez arterial e da medida central da pressão arterial; o continuum de envelhecimento cardiovascular, e aplicação do conceito de rigidez arterial na estratificação de risco cardiovascular.

Evaluation of symptomatic peripheral artery disease with media sclerosis using shear wave elastography of the lower limb muscle

Abstract Background Symptomatic peripheral artery disease (PAD) is challenging to diagnose in the presence of media sclerosis with incompressible arteries since standard ankle-brachial index (ABI) cannot be applied. Shear wave elastography (SWE) provides a novel ultrasound technique to measure muscle stiffness and to visualize muscle deficits at rest and during contraction. Furthermore, reduced muscle stiffness correlates with a possible hypoperfusion in the affected area. It is fast, non-invasive and associated with peripheral muscle weakness in chronic heart failure patients. Purpose SWE presents an important diagnostic tool for patients with PAD and concomitant media sclerosis. In this prospective observation study we evaluated the alterations of muscle stiffness (measured in kPa) at rest and during controlled activity. Methods Fifteen patients with peripheral artery disease and media sclerosis were included in this pilot study. Thirteen patients were symptomatic in different stages of PAD as a result of significant arterial stenosis/occlusions of the lower legs as assessed by oscillography and duplex sonography. ABI was invalid due to media sclerosis in all 15 patients. The examination was performed at rest and during contraction depicted by active dorsal flexion of the foot on both sides. The medial gastrocnemius muscle was used as a region of interest. Results Mean SWE measurements of medial gastrocnemius muscles showed significant muscle weakness at maximum exercise (103.4±25.9 kPa on the asymptomatic vs. 62.5±21.9 kPa in the symptomatic lower leg (p&amp;lt;0.001). Oscillography confirmed the SWE results by a decreased signal on the clinically symptomatic side. Conclusion SWE is suitable to detect muscle weakness during exercise in the symptomatic leg of mediasclerotic PAD patients. Since ABI measurements are usually invalid these patients with media sclerosis, shear wave elastography of lower limb muscles may contribute for a non-invasive diagnosis of symptomatic PAD. Larger randomized clinical trials are necessary to confirm our results. Funding Acknowledgement Type of funding sources: None.

A single-cell transcriptomic inventory of murine smooth muscle cells.

Smooth muscle cells (SMCs) execute important physiological functions in numerous vital organ systems, including the vascular, gastrointestinal, respiratory, and urogenital tracts. SMC differ morphologically and functionally at these different anatomical locations, but the molecular underpinnings of the differences remain poorly understood. Here, using deep single-cell RNA sequencing combined with in situ gene and protein expression analysis in four murine organs-heart, aorta, lung, and colon-we identify a molecular basis for high-level differences among vascular, visceral, and airway SMC, as well as more subtle differences between, for example, SMC in elastic and muscular arteries and zonation of elastic artery SMC along the direction of blood flow. Arterial SMC exhibit extensive organotypic heterogeneity, whereas venous SMC are similar across organs. We further identify a specific SMC subtype within the pulmonary vasculature. This comparative SMC cross-organ resource offers insight into SMC subtypes and their specific functions.

Mechanical stretch aggravates vascular smooth muscle cell apoptosis and vascular remodeling by downregulating EZH2

Enhancer of zeste homolog 2 (EZH2) was recently found to play an important role in cardiovascular disease. However, the role of EZH2 in vascular remodeling induced by mechanical stretch is poorly understood. The aim of the present work was to investigate the role of EZH2 in regulating smooth muscle cell function through mechanical stretch assays and to explore the underlying mechanisms. WT C57BL/6J mice underwent sham surgery or abdominal aortic constriction. The level of EZH2 expression was determined by Western blotting and immunohistochemical staining. We demonstrated the thickness of vascular remodeling by HE staining. JASPAR was used to predict transcription factors that could affect EZH2. Chromatin immunoprecipitation was used to substantiate the DNAprotein interactions. Promoter luciferase assays were performed to demonstrate the activity of the transcription factors. We found that in vivo, AAC significantly reduced EZH2 protein levels in the thoracic aorta. Smooth muscle-specific overexpression of EZH2 was sufficient to attenuate the AAC-induced reduction in trimethylation of Lys-27 in histone 3 and thickening of the arterial media. Administration of GSK-J4 (an inhibitor of H3K27me3 demethylase) induced the same effects. In addition, we found that mechanical stretch regulated the expression of EZH2 through the Yes-associated protein (YAP)- transcriptional factor TEA domain 1 (TEAD) pathway. TEAD1 bound directly to the promoter of EZH2, and blocking the YAP-TEAD1 interaction inhibited EZH2 downregulation due to mechanical stretch. This study reveals that mechanical stretch downregulates EZH2 through the YAP-TEAD1 pathway, thereby aggravating smooth muscle cell apoptosis and vascular remodeling.

