Cardiac fibrosis following myocardial infarction (MI) drives adverse ventricular remodeling and heart failure, with cardiac fibroblasts (CFs) playing a central role. GSTM1 is an important member of the glutathione S-transferase (GSTs) family, which plays an important role in maintaining cell homeostasis and detoxification. This study investigated the role and mechanism of GSTM1 in post-MI fibrosis. Multi-omics approaches (proteomics/scRNA-seq) identified GSTM1 as a dysregulated target in post-MI fibroblasts. Using a murine coronary ligation model, we assessed GSTM1 dynamics via molecular profiling, such as Western blotting, immunofluorescence, and real-time quantitative polymerase chain reaction. AAV9-mediated cardiac-specific GSTM1 overexpression was achieved through systemic delivery. In vitro studies employed transforming growth factor-β (TGF-β)-stimulated primary fibroblasts with siRNA/plasmid interventions. Mechanistic insights were derived from transcriptomics and lipid peroxidation assays. The expression of GSTM1 in mouse CFs after MI was significantly down-regulated at both transcriptional and protein levels. In human dilated cardiomyopathy (DCM) patients with severe heart failure, GSTM1 expression was decreased alongside aggravated fibrosis. Overexpression of GSTM1 in post-MI mice improved cardiac function, while significantly reducing infarct size and fibrosis compared with the control group. In vitro models demonstrated that GSTM1 markedly attenuated collagen secretion and activation of fibroblasts, as well as suppressed their proliferation and migration. Further studies revealed that GSTM1 overexpression significantly inhibited the generation of intracellular and mitochondrial reactive oxygen species (ROS) under pathological conditions, suggesting that GSTM1 exerts an antioxidative stress effect in post-infarction fibroblasts. Further investigation of molecular mechanisms indicated that GSTM1 may suppress the initiation and progression of fibrosis by modulating lipid metabolism and ferroptosis-related pathways. Overexpression of GSTM1 significantly reduced lipid peroxidation and free ferrous iron levels in fibroblasts and mitochondria, markedly decreased ferroptosis-related indicators, and alleviated oxidative lipid levels [such as 12-hydroxyeicosapentaenoic acid (HEPE) and 9-, 10-dihydroxy octadecenoic acid (DHOME)] under fibrotic conditions. GSTM1 enhanced the phosphorylation of STAT3, thereby upregulating the downstream expression of glutathione peroxidase 4 (GPX4), reducing ROS production, and mitigating fibroblast activation and phenotypic transformation by inhibiting lipid peroxidation. This study identifies GSTM1 as a key inhibitor of fibroblast activation and cardiac fibrosis, highlighting its ability to target ferroptosis through redox regulation. AAV-mediated GSTM1 therapy demonstrates significant therapeutic potential for improving outcomes post-MI.

Atherosclerosis is featured as chronic low-grade inflammation in the arteries, which leads to the formation of plaques rich in lipids. M2 macrophage-derived extracellular vesicles (M2EV) have significant potential for anti-atherosclerotic therapy. However, their therapeutic effectiveness has been hindered by their limited targeting capability in vivo. The objective of this study was to create the P-M2EV (platelet membrane-modified M2EV) using the membrane fusion technique in order to imitate the interaction between platelets and macrophages. P-M2EV exhibited excellent physicochemical properties, and microRNA (miRNA)-sequencing revealed that the extrusion process had no detrimental effects on miRNAs carried by the nanocarriers. Remarkably, miR-99a-5p was identified as the miRNA with the highest expression level, which targeted the mRNA of Homeobox A1 (HOXA1) and effectively suppressed the formation of foam cells in vitro. In an atherosclerotic low-density lipoprotein receptor-deficient (Ldlr−/−) mouse model, the intravenous injection of P-M2EV showed enhanced targeting and greater infiltration into atherosclerotic plaques compared to regular extracellular vesicles. Crucially, P-M2EV successfully suppressed the progression of atherosclerosis without causing systemic toxicity. The findings demonstrated a biomimetic platelet-mimic system that holds great promise for the treatment of atherosclerosis in clinical settings.

The extracellular matrix (ECM) is a complex and dynamic three-dimensional network that functions as an architectural scaffold to maintain cardiac homeostasis. Important biochemical and mechanical signals associated with cell‒cell communication are provided via the reciprocal interaction between cells and the ECM. By converting mechanical cues into biochemical signals, the ECM regulates many cell processes, including migration, adhesion, growth, differentiation, proliferation, and apoptosis. Moreover, the ECM facilitates the replacement of dead cells and preserves the structural integrity of the heart, making it essential in conditions such as myocardial infarction and other pathological states. When excessive ECM deposition or abnormal production of ECM components occurs, the heart undergoes fibrosis, leading to cardiac dysfunction and heart failure. However, emerging evidence suggests that the ECM may contribute to heart regeneration following cardiac injury. The present review offers a complete overview of the existing information and novel discoveries regarding the involvement of the ECM in heart regeneration from both mechanical and biochemical perspectives. Understanding the ECM and its involvement in mechanotransduction holds significant potential for advancing therapeutic approaches in heart repair and regeneration.

