Smooth Muscle Cell Nuclei Research Articles

Interplay of atherosclerosis and medial degeneration in human ascending aorta

The previous understanding has been that atherosclerosis tends to increase distally from the ascending aorta, but recent studies and practical experience have indicated that atherosclerosis occurs in the ascending aorta more than previously thought. Medial degeneration is linked to aortic aneurysms, dissection and dilatation and has been related to increased mortality. There is a lack of data on the coexistence of atherosclerosis and medial degeneration in the ascending aorta and its outcome to clinical morbidity and mortality. Earlier studies have shown coexisting atherosclerosis and medial degeneration as significant risk indicators for coronary and cerebrovascular events. We aimed to analyze aortic specimens classified according to the consensus documents of the Society for Cardiovascular Pathology and the Association for European Cardiovascular Pathology particularly the comparison of variable morphological features with the atherosclerotic grade to gain more data about the coexistence of atherosclerosis and medial degeneration. We evaluated 217 specimens of human ascending aorta resected at Tampere University Heart Hospital because of aortic aneurysm, dissection or dilatation. None of the samples contained normal aortic morphology; atherosclerosis was found in a total of 75.8% of the samples and medial degeneration in all the samples. The present study is mostly in agreement with earlier research regarding the prevalence of different histological findings, even though a higher prevalence of atherosclerosis was found compared with most studies. There was no statistically significant association between atherosclerosis and medial degeneration, but a higher atherosclerotic grade was significantly associated with the presence of smooth muscle cell nuclei loss, smooth muscle cell disorganisation, elastic fibre thinning and medial fibrosis. Our study reinforces the perception that atherosclerotic lesions significantly occur in the ascending aorta and coexist with individual components of the medial degeneration.

Endonuclear Circ-calm4 regulates ferroptosis via a circR-Loop of the COMP gene in pulmonary artery smooth muscle cells

Pulmonary hypertension (PH) is a serious pulmonary vascular disease characterized by vascular remodeling. Circular RNAs (CircRNAs) play important roles in pulmonary hypertension, but the mechanism of PH is not fully understood, particularly the roles of circRNAs located in the nucleus. Circ-calmodulin 4 (circ-calm4) is expressed in both the cytoplasm and the nucleus of pulmonary arterial smooth muscle cells (PASMCs). This study aimed to investigate the role of endonuclear circ-calm4 in PH and elucidate its underlying signaling pathway in ferroptosis. Immunoblotting, quantitative real-time polymerase chain reaction (PCR), malondialdehyde (MDA) assay, immunofluorescence, iron assay, dot blot, and chromatin immunoprecipitation (ChIP) were performed to investigate the role of endonuclear circ-calm4 in PASMC ferroptosis. Increased endonuclear circ-calm4 facilitated ferroptosis in PASMCs under hypoxic conditions. We further identified the cartilage oligomeric matrix protein (COMP) as a downstream effector of circ-calm4 that contributed to the occurrence of hypoxia-induced ferroptosis in PASMCs. Importantly, we confirmed that endonuclear circ-calm4 formed circR-loops with the promoter region of the COMP gene and negatively regulated its expression. Inhibition of COMP restored the phenotypes related to ferroptosis under hypoxia stimulation combined with antisense oligonucleotide (ASO)-circ-calm4 treatment. We conclude that the circ-calm4/COMP axis contributed to hypoxia-induced ferroptosis in PASMCs and that circ-calm4 formed circR-loops with the COMP promoter in the nucleus and negatively regulated its expression. The circ-calm4/COMP axis may be useful for the design of therapeutic strategies for protecting cellular functionality against ferroptosis and pulmonary hypertension.

Sex Differences in the Histopathology of Acute Type A Aortic Dissections.

