Gene expression profiling of acute type A aortic dissection combined with in vitro assessment.

OBJECTIVES: The mechanisms underlying aortic dissection remain to be fully elucidated. We aimed to identify key molecules driving dissection through gene expression profiling achieved by microarray analysis and subsequent in vitro experiments using human aortic endothelial cells (HAECs) and aortic vascular smooth muscle cells (AoSMCs). METHODS: Total RNA, including microRNA (miRNA), was isolated from the intima-media layer of dissected ascending aorta obtained intraoperatively from acute type A aortic dissection (ATAAD) patients without familial thoracic aortic disease (n = 8) and that of non-dissected ascending aorta obtained from transplant donors (n = 9). Gene expression profiling was performed with mRNA and miRNA microarrays, and results were confirmed by quantitative polymerase chain reaction (qPCR). Target genes and miRNA were identified by gene ontology analysis and a literature search. To reproduce the in silico results, HAECs and AoSMCs were stimulated in vitro by upstream cytokines, and expression of target genes was assessed by qPCR. RESULTS: Microarray analysis revealed 1536 genes (3.6%, 1536/42 545 probes) and 41 miRNAs (3.0%, 41/1368 probes) that were differentially expressed in the ATAAD group (versus donor group). The top 15 related pathways included regulation of inflammatory response, growth factor activity and extracellular matrix. Gene ontology analysis identified JAK2 (regulation of inflammatory response), PDGFA, TGFB1, VEGFA (growth factor activity) and TIMP3, TIMP4, SERPINE1 (extracellular matrix) as the target genes and miR-21-5p, a TIMP3 repressor, as target miRNA that interacts with the target genes. Validation qPCR confirmed the altered expression of all 7 target genes and miR-21-5p in dissected aorta specimens (all genes, P < 0.05). Ingenuity pathway analysis showed TNF-α and TGF-ß to be upstream cytokines for the target genes. In vitro experiments showed these cytokines inhibit TIMP3 expression (P < 0.05) and enhance VEGFA expression (P < 0.01) in AoSMCs but not HAECs. miR-21-5p expression increases in AoSMCs under TNF-α and TGF-ß stimulation (fold change: 1.36; P = 0.011). CONCLUSIONS: Results of our novel approach, integrating in vitro assessment into gene expression profiling, implicated chronic inflammation characterized by MMP-TIMP dysregulation, increased VEGFA expression, and TGF-ß signalling in the development of dissection. Further investigation may reveal novel diagnostic biomarkers and uncover the mechanism(s) underlying ATAAD.

Patient-specific assessment of hemodynamics by computational fluid dynamics in patients with bicuspid aortopathy.

OBJECTIVE: Hemodynamics related to eccentric blood flow may factor into the development of bicuspid aortic valve aortopathy. We investigated wall shear stress distribution by means of magnetic resonance imaging-based computational fluid dynamics in patients with a bicuspid aortic valve. METHODS: Included were 12 patients with a bicuspid aortic valve (aortic stenosis, n = 11; root enlargement, n = 1). Three patients with a normal tricuspid aortic valve (arch aneurysm, n = 1; descending aortic aneurysm, n = 2) were included for comparison. The thoracic aorta geometry was reconstructed by means of 3-dimensional computed tomography angiography, and the bicuspid aortic valve orifice was modeled. Flow rates at the sinotubular junction and 3 aortic branches were measured at various time points by cine phase-contrast magnetic resonance imaging to define boundary conditions for computational fluid dynamics, and the flow was simulated. RESULTS: Bicuspid aortic valve cusp configurations were type 0 lateral (n = 4), type 0 anterior-posterior (n = 2), type 1 L-R (n = 4), and type 1 R-N (n = 2). Abnormal aortic helical flow was seen in the ascending aorta and transverse arch in all patients with bicuspid aortic valves and was right handed in 11 patients (91%). No such flow was seen in the patients with tricuspid aortic valves. The patients with bicuspid aortic valves were likely to have jet flow/wall impingement against the greater curvature of the proximal ascending aorta, resulting in remarkably increased wall shear stress around the impingement area. CONCLUSIONS: Computational fluid dynamics simulation is useful for precise evaluation of hemodynamics related to bicuspid aortic valve aortopathy. Such evaluation will advance our understanding of the disease pathophysiology and may facilitate molecular biological investigation.

Assessment of elastin deficit in a Marfan mouse aneurysm model using an elastin-specific magnetic resonance imaging contrast agent.

BACKGROUND: Ascending aortic dissection and rupture remain a life-threatening complication in patients with Marfan syndrome. The extracellular matrix provides strength and elastic recoil to the aortic wall, thereby preventing radial expansion. We have previously shown that ascending aortic aneurysm formation in Marfan mice (Fbn1(C1039G/+)) is associated with decreased aortic wall elastogenesis and increased elastin breakdown. In this study, we test the feasibility of quantifying aortic wall elastin content using MRI with a gadolinium-based elastin-specific magnetic resonance contrast agent in Fbn1(C1039G/+) mice. METHODS AND RESULTS: Ascending aorta elastin content was measured in 32-week-old Fbn1(C1039G/+) mice and wild-type (n=9 and n=10, respectively) using 7-T MRI with a T1 mapping sequence. Significantly lower enhancement (ie, lower R1 values, where R1=1/T1) was detected post-elastin-specific magnetic resonance contrast agent in Fbn1(C1039G/+) compared with wild-type ascending aortas (1.15±0.07 versus 1.36±0.05; P<0.05). Post-elastin-specific magnetic resonance contrast agent R1 values correlated with ascending aortic wall gadolinium content directly measured by inductively coupled mass spectroscopy (P=0.006). CONCLUSIONS: Herein, we demonstrate that MRI with elastin-specific magnetic resonance contrast agent accurately measures elastin bound gadolinium within the aortic wall and detects a decrease in aortic wall elastin in Marfan mice compared with wild-type controls. This approach has translational potential for noninvasively assessing aneurysm tissue changes and risk, as well as monitoring elastin content in response to therapeutic interventions.

[Informed consent in cardiovascular surgery].

Informed consent is a core component of partnership between the surgeon and the patient. Cardiovascular surgery is a high risk area in medical and surgical fields. An appropriate informed consent is essential for safety management of cardiovascular surgery and good relationship between the surgeon and the patient and his/her family. Concrete explanation of surgical procedures including the risk and benefit is important to share the common understanding of disease and treatment. Before the surgical procedure, we need to explain at least the following 5 contents, (1) name and extent of the disease, (2) contents of surgical procedure, (3) risk of surgery, (4) other options of treatment, and (5) prognosis of the disease.