Calcific aortic valve disease is a prevalent cardiovascular disease with no available drugs capable of effectively preventing its progression. Hence, an efficient drug delivery system could serve as a valuable tool in drug screening and potentially enhance therapeutic efficacy. However, due to the rapid blood flow rate associated with aortic valve stenosis and the lack of specific markers, achieving targeted drug delivery for calcific aortic valve disease has proved to be challenging. Here we find that protease-activated-receptor 2 (PAR2) expression is up-regulated on the plasma membrane of osteogenically differentiated valvular interstitial cells. Accordingly, we develop a magnetic nanocarrier functionalized with PAR2-targeting hexapeptide for dual-active targeting drug delivery. We show that the nanocarriers effectively deliver XCT790—an anti-calcification drug—to the calcified aortic valve under extra magnetic field navigation. We demonstrate that the nano-cargoes consequently inhibit the osteogenic differentiation of valvular interstitial cells, and alleviate aortic valve calcification and stenosis in a high-fat diet-fed low-density lipoprotein receptor-deficient ( Ldlr −/− ) mouse model. This work combining PAR2- and magnetic-targeting presents an effective targeted drug delivery system for treating calcific aortic valve disease in a murine model, promising future clinical translation.

The extracellular matrix (ECM) is a complex and dynamic three-dimensional network that functions as the architectural scaffold to maintain cardiac homeostasis. Important biochemical and mechanical signals for cell-cell communication are provided via the reciprocal interaction between cells and the ECM. By converting mechanical cues into biochemical signals, the ECM regulates diverse cell processes, including migration, adhesion, growth, differentiation, proliferation, and apoptosis. Moreover, the ECM facilitates the replacement of dead cells and preserves the structural integrity of heart, making it essential in conditions such as myocardial infarction and other pathological states. When there is excessive deposition of ECM or abnormal production of ECM components, the heart undergoes fibrosis, leading to cardiac dysfunction and heart failure. However, emerging evidence suggests that the ECM may contribute to heart regeneration following cardiac injury. The present investigation offers a complete overview of the existing information and novel discoveries regarding the ECM’s involvement in heart regeneration from both mechanical and biochemical views. Gaining a better comprehension of the ECM and its involvement in mechanotransduction holds significant potential for advancing therapeutic approaches in heart repair and regeneration.

Ventricular arrhythmogenesis is a key cause of sudden cardiac death following myocardial infarction (MI). Accumulating data show that ischemia, sympathetic activation, and inflammation contribute to arrhythmogenesis. However, the role and mechanisms of abnormal mechanical stress in ventricular arrhythmia following MI remain undefined. We aimed to examine the impact of increased mechanical stress and identify the role of the key sensor Piezo1 in ventricular arrhythmogenesis in MI. Concomitant with increased ventricular pressure, Piezo1, as a newly recognized mechano-sensitive cation channel, was the most up-regulated mechanosensor in the myocardium of patients with advanced heart failure. Piezo1 was mainly located at the intercalated discs and T-tubules of cardiomyocytes, which are responsible for intracellular calcium homeostasis and intercellular communication. Cardiomyocyte-conditional Piezo1 knockout mice (Piezo1Cko) exhibited preserved cardiac function after MI. Piezo1Cko mice also displayed a dramatically decreased mortality in response to the programmed electrical stimulation after MI with a markedly reduced incidence of ventricular tachycardia. In contrast, activation of Piezo1 in mouse myocardium increased the electrical instability as indicated by prolonged QT interval and sagging ST segment. Mechanistically, Piezo1 impaired intracellular calcium cycling dynamics by mediating the intracellular Ca2+ overload and increasing the activation of Ca2+-modulated signaling, CaMKII, and calpain, which led to the enhancement of phosphorylation of RyR2 and further increment of Ca2+ leaking, finally provoking cardiac arrhythmias. Furthermore, in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), Piezo1 activation remarkably triggered cellular arrhythmogenic remodeling by significantly shortening the duration of the action potential, inducing early afterdepolarization, and enhancing triggered activity.This study uncovered a proarrhythmic role of Piezo1 during cardiac remodeling, which is achieved by regulating Ca2+ handling, implying a promising therapeutic target in sudden cardiac death and heart failure.

