Delayed management of acute type A aortic dissection with concomitant coronary artery bypass graft.

BACKGROUND: Pre-operative coronary angiography and concomitant, planned coronary artery bypass are infrequently performed with type A aortic dissection repair. We present a case in which pre-operative coronary computed tomography angiography was appropriate, and subsequent dissection repair and concomitant coronary artery bypass were successfully performed. CASE PRESENTATION: The patient is a 58-year-old male with heart failure with preserved ejection fraction, renal insufficiency, hypertension, obesity, and smoking history, who presented with a three-to-four-day history of persistent back pain, worsening exertional dyspnea, and orthopnea, as well as a two-to-three month history of dyspnea, lower extremity edema, and intermittent angina. He was diagnosed with an acute type A aortic dissection and anti-impulse control was initiated. However, repair was delayed in order to allow apixaban to metabolize and decrease the risk of bleeding, as the patient was approximately six days post-dissection, without malperfusion, with a well-controlled blood pressure on anti-impulse therapy, and had received five days of anticoagulation. During this time, coronary computed tomography angiography was performed to assess the need for concomitant revascularization and showed coronary artery disease. Ascending aorta hemiarch replacement with aortic valve resuspension, two-vessel coronary artery bypass grafting, and left atrial appendage clipping were performed successfully. CONCLUSIONS: Pre-operative imaging can be considered in a select group of acute type A aortic dissections that present without malperfusion, and with well-controlled blood pressure on anti-impulse/negative inotropic therapy.

Postoperative bioactive adrenomedullin is associated with the onset of ARDS and adverse outcomes in patients undergoing open thoracoabdominal aortic surgery.

Cytokine-mediated systemic inflammation after open thoracoabdominal aortic aneurysm (TAAA) repairs plays a pivotal role in disrupting circulatory homeostasis, potentially leading to organ dysfunction. The bioactive form of adrenomedullin (bio-ADM) is a peptide hormone with immunomodulatory and vasomotor effects, making it a potential diagnostic agent in these cases. This retrospective, bicentric study, conducted between January 2019 and December 2022, recruited 36 elective open TAAA repair patients in two German centres. Serum and plasma samples were collected at multiple time points to measure bio-ADM levels. The primary objective was to evaluate the association of bio-ADM levels with the onset of acute respiratory distress syndrome (ARDS), with secondary endpoints focusing on mortality and SIRS-related morbidity. Results showed a significant association between postoperative bio-ADM levels (12-48 h after surgery) and the onset of ARDS (p < .001), prolonged ventilation (p = .015 at 12h after surgery), atrial fibrillation (p < .001), and mortality (p = .05 at 24h). The biomarker was also strongly associated with sepsis (p = .01 at 12 h) and multi-organ dysfunction syndrome (MODS) (p = .02 at 24 h after surgery). The study underscores the potential utility of bio-ADM as a diagnostic tool for identifying patients at risk of postoperative complications following open TAAA repairs.

Divergent and Compensatory Effects of BMP2 and BMP4 on the VSMC Phenotype and BMP4's Role in Thoracic Aortic Aneurysm Development.

Vascular smooth muscle cells (VSMCs) play a key role in aortic aneurysm formation. Bone morphogenetic proteins (BMPs) have been implicated as important regulators of VSMC phenotype, and dysregulation of the BMP pathway has been shown to be associated with vascular diseases. The aim of this study was to investigate for the first time the effects of BMP-4 on the VSMC phenotype and to understand its role in the development of thoracic aortic aneurysms (TAAs). Using the angiotensin II (AngII) osmotic pump model in mice, aortas from mice with VSMC-specific BMP-4 deficiency showed changes similar to AngII-infused aortas, characterised by a loss of contractile markers, increased fibrosis, and activation of matrix metalloproteinase 9. When BMP-4 deficiency was combined with AngII infusion, there was a significantly higher rate of apoptosis and aortic dilatation. In vitro, VSMCs with mRNA silencing of BMP-4 displayed a dedifferentiated phenotype with activated canonical BMP signalling. In contrast, BMP-2-deficient VSMCs exhibited the opposite phenotype. The compensatory regulation between BMP-2 and BMP-4, with BMP-4 promoting the contractile phenotype, appeared to be independent of the canonical signalling pathway. Taken together, these results demonstrate the impact of VSMC-specific BMP-4 deficiency on TAA development.

