Platelet TGF-ß1 inhibits the migration and proliferation of smooth muscle cells in aneurysms.

BACKGROUND: The study explored the role of platelet TGF-ß1 from the perspective of inhibiting the excessive proliferation, migration and invasion of murine aortic vascular smooth muscle cells (MASMCs). METHOD: The platelets were first extracted from C57BL/6 mice, and the TGF-ß1 protein was obtained after the purification of protein. In vitro, the concentrations of angiotensin Ⅱ (Ang Ⅱ) and TGF-ß1 for intervention were screened by testing the viability of MASMCs, followed by the analysis concerning the effects of platelets, Ang Ⅱ and TGF-ß1 on the proliferation, migration, invasion, and the expressions of pathway-related proteins in MASMCs. In vivo, an Ang Ⅱ-induced mouse model was established. TGF-ß1 was injected into the tail of mice as a therapeutic agent, and its action mechanism was further verified by the treatment of inhibitor SB505124. The results of the cell experiment were validated by evaluating the maximum diameter of abdominal aorta, the proportion of total weight, the changes of both pathology and the expressions of pathway-related proteins in the mice. RESULT: 0.5 ng/mL Ang Ⅱ and 15 ng/mL TGF-ß1 were chosen for treatment. The following results of cell functional experiments and Western blot assay demonstrated that Ang Ⅱ promoted the proliferation, migration and invasion of MASMCs via regulating related pathways, the effects of which were evidently reversed by TGF-ß1 and platelets. Consistent results were also observed in the animal experiments, where TGF-ß1 effectively alleviated Ang Ⅱ-induced abdominal aortic injury in mice. CONCLUSION: TGF-ß1 in platelets inhibits Ang Ⅱ-induced proliferation, migration and invasion of MASMCs.

Tissue-specific relaxin-2 is differentially associated with the presence/size of an arterial aneurysm and the severity of atherosclerotic disease in humans.

Circulating or tissue-related biomarkers are of clinical value for risk stratification in patients with abdominal aortic aneurysms. Relaxin-2 (RL2) has been linked to the presence and size of arterial aneurysms, and to the extent of atherosclerosis in human subjects. Here, we assessed the expression levels of RL2 in aneurysmal (AA, n = 16) and atherosclerotic (ATH, n = 22) arteries, and established the correlation between RL2 levels and the presence/size of AA and the clinical severity of atherosclerosis. The expression levels of metalloproteinases (MMPs) and endothelial nitric oxide synthetase (eNOS) were also detected for correlations with different phenotypes of atherosclerosis and AA. Temporal artery biopsy specimens (n = 6) and abdominal aortic tissues harvested from accident victims during autopsy (n = 10) were used as controls. Quantitative tissue biomarker analysis revealed that tissue-specific RL2 was increased in patients with larger or symptomatic AA compared to subjects with atherosclerotic disease and healthy controls. In situ RL2 levels were proportional to the size and the severity of aneurysmatic disease, and were substantially elevated in patients with symptomatic aneurysm of any diameter or asymptomatic aneurysm of a diameter >350% of that of the normal artery. In contrast, tissue RL2 was inversely associated with the clinical severity of atherosclerotic lesions. Correlation between RL2 and MMP2 was different between ATH1 and ATH2, depending on atherosclerosis grade. Overall, tissue RL2 is differentially associated with discrete phenotypes of arterial disease and might exert multipotent biological effects on vascular wall integrity and remodeling in human subjects.

Anatomically specific reactive oxygen species production participates in Marfan syndrome aneurysm formation.

