Background: This study aimed to investigate whether miR‐146a‐5p was involved in the pathogenesis of thoracic aortic dissection (AD) via regulating the biological function of vascular smooth muscle cells (VSMCs).Methods: Circulating miR‐146a‐5p level was measured by quantitative polymerase chain reaction (qPCR) in AD patients and healthy controls. Human dissected aortic samples were obtained from patients with thoracic AD Stanford type A undergoing surgical repair, and normal control samples were from organ donors who died from nonvascular diseases. The expression level of miR‐146a‐5p was detected using qPCR in each sample. The expression of SMAD4, which is involved in the TGF‐β pathway and indicated as the target gene of miR‐146a‐5p, was measured by qPCR and Western blot analysis at the mRNA level and protein level, respectively. Subsequently, VSMCs were transfected with miR‐146a‐5p mimics or inhibitors in vitro. VSMC proliferation and migration were detected using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide and Transwell assay, respectively. Flow cytometry was used to identify apoptosis. The expression of SMAD4 in VSMCs was determined using qPCR and Western blot analysis.Results: Plasma level of miR‐146a‐5p is significantly higher in the AD group as compared with the control group. The expression of miR‐146a‐5p was significantly upregulated in dissected aorta compared with controls (P < 0.05). The overexpression of miR‐146a‐5p significantly induced VSMC proliferation and migration in vitro.Conclusions: The expression of SMAD4 was modulated by miR‐146a‐5p. miR‐146a‐5p induced VSMC proliferation and migration through targeting SMAD4 and hence might be potentially involved in the development of AD.

Background: To evaluate the safety and efficacy of femoral artery cannulation as an alternative to axillary artery cannulation, we retrospectively compared outcomes between patients with axillary or femoral artery cannulation during open aortic arch repair for type A aortic dissection (TAAD). Methods: Between January 2014 and January 2019, 646 patients underwent open aortic arch repair with circulatory arrest for TAAD using antegrade selective cerebral perfusion (SACP) and were divided into two groups according to the site of arterial cannulation: an axillary artery group (axillary group, n=558) or a femoral artery group (femoral group, n=88). The axillary artery was considered as the primary cannulation site, and the femoral artery was used as an alternative when axillary artery cannulation was deemed unsuitable or had failed. Propensity score matching was performed to correct baseline differences. Results: After propensity score matching, the patients’ characteristics were comparable between groups (n=85 in each). The incidence of in-hospital mortality (10.6% vs. 14.1%; P=0.642) and stroke (3.5% vs. 5.9%; P=0.720) were comparable between the axillary and femoral groups. The incidence of newly required dialysis was lower in the femoral group, but the difference was not statistically significant (34.1% vs. 20.0%; P=0.050). Other outcomes and major adverse events were comparable. Conclusions: Femoral artery cannulation produced similar perioperative outcomes to axillary cannulation after open arch repair for TAAD. The femoral artery can be used as a safe and effective alternative to the axillary artery for arterial cannulation in TAAD patients undergoing open arch repair.