Redo partial aortic root remodelling in type A dissection with an aorto-left atrial fistula.

A 72-year-old male with a history of a triple-vessel coronary artery bypass graft years ago presented with a DeBakey type 2 aortic dissection and an aorto-left atrial fistula with patent bypass grafts (left internal mammary artery and saphenous vein grafts). He developed pulmonary oedema and required intubation. The right axillary artery was cannulated. After the ascending aorta and left internal mammary artery were clamped, the aorta was transected, leaving aortic tissue around two saphenous vein grafts as two separate patches. An entry tear was found adjacent to the proximal anastomosis of the saphenous vein graft to the posterior descending artery. A fistula, which was located between a false lumen in the non-coronary sinus and the dome of the left atrium, was primarily closed. Because the adventitia was thinned out in the non-coronary sinus due to aortic dissection, partial aortic root remodelling was performed with resuspension of the commissures. Hemiarch repair was performed under moderate hypothermia and unilateral antegrade cerebral perfusion. After systemic perfusion was resumed, the locations of the saphenous vein graft buttons were determined. The ascending graft was cross-clamped again; the saphenous vein graft to the obtuse marginal branch graft was reimplanted using the Carrel patch technique while a saphenous vein graft to the posterior descending artery required interposition of a 10-mm Dacron graft to accommodate the length.

Study on risk factors and treatment strategies of hypoxemia after acute type a aortic dissection surgery.

Acute type A aortic dissection is a life-threatening cardiovascular disease characterized by rapid onset and high mortality. Emergency surgery is the preferred and reliable treatment option. However, postoperative complications significantly impact patient prognosis. Hypoxemia, a common complication, poses challenges in clinical treatment, negatively affecting patient outcomes and increasing the risk of mortality. Therefore, it is crucial to study and comprehend the risk factors and treatment strategies for hypoxemia following acute type A aortic dissection to facilitate early intervention.

[Analysis of the effect and safety of lumen reshaping after endovascular repair of Stanford B type aortic dissection at different intervention times].

Objective: To Compare the effects and safety of lumen reshaping after thoracic endovascular aortic repair (TEVAR) for Stanford B type aortic dissection (AD) at different intervention times. Methods: A retrospective analysis was conducted on the clinical data of 189 patients with Stanford type B aortic dissection treated with TEVAR at the Affiliated Hospital of Chengde Medical College from January 2016 to December 2020.Based on the time from onset to surgery, patients were divided into an early intervention group (≤14 days, n=127) and a delayed intervention group (>14 days, n=62).The diameters of the total aorta, true lumen and false lumen at different times and planes (S1 plane: at the bifurcation of the pulmonary artery; S2 plane: at the lower edge of the left atrium; S3 plane: at the upper edge of the celiac trunk) post-surgery were compared between the two groups, and the rate of change in diameters of true and false lumens across these planes was calculated. The patients were followed until December 1st, 2023, and the median follow-up time was 45(40, 49) months. The postoperative complications and survival of the two groups were compared. Results: The early intervention group comprised 86 men and 41 women, with an average age of (58.3±10.7) years. The delayed intervention group included 41 men and 21 women, with an average age of (58.5±9.2) years. Both groups had an operation success rate of 100%. Six months post-surgery, the early intervention group had an expansion rate of the true lumen diameter at planes S2 and S3 of 40.1%(25.5%, 56.1%) and 5.3%(-2.5%, 15.8%), respectively, which was superior to the delayed intervention group's 18.5%(10.6%, 39.8%) and 1.0%(-8.2%, 9.6%) (both P<0.05).The early intervention group had a reduction rate of the false lumen diameter at planes S1, S2, and S3 of -56.2%(-61.3%, -48.8%), -70.4%(-81.8%, -56.6%), and -5.4%(-17.4%, 0.1%), respectively, better than the delayed intervention group's -44.2%(-53.7%, -38.3%), -49.0%(-57.6%, -35.8%), and -3.1%(-6.7%, 1.8%) (all P<0.05).At plane S1, the true lumen diameter of patients in both groups showed an increasing trend over 36 months post-surgery, while the false lumen diameter showed a decreasing trend (both P<0.05).At plane S2, the true lumen diameter of patients in the early intervention group exhibited an increasing trend over 36 months post-surgery, and the false lumen diameter exhibited a decreasing trend (both P<0.05).At plane S3, the total aortic diameter of patients in the delayed intervention group showed a slight increasing trend over 36 months post-surgery (P<0.05).The overall survival time were 45.0 months (95%CI: 42.9-47.1) for patients in the early intervention group and 46.0 months (95%CI: 43.5-48.5) for those in the delayed intervention group, with no statistically significant difference observed (P>0.05).The incidence rates of complications such as aortic rupture, retrograde Type A dissection, new distal endograft dissection, endoleak, paraplegia, and others showed no statistically significant difference between the two groups (all P>0.05), with no cases of stent migration or deformation observed. Conclusion: Early intervention for Stanford type B aortic dissection provides a better aortic remodeling outcome than delayed intervention, with similar safety.

