Haploinsufficiency of Hand1 improves mice survival after acute myocardial infarction through preventing cardiac rupture

Ginsenoside Rg5 attenuates hypoxia-induced cardiomyocyte apoptosis via regulating the Akt pathway

Ginsenoside Rg5 has been implicated in a variety of diseases. However, it is unknown whether Ginsenoside Rg5 can protect against hypoxia-induced neonatal rat cardiomyocytes (NRMs). The purpose of this study was to look into the effect of Ginsenoside Rg5 on hypoxia-induced NRMs apoptosis as well as the underlying molecular mechanism. In this study, following isolation and culture of ventricular myocardial cells from neonatal rats, the appropriate concentration of Rg5 was determined using the MTT assay, the effect of Rg5 on apoptosis was assessed employing TUNEL staining and flow cytometry assays. Levels of apoptosis-related proteins and phosphorylated level of Akt (ser 473 and ser 308) were analyzed using the western blot analysis. Finally, the experimental results shown that Ginsenoside Rg5 significantly inhibited hypoxia-induced NRMs apoptosis, decreased the expression pro-apoptotic protein Bax, increased the expression of anti-apoptotic protein Bcl-2 ratio and the level of cleaved caspase 3. Akt signaling activation was found to be the mechanism of Ginsenoside Rg5s protective effect on hypoxia-induced NRMs apoptosis, as an Akt inhibitor eliminated the anti-apoptotic effects of Ginsenoside Rg5. Various analyses were performed and verified, ginsenoside Rg5 suppressed hypoxia-induced apoptosis in NRMs via activation of the Akt signaling.

Validation of diagnostic criteria and histopathological characterization of cardiac rupture in the mouse model of nonreperfused myocardial infarction

In patients with myocardial infarction (MI), cardiac rupture is an uncommon but catastrophic complication. In the mouse model of nonreperfused MI, reported rupture rates are highly variable and depend not only on the genetic background and sex of animals but also on the method used for documentation of rupture. In most studies, diagnosis of cardiac rupture is based on visual inspection during autopsy; however, criteria are poorly defined. We performed systematic histopathological analysis of whole hearts from C57BL/6J mice dying after nonreperfused MI and evaluated the reliability of autopsy-based criteria in identification of rupture. Moreover, we compared the cell biological environment of the infarct between rupture-related and rupture-independent deaths. Histopathological analysis documented rupture in 50% of mice dying during the first week post-MI. Identification of a gross rupture site was highly specific but had low sensitivity; in contrast, hemothorax had high sensitivity but low specificity. Mice with rupture had lower myofibroblast infiltration, accentuated macrophage influx, and a trend toward reduced collagen content in the infarct. Male mice had increased mortality and higher incidence of rupture. However, infarct myeloid cells harvested from male and female mice at the peak of the incidence of rupture had comparable inflammatory gene expression. In conclusion, the reliability of autopsy in documentation of rupture in infarcted mice is dependent on the specific criteria used. Macrophage-driven inflammation and reduced activation of collagen-secreting reparative myofibroblasts may be involved in the pathogenesis of post-MI cardiac rupture.NEW & NOTEWORTHY We show that cardiac rupture accounts for 50% of deaths in C57BL/6J mice undergoing nonreperfused myocardial infarction protocols. Overestimation of rupture events in published studies likely reflects the low specificity of hemothorax as a criterion for documentation of rupture. In contrast, identification of a gross rupture site has high specificity and low sensitivity. We also show that mice dying of rupture have increased macrophage influx and attenuated myofibroblast infiltration in the infarct. These findings are consistent with a role for perturbations in the balance between inflammatory and reparative responses in the pathogenesis of postinfarction cardiac rupture. We also report that the male predilection for rupture in infarcted mice is not associated with increased inflammatory activation of myeloid cells.

Hand Factors in Cardiac Development

Congenital heart defects account for 1% of infant mortality and 10% of in utero deaths. As the vertebrate embryo develops, multiple tissue types develop in tandem to morphologically pattern the functional heart. Underlying cardiac development is a network of transcription factors known to tightly control these morphological events. Members of the Twist family of basic helix-loop-helix transcription factors, Hand1 and Hand2, are essential to this process. The expression patterns and functional role of Hand factors in neural crest cells, endocardium, myocardium, and epicardium is indicative of their importance during cardiogenesis; however, to date, an extensive understanding of the transcriptional targets of Hand proteins and their overall mechanism of action remain unclear. In this review, we summarize the recent findings that further outline the crucial functions of Hand factors during heart development and in post-natal heart function. Anat Rec, 302:101-107, 2019. © 2018 Wiley Periodicals, Inc.