Long-term outcomes of total arch replacement with bilateral antegrade cerebral perfusion using the "arch first" approach.

OBJECTIVE: To report outcomes of total arch replacement (TAR) with hypothermic circulatory arrest and bilateral antegrade cerebral perfusion (bACP) using an "arch first" approach for acute Type A aortic dissection (ATAAD). The "arch first" approach involved revascularization of the aortic arch branch vessels with uninterrupted ACP, before lower body circulatory arrest, while the patient was cooling. METHODS: This was an observational study of aortic surgeries from 2010 to 2021. All patients who underwent TAR with bACP for ATAAD were included. Short-term and long-term outcomes were reported utilizing descriptive statistics and Kaplan-Meier survival estimation. RESULTS: A total of 215 patients were identified who underwent TAR + bACP for ATAAD. Age was 59.0 [49.0-67.0] years and 35.3% were female. 73 patients (34.0%) underwent a concomitant aortic root replacement, 188 (87.4%) had aortic cannulation, circulatory arrest time was 37.0 [26.0-52.0] minutes, and nadir temperature was 20.8 [19.4-22.5] degrees Celsius. 35 patients (16.3%) had operative mortality (STS definition), 17 (7.9%) had a new stroke, 79 (36.7%) had prolonged mechanical ventilation (>24 h), 35 (16.3%) had acute renal failure (by RIFLE criteria), and 128 (59.5%) had blood product transfusions. One-year survival was 77.1%, while 5-years survival was 67.1%. During follow-up, there were 23 (10.7%) reinterventions involving the descending thoracic aorta - either thoracic endovascular aortic repair or open thoracoabdominal aortic replacement. CONCLUSIONS: Among patients with ATAAD, short-term postoperative outcomes after TAR + bACP using the "arch first" approach are acceptable. Moreover, this operative strategy may furnish long-term durability, with a reasonably low reintervention rate and satisfactory overall survival.

External validation of the ARCH score in patients undergoing aortic arch reconstruction under circulatory arrest.

BACKGROUND: Aortic arch surgery with hypothermic circulatory arrest (HCA) carries a higher risk of morbidity and mortality compared to routine cardiac surgical procedures. The newly developed ARCH (arch reconstruction under circulatory arrest with hypothermia) score has not been externally validated. We sought to externally validate this score in our local population. METHODS: All consecutive open aortic arch surgeries with HCA performed between 2014 and 2023 were included. Univariable and multivariable analyses were performed. Model discrimination was assessed by the C-statistic with 95% confidence intervals as part of the receiver operating characteristic (ROC) curve analysis. Model performance was visualized by a calibration plot and quantified by the Brier score. RESULTS: A total of 760 patients (38.3% females) were included. The mean age was 61 (±13.6) years, with 56.4% of patients' age >60 years. The procedures were carried out mostly emergently or urgently (59.6%). Total arch replacement was performed in 32.5% of the patients, and aortic root procedures were carried out in 74.6%. In-hospital death occurred in 64 patients (8.4%), and stroke occurred in 5.4%. The C-statistic revealed a low discriminatory ability for predicting in-hospital mortality (area under the ROC curve, 0.62; 95% confidence interval, 0.54-0.69; P = .002); however, model calibration was found to be excellent (Brier score of 0.07). CONCLUSIONS: The ARCH score for in-hospital mortality showed low discriminatory ability in our local population, although with excellent ability for prediction of mortality.

Outcomes of Aortomitral Continuity Reconstruction During Concomitant Aortic and Mitral Valve Replacement.