Retrograde cerebral perfusion reduces embolic and watershed lesions after acute type a aortic dissection repair with deep hypothermic circulatory arrest.

BACKGROUND: To assess whether retrograde cerebral perfusion reduces neurological injury and mortality in patients undergoing surgery for acute type A aortic dissection. METHODS: Single-center, retrospective, observational study including all patients undergoing acute type A aortic dissection repair with deep hypothermic circulatory arrest between January 1998 and December 2022 with or without the adjunct of retrograde cerebral perfusion. 515 patients were included: 257 patients with hypothermic circulatory arrest only and 258 patients with hypothermic circulatory arrest and retrograde cerebral perfusion. The primary endpoints were clinical neurological injury, embolic lesions, and watershed lesions. Multivariable logistic regression was performed to identify independent predictors of the primary outcomes. Survival analysis was performed using Kaplan-Meier estimates. RESULTS: Clinical neurological injury and embolic lesions were less frequent in patients with retrograde cerebral perfusion (20.2% vs. 28.4%, p = 0.041 and 13.7% vs. 23.4%, p = 0.010, respectively), but there was no significant difference in the occurrence of watershed lesions (3.0% vs. 6.1%, p = 0.156). However, after multivariable logistic regression, retrograde cerebral perfusion was associated with a significant reduction of clinical neurological injury (OR: 0.60; 95% CI 0.36-0.995, p = 0.049), embolic lesions (OR: 0.55; 95% CI 0.31-0.97, p = 0.041), and watershed lesions (OR: 0.25; 95%CI 0.07-0.80, p = 0.027). There was no significant difference in 30-day mortality (12.8% vs. 11.7%, p = ns) or long-term survival between groups. CONCLUSION: In this study, we showed that the addition of retrograde cerebral perfusion during hypothermic circulatory arrest in the setting of acute type A aortic dissection repair reduced the risk of clinical neurological injury, embolic lesions, and watershed lesions.

Clinical predictive value of the age, creatinine, and ejection fraction score in patients in acute type A aortic dissection after total arch replacement.

The age, creatinine, and ejection fraction (ACEF) score has been accepted as a predictor of poor outcome in elective operations. This study aimed to investigate the predictive value of ACEF score in acute type A aortic dissection (AAAD) patients after total arch replacement. A total of 227 AAAD patients from July 2021 and June 2022 were enrolled and divided into Tertiles 1 (ACEF ≤ 0.73), Tertiles 2 (0.73 < ACEF ≤ 0.95), and Tertiles 3 (ACEF > 0.95). Using inverse probability processing weighting (IPTW) to balance the baseline characteristics and compare the outcomes. Cox logistic regression was used to further evaluate the survival prediction ability of ACEF score. The in-hospital mortality was 9.8%. After IPTW, in the baseline characteristics reached an equilibrium, a higher ACEF score before operation still associated with higher in-hospital mortality. After 1 year follow-up, 184 patients (90.6%) survival. Multivariable analysis revealed that ACEF score (adjusted hazard ratio 1.68; 95% confidence interval 1.34-4.91; p = 0.036) and binary ACEF score (adjusted HR 2.26; 95% CI 1.82-6.20; p < 0.001) was independently associated with 1-year survival. In addition, net reclassification improvement (NRI) and integrated differentiation improvement (IDI) verified that the ACEF score and binary ACEF score is an accurate predictive tool in clinical settings. In conclusions, ACEF score could be considered as a useful tool to risk stratification in patients with AAAD before operation in daily clinical work.