Although sex-related differences in cardiovascular surgery outcomes have increasingly garnered attention in the past decades, knowledge about sex disparities in the pathophysiology of acute type A aortic dissections (ATAADs) remains sparse. In this study, we evaluate the histopathologic and atherosclerotic lesions in female and male ATAAD patients. A total of 68 patients were studied: 51 ATAAD patients (mean age: 62.5 ± 10.8 years; 49% women) and 17 control patients (mean age: 63 ± 5.5 years; 53% women). Cardiovascular risk factors were assessed clinically. Intimal and medial histopathological features were systematically evaluated in all. Compared to the control group, all ATAAD patients showed significantly more elastic fiber pathology, mucoid extracellular matrix accumulation, smooth muscle cell nuclei loss, and overall medial degeneration (p < 0.0001). The tunica intima was significantly thinner in the ATAAD patients than in the control group (p < 0.023), with the latter exhibiting significantly more progressive atherosclerotic lesions than the former. No difference in medial vessel wall pathology was seen between female and male patients. As compared to male ATAAD patients, atherosclerotic lesions were more severe in female ATAAD patients, independent of age and the cardiovascular risk factor hypertension. All ATAAD patients had a significantly thinner tunica intima and significantly diseased tunica media compared to the control patients. Our results suggest that the severity of medial aortic pathology is not sex specific in ATAAD patients. Intimal differences between females and males could, however, be considered a potential risk factor for the development of an aortic dissection.

Macrophage-mediated downregulation of lncRNA Carmn in mouse abdominal aortic aneurysm

The long noncoding RNA (lncRNA) CARMN (cardiac mesoderm enhancer associated noncoding RNA) is a highly conserved lncRNA that expresses primarily by smooth muscle cells (SMCs). Recent literature demonstrates that CARMN plays a critical role in the differentiation and maintaining of the contractile state of vascular SMCs. Because aortic SMCs show diminished contractile proteins in abdominal aortic aneurysms (AAAs), we hypothesize that the expression of CARMN is downregulated in the aortic wall affected by aneurysm. In this study, we analyzed publicly available single-cell or bulk RNA sequencing data comparing healthy and aneurysmal mouse aortic tissues. In both healthy and diseased aortas, Carmn expression was enriched in SMCs characterized by the high expression of SMC-specific contractile proteins including Myh11 and Acta2. Carmn expression levels varied among the sub-clusters of SMCs and consequently along the aortic tree. Comparing to the corresponding sham aorta, aortas from 3 distinct AAA models contained less Carmn. To validate the Carmn downregulation, we induced AAA using the Angiotensin II and CaCl2 models. In situ hybridization showed that Carmn mRNA located in the nuclei of SMCs and became downregulated within a few days following the aneurysm induction. Mechanistically, we tested whether Carmn expression is regulated by infiltrating macrophages --- the predominant inflammatory cells found in aneurysmal tissues --- by treating healthy mouse aortic SMCs with media conditioned by macrophages primed with pro-inflammatory or anti-inflammatory cytokines. PCR analysis showed that inflammatory macrophages reduced the expression of Carmn and contractile genes including Myh11 and Acta2. Taken together, our results from bioinformatic and experimental analyses demonstrate that Carmn is downregulated in different AAA models, likely by inflammatory macrophages. The negative regulation of Carmn in AAA tissues may explain at least in part the loss of SMC contractile state during the pathogenesis of this progressive degenerative disease.

Abstract 17276: NOTCH3-BMPR Interactions Drive Smooth Muscle Cell Proliferation and Medial Hyperplasia in Pulmonary Arterial Hypertension