Marfan syndrome (MFS) is a connective tissue disorder that results in aortic root aneurysm formation. Reactive oxygen species (ROS) seem to play a role in aortic wall remodelling in MFS, although the mechanism remains unknown. MFS Fbn1C1039G/+ mouse root/ascending (AS) and descending (DES) aortic samples were examined using DHE staining, lucigenin-enhanced chemiluminescence (LGCL), Verhoeff's elastin-Van Gieson staining (elastin breakdown) and in situ zymography for protease activity. Fbn1C1039G/+ AS- or DES-derived smooth muscle cells (SMC) were treated with anti-TGF-ß antibody, angiotensin II (AngII), anti-TGF-ß antibody + AngII, or isotype control. ROS were detected during early aneurysm formation in the Fbn1C1039G/+ AS aorta, but absent in normal-sized DES aorta. Fbn1C1039G/+ mice treated with the unspecific NADPH oxidase inhibitor, apocynin reduced AS aneurysm formation, with attenuated elastin fragmentation. In situ zymography revealed apocynin treatment decreased protease activity. In vitro SMC studies showed Fbn1C1039G/+ -derived AS SMC had increased NADPH activity compared to DES-derived SMC. AS SMC NADPH activity increased with AngII treatment and appeared TGF-ß dependent. In conclusion, ROS play a role in MFS aneurysm development and correspond anatomically with aneurysmal aortic segments. ROS inhibition via apocynin treatment attenuates MFS aneurysm progression. AngII enhances ROS production in MFS AS SMCs and is likely TGF-ß dependent.

IL-1 family cytokines in cardiovascular disease.

The interleukin (IL)-1 family is a group of cytokines crucially involved in regulating immune responses to infectious challenges and sterile insults. The family consists of the eponymous pair IL-1α and IL-1ß, IL-18, IL-33, IL-37, IL-38, and several isoforms of IL-36. In addition, two endogenous inhibitors of functional receptor binding, IL-1R antagonist (IL-1Ra) and IL-36Ra complete the family. To gain biological activity IL-1ß and IL-18 require processing by the protease caspase-1 which is associated with the multi-protein complex inflammasome. Numerous clinical association studies and experimental approaches have implicated members of the IL-1 family, their receptors, or component of the processing machinery in underlying processes of cardiovascular diseases (CVDs). Here we summarize the current state of knowledge regarding the pro-inflammatory and disease-modulating role of the IL-1 family in atherosclerosis, myocardial infarction, aneurysm, stroke, and other CVDs. We discuss clinical evidence, experimental approaches and lastly lend a perspective on currently developing therapeutic strategies involving the IL-1 family in CVD.

Differentiation and Application of Induced Pluripotent Stem Cell-Derived Vascular Smooth Muscle Cells.

Vascular smooth muscle cells (VSMCs) play a role in the development of vascular disease, for example, neointimal formation, arterial aneurysm, and Marfan syndrome caused by genetic mutations in VSMCs, but little is known about the mechanisms of the disease process. Advances in induced pluripotent stem cell technology have now made it possible to derive VSMCs from several different somatic cells using a selection of protocols. As such, researchers have set out to delineate key signaling processes involved in triggering VSMC gene expression to grasp the extent of gene regulatory networks involved in phenotype commitment. This technology has also paved the way for investigations into diseases affecting VSMC behavior and function, which may be treatable once an identifiable culprit molecule or gene has been repaired. Moreover, induced pluripotent stem cell-derived VSMCs are also being considered for their use in tissue-engineered blood vessels as they may prove more beneficial than using autologous vessels. Finally, while several issues remains to be clarified before induced pluripotent stem cell-derived VSMCs can become used in regenerative medicine, they do offer both clinicians and researchers hope for both treating and understanding vascular disease. In this review, we aim to update the recent progress on VSMC generation from stem cells and the underlying molecular mechanisms of VSMC differentiation. We will also explore how the use of induced pluripotent stem cell-derived VSMCs has changed the game for regenerative medicine by offering new therapeutic avenues to clinicians, as well as providing researchers with a new platform for modeling of vascular disease.

Overexpression of Angiopoietin-1 Potentiates Endothelial Progenitor Cells for the Treatment of Aneurysm.