Background: Angiogenesis is a promising strategy for those with peripheral artery disease. Macrophage-centered inflammation is intended to govern the deficiency of the angiogenic response after hindlimb ischemia. However, little is known about the mechanism of macrophage activation beyond signals from cytokines and chemokines. We sought to identify a novel mechanical signal from the ischemic microenvironment that provokes macrophages and the subsequent inflammatory cascade and to investigate the potential role of Piezo-type mechanosensitive ion channels (Piezo) on macrophages during this process. Methods: Myeloid cell-specific Piezo1 (Piezo-type mechanosensitive ion channel component 1) knockout ( Piezo1 ΔMΦ ) mice were generated by crossing Piezo1 fl/fl ( LysM-Cre −/− ; Piezo1 flox/flox ) mice with LysM-Cre transgenic mice to assess the roles of Piezo1 in macrophages after hindlimb ischemia. Furthermore, in vitro studies were carried out in bone marrow–derived macrophages to decipher the underlying mechanism. Results: We found that tissue stiffness gradually increased after hindlimb ischemia, as indicated by Young’s modulus. Compared to Piezo2, Piezo1 expression and activation were markedly upregulated in macrophages from ischemic tissues in concurrence with increased tissue stiffness. Piezo1 ΔMΦ mice exhibited improved perfusion recovery by enhancing angiogenesis. Matrigel tube formation assays revealed that Piezo1 deletion promoted angiogenesis by enhancing FGF2 (fibroblast growth factor-2) paracrine signaling in macrophages. Conversely, activation of Piezo1 by increased stiffness or the agonist Yoda1 led to reduced FGF2 production in bone marrow–derived macrophages, which could be blocked by Piezo1 silencing. Mechanistically, Piezo1 mediated extracellular Ca 2+ influx and activated Ca 2+ -dependent CaMKII (calcium/calmodulin-dependent protein kinase II)/ETS1 (ETS proto-oncogene 1) signaling, leading to transcriptional inactivation of FGF2. Conclusions: This study uncovers a crucial role of microenvironmental stiffness in exacerbating the macrophage-dependent deficient angiogenic response. Deletion of macrophage Piezo1 promotes perfusion recovery after hindlimb ischemia through CaMKII/ETS1-mediated transcriptional activation of FGF2. This provides a promising therapeutic strategy to enhance angiogenesis in ischemic diseases.

Heart failure is typically caused by different cardiovascular conditions and has a poor prognosis. Despite the advances in treatment in recent decades, heart failure has remained a major cause of morbidity and mortality worldwide. As revealed by in vivo and in vitro experiments, inflammation plays a crucial role in adverse cardiac remodeling, ultimately leading to heart failure. Macrophages are central to the innate immune system, and they are the most indispensable cell type for all cardiac injuries and remodeling stages. The immediate microenvironment regulates their polarization and secretion. In this review, we summarize the phenotypic heterogeneity and governing roles of macrophages in the infarcted, inflamed, and aging heart and assess their significance as potential therapeutic targets in heart failure. We also highlight the current missing links and major challenges in the field that remain to be addressed before macrophages can be exploited for therapeutic applications.

Background. The poor survival rates of transplanted mesenchymal stem cells (MSCs) in harsh microenvironments impair the efficacy of MSCs transplantation in myocardial infarction (MI). Extrinsic apoptosis pathways play an important role in the apoptosis of transplanted MSCs, and Fas apoptosis inhibitory molecule (FAIM) is involved in regulation of the extrinsic apoptosis pathway. Thus, we aimed to explore whether FAIM augmentation protects MSCs against stress-induced apoptosis and thereby improves the therapeutic efficacy of MSCs. Methods. We ligated the left anterior descending coronary artery (LAD) in the mouse heart to generate an MI model and then injected FAIM-overexpressing MSCs (MSCsFAIM) into the peri-infarction area in vivo. Moreover, FAIM-overexpressing MSCs were challenged with oxygen, serum, and glucose deprivation (OGD) in vitro, which mimicked the harsh microenvironment that occurs in cardiac infarction. Results. FAIM was markedly downregulated under OGD conditions, and FAIM overexpression protected MSCs against OGD-induced apoptosis. MSCsFAIM transplantation improved cell retention, strengthened angiogenesis, and ameliorated heart function. The antiapoptotic effect of FAIM was mediated by cellular-FLICE inhibitory protein (c-FLIP), and FAIM augmentation improved the protein expression of c-FLIP by reducing ubiquitin–proteasome-dependent c-FLIP degradation. Furthermore, FAIM inhibited the activation of JNK, and treatment with the JNK inhibitor SP600125 abrogated the reduction in c-FLIP protein expression caused by FAIM silencing. Conclusions. Overall, these results indicated that FAIM curbed the JNK-mediated, ubiquitination–proteasome-dependent degradation of c-FLIP, thereby improving the survival of transplanted MSCs and enhancing their efficacy in MI. This study may provide a novel approach to strengthen the therapeutic effect of MSC-based therapy.

Patients with heart failure (HF) are prone to combine with renal insufficiency. Recently, LCZ696 has been used in the treatment of HF, but whether LCZ696 is better than angiotensin converting enzyme inhibitors/angiotensin receptor antagonists (ACEI/ARB) in renal protection for HF patients has not been investigated. Therefore, we conducted a meta-analysis focusing on LCZ696 and its role in preservation of renal function in HF patients. Embase, PubMed, the Cochrane Library and ClinicalTrials.gov databases were electronically searched for available randomized controlled trials (RCTs). HF patients taking LCZ696 or ACEI/ARB were assessed for renal adverse events. The last search date was Sep 20, 2019. A total of 14959 patients from 6 trials were included in this meta-analysis. As compared to ACEI/ARB, LCZ696 significantly reduced the risk of renal function deterioration (odds ratio 0.77, 95% confidence interval 0.61-0.97, P = 0.02). In summary, LCZ696 may have superior renal protection in HF patients compared with ACEI/ARB.