Ex Vivo Study Using Diffusion Tensor Imaging to Identify Biomarkers of Atherosclerotic Disease in Human Cadaveric Carotid Arteries.

Background:This study aims to address the potential of ex vivo diffusion tensor imaging to provide insight into the microstructural composition and morphological arrangement of aged human atherosclerotic carotid arteries.Methods:In this study, whole human carotid arteries were investigated both anatomically and by comparing healthy and diseased regions. Nonrigid image registration was used with unsupervised segmentation to investigate the influence of elastin, collagen, cell density, glycosaminoglycans, and calcium on diffusion tensor imaging derived metrics (fractional anisotropy and mean diffusivity). Early stage atherosclerotic features were also investigated in terms of microstructural components and diffusion tensor imaging metrics.Results:All vessels displayed a dramatic decrease in fractional anisotropy compared with healthy animal arterial tissue, while the mean diffusivity was sensitive to regions of advanced disease. Elastin content strongly correlated with both fractional anisotropy (r>0.7, P<0.001) and mean diffusivity (r>−0.79, P<0.0002), and the thickened intima was also distinguishable from arterial media by these metrics.Conclusions:These different investigations point to the potential of diffusion tensor imaging to identify characteristics of arterial disease progression, at early and late-stage lesion development.

Activation of Autophagy Induces Monocrotaline-Induced Pulmonary Arterial Hypertension by FOXM1-Mediated FAK Phosphorylation.

It has been shown that activation of autophagy promotes the development of pulmonary arterial hypertension (PAH). Meanwhile, forkhead box M1 (FOXM1) has been found to induce autophagy in several types of cancer. However, it is still unclear whether FOXM1 mediates autophagy activation in PAH, and detailed mechanisms responsible for these processes are indefinite. PAH was induced by a single intraperitoneal injection of monocrotaline (MCT) to rats. The right ventricle systolic pressure (RVSP), right ventricular hypertrophy index (RVHI), percentage of medial wall thickness (%MT), α-smooth muscle actin (α-SMA) staining, and Ki67 staining were performed to evaluate the development of PAH. The protein levels of FOXM1, phospho-focal adhesion kinase (p-FAK), FAK, and LC3B were determined by immunoblotting or immunohistochemistry. FOXM1 protein level and FAK activity were significantly increased in MCT-induced PAH rats, this was accompanied with the activation of autophagy. Pharmacological inhibition of FOXM1 or FAK suppressed MCT-induced autophagy activation, decreased RVSP, RVHI and %MT in MCT-induced PAH rats, and inhibited the proliferation of pulmonary arterial smooth muscle cells and pulmonary vessel muscularization in MCT-induced PAH rats. FOXM1 promotes the development of PAH by inducing FAK phosphorylation and subsequent activation of autophagy in MCT-treated rats.

The concise review of etiology, pathology, and treatment strategy of polyarteritis nodosa

Polyarteritis nodosa (PAN) is a necrotizing vasculitis that targets medium-sized muscular arteries and can involve small-sized arteries. The pathogenesis of classic PAN remains unclear, except for secondary PAN or vasculitis that is indistinguishable from PAN due to genetic abnormalities such as deficiency of adenosine deaminase 2. The histopathological characters of PAN change over time from the onset. The type of remission induction therapy to be adopted depends on the disease severity. When it results in remission, corticosteroid dose reduction will begin and will be shifted to remission maintenance therapy.

Ligamentum arteriosum: Muscular and contractile.