OBJECTIVES: To describe outcomes of reconstruction of the aortomitral continuity (AMC) during concomitant aortic and mitral valve replacement (ie, the "Commando" procedure). DESIGN: A retrospective study of consecutive cardiac surgeries from 2010 to 2022. SETTING: At a single institution. PARTICIPANTS: All patients undergoing double aortic and mitral valve replacement. INTERVENTIONS: Patients were dichotomized by the performance (or not) of AMC reconstruction. MEASUREMENTS AND MAIN RESULTS: A total of 331 patients underwent double-valve replacement, of whom 21 patients (6.3%) had a Commando procedure. The Commando group was more likely to have had a previous aortic valve replacement (AVR) or mitral valve replacement (MVR) (66.7% v 27.4%, p < 0.001), redo cardiac surgery (71.4% v 31.3%, p < 0.001), and emergent/salvage surgery (14.3% v 1.61%, p = 0.001), whereas surgery was more often performed for endocarditis in the Commando group (52.4% v 22.9%, p = 0.003). The Commando group had higher operative mortality (28.6% v 10.7%, p = 0.014), more prolonged ventilation (61.9% v 31.9%, p = 0.005), longer cardiopulmonary bypass time (312 ± 118 v 218 ± 85 minutes, p < 0.001), and longer ischemic time (252 ± 90 v 176 ± 66 minutes, p < 0.001). Despite increased short-term morbidity in the Commando group, Kaplan-Meier survival estimation showed no difference in long-term survival between each group (p = 0.386, log-rank). On multivariate Cox analysis, the Commando procedure was not associated with an increased hazard of death, compared to MVR + AVR (hazard ratio 1.29, 95% CI: 0.65-2.59, p = 0.496). CONCLUSIONS: Although short-term postoperative morbidity and mortality were found to be higher for patients undergoing the Commando procedure, AMC reconstruction may be equally durable in the long term.

Reinterventions After Repair of Acute Type A Aortic Dissection: Incidence, Outcomes, and Risk Factors.

BACKGROUND: This study reports the incidence, outcomes, and risk factors for aortic reinterventions after repair of acute type A aortic dissection (ATAAD). METHODS: This was an observational study of aortic operations from 2010 to 2021. All patients with ATAAD undergoing open aortic arch reconstruction were included. Patients were dichotomized by the need for reintervention, which included reinterventions proximal to or distal to the index aortic repair. Propensity matching was used to determine the impact of reintervention on long-term outcomes. The cumulative incidence function for reintervention was estimated, and multivariable Fine-Gray analysis was performed to identify variables associated with reintervention, with death treated as a competing event. RESULTS: We identified 601 patients undergoing surgery for ATAAD. An aortic reintervention was required in 71 (11.8%), comprising a proximal reintervention in 12 patients, a distal reintervention in 56, and both in 3. The cumulative incidence of reintervention was 11.6% (95% CI, 8.9%-14.6%) at 5 years and was 16.0% (95% CI, 12.2%-20.3%) at 10 years, with a median time to reintervention of 4.0 years (interquartile range, 0.9-7.5 years). Multivariable analysis using the Fine-Gray method showed no operative variables were associated with reinterventions. Among the 71 reinterventions, there were 4 (5.6%) operative deaths. After propensity matching, there was no difference in Kaplan-Meier survival estimates across each group (P = .138 by log-rank statistics). CONCLUSIONS: The cumulative incidence of aortic reintervention after ATAAD repair was reasonably low (16% at 10 years), reinterventions were relatively safe (6% operative mortality), and reinterventions did not significantly impact long-term survival.

A Novel Risk Score to Predict Thirty-Day Readmissions after Acute Type A Aortic Dissections.

BACKGROUND: Readmissions following acute type A aortic dissections (ATAAD) are associated with potentially worse clinical outcomes and increased hospital costs. Predicting which patients are at risk for readmission may guide patient management prior to discharge. METHODS: The National Readmissions Database was utilized to identify patients treated for ATAAD between 2010 and 2018. Univariate mixed effects logistic regression was used to assess each variable. Variables were assigned risk points based off the bootstrapped (bias-corrected) odds ratio of the final variable model according to the Johnson's scoring system. A mixed effect logistic regression was run on the risk score (sum of risk points) and 30-day readmission. Calibration plots and predicted readmission curves were generated for model assessment. RESULTS: A total of 30,727 type A aortic dissections were identified. The majority of ATAAD (66%) were in men with a median age of 61 years and 30-day readmission rate of 19.4%. The risk scores ranging from -1 to 14 mapped to readmission probabilities between 3.5% and 29% for ATAAD. The predictive model showed good calibration and receiver operator characteristics with an area under the curve (AUC) of 0.81. Being a resident of the hospital state (OR: 2.01 [1.64, 2.47], p < 0.001) was the highest contributor to readmissions followed by chronic kidney disease (1.35 [1.16, 1.56], p = 0), discharge to a short-term facility (1.31 [1.09, 1.57], p = 0.003), and developing a myocardial infarction (1.20 [1.00, 1.45], p = 0.048). CONCLUSIONS: The readmission model had good predictive capability given by the large AUC. Being a resident in the State of the index admission was the most significant contributor to readmission.

