Single-cell transcriptomic analysis reveals differential cell subpopulations and distinct phenotype transition in normal and dissected ascending aorta.

BACKGROUND: Acute thoracic aortic dissection (ATAD) is a fatal condition characterized by tear of intima, formation of false lumen and rupture of aorta. However, the subpopulations of normal and dissected aorta remain less studied. METHODS: Single-cell RNA sequencing was performed including 5 patients with ATAD and 4 healthy controls. Immunohistochemistry and immunofluorescence were used to verify the findings. RESULTS: We got 8 cell types from human ascending aorta and identified 50 subpopulations including vascular smooth muscle cells (VSMCs), endothelial cells, fibroblasts, neutrophils, monocytes and macrophages. Six transmembrane epithelial antigen of prostate 4 metalloreductase (STEAP4) was identified as a new marker of synthetic VSMCs. CytoTRACE identified subpopulations with higher differentiation potential in specified cell types including synthetic VSMCs, enolase 1+ fibroblasts and myeloid-derived neutrophils. Synthetic VSMCs-derived C-X-C motif chemokine ligand 12 (CXCL12) might interact with neutrophils and fibroblasts via C-X-C motif chemokine receptor 4 (CXCR4) and atypical chemokine receptor 3 (ACKR3), respectively, which might recruit neutrophils and induce transdifferentitation of fibroblasts into synthetic VSMCs. CONCLUSION: We characterized signatures of different cell types in normal and dissected human ascending aorta and identified a new marker for isolation of synthetic VSMCs. Moreover, we proposed a potential mechanism that synthetic VSMCs might interact with neutrophils and fibroblasts via CXCL12-CXCR4/ACKR3 axis whereby deteriorating the progression of ATAD, which might provide new insights to better understand the development and progression of ATAD.

CircLDLR Modulates the Proliferation and Apoptosis of Vascular Smooth Muscle Cells in Coronary Artery Disease Through miR-26-5p/KDM6A Axis.

ABSTRACT: The purpose of this study was to investigate the effect of circLDLR on the proliferation and apoptosis of vascular smooth muscle cells (VSMCs) in coronary artery disease and its regulatory mechanism. The expression of KDM6A was detected by qRT-PCR or Western blot. VSMCs were transfected with miR-26-5p mimic/inhibitor or OE KDM6A. Cell proliferation and apoptosis were assessed. Luciferase reporter gene assays were used to examine interactions between miR-26-5p and KDM6A in VSMCs. Downregulation of circLDLR was associated with increased miR-26-5p in coronary artery disease tissues. In addition, circLDLR could inhibit cell proliferation and promote cell apoptosis by regulating miR-26-5p. Moreover, the overexpression of KDM6A reduced VSMCs proliferation and increased apoptosis in an miR-26-5p/circLDLR axis-dependent manner. CircLDLR modulates the proliferation and apoptosis of VSMCs through miR-26-5p/KDM6A axis.

LncRNA Nuclear-Enriched Abundant Transcript 1 Regulates Atrial Fibrosis via the miR-320/NPAS2 Axis in Atrial Fibrillation.

Atrial fibrosis is a key contributor to atrial fibrillation (AF). Long non-coding ribonucleic acids (lncRNAs) were demonstrated to exhibit a key role in fibrotic remodeling; however, the function of nuclear-enriched abundant transcript 1 (NEAT1) in atrial fibrosis remains unclear. In the present study, we showed that NEAT1 was upregulated in atrial tissues of AF patients and was positively related to collagen I (coll I) and collagen III (coll III) expressions. Furthermore, the deletion of NEAT1 attenuated angiotensin II (Ang II)-caused atrial fibroblast proliferation, migration, and collagen production. We further observed that NEAT1 knockdown improved Ang II caused mouse atrial fibrosis in in vivo experiments. Moreover, we demonstrated that NEAT1 could negatively regulate miR-320 expression by acting as a competitive endogenous RNA (ceRNA). miR-320 directly targeted neuronal per arnt sim domain protein 2 (NPAS2) and suppressed its expression. We observed that NEAT1 exerted its function via the miR-320-NPAS2 axis in cardiac fibroblasts. These findings indicate that NEAT1 exerts a significant effect on atrial fibrosis and that this lncRNA is a new potential molecular target for AF treatment.

Modified Yacoub technique with aortic annuloplasty in patients with aortic root aneurysm / 中国胸心血管外科临床杂志