Background: One of the characteristics of pulmonary arterial hypertension (PAH) is the proliferation of smooth muscle cells. In heritable PAH, aberrant BMPR2 signaling results in low levels of intracellular ID1. An important pathway involved in vascular smooth muscle cell proliferation and the development of non-heritable PAH is the NOTCH3-HES5 signaling pathway. Previous studies have demonstrated that HES-5 and ID-1 are peptides belonging to the basic helix-loop-helix family, and they act as transcriptional enhancers of cell cycle genes. Transcriptional enhancement or repression requires the heterodimerization of different HES and ID proteins. Hypothesis: We hypothesize that HES-5 binds to and degrades IDs in non-heritable cases of PAH. Methods: The half-life of ID proteins was assessed in human small pulmonary artery smooth muscle cells that either constitutively expressed or minimally expressed HES-5. In order to understand whether this effect was due to direct binding between HES-5 and ID1, co-immunoprecipitation experiments were performed. Immunofluorescent staining was used to detect the expression level of ID1 and HES-5. Proximity ligation assay (PLA) was utilized to examine of endogenous in-situ interaction of ID1-HES5. Results: We found that overexpression of HES-5 significantly diminished the half-life of ID1 and ID3, and had little effect on ID2. All three proteins localized to the nucleus of small pulmonary artery smooth muscle cells. Immunofluorescent staining confirmed elevated levels of HES and reduced levels of ID1 and ID3 in the medial layer of PAH vessels. By PLA assay, we show that HES-5 and ID1 as well as HES-5 and ID-3 physically associate with each other to the level of 40 nanometers. Conclusions: Constitutive NOTCH3 signaling and high intracellular HES-5 levels drive vascular smooth muscle cell proliferation in non-familial PAH by binding to and degrading ID intracellular proteins. Our study demonstrates cross-talk between the NOTCH3-pathway and the BMPR2 pathway in this disease, at the level of their downstream effectors: ID1 and HES-5. Further studies should shed light on how these two pathways control the PAH disease process.

Regulation of DNA damage and transcriptional output in the vasculature through a cytoglobin-HMGB2 axis

Identifying novel regulators of vascular smooth muscle cell function is necessary to further understand cardiovascular diseases. We previously identified cytoglobin, a hemoglobin homolog, with myogenic and cytoprotective roles in the vasculature. The specific mechanism of action of cytoglobin is unclear but does not seem to be related to oxygen transport or storage like hemoglobin. Herein, transcriptomic profiling of injured carotid arteries in cytoglobin global knockout mice revealed that cytoglobin deletion accelerated the loss of contractile genes and increased DNA damage. Overall, we show that cytoglobin is actively translocated into the nucleus of vascular smooth muscle cells through a redox signal driven by NOX4. We demonstrate that nuclear cytoglobin heterodimerizes with the non-histone chromatin structural protein HMGB2. Our results are consistent with a previously unknown function by which a non-erythrocytic hemoglobin inhibits DNA damage and regulates gene programs in the vasculature by modulating the genome-wide binding of HMGB2.

Matrix metalloproteinase-9 regulates afferent arteriolar remodeling and function in hypertension-induced kidney disease

This study tested if matrix metalloproteinase (MMP)-9 promoted microvascular pathology that initiates hypertensive (HT) kidney disease in salt-sensitive (SS) Dahl rats. SS rats lacking Mmp9 (Mmp9-/-) and littermate control SS rats were studied after one week on a normotensive 0.3% sodium chloride (Pre-HT SS and Pre-HT Mmp9-/-) or a hypertension-inducing diet containing 4.0% sodium chloride (HT SS and HT Mmp9-/-). Telemetry-monitored blood pressure of both the HT SS and HT Mmp9-/- rats increased and did not differ. Kidney microvessel transforming growth factor-beta 1 (Tgfb1) mRNA did not differ between Pre-HT SS and Pre-HT Mmp9-/- rats, but with hypertension and expression of Mmp9 and Tgfb1 increased in HT SS rats, along with phospho-Smad2 labeling of nuclei of vascular smooth muscle cells, and with peri-arteriolar fibronectin deposition. Loss of MMP-9 prevented hypertension-induced phenotypic transformation of microvascular smooth muscle cells and the expected increased microvascular expression of pro-inflammatory molecules. Loss of MMP-9 in vascular smooth muscle cells invitro prevented cyclic strain-induced production of active TGF-β1 and phospho-Smad2/3 stimulation. Afferent arteriolar autoregulation was impaired in HT SS rats but not in HT Mmp9-/- rats or the HT SS rats treated with doxycycline, an MMP inhibitor. HT SS but not HT Mmp9-/- rats showed decreased glomerular Wilms Tumor 1 protein-positive cells (a marker of podocytes) along with increased urinary podocin and nephrin mRNA excretion, all indicative of glomerular damage. Thus, our findings support an active role for MMP-9 in a hypertension-induced kidney microvascular remodeling process that promotes glomerular epithelial cell injury in SS rats.