The predictive capability of aortic stiffness index for aortic dissection among dilated ascending aortas.

OBJECTIVE: We created a finite element model to predict the probability of dissection based on imaging-derived aortic stiffness and investigated the link between stiffness and wall tensile stress using our model. METHODS: Transthoracic echocardiogram measurements were used to calculate aortic diameter change over the cardiac cycle. Aortic stiffness index was subsequently calculated based on diameter change and blood pressure. A series of logistic models were developed to predict the binary outcome of aortic dissection using 1 or more series of predictor parameters such as aortic stiffness index or patient characteristics. Finite element analysis was performed on a subset of diameter-matched patients exhibiting patient-specific material properties. RESULTS: Transthoracic echocardiogram scans of patients with type A aortic dissection (n = 22) exhibited elevated baseline aortic stiffness index when compared with aneurysmal patients' scans with tricuspid aortic valve (n = 83, P < .001) and bicuspid aortic valve (n = 80, P < .001). Aortic stiffness index proved an excellent discriminator for a future dissection event (area under the curve, 0.9337, odds ratio, 2.896). From the parametric finite element study, we found a correlation between peak longitudinal wall tensile stress and stiffness index (ρ = .6268, P < .001, n = 28 pooled). CONCLUSIONS: Noninvasive transthoracic echocardiogram-derived aortic stiffness measurements may serve as an impactful metric toward predicting aortic dissection or quantifying dissection risk. A correlation between longitudinal stress and stiffness establishes an evidence-based link between a noninvasive stiffness parameter and stress state of the aorta with clinically apparent dissection events.

Adventitia-derived extracellular matrix hydrogel enhances contractility of human vasa vasorum-derived pericytes via α2 ß1 integrin and TGFß receptor.

Pericytes are essential components of small blood vessels and are found in human aortic vasa vasorum. Prior work uncovered lower vasa vasorum density and decreased levels of pro-angiogenic growth factors in adventitial specimens of human ascending thoracic aortic aneurysm. We hypothesized that adventitial extracellular matrix (ECM) from normal aorta promotes pericyte function by increasing pericyte contractile function through mechanisms deficient in ECM derived from aneurysmal aortic adventitia. ECM biomaterials were prepared as lyophilized particulates from decellularized adventitial specimens of human and porcine aorta. Immortalized human aortic adventitia-derived pericytes were cultured within Type I collagen gels in the presence or absence of human or porcine adventitial ECMs. Cell contractility index was quantified by measuring the gel area immediately following gelation and after 48 h of culture. Normal human and porcine adventitial ECM increased contractility of pericytes when compared with pericytes cultured in absence of adventitial ECM. In contrast, aneurysm-derived human adventitial ECM failed to promote pericyte contractility. Pharmacological inhibition of TGFßR1 and antibody blockade of α2 ß1 integrin independently decreased porcine adventitial ECM-induced pericyte contractility. By increasing pericyte contractility, adventitial ECM may improve microvascular function and thus represents a candidate biomaterial for less invasive and preventative treatment of human ascending aortic disease.

On vasa vasorum: A history of advances in understanding the vessels of vessels.

The vasa vasorum are a vital microvascular network supporting the outer wall of larger blood vessels. Although these dynamic microvessels have been studied for centuries, the importance and impact of their functions in vascular health and disease are not yet fully realized. There is now rich knowledge regarding what local progenitor cell populations comprise and cohabitate with the vasa vasorum and how they might contribute to physiological and pathological changes in the network or its expansion via angiogenesis or vasculogenesis. Evidence of whether vasa vasorum remodeling incites or governs disease progression or is a consequence of cardiovascular pathologies remains limited. Recent advances in vasa vasorum imaging for understanding cardiovascular disease severity and pathophysiology open the door for theranostic opportunities. Approaches that strive to control angiogenesis and vasculogenesis potentiate mitigation of vasa vasorum-mediated contributions to cardiovascular diseases and emerging diseases involving the microcirculation.

Layer-specific Nos3 expression and genotypic distribution in bicuspid aortic valve aortopathy.