BACKGROUND: To investigate whether angiopoietin-1 (Ang-1) could regulate the endothelial progenitor cells (EPCs) survival and the effect of accelerating intra-aneurysmal organization and occlusion of the aneurysm neck. METHODS: EPCs were isolated from Wistar rats. EPCs were cultured and transfected with lentivirus-Ang-1-endothelial progenitor cells (Ang-1-EPCs) and lentivirus-NC-endothelial progenitor cells (NC-EPCs). The effects of Ang-1 on viability and functioning of EPCs were explored via tube formation, migration, and MTT (3-[4,5-dimethylthiazolyl-2]-2,5-diphenyltetrazolium bromide) assays. Eighteen Wistar rats were randomly allocated into 3 groups. Eighteen bare coils were inserted into the ligated external carotid artery (ECA) sacs of rats. The ECA sacs were removed 2 weeks after the coils were implanted and examined by histology assay. RESULTS: Ang-1 significantly promoted EPCs tube formation, migration, and proliferation ability in vitro. Histology analyses revealed that the organized areas in the ECA sacs in the Ang-1-EPCs group are higher than NC-EPCs group and control group at 2 weeks. Immunofluorescence revealed that organized tissues were characterized by an accumulation of cells positive for α-smooth muscle actin-positive cells in aneurysm sacs. CONCLUSIONS: Overexpression of Ang-1 enhanced the tube formation, migration, and proliferation ability of EPCs. Ang-1 gene-modified EPCs accelerated organization within the aneurysms and occlusion of aneurysm neck. Transplantation of Ang-1-transfected EPCs may be a new method for the treatment of aneurysm.

Heterogeneous histomorphology, yet homogeneous vascular smooth muscle cell dedifferentiation, characterize human aneurysm disease.

OBJECTIVE: Abdominal aortic aneurysm (AAA) is a frequent, potentially life-threatening, disease that can only be treated by surgical means such as open surgery or endovascular repair. No alternative treatment is currently available, and despite expanding knowledge about the pathomechanism, clinical trials on medical aneurysm abrogation have led to inconclusive results. The heterogeneity of human AAA based on histologic examination is thereby generally neglected. In this study we aimed to further elucidate the role of these differences in aneurysm disease. METHODS: Tissue samples from AAA and popliteal artery aneurysm patients were examined by histomorphologic analysis, immunohistochemistry, Western blot, and polymerase chain reaction. The results were correlated with clinical data such as aneurysm diameter and laboratory results. RESULTS: The morphology of human AAA vessel wall probes varies tremendously based on the grade of inflammation. This correlates with increasing intima/media thickness and upregulation of the vascular endothelial growth factor cascade but not with any clinical parameter or the aneurysm diameter. The phenotypic switch of vascular smooth muscle cells occurred regardless of the inflammatory state and expressional changes of the transcription factors Kruppel-like factor-4 and transforming growth factor-ß lead to differential protein localization in aneurysmal compared with control arteries. These changes were in similar manner also observed in samples from popliteal artery aneurysms, which, however, showed a more homogenous phenotype. CONCLUSIONS: Heterogeneity of AAA vessel walls based on inflammatory morphology does not correlate with AAA diameter yet harbors specific implications for basic research and possible aneurysm detection.

Recombinant human SDF-1α administration accelerates aneurysm neck reendothelialization in rabbit saccular aneurysm after flow diverter treatment.

Reendothelialization in the aneurysm neck is pivotal to vascular repair for intracranial aneurysm after flow diverter (FD) implantation. Recombinant human stromal cell-derived factor 1α (rhSDF-1α) is a vital chemoattractant to stem cells and potentially facilitates reendothelialization. Here, we sought to investigate the therapeutic effects of intravenous administration of rhSDF-1α and uncover its potential mechanism for promoting aneurysm neck reendothelialization. Recombinant pET32a-186 plasmid was transformed into Escherichia coli to produce the rhSDF-1α protein with biological activity. FD was implanted into the elastase-induced saccular aneurysm in New Zealand white rabbits. rhSDF-1α (50 µg/kg/day) was intravenously administrated for consecutive 7 days after FD implantation. After these procedures, aneurysms were harvested after 2 or 4 weeks. Scanning electron microscopy was used to measure the neointima thickness and count the endothelial-like cells at aneurysm neck. Four weeks later, the mRNA levels of endothelial markers in the neointima at aneurysm neck were examined. Migration assay showed that rhSDF-1α could induce migration of endothelial progenitor cells in a dose-dependent manner. Two weeks after stent implantation, follow-up angiography showed partial aneurysm occlusion in one of each group and total aneurysm occlusion in 17 saccular aneurysm rabbits (9 of the rhSDF-1α group and 8 of the control group). No significant change of neointima thickness at aneurysm neck was observed. Intriguingly, more endothelial-like cells were observed at aneurysm neck in the rhSDF-1α group at 2 weeks (55 vs 13 cells per high-power field) and 4 weeks (104 vs 60 cells per high-power field). The mRNA levels of Tie-2, VE-cadherin, KDR and E-selectin were significantly enhanced compared with those of the control group. These results showed that intravenous administration of rhSDF-1α can accelerate reendothelialization in the aneurysm neck after FD implantation. Our study reveals an important role of rhSDF-1α in inducing aneurysm occlusion and suggests that it achieves its function through modulating the reendothelialization.