Intrinsic histological and morphological abnormalities of the pediatric thoracic aorta in bicuspid aortic valve patients are predictive for future aortopathy

BackgroundPatients with a bicuspid aortic valve (BAV) have an increased risk to develop aortic complications. Many studies are pointing towards a possible embryonic explanation for the development of both a bicuspid aortic valve as well as a defective ascending aortic wall in these patients. The fetal and newborn ascending aortic wall has however scarcely been studied in bicuspid aortic valve patients. We hypothesize that early histopathological defects might already be visible in the fetal and pediatric ascending aortic wall of bicuspid aortic valve patients, indicating at an early embryonic defect. MethodsNon-dilated BAV ascending aortic wall samples were collected (n = 40), categorized in five age groups: premature (age range 17.5 weeks + days GA till 37.6 weeks + days GA) 2. neonate (age range 1 – 21 days) 3. infant (age range 1 month – 4 years) 4. adolescent (age range 12 years – 15 years) and 5. adult (age range 41 – 72 years). Specimen were studied for intimal and medial histopathological features. ResultsThe premature ascending aortic wall has a significantly thicker intimal and significantly thinner medial layer as compared to all other age categories (p < 0.05). After birth the intimal thickness decreases significantly. The medial layer increases in thickness before adulthood (p < 0.05) with an increasing number of elastic lamellae (p < 0.01) and interlamellar mucoid extracellular matrix accumulation (p < 0.0001). Intimal atherosclerosis was scarce and medial histopathological features such as overall medial degeneration, smooth muscle cell nuclei loss and elastic fiber fragmentation were not appreciated in the BAV ascending aortic wall of any age. ConclusionsThe main characteristics of a bicuspid ascending aortic wall are already present before adulthood, albeit not before birth. Considering the early manifestations of ascending aortic wall pathology in bicuspid aortic valve patients, the pediatric population should be considered while searching for markers predictive for future aortopathy.

Hallazgos histopatológicos en la disección y rotura de la aorta torácica. Estudio de 54 casos de autopsia

IntroductionThoracic aortic dissection/rupture has a high mortality, constituting 3.9-5.4% of sudden deaths in forensic series. Medial histopathological findings associated with these entities have received multiple terms and definitions. In 2016, the European Association for Cardiovascular Pathology and the Society for Cardiovascular Pathology published a consensus document, applied to surgical specimens, to unify criteria. The aim of this work is to assess its application in forensic autopsies. A secondary objective is to study inflammatory changes useful for dating. Material and methodsAortic histological preparations of the 54 cases of sudden deaths due to aortic rupture/dissection studied between 2019 and 2022 were reviewed. ResultsMedial degeneration was observed in 49 cases (90.8%) (severe in 42.9%). By lesions, the order of frequency was: fragmentation and/or loss of elastic fibers (74.1%); accumulation of extracellular mucoid matrix (61.1%); loss of smooth muscle cell nuclei (48.1%) and collapse of the media (44.4%). Some lesions of the consensus paper could not be assessed. No significant differences were found by age; presence or not of collagenopathies; or bi/tricuspid aortic valves. Granulation tissue or neutrophilic infiltrate was observed in those deceased with pain several days or <24 h before death, respectively. ConclusionWith the application of the document, lesions in the media are found in >90% of cases and fundamental lesions can be studied. The inflammatory response to rupture/dissection appears to correlate with the timing of dissection/rupture.

Ligustrazine alleviates pulmonary arterial hypertension in rats by promoting the formation of myocardin transcription complex in the nucleus of pulmonary artery smooth muscle cells.