Clinical Outcome of the Type A Acute Aortic Dissection Repair Using the "Tailored Stand-Up Collar" Technique.

PURPOSE: Achieving a secure anastomosis and complete hemostasis is essential for surgically treating type A acute aortic dissection (TAAAD). This study assessed the clinical feasibility of "tailored stand-up collar (TSC)" technique for constructing the distal stump. METHODS: We enrolled 68 patients who underwent ascending aortic repair for TAAAD. Patients were categorized according to the technique for distal stump construction: conventional (C) group using only a felt strip (32 cases); post-aortotomy (P) group, with a Hydrofit-felt strip attached after aortotomy (18 cases), and TSC group, where a Hydrofit-felt strip attached during cooling (18 cases). Pre-operative characteristics, procedural profiles, and post-operative outcomes were evaluated. RESULTS: The pre-operative characteristics were identical among the groups. The durations of cardiopulmonary bypass, hemostasis, and surgery were significantly shorter in the P and TSC groups. The duration of open distal in the TSC group (21 min) was significantly shorter than the other two groups. Post-operative additional procedures were not required for the TSC group and their post-operative hospital stay was significantly shorter (47.1% of patients were discharged within 2 weeks). CONCLUSION: The TSC technique would be practical because of its high reproducibility in terms of ease of use, shorter anastomotic time, and secure hemostasis.

Aortic arch surgery for DeBakey type 1 aortic dissection in patients aged 60 years or younger.

BACKGROUND: Extended aortic repair is considered a key issue for the long-term durability of surgery for DeBakey type 1 aortic dissection. The risk of aortic degeneration may be higher in young patients due to their long life expectancy. The early outcome and durability of aortic surgery in these patients were investigated in the present study. METHODS: The subjects of the present analysis were patients under 60 years old who underwent surgical repair for acute DeBakey type 1 aortic dissection at 18 cardiac surgery centres across Europe between 2005 and 2021. Patients underwent ascending aortic repair or total aortic arch repair using the conventional technique or the frozen elephant trunk technique. The primary outcome was 5-year cumulative incidence of reoperation on the distal aorta. RESULTS: Overall, 915 patients underwent surgical ascending aortic repair and 284 patients underwent surgical total aortic arch repair. The frozen elephant trunk procedure was performed in 128 patients. Among 245 propensity score-matched pairs, total aortic arch repair did not decrease the rate of distal aortic reoperation compared to ascending aortic repair (5-year cumulative incidence, 6.7% versus 6.7%, subdistributional hazard ratio 1.127, 95% c.i. 0.523 to 2.427). Total aortic arch repair increased the incidence of postoperative stroke/global brain ischaemia (25.7% versus 18.4%, P = 0.050) and dialysis (19.6% versus 12.7%, P = 0.003). Five-year mortality was comparable after ascending aortic repair and total aortic arch repair (22.8% versus 27.3%, P = 0.172). CONCLUSIONS: In patients under 60 years old with DeBakey type 1 aortic dissection, total aortic arch replacement compared with ascending aortic repair did not reduce the incidence of distal aortic operations at 5 years. When feasible, ascending aortic repair for DeBakey type 1 aortic dissection is associated with satisfactory early and mid-term outcomes. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04831073.

Antegrade cerebral perfusion via the right subclavian artery during open distal arch or proximal descending aortic repair from left thoracotomy.