Smooth muscle cell deletion of low-density lipoprotein receptor-related protein 1 augments angiotensin II-induced superior mesenteric arterial and ascending aortic aneurysms.

OBJECTIVE: Low-density lipoprotein receptor-related protein 1 (LRP1), a multifunctional protein involved in endocytosis and cell signaling pathways, leads to several vascular pathologies when deleted in vascular smooth muscle cells (SMCs). The purpose of this study was to determine whether LRP1 deletion in SMCs influenced angiotensin II-induced arterial pathologies. APPROACH AND RESULTS: LRP1 protein abundance was equivalent in selected arterial regions, but SMC-specific LRP1 depletion had no effect on abdominal and ascending aortic diameters in young mice. To determine the effects of LRP1 deficiency on angiotensin II vascular responses, SMC-specific LRP1 (smLRP1(+/+)) and smLRP1-deficient (smLRP1(-/-)) mice were infused with saline, angiotensin II, or norepinephrine. Several smLRP(-/-) mice died of superior mesenteric arterial (SMA) rupture during angiotensin II infusion. In surviving mice, angiotensin II profoundly augmented SMA dilation in smLRP1(-/-) mice. SMA dilation was blood pressure dependent as demonstrated by a similar response during norepinephrine infusion. SMA dilation was also associated with profound macrophage accumulation, but minimal elastin fragmentation. Angiotensin II infusion led to no significant differences in abdominal aorta diameters between smLRP1(+/+) and smLRP1(-/-) mice. In contrast, ascending aortic dilation was exacerbated markedly in angiotensin II-infused smLRP1(-/-) mice, but norepinephrine had no significant effect on either aortic region. Ascending aortas of smLRP1(-/-) mice infused with angiotensin II had minimal macrophage accumulation but significantly increased elastin fragmentation and mRNA abundance of several LRP1 ligands including MMP-2 (matrix metalloproteinase-2) and uPA (urokinase plasminogen activator). CONCLUSIONS: smLRP1 deficiency had no effect on angiotensin II-induced abdominal aortic aneurysm formation. Conversely, angiotensin II infusion in smLRP1(-/-) mice exacerbated SMA and ascending aorta dilation. Dilation in these 2 regions had differential association with blood pressure and divergent pathological characteristics.

SMAD2 Mutations Are Associated with Arterial Aneurysms and Dissections.

We report three families with arterial aneurysms and dissections in which variants predicted to be pathogenic were identified in SMAD2. Moreover, one variant occurred de novo in a proband with unaffected parents. SMAD2 is a strong candidate gene for arterial aneurysms and dissections given its role in the TGF-ß signaling pathway. Furthermore, although SMAD2 and SMAD3 probably have functionally distinct roles in cell signaling, they are structurally very similar. Our findings indicate that SMAD2 mutations are associated with arterial aneurysms and dissections and are in accordance with the observation that patients with pathogenic variants in genes encoding proteins involved in the TGF-ß signaling pathway exhibit arterial aneurysms and dissections as key features.

Neurofibromin-deficient myeloid cells are critical mediators of aneurysm formation in vivo.