Pulmonary arterial hypertension (PAH) is a pathophysiological state of abnormally elevated pulmonary arterial pressure caused by drugs, inflammation, toxins, viruses, hypoxia, and other risk factors. We studied the therapeutic effect and target of tetramethylpyrazine (tetramethylpyrazine [TMP]; ligustrazine) in the treatment of PAH and we speculated that dramatic changes in myocardin levels can significantly affect the progression of PAH. In vivo, the results showed that administration of TMP significantly prolonged the survival of PAH rats by reducing the proliferative lesions, right ventricular systolic pressure (RVSP), mean pulmonary arterial pressure (mPAP), and the Fulton index in the heart and lung of PAH rats. In vitro, TMP can regulate the levels of smooth muscle protein 22-alpha (SM22-α), and myocardin as well as intracellular cytokines such as NO, transforming growth factor beta (TGF-β), and connective tissue growth factor (CTGF) in a dose-dependent manner (25, 50, or 100 μM). Transfection of myocardin small interfering RNA (siRNA) aggravated the proliferation of pulmonary artery smooth muscle cells (PSMCs), and the regulatory effect of TMP on α-smooth muscle actin (α-SMA) and osteopontin (OPN) disappeared. The application of 10 nM estrogen receptor alpha (ERα) inhibitor MPP promoted the proliferation of PSMCs, but it does not affect the inhibition of TMP on PSMCs proliferation. Finally, we found that TMP promoted the nucleation of myocardin-related transcription factor-A (MRTF-A) and combined it with myocardin. In conclusion, TMP can inhibit the transformation of PSMCs from the contractile phenotype to the proliferative phenotype by promoting the formation of the nuclear (MRTF-A/myocardin) transcription complex to treat PAH.

The effects of irisin on the rat thoracic aorta: a histological study.

Irisin, a polypeptide hormone that is released from skeletal muscle in response to exercise, has been found to improve endothelial functions, protect against endothelial injuries and change blood pressure, which also affected blood vessels. The aim of this study was to assess the histological changes of the rat thoracic aorta in response to irisin injection. Twenty-four rats were used. They were divided into two groups: the control group without irisin injection and the irisin-injected group subdivided into three subgroups treated with different irisin concentrations (20, 40 and 160 nM, respectively) twice a week for 4 weeks. The control group and irisin-treated subgroups consisted of 6 rats each. After 4 weeks all rats were sacrificed, and the descending thoracic aorta was treated for histological evaluation. Sections were stained with haematoxylin and eosin and orcein stains. Morphometric measurement included: intima-media thickness, number of elastic lamellae and number of smooth muscle cells' nuclei. Histological study showed that intraperitoneal injection of different concentrations of irisin (20, 40 and 160 nM) in rats increased intima-media thickness, the number of smooth muscle cell's nuclei and the number of elastic lamellae in media layer of the thoracic aorta in a dose-dependent manner. Irisin significantly affected the morphology of the wall of the rat thoracic aorta indicating a role of irisin in influencing the growth factors of the thoracic aorta walls and activating smooth muscle cells in the thoracic aorta layers.

Structural abnormalities in the non-dilated ascending aortic wall of bicuspid aortic valve patients

BackgroundA bicuspid aortic valve (BAV) is the most common congenital cardiac malformation. The development of the aortic valve is closely related to the development of the ascending aorta, associated with structural differences in the bicuspid aorta. Here we describe the non-dilated ascending aortic wall in bicuspid aortic valve patients. MethodsBAV (n=41) and tricuspid aortic valve (TAV) (n=18) non-dilated ascending aortic wall samples were studied. We investigated the following features of the aortic wall: vessel wall thickness, endothelial cell morphology, atherosclerosis, and elastic lamellae organization. Medial pathologic features encompassing elastic fiber thinning, fragmentation and degeneration, overall medial degeneration, mucoid extracellular matrix accumulation, and smooth muscle cell nuclei loss were studied. Furthermore, we included apoptosis, periaortic inflammation, and the level of expression of differentiated vascular smooth muscle cells. ResultsThe non-dilated BAV ascending aortic wall is characterized by a significantly thinner intimal layer, without features of atherosclerosis (P<.001). The medial layer is significantly thicker (P<.001) with more mucoid extracellular matrix accumulation (P<.001). All other medial pathologic features were more prominent in the TAV (P<.001). The media has significantly less differentiated vascular smooth muscle cells (P<.001) between the neatly regulated elastic lamellae which are thinner in the BAV as compared to the TAV (P<.0001). ConclusionsThe BAV ascending aorta without dilatation is characterized by a differentiation defect of vascular smooth muscle cells in the media and a significantly thinner intimal layer without overt pathologic features.