Ductus arteriosus is a muscular artery in fetal circulation, spanning from the bifurcation of the pulmonary trunk to the aortic arch, shunting blood directly from pulmonary circulation into systemic circulation thus by-passing the fluid-filled lungs. Postnatally, it changes name to the ligamentum arteriosum (LA), when a cascade of anatomical and physiological processes leads to its closure. Though the LA has generally been considered as a fibrosed remnant of the ductus arteriosus, anecdotal and contradictory reports still describe the LA as a small muscular artery. We hypothesized the likelihood of contractile muscular elements retainment in this so-called ligament. To investigate this, mediastinum of wild-type mouse, pig, and human LA were subjected to routine and special histological staining, single-immunolabeling, electron microscopy (mouse and pig only), and tension recording of explanted pig LA in organ bath experiments. Contrary to a canonical ligament, the LA was mainly made up of α-smooth muscle actin-positive cells in all three species, confirmed by routine and special histological staining as well as transmission electron microscopy. Myocytes within the LA contracted in response to exogenous noradrenalin (NA). NA-induced precontracted LA relaxed upon administration of the α1-adrenergic blockers (prazosin and tamsulosin). Though the LA does not function in its original capacity as fetal shunt, it is clearly not a passive structure, and may be described as muscular and contractile. The contractile abilities of LA myocytes may act on the two great vessels to which it is attached causing a change in their distensibility.

Pulmonary Vascular Remodeling Characteristics of Pulmonary Arterial Hypertension Mouse Model Induced by Left Pneumonectomy and Jugular Vein Injection of Monocrotaline Pyrrole

To compare and investigate the differences and characteristics of pulmonary vascular remodeling in three mouse models of pulmonary arterial hypertension (PAH) constructed by left pneumonectomy, jugular vein injection of monocrotaline pyrrole, and left pneumonectomy combined with jugular vein injection of monocrotaline pyrrole, to explore for a PAH animal model that approximates the clinical pathogenesis of PAH, and to create a model that will provide sound basis for thorough investigation into the pathogenesis of severe PAH. 59 male C57/BL mice (10-12 weeks, 24-30 g) were randomized into four groups, a control group ( n=9), a group that had left pneumonectomy (PE, n=15), a group that had jugular vein injection of monocrotaline pyrrole (MCTP, n=15), and the last group that had left pneumonectomy combined with jugular injection of monocrotaline pyrrole (P+M, n=20). To evaluate the effect of modeling and the characteristics of pulmonary vascular remodeling, hemodynamic and morphological parameters, including right ventricular systolic pressure (RVSP), right ventricle/(left ventricle plus septum) (RV/LV+S), percent of wall thickness in the pulmonary artery (WT%), muscularization of non-muscular arteries, neointima formation, and vascular obstruction score (VOS), were measured in each group. 1) Compared with those of the control group, the RVSP, RV/LV+S, WT%, and the degree of small pulmonary arteries muscularization in the P+M group were significantly increased ( P<0.01). The MCTP group had just slightly higher findings for these indicators ( P<0.05), while no significant change in these indicators was observed in the PE group ( P>0.05). 2) Neointima formation in the acinus pulmonary arteries, which caused obvious stenosis of the lumen, was observed in the P+M group, the VOS being 1.25±0.80 points ( P<0.001). In contrast, neointima formation was not observed in the MCTP group or the PE groups, the VOS being 0 point ( P>0.05). Left pneumonectomy combined with jugular intravenous injection of MCTP could induce severe PAH formation in mouse. The model provides a good simulation of neointima formation, the characteristic pathological change of clinical severe PAH.

Abstract P326: Trimethylamine, A Gut Bacteria Metabolite And Air Pollutant, Increases Blood Pressure, Proteinuria And Markers Of Kidney Damage In Rats.