BACKGROUND: Neurofibromatosis type 1 (NF1) is a genetic disorder resulting from mutations in the NF1 tumor suppressor gene. Neurofibromin, the protein product of NF1, functions as a negative regulator of Ras activity in circulating hematopoietic and vascular wall cells, which are critical for maintaining vessel wall homeostasis. NF1 patients have evidence of chronic inflammation resulting in the development of premature cardiovascular disease, including arterial aneurysms, which may manifest as sudden death. However, the molecular pathogenesis of NF1 aneurysm formation is unknown. METHOD AND RESULTS: With the use of an angiotensin II-induced aneurysm model, we demonstrate that heterozygous inactivation of Nf1 (Nf1(+/-)) enhanced aneurysm formation with myeloid cell infiltration and increased oxidative stress in the vessel wall. Using lineage-restricted transgenic mice, we show that loss of a single Nf1 allele in myeloid cells is sufficient to recapitulate the Nf1(+/-) aneurysm phenotype in vivo. Finally, oral administration of simvastatin or the antioxidant apocynin reduced aneurysm formation in Nf1(+/-) mice. CONCLUSION: These data provide genetic and pharmacological evidence that Nf1(+/-) myeloid cells are the cellular triggers for aneurysm formation in a novel model of NF1 vasculopathy and provide a potential therapeutic target.

Survivin-induced abnormal ploidy contributes to cystic kidney and aneurysm formation.

BACKGROUND: Cystic kidneys and vascular aneurysms are clinical manifestations seen in patients with polycystic kidney disease, a cilia-associated pathology (ciliopathy). Survivin overexpression is associated with cancer, but the clinical pathology associated with survivin downregulation or knockout has never been studied before. The present studies aim to examine whether and how cilia function (Pkd1 or Pkd2) and structure (Tg737) play a role in cystic kidney and aneurysm through survivin downregulation. METHODS AND RESULTS: Cysts and aneurysms from polycystic kidney disease patients, Pkd mouse, and zebrafish models are characterized by chromosome instability and low survivin expression. This triggers cytokinesis defects and formation of nuclear polyploidy or aneuploidy. In vivo conditional mouse and zebrafish models confirm that survivin gene deletion in the kidneys results in a cystic phenotype. As in hypertensive Pkd1, Pkd2, and Tg737 models, aneurysm formation can also be induced in vascular-specific normotensive survivin mice. Survivin knockout also contributes to abnormal oriented cell division in both kidney and vasculature. Furthermore, survivin expression and ciliary localization are regulated by flow-induced cilia activation through protein kinase C, Akt and nuclear factor-κB. Circumventing ciliary function by re-expressing survivin can rescue polycystic kidney disease phenotypes. CONCLUSIONS: For the first time, our studies offer a unifying mechanism that explains both renal and vascular phenotypes in polycystic kidney disease. Although primary cilia dysfunction accounts for aneurysm formation and hypertension, hypertension itself does not cause aneurysm. Furthermore, aneurysm formation and cyst formation share a common cellular and molecular pathway involving cilia function or structure, survivin expression, cytokinesis, cell ploidy, symmetrical cell division, and tissue architecture orientation.

Popliteal artery aneurysms differ from abdominal aortic aneurysms in cellular topography and inflammatory markers.

OBJECTIVE: Popliteal artery aneurysms (PAAs) and abdominal aortic aneurysms (AAAs) frequently coincide; however, symptoms differ. We systematically assessed aneurysm cellular wall composition and inflammatory markers to compare both anatomic locations. METHODS: Aneurysmal walls of 38 PAAs and 198 AAAs were harvested from patients undergoing elective open surgical repair. Elastin, collagen, smooth muscle cells, iron, and inflammatory cells were quantified by immunohistochemistry. In addition, protease and cytokine levels were measured. RESULTS: Aneurysmal degradation resulted in similarly degraded media. The location of inflammation differed: the focus for T and B lymphocytes and plasma cells was the intima in PAAs (all P < .001) and the adventitia for AAAs (all P < .001). Iron was more often observed in PAAs than in AAAs (68% vs 1%; P < .001), indicating more previous intramural hemorrhages. Matrix metalloproteinase 2 activity was higher in PAAs than in AAAs (median [interquartile range], 0.363 [0.174-0.556] vs 0.187 [0.100-0.391]; P = .008), whereas matrix metalloproteinase 9 showed no difference. Walls of AAAs were richer in tested cytokine levels than were walls of PAAs. CONCLUSIONS: PAAs showed more signs of previous intramural hemorrhages compared with AAAs. In addition, inflammation in PAAs is mainly located in the intima, whereas its focus in AAAs is the adventitia. These results suggest important differences in the pathophysiologic mechanism of aneurysm formation between these locations and might explain the differences in presentation on diagnosis.