YAP/Smad3 promotes pathological extracellular matrix microenviroment-induced bladder smooth muscle proliferation in bladder fibrosis progression.

Fibrosis is a chronic inflammation process with excess extracellular matrix (ECM) deposition that cannot be reversed. Patients suffer from bladder dysfunction caused by bladder fibrosis. Moreover, the interactive mechanisms between ECM and bladder fibrosis are still obscure. Hence, we assessed the pivotal effect of Yes‐associated protein (YAP) on the proliferation of bladder smooth muscle in fibrosis process. We identified that stiff ECM increased the expression and translocation of YAP in the nucleus of human bladder smooth muscle cell (hBdSMC). Sequencings and proteomics revealed that YAP bound to Smad3 and promoted the proliferation of hBdSMC via MAPK/ERK signaling pathway in stiff ECM. Moreover, CUT and TAG sequencing and dual‐luciferase assays demonstrated that Smad3 inhibited the transcription of JUN. The YAP inhibitor CA3 was used in a partial bladder outlet obstruction (pBOO) rat model. The results showed that CA3 attenuated bladder smooth muscle proliferation. Collectively, YAP binding with Smad3 in the nucleus inhibited the transcription of JUN, and promoted the proliferation of bladder smooth muscle through the MAPK/ERK signaling pathway. The current study identified a novel mechanism of mechanical force induced bladder fibrosis that provided insights in YAP‐associated organ fibrosis.

Dependency of deformation of cell nucleus on stretch direction of tissue: Relation to anisotropic response of aortic media to hypertension

The deformation of the cell nucleus may cause dispersion of chromatin and eventually enhance transcription, translation, and protein expression. If this happens in the hypertensive artery, an excessive stretch of smooth muscle cell (SMC) nuclei caused by hypertension may provoke wall thickening. Here, we measured deformation of SMC nuclei in rabbit thoracic aortas stretched in different directions. Thin 0.2-mm-thick specimens were sliced in the direction perpendicular to their axial and circumferential directions, and stretched in the circumferential and axial directions, respectively. The deformation of the actin filament (AF) network was similar to that of the whole tissue, whereas the deformation of the nucleus was significantly smaller than the others. Notably, the nucleus seldom deformed when the tissue was stretched in the axial direction. A novel cell model in which the nucleus is connected to the extracellular matrix via the AF network successfully explained the relative unresponsiveness of the nucleus to the axial stretch. It has been pointed out that stress is maintained constant in the circumferential direction but not in the axial direction in the artery wall during hypertension. The relative unresponsiveness of the nucleus to the axial stretch represented in this study explains this phenomenon.

Through the cleared aorta: three-dimensional characterization of mechanical behaviors of rat thoracic aorta under intraluminal pressurization using optical clearing method

The media of aortic wall is characterized by altering layers of elastin and smooth muscle cells (SMCs), along with collagen fibers in both layers, and plays a central role in functional and pathological remodeling such as hypertension and atherosclerosis. Because the arterial function is linked closely to the arterial wall internal structure, it is essential to investigate the alteration of the arterial microstructure during macroscopic deformation to understand cardiovascular pathologies. The present study adopted a tissue clearing method in three-dimensional mechanical characterization of rat thoracic aorta, and successfully observed changes in the structure of each of the three primary components of the aorta under intraluminal pressurization while maintaining tissue mechanical integrity and flexibility. Layers of elastic fibers and SMCs deformed greater on the intimal side than those on the adventitial side. Furthermore, there was a structural agreement in the alignment angle between SMC nuclei and elastic fibers on their intimal side, but not on the adventitial side. This is the first study that changes in the microstructure of three primary components of the aorta were visualized and evaluated through the aorta. The method established here would also be useful to understand tissue mechanics of other load-bearing soft tissues.