OBJECTIVES: We hypothesized that expression and activity of nitric oxide synthase-3 enzyme (Nos3) in bicuspid aortic valve (BAV) aortopathy are related to tissue layer and Nos3 genotype. METHODS: Gene expression of Nos3 and platelet and endothelial cell adhesion molecule-1 (Pecam1) and NOS activity were measured in intima-containing media and adventitial specimens of ascending aortic tissue. The presence of 2 Nos3 single-nucleotide polymorphisms (SNPs; -786T/C and 894G/T) was determined for non-aneurysmal (NA) and aneurysmal patients with BAV (n = 40, 89, respectively); patients with tricuspid aortic valve (TAV) and aneurysm (n = 151); and NA patients with TAV (n = 100). RESULTS: Elevated Nos3 relative to Pecam1 and reduced Pecam1 relative to a housekeeping gene were observed within intima-containing aortic specimens from BAV patients when compared with TAV patients. Lower Nos3 in the adventitia of aneurysmal specimens was noted when compared with specimens of NA aorta, independent of valve morphology. NOS activity was similar among cohorts in media/intima and decreased in the diseased adventitia, relative to control patients. Aneurysmal BAV patients exhibited an under-representation of the wild-type genotype for -786 SNP. No differences in genotype distribution were noted for 894 SNP. Primary intimal endothelial cells from patients with at least 1 C allele at -786 SNP exhibited lower Nos3 when compared with wild-type cells. CONCLUSIONS: These findings of differential Nos3 in media/intima versus adventitia depending on valve morphology or aneurysm reveal new information regarding aneurysmal pathophysiology and support our ongoing assertion that there are distinct mechanisms giving rise to ascending aortopathy in BAV and TAV patients.

Post-GWAS functional analysis identifies CUX1 as a regulator of p16INK4a and cellular senescence.

Accumulation of senescent cells with age is an important driver of aging and age-related diseases. However, the mechanisms and signaling pathways that regulate senescence remain elusive. In this report, we performed post-genome-wide association studies (GWAS) functional studies on the CDKN2A/B locus, a locus known to be associated with multiple age-related diseases and overall human lifespan. We demonstrate that transcription factor CUX1 (Cut-Like Homeobox 1) specifically binds to an atherosclerosis-associated functional single-nucleotide polymorphism (fSNP) (rs1537371) within the locus and regulates the CDKN2A/B-encoded proteins p14ARF, p15INK4b and p16INK4a and the antisense noncoding RNA in the CDK4 (INK4) locus (ANRIL) in endothelial cells (ECs). Endothelial CUX1 expression correlates with telomeric length and is induced by both DNA-damaging agents and oxidative stress. Moreover, induction of CUX1 expression triggers both replicative and stress-induced senescence via activation of p16INK4a expression. Thus, our studies identify CUX1 as a regulator of p16INK4a-dependent endothelial senescence and a potential therapeutic target for atherosclerosis and other age-related diseases.

Common deletion variants causing protocadherin-α deficiency contribute to the complex genetics of BAV and left-sided congenital heart disease.

Bicuspid aortic valve (BAV) with ~1%-2% prevalence is the most common congenital heart defect (CHD). It frequently results in valve disease and aorta dilation and is a major cause of adult cardiac surgery. BAV is genetically linked to rare left-heart obstructions (left ventricular outflow tract obstructions [LVOTOs]), including hypoplastic left heart syndrome (HLHS) and coarctation of the aorta (CoA). Mouse and human studies indicate LVOTO is genetically heterogeneous with a complex genetic etiology. Homozygous mutation in the Pcdha protocadherin gene cluster in mice can cause BAV, and also HLHS and other LVOTO phenotypes when accompanied by a second mutation. Here we show two common deletion copy number variants (delCNVs) within the PCDHA gene cluster are associated with LVOTO. Analysis of 1,218 white individuals with LVOTO versus 463 disease-free local control individuals yielded odds ratios (ORs) at 1.47 (95% confidence interval [CI], 1.13-1.92; p = 4.2 × 10-3) for LVOTO, 1.47 (95% CI, 1.10-1.97; p = 0.01) for BAV, 6.13 (95% CI, 2.75-13.7; p = 9.7 × 10-6) for CoA, and 1.49 (95% CI, 1.07-2.08; p = 0.019) for HLHS. Increased OR was observed for all LVOTO phenotypes in homozygous or compound heterozygous PCDHA delCNV genotype comparison versus wild type. Analysis of an independent white cohort (381 affected individuals, 1,352 control individuals) replicated the PCDHA delCNV association with LVOTO. Generalizability of these findings is suggested by similar observations in Black and Chinese individuals with LVOTO. Analysis of Pcdha mutant mice showed reduced PCDHA expression at regions of cell-cell contact in aortic smooth muscle and cushion mesenchyme, suggesting potential mechanisms for BAV pathogenesis and aortopathy. Together, these findings indicate common variants causing PCDHA deficiency play a significant role in the genetic etiology of common and rare LVOTO-CHD.