Geometric, hemodynamic, and pathological study of a distal internal carotid artery aneurysm model in dogs.

BACKGROUND AND PURPOSE: We created a distal internal carotid artery side-wall aneurysm model in dogs and compared its geometric, hemodynamic, and histological similarities with human models. METHODS: Eight distal internal carotid artery-shaped devices were constructed using rapid prototyping, and 8 aneurysms were created via surgical reconstruction and elastase incubation. The geometric and hemodynamic parameters of the aneurysm and the parent artery of the dog and human models were compared, and histological response was evaluated at 12 weeks. RESULTS: Eight aneurysms were successfully created with good geometric simulation of the arteries between the dog and human models. Hemodynamic analysis revealed similar changes in the hemodynamic parameters both in the aneurysm sac and in the parent artery of the dog and human models. Histological analysis revealed internal elastic lamina discontinuity, elastic fiber disruption, a thinner muscular layer, increased smooth muscle cell proliferation rate, increased inflammation cell infiltration, and higher matrix metalloproteinase-2 and matrix metalloproteinase-9 expression indices in the medial aneurysm wall. CONCLUSIONS: The distal internal carotid artery aneurysm model in dogs is feasible and exhibited considerable geometric, hemodynamic, and histological similarities with the original human models.

Endoluminal gingival fibroblast transfer reduces the size of rabbit carotid aneurisms via elastin repair.

OBJECTIVE: Matrix metalloproteinase-9 is considered to play a pivotal role in aneurismal formation. We showed that gingival fibroblasts (GF) in vitro reduced matrix metalloproteinase-9 activity via increased secretion of tissue inhibitor of metalloproteinase 1. We aimed to evaluate in vivo the efficacy of GF transplantation to reduce aneurism development in a rabbit model. METHODS AND RESULTS: Seventy rabbit carotid aneurisms were induced by elastase infusion. Four weeks later, GF, dermal fibroblast, or culture medium (DMEM) were infused into established aneurisms. Viable GF were abundantly detected in the transplanted arteries 3 months after seeding. GF engraftment resulted in a significant reduction of carotid aneurisms (decrease of 23.3% [P<0.001] and 17.6% [P=0.01] of vessel diameter in GF-treated arteries, 1 and 3 months after cell therapy, respectively), whereas vessel diameter of control DMEM and dermal fibroblast-treated arteries increased. GF inhibited matrix metalloproteinase-9 activity by tissue inhibitor of metalloproteinase 1 overexpression and matrix metalloproteinase-9/tissue inhibitor of metalloproteinase 1 complex formation, induced elastin repair, and increased elastin density in the media compared with DMEM-treated arteries (38.2 versus 18.0%; P=0.02). Elastin network GF-induced repair was inhibited by tissue inhibitor of metalloproteinase 1 blocking peptide. CONCLUSIONS: Our results demonstrate that GF transplantation results in significant aneurism reduction and elastin repair. This strategy may be attractive because GF are accessible and remain viable within the grafted tissue.

Association between fluorescein leakage and optical coherence tomographic characteristics of microaneurysms in diabetic retinopathy.

PURPOSE: To evaluate the characteristics of microaneurysms seen on color fundus photography, fluorescein angiography, and spectral-domain optical coherence tomography in diabetic retinopathy. METHODS: One hundred and thirty-two consecutive eyes of 92 patients with diabetic retinopathy were reviewed retrospectively. The characteristics of microaneurysms, including capsular structure (ring sign), hyperreflective spots in the lumen, the retinal layers in which they are located, and adjacent cystoid spaces, were documented on spectral-domain optical coherence tomography as sectional images. Their appearance on fundus photographs and focal fluorescein leakage were recorded. The association among these characteristics was evaluated. RESULTS: Eighty-eight of 118 microaneurysms (74.6%) with no capsular structure had focal fluorescein leakage, whereas 7 of 34 microaneurysms (20.6%) with complete capsular structure had leakage (P < 0.001). Focal leakage from the microaneurysms correlated positively with hyperreflective spots in the lumen and nearby cystoid spaces (P = 0.013 and P < 0.001, respectively) but not in the layers in which they were located. Multicolored microaneurysms contained hyperreflective spots in the lumens more frequently than whitish or reddish spots (P = 0.038), compared with no significant associations between the appearance and the other optical coherence tomography characteristics. CONCLUSION: Focal fluorescein leakage from microaneurysms was associated positively with the absence of a capsular structure, hyperreflective spots, and nearby cystoid spaces.