Ascending aortic wall degeneration in patients with bicuspid versus tricuspid aortic valve

BackgroundThe magnitude of ascending aortic degeneration in patients with bicuspid aortic valves (BAV) is controversial.MethodsThe aim of this study was to investigate ascending aortic wall degeneration in patients with BAV as compared with tricuspid aortic valves (TAV). The ascending aortic wall of 67 consecutive patients was processed for histology and immunohistochemistry. The extent of surgery and wall degeneration were investigated. Unadjusted survival was evaluated by Kaplan–Meier analysis. Median follow-up for patients with BAV and TAV was 3.8 years (interquartile range [IQR] 3.5–4.1) and 3.7 years (IQR 3.4–3.9), respectively.ResultsThere were 33 patients with BAV and 34 with TAV. Mid-ascending aorta diameter was 54 mm (IQR 50–60). Replacement of the aortic valve, together with an ascending aortic prosthesis, was more frequent in BAV vs TAV patients (24% vs. 3%, P = 0.013). However, medial fibrosis, elastic fiber thinning, incremental medial degeneration and smooth muscle cell nuclei loss were less prominent in BAV vs TAV patients (0.1 ± 0.4 vs. 0.8 ± 1.4, P = 0.016; 0.6 ± 1.4 vs. 1.6 ± 2.0, P = 0.027; 1.7 ± 0.7 vs. 2.2 ± 0.8, P = 0.045 and 2.3 ± 1.5 vs. 3.2 ± 1.3, P = 0.026, respectively).ConclusionsSince degeneration of the ascending aortic wall was seldom prominent, histopathology alone may not support the need for surgery of the dilated ascending aorta in BAV patients as compared with TAV patients.

The effects of mechanical trapping of cells into the concave micro-grooves on the cell nucleus and differentiation of the vascular smooth muscle cells.

Vascular smooth muscle cells (VSMCs) in arterial walls in vivo have contractile phenotype with an elongated shape and significant alignment to the circumference of the arterial wall. On the other hand, VSMCs spread randomly and form irregular shapes during cultivation on a rigid dish, and dedifferentiated to synthetic phenotype. To clarify the mechanisms of such morphological and phenotypic changes in vascular smooth muscle cells, it is essential to develop a cell culture model that consider the mechanical environment of aortic tissue. In this study, we fabricated silicone rubber (PDMS) micro-grooved substrates with three different groove widths (5, 10, 20 μm) using microfabrication technology to promote cell elongation and alignment, and optimized the groove size to improve contractile differentiation. We found that VSMCs adhering into the concaves of grooves allowed remarkable elongation of the cell nucleus and the 5 μm micro-grooved substrates significantly suppressed cell proliferation and promoted vascular smooth muscle cells differentiation.

Ascending aorta dissection in a new classification system: Clinicopathological features of 62 cases