In the current endovascular era, open surgery through left posterolateral thoracotomy with moderate to deep hypothermic circulatory arrest remains an alternative for treating chronic distal arch or proximal descending aortic diseases, allowing cardiovascular surgeons to definitively repair the aorta in a single stage. When utilizing this approach, this report illustrates an alternative surgical technique for antegrade body perfusion during cooling, antegrade selective cerebral perfusion and rewarming, through a prosthetic graft on the right subclavian artery. This report shows the safety and feasibility of this technique during open distal arch and/or proximal descending aortic surgery through left posterolateral thoracotomy, after shifting the patient from a supine to the right lateral decubitus position.

Aortic remodelling based on false lumen communications in patients undergoing acute type I dissection repair with AMDS hybrid prosthesis: a substudy of the DARTS trial.

OBJECTIVES: The Dissected Aorta Repair Through Stent (DARTS) Implantation trial demonstrated positive proximal aortic remodelling following aortic dissection repair with the AMDS hybrid prosthesis. In this study, we look to identify predictors of aortic remodelling following aortic dissection repair with AMDS including whether communications between branch vessels and the false lumen (FL) predict aortic growth. METHODS: The DARTS implantation trial included patients who underwent acute DeBakey type I aortic dissection (ATAD I) repair with the AMDS from March 2017 to January 2019. Anatomic measurements were collected from original computerized tomography scans. Measurements were taken at zones 2, 3, 6 and 9. Patients were grouped based on the number of FL communications with the supra-aortic branch vessels or visceral branch vessels. RESULTS: Forty-seven patients were included in the original DARTS implantation trial. Patients with FL communications with the supra-aortic branch vessels tended to have significant growth at zone 3 (P = 0.02-0.0018), while greater numbers of visceral FL communications tended to predict aortic growth at zones 3 (P = 0.003), 6 (P = 0.017-0.0087) and 9 (P = 0.0016-0.0003). CONCLUSIONS: Aortic remodelling following ATAD I repair using the AMDS may be predicted by local FL communications with branch vessels. Patients undergoing ATAD I repair were more likely to experience significant aortic growth in zone 3 with more head vessel communications and in zones 3, 6 and 9 with more visceral FL communications. Predictors of aortic remodelling may help to guide initial surgical management for aortic dissection patients.

Circumferent dissection of the ascending aorta resulting in the occlusion of supra-aortic vessels repaired using the frozen elephant trunk technique - a case report.

BACKGROUND: Our patient presented with acute back pain and dyspnea, without neurological symptoms. The computed tomography (CT) scan showed a circumferent rupture of the ascending aortic intima which was invaginated in the arch and descending aorta. CASE PRESENTATION: A 54-year-old male patient was diagnosed with a Type A aortic dissection. He was immediately transferred to our operation room (OR) from the emergency department of a peripheral hospital. He presented with a circumferential dissection of the ascending aorta originating just distal to the coronary ostia, with the invaginated intimal mass extending through the arch down the descending aorta. In mild hypothermia, the intimal mass was safely extracted and a frozen elephant trunk (FET) procedure was performed. CONCLUSIONS: Despite the extensive dissection affecting the ascending aorta and aortic arch, resulting in partially occluded supra-aortic vessels by an intimal mass, the patient remained without neurological symptoms in the pre- and post-operative period and remains well one year post surgery.

[Surgical treatment of a patient with syphilitic aortitis]. / Khirurgicheskoe lechenie patsienta s sifiliticheskim aortitom.

Syphilitic aortitis is a rare disease caused by Treponema pallidum affecting the aorta and leading to inflammation. Syphilitic aortitis is one of the causes of aortic aneurysms. This article presents surgical treatment of a patient with syphilitic aortitis and thoracic aortic aneurysm. This clinical case confirms the difficulties of surgical treatment.

Single-cell sequencing reveals the impact of endothelial cell PIEZO1 expression on thoracic aortic aneurysm.