Heparanase inhibition preserves the endothelial glycocalyx in lung grafts and improves lung preservation and transplant outcomes.

The endothelial glycocalyx (eGC) is considered a key regulator of several mechanisms that prevent vascular injury and disease. Degradation of this macromolecular layer may be associated with post-transplant graft dysfunction. In this study, we aimed to demonstrate the benefits of eGC protection via heparanase inhibition on graft quality. We established rat models of lung grafts with damaged or preserved eGC using ischemic insult and transplanted the grafts into recipients. Lung grafts were also subjected to normothermic ex vivo lung perfusion for detailed assessment under isolated conditions. Physiologic parameters and eGC-associated cellular events were assessed in grafts before and after reperfusion. Structurally degraded eGC and highly activated heparanase were confirmed in lungs with ischemic insult. After transplant, lungs with damaged eGC exhibited impaired graft function, inflammation, edema, and inflammatory cell migration. Increased eGC shedding was evident in the lungs after reperfusion both in vivo and ex vivo. These reperfusion-related deficiencies were significantly attenuated in lungs with preserved eGC following heparanase inhibition. Our studies demonstrated that eGC plays a key role in maintaining lung graft quality and function. Heparanase inhibition may serve as a potential therapeutic to preserve eGC integrity, leading to improved post-transplant outcomes.

Predissection-derived geometric and distensibility indices reveal increased peak longitudinal stress and stiffness in patients sustaining acute type A aortic dissection: Implications for predicting dissection.

OBJECTIVE: To assess ascending aortic distensibility and build geometry and distensibility-based patient-specific stress distribution maps in patients sustaining type A aortic dissection (TAAD) using predissection noninvasive imaging. METHODS: Review of charts from patients undergoing surgical repair of TAAD (n = 351) led to the selection of a subset population (n = 7) with 2 or more predissection computed tomography angiography scans and echocardiograms at least 1 year before dissection. Ascending aortic wall biomechanical properties (aortic strain, distensibility, and stiffness) were compared with age- and size-matched nondissected nonaneurysmal controls. Patient-specific aortic strain served as an input in aortic geometry-based simulated 3-dimensional reconstructions to generate longitudinal and circumferential wall stress maps. Inspection of perioperative dissection scans and intraoperative visual examination confirmed primary tear locations. RESULTS: Predissection echocardiography revealed ascending aortas of patients sustaining TAAD to exhibit decreased aortic wall strain (14.50 ± 1.13% vs 8.49 ± 1.08%; P < .01), decreased distensibility (4.26 ± 0.44 vs 2.39 ± 0.33 10-6 cm2·dyne-1; P < .01), increased stiffness (3.84 ± 0.24 vs 7.48 ± 1.05; P < .001), and increased longitudinal wall stress (246 ± 22 vs 172 ± 37 kPa; P < .01). There was no significant difference in circumferential wall stress. Predissection computed tomography angiography models revealed overlap between regions of increased longitudinal wall stress and primary tear sites. CONCLUSIONS: Using predissection imaging, we identified increased stiffness and longitudinal wall stress in ascending aortas of patients with dissection. Patient-specific imaging-derived biomechanical property maps like these may be instrumental toward designing better prediction models of aortic dissection potential.

Medial Hypoxia and Adventitial Vasa Vasorum Remodeling in Human Ascending Aortic Aneurysm.