Effects of dispersion of fiber orientation on the mechanical property of the arterial wall.

Effects of dispersion of the fiber orientation on the mechanical property of the arterial wall in health and disease subjected to the combined internal pressure and axial loading are examined within the framework of the finite deformation hyper-elasticity theory. Taking into account the residual stress, a two layer thick-walled circular cylindrical tube model with the fiber-reinforced incompressible composite hyper-elastic material is employed. Stress-radius curves and stress distributions of the arterial wall are given in health and disease considering dispersion of the fiber orientation. With instability/bifurcation analysis, it is found that not only the uniform inflation of the arterial wall in health, but also the instability or bifurcation problem for the arterial wall in disease may be described by this model.

Dapagliflozin attenuates residual cardiac remodeling after surgical ventricular reconstruction in mice with an enlarged heart after myocardial infarction.

BACKGROUND: Severe heart failure refractory to conventional therapy requires alternative treatment modalities. Surgical ventricular reconstruction (SVR) has been used to reverse cardiac remodeling in post-myocardial infarction (MI) patients with large left ventricular (LV) aneurysm, however, residual LV remodeling and dysfunction remain postoperatively. It is unclear whether SVR recovers response to drug treatment and whether the sodium-glucose co-transporter 2 inhibitor dapagliflozin (DAPA) reverses residual LV remodeling after SVR. METHODS: Adult male C57 mice were subjected to MI or sham surgery. Four-week later, MI mice with LV aneurysm underwent modified SVR or second open-chest sham operation and were randomized to DAPA or vehicle for four-week. Cardiac remodeling, LV function, and the underlying mechanisms were evaluated by echocardiography, invasive LV hemodynamic measurements, mRNA sequencing, and bioinformatics analysis. RESULTS: SVR significantly decreased LV volume; increased myocardial strain, LV pressure change rates and end-systolic elastance; and decreased heart-to-body weight ratio and myocardial fibrosis. However, significant residual cardiac remodeling remained. DAPA significantly attenuated residual cardiac remodeling and improved LV function in SVR mice but did not have curative effects in non-SVR mice. Of the 1532 genes differentially expressed in SVR and MI mice, 1037 were associated with cardiac metabolism; Src, Crebbp, Fn1, Grb2, and Mapk14 were the top 5 hub genes. Unlike sham surgery, MI upregulated those 5 genes, and treatment with SVR + DAPA normalized their expression. CONCLUSIONS: SVR restores therapeutic response in the post-MI heart with large LV aneurysm, and DAPA attenuates residual cardiac remodeling after SVR by normalizing some cardiac metabolism-related hub genes.

Vascular Remodeling and Immune Cell Infiltration in Splenic Artery Aneurysms.

Rupture of splenic artery aneurysms (SAAs) is associated with a high mortality rate. The aim of this study was to identify the features of SAAs. Tissue sections from SAAs were compared to nonaneurysmal splenic arteries using various stains. The presence of intraluminal thrombus (ILT), vascular smooth muscle cells (VSMCs), cluster of differentiation (CD)-68+ phagocytes, myeloperoxidase+ neutrophils, CD3+, and CD20+ adaptive immune cells were studied using immunofluorescence microscopy. Analysis of SAAs revealed the presence of atherosclerotic lesions, calcifications, and ILT. Splenic artery aneurysms were characterized by a profound vascular remodeling with a dramatic loss of VSMCs, elastin degradation, adventitial fibrosis associated with enhanced apoptosis, and increased matrix metalloproteinase 9 expression. We observed an infiltration of immune cells comprising macrophages, neutrophils, T, and B cells. The T and B cells were found in the adventitial layer of SAAs, but their organization into tertiary lymphoid organs was halted. We failed to detect germinal centers even in the most organized T/B cell follicles and these lymphoid clusters lacked lymphoid stromal cells. This detailed histopathological characterization of the vascular remodeling during SAA showed that lymphoid neogenesis was incomplete, suggesting that critical mediators of their development must be missing.