@#Objective    To evaluate the feasibility and safety of modified Yacoub technique with aortic annuloplasty in the patients with aortic root aneurysm and dilatation of aortic annular base. Methods    We performed a retrospective review of 6 patients with aortic root aneurysm undergoing modified Yacoub technique with aortic annuloplasty from November 2017 to January 2019. There were 5 males and 1 female, with a mean age of 54.1±12.3 years. The preoperative cardiac function of 3 patients was in New York Heart Association (NYHA) classⅡand the other 3 patients were in class Ⅲ. There were two patients with bicuspid aortic valve, and no Marfan syndrome. There was aortic regurgitation in the patients measured by the echocardiogram, 1 in mild aortic regurgitation, 1 in moderate aortic regurgitation, and 4 in severe aortic regurgitation. The diameter of aortic annular base was 27.8±1.9 mm, and the largest diameter of aortic root was 49.8±3.7 mm. Six patients underwent modified Yacoub technique with aortic annuloplasty, including 5 patients who underwent aortic cusp repair at the same time. Results    All 6 identified patients survived. There was no severe complication (bleeding, stroke, or acute renal failure). The cardiopulmonary bypass time was 204.6±13.5 min, aortic cross-clamping time 168.0±17.1 min, mechanical ventilation time 21.3±19.5 h, ICU stay time 67.8±62.2 h. The follow-up time ranged from 4 to 18 months with an average time of 12.8±4.7 months. Patients' cardiac function improved postoperatively with four patients in NYHA classⅠand two patients with classⅡ. Two patients had no aortic valve regurgitation, four patients had mild regurgitation. Left ventricular end diastolic volume decreased significantly (118.6±20.4 mL vs. 169.1±58.4 mL, P<0.05). Conclusion    The modified Yacoub technique with aortic annuloplasty is effective and safe for the patients with aortic root aneurysm and dilatation of aortic annular base, and the early- and mid-term outcomes are satisfactory.

Mesenchymal stem cells rejuvenate cardiac muscle through regulating macrophage polarization.

We have shown that the effects of transplantation of CD146+ mesenchymal stem cells (MSCs) on myocardial regeneration after myocardial infarction (MI) exceeds the effects of transplantation of MSCs, likely resulting from reduction of aging-associated cellular reactive oxygen species in injured cardiac muscle cells (CMCs). Since the role of macrophages in the MSC-mediated recovery of heart function after MI remains unclear, this question was thus addressed in the current study. We found that transplantation of MSCs did not alter the total number of the macrophages in the injured heart, but induced their polarization towards a M2-phenotype. Moreover, administration of tumor necrosis factor alpha (TNFα) into MSC-transplanted mice, which prevented M2-polarization of macrophages, abolished the effects of MSCs on recovery of heart function and on the reduction of infarcted cardiac tissue. Thus, our data suggest that MSCs may rejuvenate CMCs after ischemic injury at least partially through induction of M2-polarization of macrophages.

Role of alternative splicing of VEGF-A in the development of atherosclerosis.

Vascular endothelial cell growth factor A (VEGF-A) signaling promotes the endothelial cell proliferation, macrophage infiltration and foam cell formation, which play pivotal roles in the pathogenesis of atherosclerosis (AS). However, the role of alternative splicing of VEGF here is not known. Here, ApoE (-/-) mice supplied high-fat diet (HFD mice) were used to generate AS, while ApoE (-/-) mice supplied with normal diet (NOR mice) were used as a control. Aortic endothelial cells (AECs) and infiltrated macrophages were purified and quantified by flow cytometry. Alternative splicing of VEGF and the regulator of VEGF splicing, SRPK1, were assessed by RT-qPCR and immunoblotting in both AECs and aortic macrophages. We found that HFD mice developed AS in 12 weeks, while the NOR did not. Compared to NOR mice, HFD mice possessed significantly more AECs and AEC proliferation, and had significantly more aortic infiltrated macrophages and more apoptosis of them. Significant shift of VEGF-A splicing to pro-angiogenic VEGF165 was detected in both AECs and macrophages from HFD mice, seemingly through upregulation of SRPK1. In vitro, SRPK1 overexpression significantly increased EC proliferation and macrophage apoptosis. Thus, our data suggest that alternative splicing of VEGF-A to pro-angiogenic VEGF165 may contribute to the development of AS.

Study on Left Atrial Dimension and Function After Modified Endoscopic Procedure for Atrial Fibrillation at Two Years' Follow-Up.

BACKGROUND: Modified endoscopic procedures for atrial fibrillation (AF) have a greater success rate because of the increased number of linear lesions. Concerns have been raised about the impact of ablation scars on the left atrium. This study aimed to examine the impact of ablation on left atrial dimension and systolic function after modified endoscopic procedures with echocardiographic measurement. METHODS: Of 107 patients undergoing modified endoscopic ablation, 58 had paroxysmal AF and 49 had persistent or long-standing AF. The procedure was performed on the beating heart through three ports on the left chest wall. Three circular and two linear lesions were made on the left atrium. The left atrial appendage was excised by stapler. Echocardiography was performed preoperatively and at the 2-year follow-up. RESULTS: Most patients (86.9%) patients were in sinus rhythm (SR) postoperatively. Fourteen patients (5 with paroxysmal AF and 9 with persistent/long-standing AF) failed to maintain SR. Echocardiographic data indicated that the left atrial diameter decreased only in the patients with postoperative SR but continued to increase in patients with fail SR maintenance. Left atrial function was also improved after the procedure, especially in patients with preoperative nonparoxysmal AF or with postoperative SR maintenance. Furthermore, left atrial function in patients who failed to restore SR was not worsened even with left atrial appendage excision. CONCLUSIONS: Modified endoscopic procedure for AF improved post-procedural left atrial function of patients with SR maintenance. The left atrial function of patients with failed SR maintenance was also not worsened after left atrial appendage excision.