Trimethylamine oxide (TMAO) is a biomarker in cardiovascular and renal diseases. TMAO originates from the oxidation of trimethylamine (TMA), a product of gut microbiota and industry-derived pollutant, by flavin monooxygenases (FMOs). The effect of chronic exposure to TMA on cardiovascular and renal systems is undetermined. Metabolic, hemodynamic, echocardiographic, biochemical and histopathological evaluations were performed in male, 12-week-old rats receiving water (control group) or TMA (500 μM/day) in water for 18 weeks (each group: n=9). TMA and TMAO levels, the expression of FMOs and RAS genes were evaluated in various tissues. Data are expressed as the median (Q1; Q3) or mean ± SE. In comparison to controls, rats receiving TMA had significantly increased systolic blood pressure (mmHg; 151.2 ± 7.0 vs. 126.3 ± 3.8; P&lt;0.05), urine protein to creatinine ratio [3.4 (3.3; 4.2) vs. 1.6 (1.5; 2.8); P&lt;0.05], urine KIM-1 levels (pg/ml; 3 519.0 ± 301.6 vs. 2 338.3 ± 244.0; P&lt;0.05), mild degeneration of renal bodies with glomerulosclerosis, and hypertrophy of the tunica media of arteries and arterioles. There was no significant difference between the groups in body weight, water-electrolyte balance and echocardiographic parameters and RAS expression. TMA group had marginally increased 24hr TMA urine excretion [μM; 5.0 (3.8; 5.5) vs. 0.3 (0.2; 0.4); P&lt;0.01]. However, TMA serum level [μM/l; 0.32 (0.27; 0.64) vs. 0.04 (0.03; 0.04)], TMAO serum level [49.5 (45.8; 84.8) vs. 9.0 (6.5; 11.9)] and 24hr TMAO urine excretion [255.4 (237.2; 311.1) vs. 10.6 (10.3; 11.2); all P&lt;0.001] were increased. TMA group had lower FMOs expression in the kidneys but significantly increased TMAO levels in the liver [μM/kg; 35.9 (29.3; 41.9) vs. 5.4 (4.2; 9.6)], renal cortex [189.7 (82.2; 204.5) vs. 14.5 (13.1; 21.9)], renal medulla [192.0 (74.0; 213.7) vs. 18.5 (14.4; 27.8)] and heart [96.3 (90.3; 112.4) vs. 3.2 (2.4; 5.8); all P&lt;0.001]. In conclusion, chronic exposure to TMA increases blood pressure and increases markers of kidney damage including proteinuria and KIM-1. TMA is rapidly oxidized to TMAO in rats, which may limit toxic effects of TMA.

A Mathematical Model of Maladaptive Inward Eutrophic Remodeling of Muscular Arteries in Hypertension.

We propose a relatively simple two-dimensional mathematical model for maladaptive inward remodeling of resistive arteries in hypertension in terms of vascular solid mechanics. The main premises are: (i) maladaptive inward remodeling manifests as a reduced increase in the arterial mass compared to the case of adaptive remodeling under equivalent hypertensive pressures and (ii) the pressure-induced circumferential stress in the arterial wall is restored to its basal target value as happens in the case of adaptive remodeling. The rationale for these assumptions is the experimental findings that elevated tone in association with sustained hypertensive pressure down-regulate the normal differentiation of vascular smooth muscle cells from contractile to synthetic phenotype and the data for the calculated hoop stress before and after completion of remodeling. Results from illustrative simulations show that as the hypertensive pressure increases, remodeling causes a nonmonotonic variation of arterial mass, a decrease in inner arterial diameter, and an increase in wall thickness. These findings and the model prediction that inward eutrophic remodeling is preceded by inward hypertrophic remodeling are supported by published observations. Limitations and perspectives for refining the mathematical model are discussed.

Regions of the human renal artery: histomorphometric analysis.

The renal artery is frequently involved in the pathogenesis of vasculorenal diseases, and it is a target in kidney surgery and therapeutic techniques for refractory hypertension. However, few detailed structural studies on the human renal artery have been conducted. Using histocytochemistry, immunohistochemistry, and quantitative image analysis, the wall thickness, structure, smooth muscle cells, extracellular matrix, and proportion of elastic tissue in the tunica media of main human renal arteries were used estimated. Ninety-six tissue samples were collected from sections of the right and left main renal arteries. The results showed that the renal artery changed from an elastic vessel in its proximal segment to a muscular artery in its distal part. A critical characteristic of the renal artery was the presence of longitudinal smooth muscle cell formations in the tunica adventitia of middle and distal segments but not in the proximal part of the artery. In addition, the tunica adventitia of the renal artery showed a rich vascularization and the presence of numerous nerves profiles. The artery's regional structural and morphometric features explain that a particular arterial pathology is more frequent in a specific vessel sector than in others. In addition, those characteristics could determine a different therapeutic response attending to the arterial sector.