A Modified Surgical Ventricular Reconstruction in Post-infarction Mice Persistently Alleviates Heart Failure and Improves Cardiac Regeneration

CircMap4k2 reactivated by aneurysm plication alleviates residual cardiac remodeling after SVR by enhancing cardiomyocyte proliferation in post-MI mice

INTRODUCTION

Surgical ventricular reconstruction (SVR) is an alternative therapeutic approach in patients with refractory heart failure (HF), but residual remodeling after SVR limits the improvement of HF. Recently, we reported that SVR may act as an environmental cue to reactivate endogenous proliferation of cardiomyocytes; however, it is unclear whether enhancing endogenous cardiomyocyte regeneration further improves HF after SVR.

OBJECTIVES

We aimed to explore whether circular RNAs (circRNAs) would involved in SVR and their mechanisms.

METHODS

Male C57BL/6 mice were subjected to myocardial infarction (MI) or sham surgery. Four weeks later, MI mice with a large ventricular aneurysm underwent SVR or a second open-chest operation only. Echocardiography and histological analysis were used to evaluate heart function, cardiac remodeling, and myocardial regeneration. Sequencing of circular RNAs, RNA immunoprecipitation, RNA pulldown, and luciferase reporter assay were used to explore the underlying mechanisms.

RESULTS

SVR markedly attenuated cardiac remodeling and induced cardiomyocyte regeneration, as evidenced by positive staining of Ki-67, phospho-histone H3 (pH3), and Aurora B in the plication zone, but significant residual remodeling still existed in comparison with the sham group. Sequencing results showed that SVR altered the expression profile of cardiac circRNAs, and circMap4k2 was identified as the most upregulated one. After characterizing circMap4k2, we noted that overexpression of circMap4k2 significantly promoted proliferation of cardiomyocytes in cultured neonatal rat cardiomyocytes and silencing of circMap4k2 significantly inhibited it; similar results were obtained in SVR-treated MI mice but not in MI mice without SVR treatment. Residual cardiac remodeling after SVR was further attenuated by circMap4k2 overexpression. CircMap4k2 bound with miR-106a-3p and inhibited cardiomyocyte proliferation by targeting a downstream effector of the antizyme inhibitor 1 (Azin1) gene.

CONCLUSIONS

CircMap4k2 acts as an environmental cue and targets the miR-106a-3p/Azin1 pathway to increase cardiac regeneration in the plication zone and attenuate residual remodeling after SVR.

Bioinformatics exploration of potential common therapeutic targets for systemic and pulmonary arterial hypertension-induced myocardial hypertrophy

Systemic and pulmonary arterial hypertension (PAH) can induce left and right ventricular hypertrophy, respectively, but common therapeutic targets for both left and right hypertrophy are limited. In this study, we attempt to explore potential common therapeutic targets and screen out potential target drugs for further study. Cardiac mRNA expression profiles in mice with transverse aortic constriction (TAC) and pulmonary arterial constriction (PAC) are obtained from online databases. After bioinformatics analyses, we generate TAC and PAC mouse models to validate the phenotypes of cardiac remodelling as well as the identified hub genes. Bioinformatics analyses show that there are 214 independent differentially expressed genes (DEGs) in GSE136308 (TAC related) and 2607 independent DEGs in GSE30922 (PAC related), while 547 shared DEGs are associated with the function of the extracellular matrix (ECM) or involved in the PI3K-Akt signaling pathway, cytokine-cytokine receptor interactions, and ECM-receptor interactions. We identifyd Fn1, Il6, Col1a1, Igf1, Col1a2, Timp1, Col3a1, Cd44, Ctgf and Postn as hub genes of the shared DEGs, and most of them are associated with myocardial fibrosis. Those hub genes and phenotypes of cardiac remodelling are validated in our TAC and PAC mouse models. Furthermore, we identify dehydroisoandrosterone (DHEA), iloprost and 4,5-dianilinophthalimide (DAPH) as potential therapeutic drugs targeting both left and right ventricular hypertrophy and validate the effect of DHEA. These findings suggest that DHEA could be an effective drug for pressure overload-induced left or right ventricular hypertrophy by regulating the shared hub differentially expressed genes associated with fibrosis.

Dapagliflozin attenuates residual cardiac remodeling after surgical ventricular reconstruction in mice with an enlarged heart after myocardial infarction

BACKGROUND

Severe heart failure refractory to conventional therapy requires alternative treatment modalities. Surgical ventricular reconstruction (SVR) has been used to reverse cardiac remodeling in post-myocardial infarction (MI) patients with large left ventricular (LV) aneurysm, however, residual LV remodeling and dysfunction remain postoperatively. It is unclear whether SVR recovers response to drug treatment and whether the sodium-glucose co-transporter 2 inhibitor dapagliflozin (DAPA) reverses residual LV remodeling after SVR.

METHODS

Adult male C57 mice were subjected to MI or sham surgery. Four-week later, MI mice with LV aneurysm underwent modified SVR or second open-chest sham operation and were randomized to DAPA or vehicle for four-week. Cardiac remodeling, LV function, and the underlying mechanisms were evaluated by echocardiography, invasive LV hemodynamic measurements, mRNA sequencing, and bioinformatics analysis.

RESULTS

SVR significantly decreased LV volume; increased myocardial strain, LV pressure change rates and end-systolic elastance; and decreased heart-to-body weight ratio and myocardial fibrosis. However, significant residual cardiac remodeling remained. DAPA significantly attenuated residual cardiac remodeling and improved LV function in SVR mice but did not have curative effects in non-SVR mice. Of the 1532 genes differentially expressed in SVR and MI mice, 1037 were associated with cardiac metabolism; Src, Crebbp, Fn1, Grb2, and Mapk14 were the top 5 hub genes. Unlike sham surgery, MI upregulated those 5 genes, and treatment with SVR + DAPA normalized their expression.

CONCLUSIONS

SVR restores therapeutic response in the post-MI heart with large LV aneurysm, and DAPA attenuates residual cardiac remodeling after SVR by normalizing some cardiac metabolism-related hub genes.

Revascularization of chronic total occlusion coronary artery and cardiac regeneration

Coronary chronic total occlusion (CTO) contributes to the progression of heart failure in patients with ischemic cardiomyopathy. Randomized controlled trials demonstrated that percutaneous coronary intervention (PCI) for CTO significantly improves angina symptoms and quality of life but fails to reduce clinical events compared with optimal medical therapy. Even so, intervening physicians strongly support CTO-PCI. Cardiac regeneration therapy after CTO-PCI should be a promising approach to improving the prognosis of ischemic cardiomyopathy. However, the relationship between CTO revascularization and cardiac regeneration has rarely been studied, and experimental studies on cardiac regeneration usually employ rodent models with permanent ligation of the coronary artery rather than reopening of the occlusive artery. Limited early-stage clinical trials demonstrated that cell therapy for cardiac regeneration in ischemic cardiomyopathy reduces scar size, reverses cardiac remodeling, and promotes angiogenesis. This review focuses on the status quo of CTO-PCI in ischemic cardiomyopathy and the clinical prospect of cardiac regeneration in this setting.