Herein we present a single institution 5-year experience with ascending aorta dissection biopsies depicting the clinicopathological features of 62 cases. To detect microscopic abnormalities in the aortic wall beside the dissection itself, we applied a new histopathological classification scheme from the consensus documents issued by The Society for Cardiovascular Pathology and The Association for the European Cardiovascular Pathology in 2015 and 2016. The most common finding was medial degeneration (MD) - 61 cases (98.4%); atherosclerosis (AS) was found in 19 aortae (30.6%), and chronic aortitis- giant cell pattern described in one aorta (1.6%). The medial degeneration constituents included mucoid matrix accumulation, smooth muscle cells and elastic fibers abnormalities, and medial fibrosis. The consensus document application led to increased MD reporting compared to older studies and to our previous experience, probably due to assessing more subtle and focal changes such as intralamellar fibrosis, intralamellar mucoid matrix accumulation, and loss of smooth muscle cell nuclei- these changes being also the most common MD abnormalities we are reporting. We have compared the results in patients with bicuspid (n = 7; 11.3%) versus tricuspid (n = 55; 88.7%) aortic valve, suggesting no significant differences except for translamellar fibrosis, which appeared to be more severe in the bicuspid valve group (p = 0.0397). The results might imply similar histopathological findings regardless of the aortic valve cuspidity in aortic dissection. These findings are in contrast to ascending aorta dilation (aneurysm), where more severe medial degeneration changes have been described in patients with the tricuspid aortic valve.

Application of deep learning neural network in pathological image classification of non-inflammatory aortic membrane degeneration

Objective: To investigate the value of deep learning in classifying non-inflammatory aortic membrane degeneration. Methods: Eighty-nine cases of non-inflammatory aortic media degeneration diagnosed from January to June 2018 were collected at Beijing Anzhen Hospital, Capital Medical University, China and scanned into digital sections. 1 627 hematoxylin and eosin stained photomicrographs were extracted. Combined with the ResNet18-based deep convolution neural network model, 4-category classification of pathological images were performed to diagnose the non-inflammatory aortic lesion. Results: The prediction model of artificial intelligence assisted diagnosis had the best accuracy, sensitivity and precision in identifying lesions with smooth muscle cell nuclei loss, which were 99.39%, 98.36% and 98.36%, respectively. The classification accuracy of elastic fiber fragmentation and/or loss lesions was 98.08%, while that of intralamellar mucoid extracellular matrix accumulation lesions was 96.93%. The overall accuracy of the classification model was 96.32%, and the area under the curve was 0.982. Conclusions: The accuracy of deep learning neural network model in the 4-category classification of non-inflammatory aortic lesionsis confirmed based on digital photomicrographs. This method can effectively improve the diagnostic efficiency of pathologists.

Aortic aneurysms with tricuspid aortic valve have more degeneration than unicuspid aortic valve aneurysms.

The unicuspid aortic valve (UAV) is a rare cardiac malformation and is associated with the formation of ascending aortic aneurysms. To characterize its associated aortic wall changes, normal and aneurysmatic ascending aortic wall specimens were analysed, focusing on the potential mechanisms of aneurysm formation. Patients with tricuspid aortic valve (TAV) served as controls. In a retrospective observational study, 74 specimens (dilated and non-dilated aortas; individuals with UAV and TAV) obtained intraoperatively were studied. Standard stains and immunohistochemical labelling of cleaved caspase-3, cluster of differentiation 31 and endothelial nitric oxide synthase (eNOS) were performed to assess the degree of apoptosis, distribution of eNOS within the aortic wall, smooth muscle cell (SMC) nuclei loss and mucoid extracellular matrix accumulation (MEMA). Deeper ingrowth of vasa vasorum was found in dilated aortas. Interestingly, eNOS was expressed mostly in vasa vasorum. More apoptosis was seen in UAV aortas compared to TAV aortas (P < 0.001). Both UAV and TAV aortas were comparable regarding SMC nuclei loss (P = 0.419). In dilated compared to non-dilated aortas regardless valve morphology SMC nuclei loss was increased (P = 0.005) and more pronounced translamellar MEMA was present (P = 0.011). The highest grade of distribution (P = 0.043) and the highest severity (P = 0.005) regarding MEMA were seen in TAV dilated specimens compared to UAV dilated specimens. Aneurysms with UAV show increased apoptosis, the role of which is unclear. Strikingly, more severe MEMA was found in TAV aneurysms compared to UAV aneurysms. Thus, UAV-associated aortic wall changes and resulting aneurysm may be less aggressive than aneurysms with TAV.