INTRODUCTION: Thoracic aortic aneurysm (TAA) is a severe vascular disease that threatens human life, characterized by focal dilatation of the entire aortic wall, with a diameter 1.5 times larger than normal. PIEZO1, a mechanosensitive cationic channel, monitors mechanical stimulations in the environment, transduces mechanical signals into electrical signals, and converts them into biological signals to activate intracellular signaling pathways. However, the role of PIEZO1 in TAA is still unclear. METHODS: We analyzed a single-cell database to investigate the expression level of PIEZO1 in TAA. We constructed a conditional knockout mouse model of Piezo1 and used the PIEZO1 agonist Yoda1 to intervene in the TAA model mice established by co-administration of BAPN and ANG-II. Finally, we explored the effect of Yoda1 on TAA in vitro. RESULTS AND DISCUSSION: We observed decreased PIEZO1 expression in TAA at both RNA and protein levels. Single-cell sequencing identified a specific reduction in Piezo1 expression in endothelial cells. Administration of PIEZO1 agonist Yoda1 prevented the formation of TAA. In PIEZO1 endothelial cell conditional knockout mice, Yoda1 inhibited TAA formation by interfering with PIEZO1. In vivo and in vitro experiments demonstrated that the effect of Yoda1 on endothelial cells involved macrophage infiltration, extracellular matrix degradation, and neovascularization. This study highlights the role of PIEZO1 in TAA and its potential as a therapeutic target, providing opportunities for clinical translation.

Complex genotype-phenotype correlation of MYH11: new insights from monozygotic twins with highly variable expressivity and outcomes.

BACKGROUND: Thoracic aortic aneurysm/dissection (TAAD) and patent ductus arteriosus (PDA) are serious autosomal-dominant diseases affecting the cardiovascular system. They are mainly caused by variants in the MYH11 gene, which encodes the heavy chain of myosin 11. The aim of this study was to evaluate the genotype-phenotype correlation of MYH11 from a distinctive perspective based on a pair of monozygotic twins. METHODS: The detailed phenotypic characteristics of the monozygotic twins from the early fetal stage to the infancy stage were traced and compared with each other and with those of previously documented cases. Whole-exome and Sanger sequencing techniques were used to identify and validate the candidate variants, facilitating the analysis of the genotype-phenotype correlation of MYH11. RESULTS: The monozygotic twins were premature and presented with PDA, pulmonary hypoplasia, and pulmonary hypertension. The proband developed heart and brain abnormalities during the fetal stage and died at 18 days after birth, whereas his sibling was discharged after being cured and developed normally post follow-up. A novel variant c.766 A > G p. (Ile256Val) in MYH11 (NM_002474.2) was identified in the monozygotic twins and classified as a likely pathogenic variant according to the American College of Medical Genetics/Association for Molecular Pathology guidelines. Reviewing the reported cases (n = 102) showed that the penetrance of MYH11 was 82.35%, and the most common feature was TAAD (41.18%), followed by PDA (22.55%), compound TAAD and PDA (9.80%), and other vascular abnormalities (8.82%). The constituent ratios of null variants among the cases with TAAD (8.60%), PDA (43.8%), or compound TAAD and PDA (28.6%) were significantly different (P = 0.01). Further pairwise comparison of the ratios among these groups showed that there were significant differences between the TAAD and PDA groups (P = 0.006). CONCLUSION: This study expands the mutational spectrum of MYH11 and provides new insights into the genotype-phenotype correlation of MYH11 based on the monozygotic twins with variable clinical features and outcomes, indicating that cryptic modifiers and complex mechanisms beside the genetic variants may be involved in the condition.

Multicentre experience of antegrade thoracic endovascular aortic repair for the treatment of thoracic aortic diseases.

