Role of miR-133a in regulating TGF-ß1 signaling pathway in myocardial fibrosis after acute myocardial infarction in rats.

OBJECTIVE: The aim of this research was to explore the effect of microRNA-133a (miR-133a) on myocardial fibrosis and cardiac function after myocardial infarction in rats, and to investigate the possible regulatory mechanism. MATERIALS AND METHODS: Myocardial infarction model was successfully established in rats by ligation of the left anterior descending coronary artery. After miR-133a overexpression in rats myocardium, cardiac function was examined by echocardiography. Meanwhile, the degree of myocardial fibrosis was detected by Masson staining. In addition, the expression of α-smooth muscle actin (α-SMA) in cardiomyocytes was detected by immunohistochemistry. Quantitative Real-time polymerase chain reaction (qRT-PCR) was performed to analyze the expression level of miR-133a in the junction of myocardial infarction. The mRNA expressions of transforming growth factor-ß1 (TGF-ß1), connective tissue growth factor (CTGF), collagen type 1 (col 1), collagen type 3 (col 3) and α-SMA were measured by qRT-PCR as well. Furthermore, the protein levels of the above genes were detected by Western blotting. RESULTS: MiR-133a expression in the infarct border zone of myocardial tissue was significantly decreased on the 28th day after myocardial infarction surgery (p<0.05). In addition, up-regulation of miRNA-133a in myocardial tissue of rats with myocardial infarction could remarkably improve cardiac function and reduce collagen volume fraction. Furthermore, the mRNA and protein expression levels of TGF-ß1, CTGF, col1, col3, α-SMA in myocardial tissue were obviously decreased after miRNA-133a up-regulation (p<0.001). CONCLUSIONS: Overexpression of miR-133a down-regulates the mRNA and protein levels of TGF-ß1 and CTGF after myocardial infarction. Moreover, this may eventually reduce myocardial collagen deposition, inhibit myocardial fibrosis and improve cardiac function.

Hypoxic preconditioning BMSCs-exosomes inhibit cardiomyocyte apoptosis after acute myocardial infarction by upregulating microRNA-24.

OBJECTIVE: To elucidate the regulatory effect of hypoxic preconditioning bone marrow mesenchymal stem cells (BMSCs)-exosomes on cardiomyocyte apoptosis in acute myocardial infarction (AMI) rats. MATERIALS AND METHODS: BMSCs-derived exosomes were extracted by Exoquick method. Expressions of exosome surface markers were determined by Western blot. The AMI model in rats was established by LAD ligation. Rats were randomly assigned into sham group, AMI group, AMI+H-exo group and AMI+N-exo group. MicroRNA-24 expression in rat myocardium was detected at different time points. Subsequently, hypoxic preconditioning or normoxic preconditioning BMSCs-exosomes were intramyocardially injected into rats. Infarct size was calculated through TTC (triphenyltetrazolium chloride) staining. Cardiomyocyte apoptosis was accessed with Terminal Deoxynucleotidyl Transferase dUTP Nick-end Labeling (TUNEL). Heart function of AMI rats was evaluated by echocardiography. Protein expressions of apoptotic genes in rat myocardium were detected by Western blot. RESULTS: The mRNA level of microRNA-24 was higher in H-exo group than N-exo group. Injection of hypoxic preconditioning BMSCs-exosomes markedly upregulated microRNA-24 level, reduced infarct size and improved cardiac function in AMI rats. Protein expressions of Bax, caspase-3 and cleaved-caspase-3 were downregulated by BMSCs-exosomes treatment. H9c2 cells showed upregulated microRNA-24 level and decreased apoptotic rate after incubation with hypoxic preconditioning BMSCs-exosomes. The above cellular performances were partially reversed by transfection of microRNA-24 inhibitor. CONCLUSIONS: Hypoxic preconditioning BMSCs-exosomes inhibit cardiomyocyte apoptosis in AMI rats by upregulating microRNA-24.

MicroRNA-298 regulates apoptosis of cardiomyocytes after myocardial infarction.