Human ascending aortic aneurysms characteristically exhibit cystic medial degeneration of the aortic wall encompassing elastin degeneration, proteoglycan accumulation and smooth muscle cell loss. Most studies have focused on the aortic media and there is a limited understanding of the importance of the adventitial layer in the setting of human aneurysmal disease. We recently demonstrated that the adventitial ECM contains key angiogenic factors that are downregulated in aneurysmal aortic specimens. In this study, we investigated the adventitial microvascular network (vasa vasorum) of aneurysmal aortic specimens of different etiology and hypothesized that the vasa vasorum is disrupted in patients with ascending aortic aneurysm. Morphometric analyses of hematoxylin and eosin-stained human aortic cross-sections revealed evidence of vasa vasorum remodeling in aneurysmal specimens, including reduced density of vessels, increased lumen area and thickening of smooth muscle actin-positive layers. These alterations were inconsistently observed in specimens of bicuspid aortic valve (BAV)-associated aortopathy, while vasa vasorum remodeling was typically observed in aneurysms arising in patients with the morphologically normal tricuspid aortic valve (TAV). Gene expression of hypoxia-inducible factor 1α and its downstream targets, metallothionein 1A and the pro-angiogenic factor vascular endothelial growth factor, were down-regulated in the adventitia of aneurysmal specimens when compared with non-aneurysmal specimens, while the level of the anti-angiogenic factor thrombospondin-1 was elevated. Immunodetection of glucose transporter 1 (GLUT1), a marker of chronic tissue hypoxia, was minimal in non-aneurysmal medial specimens, and locally accumulated within regions of elastin degeneration, particularly in TAV-associated aneurysms. Quantification of GLUT1 revealed elevated levels in the aortic media of TAV-associated aneurysms when compared to non-aneurysmal counterparts. We detected evidence of chronic inflammation as infiltration of lymphoplasmacytic cells in aneurysmal specimens, with a higher prevalence of lymphoplasmacytic infiltrates in aneurysmal specimens from patients with TAV compared to that of patients with BAV. These data highlight differences in vasa vasorum remodeling and associated medial chronic hypoxia markers between aneurysms of different etiology. These aberrations could contribute to malnourishment of the aortic media and could conceivably participate in the pathogenesis of thoracic aortic aneurysm.

Structural modeling reveals microstructure-strength relationship for human ascending thoracic aorta.

High lethality of aortic dissection necessitates accurate predictive metrics for dissection risk assessment. The not infrequent incidence of dissection at aortic diameters <5.5 cm, the current threshold guideline for surgical intervention (Nishimura et al., 2014), indicates an unmet need for improved evidence-based risk stratification metrics. Meeting this need requires a fundamental understanding of the structural mechanisms responsible for dissection evolution within the vessel wall. We present a structural model of the repeating lamellar structure of the aortic media comprised of elastic lamellae and collagen fiber networks, the primary load-bearing components of the vessel wall. This model was used to assess the role of these structural features in determining in-plane tissue strength, which governs dissection initiation from an intimal tear. Ascending aortic tissue specimens from three clinically-relevant patient populations were considered: non-aneurysmal aorta from patients with morphologically normal tricuspid aortic valve (CTRL), aneurysmal aorta from patients with tricuspid aortic valve (TAV), and aneurysmal aorta from patients with bicuspid aortic valve (BAV). Multiphoton imaging derived collagen fiber organization for each patient cohort was explicitly incorporated in our model. Model parameters were calibrated using experimentally-measured uniaxial tensile strength data in the circumferential direction for each cohort, while the model was validated by contrasting simulated tissue strength against experimentally-measured strength in the longitudinal direction. Orientation distribution, controlling the fraction of loaded collagen fibers at a given stretch, was identified as a key feature governing anisotropic tissue strength for all patient cohorts.

Elevated oxidative stress in the aortic media of patients with bicuspid aortic valve.

OBJECTIVE: Congenital bicuspid aortic valve (BAV) is distinctly associated with the development of ascending aortopathy in adulthood, portending risk of both ascending aortic aneurysm and dissection. Our previous work implicated deficiency in oxidative stress response as a mediator of the BAV-associated aortopathy. We hypothesize that reactive oxygen species generation invokes elevated local oxidative tissue damage in ascending aorta of patients with BAV. METHODS: Ascending aortic specimens were obtained from patients undergoing elective aortic replacement and/or aortic valve replacement and during heart transplant operations. Levels of superoxide anion were measured via high-pressure liquid chromatography-based detection of 2-hydroxyethidium in aortic specimens. Lipid peroxidation and enzymatic activity of superoxide dismutase and peroxidase were quantified in aortic specimens. RESULTS: Superoxide anion production was elevated in aortic specimens from patients with nonaneurysmal BAV (n = 59) compared with specimens from patients with the morphologically normal tricuspid aortic valve (TAV, n = 38). Total superoxide dismutase activity was similar among aortic specimens from patients with TAV versus BAV (n = 27 and 26, respectively), whereas peroxidase activity was increased in aortic specimens from patients with BAV compared with specimens from patients with TAV (n = 14 for both groups). Lipid peroxidation was elevated in aortic specimens from BAV patients compared with TAV patients (n = 14 and 11, respectively). CONCLUSIONS: Superoxide anion accumulation and increased lipid peroxidation demonstrate that, despite increased peroxidase activity, the ascending aortopathy of patients with BAV involves oxidative stress. In addition, the absence of increased superoxide dismutase activity in BAV specimens indicates a deficiency in antioxidant defense. This suggests that the characteristic smooth muscle cell loss observed in BAV aortopathy may be a consequence of superoxide-mediated cell damage.

