Cell Death and Exosomes Regulation After Myocardial Infarction and Ischemia-Reperfusion

Cardiovascular disease (CVD) is the leading cause of death in the global population, accounting for about one-third of all deaths each year. Notably, with CVDs, myocardial damages result from myocardial infarction (MI) or cardiac arrhythmias caused by interrupted blood flow. Significantly, in the process of MI or myocardial ischemic-reperfusion (I/R) injury, both regulated and non-regulated cell death methods are involved. The critical factor for patients’ prognosis is the infarct area’s size, which determines the myocardial cells’ survival. Cell therapy for MI has been a research hotspot in recent years; however, exosomes secreted by cells have attracted much attention following shortcomings concerning immunogens. Exosomes are extracellular vesicles containing several biologically active substances such as lipids, nucleic acids, and proteins. New evidence suggests that exosomes play a crucial role in regulating cell death after MI as exosomes of various stem cells can participate in the cell damage process after MI. Hence, in the review herein, we focused on introducing various cell-derived exosomes to reduce cell death after MI by regulating the cell death pathway to understand myocardial repair mechanisms better and provide a reference for clinical treatment

TMSB4 Overexpression Enhances the Potency of Marrow Mesenchymal Stromal Cells for Myocardial Repair

ObjectiveThe actin-sequestering proteins, thymosin beta-4 (Tβ4) and hypoxia-inducible factor (HIF)-1α, are known to be associated with angiogenesis after myocardial infarction (MI). Herein, we aimed to identify the mechanism of HIF-1α induction by Tβ4 and investigate the effects of bone marrow mesenchymal stromal cells (BMMSCs) transfected with the Tβ4 gene (TMSB4) in a rat model of MI.MethodsRat BMMSCs were isolated, cultured, and transfected with the TMSB4 gene by using the lentivirus-mediated method. Rats with surgically induced MI were randomly divided into three groups (n = 9/group); after 1 week, the rats were injected at the heart infarcted border zone with TMSB4-overexpressed BMMSCs (BMMSC-TMSB4OE), wild-type BMMSCs that expressed normal levels of TMSB4 (BMMSC-TMSB4WT), or medium (MI). The fourth group of animals (n = 9) underwent all surgical procedures necessary for MI induction except for the ligation step (Sham). Four weeks after the injection, heart function was measured using transthoracic echocardiography. Infarct size was calculated by TTC staining, and collagen volume was measured by Masson staining. Angiogenesis in the infarcted heart area was evaluated by CD31 immunofluorescence histochemistry. In vitro experiments were carried out to observe the effect of exogenous Tβ4 on HIF-1α and explore the various possible mechanism(s).ResultsIn vivo experiments showed that vascular density 4 weeks after treatment was about twofold higher in BMMSC-TMSB4OE-treated animals than in BMMSC-TMSB4WT-treated animals (p < 0.05). The cardiac function and infarct size significantly improved in both cell-treatment groups compared to controls. Notably, the cardiac function and infarct size were most prominent in BMMSC-TMSB4OE-treated animals (both p < 0.05). HIF-1α and phosphorylated HIF-1α (p-HIF-1α) in vitro were significantly enhanced by exogenous Tβ4, which was nonetheless blocked by the factor-inhibiting HIF (FIH) promoter (YC-1). The expression of prolyl hydroxylase domain proteins (PHD) was decreased upon treatment with Tβ4 and further decreased with the combined treatment of Tβ4 and FG-4497 (a specific PHD inhibitor).ConclusionTMSB4-transfected BMMSCs might significantly improve recovery from myocardial ischemia and promote the generation of HIF-1α and p-HIF-1α via the AKT pathway, and inhibit the degradation of HIF-1α via the PHD and FIH pathways

Application of Modified Sliding Anastomosis in the Repair of Aortic Coarctation

Objectives. To evaluate the early and midterm results of a modified sliding anastomosis technique in patients with aortic coarctation. Materials and Methods. In this study, we reported a new repair method and compared the early and midterm outcome(s) with a conventional surgical approach for the management of patients with aortic coarctation. Forty-eight aortic coarctation patients with a narrowed segment length longer than 2 cm were operated at our department’s pediatric surgical division. Excision of the coarctation and end-to-end anastomosis was carried out in twenty-five patients (control group). In contrast, a modified sliding technique was used for twenty-three cases in the observation group. Other accompanying cardiac anomalies simultaneously repaired included ventricular septal defect and patent ductus arteriosus. All patients received 1.5-10 years of postoperative echocardiographic follow-up. Results. This is a retrospective study carried out between January 2005 and June 2018. The study population consisted of forty-eight patients, which included twenty-six male and twenty-two female patients, with an average age of 5.2±1.9 months (range, 28 days to 1 year). There was no mortality. The operative time, the number of intercostal artery disconnection, the drainage volume, and arm-leg systolic pressure gradient postoperation were less in the observation group as compared to the control group (p20 mmHg). After reintervention, the anastomotic pressure gradient reduced to 14 mmHg, 15 mmHg, and 17 mmHg, respectively. Conclusions. For long segment aortic coarctation patients (longer than 2 cm), the use of the modified sliding anastomotic technique effectively helps to retain more autologous tissues, enlarge the diameter of the anastomosis, and decrease anastomotic tension and vascular injury. Therefore, this technique provides a new idea for the surgical treatment of aortic coarctations