OBJECTIVE: To investigate the role and mechanism of micro ribonucleic acid (miR)-298 in myocardial apoptosis after myocardial infarction. MATERIALS AND METHODS: In vivo experiments, the rat model of myocardial infarction was established, and miR-298 was up-regulated via lentivirus with miR-298 overexpression. Cardiac function of rats was detected via echocardiography, Bcl-2 associated X protein (BAX) expressions in infarction border zone were detected via Real-time Quantitative PCR (qT-PCR) and Western blot, and TUNEL assay was used to detect the myocardial apoptosis. In vitro experiments, myocardial cells were isolated and cultured, an oxygen-glucose deprivation (OGD) model was established to mimicking the ischemic condition, the relationship between miR-298 and BAX was verified using luciferase reporter vector, lentivirus and small-interfering RNA (siRNA) in BAX. RESULTS: In vivo experiments showed that the miR-298 expression was down-regulated at 2 and 4 weeks after myocardial infarction. The up-regulation of miR-298 significantly improved the cardiac function, decreased the expressions of BAX, reduced the myocardial apoptosis and inhibit the apoptosis proteins expression including cytochrome-c and cleaved caspase-3. In vitro experiments revealed that BAX was a target gene of miR-298 and further proof that miR-298 could inhibit the cytochrome-c and cleaved caspase-3 expression and myocardial apoptosis through BAX. CONCLUSIONS: MiR-298 can improve the myocardial apoptosis through the target gene BAX.

Transthoracic closure of atrial septal defect and ventricular septal defect without cardiopulmonary bypass.

The minimally invasive surgical transthoracic occlusion of an atrial septal defect (ASD) or a ventricular septal defect (VSD) is an increasingly widespread alternative treatment for congenital heart disease. The aim of this study is to summarize our clinical experience with minimally invasive surgical transthoracic occlusion of ASD and VSD without cardiopulmonary bypass (CPB). Between April 2011 and October 2012, 27 patients with ASD and 95 patients with VSD (78 men and 44 women) were considered for minimally invasive surgical transthoracic occlusion without CPB. A small infrasternal incision (2.0-4.0 cm) was made under general anesthesia, under transesophageal echocardiography (TEE) guidance; the ASD and VSD were closed by using an appropriate occluder; and TEE was performed simultaneously to demonstrate the position of the device, any residual shunting, or encroachment on the atrioventricular valve, coronary sinus, or aortic valve. Successful transthoracic occlusion was performed in all 122 patients without complications. No complications such as third-degree atrioventricular block and residual shunting occurred after the procedures. The ventilation time was 2.2 ± 1.2 h, and the average length of hospital stay was 4.7 ± 1.7 days. All patients received aspirin at 3 mg·kg(-1)·day(-1) (maximum 100 mg/day) 24 h after the procedure. Minimally invasive surgical transthoracic occlusion without CPB is a new treatment that has many advantages such as causing little trauma, promoting quick recovery, having less complications, and avoiding radiation damage. However, the appropriate selection of patients is still key to improving the success rate of the operation.

Comparative study of the Triton X-100-sodium deoxycholate method and detergent-enzymatic digestion method for decellularization of porcine aortic valves.

BACKGROUND: Valve replacement is the primary surgical treatment for heart valve disease. However, the clinical benefit of biological valve substitutes is limited by their potential immunogenicity. AIM: To seek a better method of preparing biological scaffolds for tissue engineering heart valves, we compared the ability of different decellularization procedures to remove cells and maintain the scaffold structure. MATERIALS AND METHODS: Specimens of fresh porcine aortic valve leaflets were randomly divided into group I (n = 16), group II (n = 16) and group III (n = 16). The valve leaflets in group I were not decellularized; group II were treated with Triton X-100 and sodium deoxycholate; and group III were treated by a detergent-enzymatic digestion method. The valve leaflets were investigated by gross examination, hematoxylin-eosin staining, Masson's trichrome staining, and scanning electron microscopy to observe the valve structure and the integrity of collagen and elastin. The DNA content was measured to confirm the removal of cells. RESULTS: The detergent-enzymatic digestion method completely removed cells and led to valve fiber structural alterations in group III. The Triton X-100-sodium deoxycholate method achieved both complete decellularization and preservation of the valve fiber structure in group II. CONCLUSIONS: The detergent-enzymatic digestion method is a better technique for decellularization than the Triton X-100-sodium deoxycholate method, as it enables both complete decellularization and preservation of the valve scaffold structure.