Classification and Functional Characterization of Vasa Vasorum-Associated Perivascular Progenitor Cells in Human Aorta.

In the microcirculation, pericytes are believed to function as mesenchymal stromal cells (MSCs). We hypothesized that the vasa vasorum harbor progenitor cells within the adventitia of human aorta. Pericytes, endothelial progenitor cells, and other cell subpopulations were detected among freshly isolated adventitial cells using flow cytometry. Purified cultured pericytes were enriched for the MSC markers CD105 and CD73 and depleted of the endothelial markers von Willebrand factor and CD31. Cultured pericytes were capable of smooth muscle lineage progression including inducible expression of smooth muscle myosin heavy chain, calponin, and α-smooth muscle actin, and adopted a spindle shape. Pericytes formed spheroids when cultured on Matrigel substrates and peripherally localized with branching endothelial cells in vitro. Our results indicate that the vasa vasorum form a progenitor cell niche distinct from other previously described progenitor populations in human adventitia. These findings could have important implications for understanding the complex pathophysiology of human aortic disease.

Aneurysm-Specific miR-221 and miR-146a Participates in Human Thoracic and Abdominal Aortic Aneurysms.

Altered microRNA expression is implicated in cardiovascular diseases. Our objective was to determine microRNA signatures in thoracic aortic aneurysms (TAAs) and abdominal aortic aneurysms (AAAs) compared with control non-aneurysmal aortic specimens. We evaluated the expression of fifteen selected microRNA in human TAA and AAA operative specimens compared to controls. We observed significant upregulation of miR-221 and downregulation of miR-1 and -133 in TAA specimens. In contrast, upregulation of miR-146a and downregulation of miR-145 and -331-3p were found only for AAA specimens. Upregulation of miR-126 and -486-5p and downregulation of miR-30c-2*, -155, and -204 were observed in specimens of TAAs and AAAs. The data reveal microRNA expression signatures unique to aneurysm location and common to both thoracic and abdominal pathologies. Thus, changes in miR-1, -29a, -133a, and -221 are involved in TAAs and miR-145, -146, and -331-3p impact AAAs. This work validates prior studies on microRNA expression in aneurysmal diseases.

Nanonet force microscopy for measuring forces in single smooth muscle cells of the human aorta.

A number of innovative methods exist to measure cell-matrix adhesive forces, but they have yet to accurately describe and quantify the intricate interplay of a cell and its fibrous extracellular matrix (ECM). In cardiovascular pathologies, such as aortic aneurysm, new knowledge on the involvement of cell-matrix forces could lead to elucidation of disease mechanisms. To better understand this dynamics, we measured primary human aortic single smooth muscle cell (SMC) forces using nanonet force microscopy in both inside-out (I-O intrinsic contractility) and outside-in (O-I external perturbation) modes. For SMC populations, we measured the I-O and O-I forces to be 12.9 ± 1.0 and 57.9 ± 2.5 nN, respectively. Exposure of cells to oxidative stress conditions caused a force decrease of 57 and 48% in I-O and O-I modes, respectively, and an increase in migration rate by 2.5-fold. Finally, in O-I mode, we cyclically perturbed cells at constant strain of varying duration to simulate in vivo conditions of the cardiac cycle and found that I-O forces decrease with increasing duration and O-I forces decreased by half at shorter cycle times. Thus our findings highlight the need to study forces exerted and felt by cells simultaneously to comprehensively understand force modulation in cardiovascular disease.