OBJECTIVES: The goal of this multicentre retrospective cohort study was to evaluate technical success and early and late outcomes of thoracic endovascular repair (TEVAR) with grafts deployed upside down through antegrade access, to treat thoracic aortic diseases. METHODS: Antegrade TEVAR operations performed between January 2010 and December 2021 were collected and analysed. Both elective and urgent procedures were included. Exclusion criteria were endografts deployed in previous or concomitant surgical or endovascular repairs. RESULTS: Fourteen patients were enrolled; 13 were males (94%) with a mean age of 71 years (interquartile range 62; 78). Five patients underwent urgent procedures (2 ruptured aortas and 3 symptomatic patients). Indications for treatment were 8 (57%) aneurysms/pseudoaneurysms, 3 (21%) dissections and 3 (21%) penetrating aortic ulcers. Technical success was achieved in all procedures. Early mortality occurred in 4 (28%) cases, all urgent procedures. Median follow-up was 13 months (interquartile range 1; 44). Late deaths occurred in 2 (20%) patients, both operated on in elective settings. The first died at 19 months of aortic-related reintervention; the second died at 34 months of a non-aortic-related cause. Two patients (14%) underwent aortic-related reinterventions for late type I endoleak. The survival rate of those having the elective procedures was 100%, 84% and 67% at 12, 24 and 36 months, respectively. Freedom from reintervention was 92%, 56% and 56% at 12, 24 and 36 months, respectively. CONCLUSIONS: Antegrade TEVAR can seldom be considered an alternative when traditional retrograde approach is not feasible. Despite good technical success and few access-site complications, this study demonstrates high rates of late type I endoleak and aortic-related reinterventions.

Bioengineered vascular grafts with a pathogenic TGFBR1 variant model aneurysm formation in vivo and reveal underlying collagen defects.

Thoracic aortic aneurysm (TAA) is a life-threatening vascular disease frequently associated with underlying genetic causes. An inadequate understanding of human TAA pathogenesis highlights the need for better disease models. Here, we established a functional human TAA model in an animal host by combining human induced pluripotent stem cells (hiPSCs), bioengineered vascular grafts (BVGs), and gene editing. We generated BVGs from isogenic control hiPSC-derived vascular smooth muscle cells (SMCs) and mutant SMCs gene-edited to carry a Loeys-Dietz syndrome (LDS)-associated pathogenic variant (TGFBR1A230T). We also generated hiPSC-derived BVGs using cells from a patient with LDS (PatientA230T/+) and using genetically corrected cells (Patient+/+). Control and experimental BVGs were then implanted into the common carotid arteries of nude rats. The TGFBR1A230T variant led to impaired mechanical properties of BVGs, resulting in lower burst pressure and suture retention strength. BVGs carrying the variant dilated over time in vivo, resembling human TAA formation. Spatial transcriptomics profiling revealed defective expression of extracellular matrix (ECM) formation genes in PatientA230T/+ BVGs compared with Patient+/+ BVGs. Histological analysis and protein assays validated quantitative and qualitative ECM defects in PatientA230T/+ BVGs and patient tissue, including decreased collagen hydroxylation. SMC organization was also impaired in PatientA230T/+ BVGs as confirmed by vascular contraction testing. Silencing of collagen-modifying enzymes with small interfering RNAs reduced collagen proline hydroxylation in SMC-derived tissue constructs. These studies demonstrated the utility of BVGs to model human TAA formation in an animal host and highlighted the role of reduced collagen modifying enzyme activity in human TAA formation.

Unveiling cellular and molecular aspects of ascending thoracic aortic aneurysms and dissections.

Ascending thoracic aortic aneurysm (ATAA) remains a significant medical concern, with its asymptomatic nature posing diagnostic and monitoring challenges, thereby increasing the risk of aortic wall dissection and rupture. Current management of aortic repair relies on an aortic diameter threshold. However, this approach underestimates the complexity of aortic wall disease due to important knowledge gaps in understanding its underlying pathologic mechanisms.Since traditional risk factors cannot explain the initiation and progression of ATAA leading to dissection, local vascular factors such as extracellular matrix (ECM) and vascular smooth muscle cells (VSMCs) might harbor targets for early diagnosis and intervention. Derived from diverse embryonic lineages, VSMCs exhibit varied responses to genetic abnormalities that regulate their contractility. The transition of VSMCs into different phenotypes is an adaptive response to stress stimuli such as hemodynamic changes resulting from cardiovascular disease, aging, lifestyle, and genetic predisposition. Upon longer exposure to stress stimuli, VSMC phenotypic switching can instigate pathologic remodeling that contributes to the pathogenesis of ATAA.This review aims to illuminate the current understanding of cellular and molecular characteristics associated with ATAA and dissection, emphasizing the need for a more nuanced comprehension of the impaired ECM-VSMC network.