Post-myocardial Infarction Remodeling Research Articles

Endogenous complement 1q binding protein (C1qbp) regulates mitochondrial permeability transition and post-myocardial infarction remodeling and dysfunction

The mitochondrial permeability transition (MPT) pore regulates necrotic cell death following diverse cardiac insults. While the componentry of the pore itself remains controversial, Cyclophilin D (CypD) has been well-established as a positive regulator of pore opening. We have previously identified Complement 1q-binding protein (C1qbp) as a novel CypD-interacting molecule and a negative regulator of MPT-dependent cell death in vitro. However, its effects on the MPT pore and sensitivity to cell death in the heart remain untested. We therefore hypothesized that C1qbp would inhibit MPT in cardiac mitochondria and protect cardiac myocytes against cell death in vivo. To investigate the effects of C1qbp in the myocardium we generated gain- and loss-of-function mice. Transgenic C1qbp overexpression resulted in decreased complex protein expression and reduced mitochondrial respiration and ATP production but MPT was unaffected. In contrast, while C1qbp+/− mice did not exhibit any changes in mitochondrial protein expression, respiration, or ATP, the MPT pore was markedly sensitized to Ca2+ in these animals. Neither overexpression nor depletion of C1qbp significantly affected baseline heart morphology or function at 3 months of age. When subjected to myocardial infarction, C1qbp transgenic mice exhibited similar infarct sizes and cardiac remodeling to non-transgenic mice, consistent with the lack of an effect on MPT. In contrast, cardiac scar formation and dysfunction were significantly increased in the C1qbp+/− mice compared to C1qbp+/+ controls. Our results suggest that C1qbp is required for normal regulation of the MPT pore and mitochondrial function, and influences cardiac remodeling following MI, the latter more likely being independent of C1qbp effects on the MPT pore.

KIAA1199/CEMIP knockdown attenuates cardiac remodeling post myocardial infarction by activating TSP4 pathway in mice

BackgroundExcessive activation of cardiac fibroblasts (CFs) significantly contributes to adverse cardiac remodeling post-myocardial infarction (MI). CEMIP, initially recognized as an enzyme involved in hyaluronic acid (HA) degradation, has also been implicated in the activation of pulmonary fibroblasts. Nevertheless, the role and mechanism of CEMIP in adverse cardiac remodeling following MI remain largely unexplored. Materials and methodsRNA sequencing (RNA-seq) was performed on cardiac tissue harvested from the infarct/peri-infarct region of mice 28 days post-MI. RNA-seq was conducted on primary cardiac fibroblasts (CFs) transfected with adenovirus overexpressing CEMIP. Adeno-associated virus serotype 9 (AAV9) was engineered for in vivo CEMIP knockdown to elucidate its impact on cardiac remodeling. Immunoprecipitation coupled with mass spectrometry (IP-MS) and co-immunoprecipitation (co-IP) were employed to elucidate the mechanism by which CEMIP affected cardiac remodeling. Key findingsRNA-seq of fibrotic heart tissue at day 28 post-MI revealed a significant upregulation of CEMIP. In vitro, CEMIP facilitated the activation of cardiac fibroblasts. In vivo, knockdown of CEMIP markedly reduced cardiac fibrosis and improved cardiac function post-MI. IP-MS and co-immunoprecipitation (co-IP) confirmed that CEMIP interacted with TSP4 through the G8 domain. Further experiments confirmed that CEMIP promoted TSP4 degradation in lysosomes in an ACTN4-dependent manner, thereby activating the FAK signaling pathway. SignificanceOur findings suggest that CEMIP significantly contributes to cardiac remodeling post-MI, which might be a novel approach for treating cardiac fibrosis following MI.

Pericardial Delivery of Sodium Alginate-Infusible Extracellular Matrix Composite Hydrogel Promotes Angiogenesis and Intercellular Electrical Conduction after Myocardial Infarction.

Injectable extracellular matrix (iECM) is a versatile biological material with beneficial properties such as good degradability, promotion of cell survival, immunomodulation, and facilitation of vascular formation. However, intravenous injection of iECM faces challenges like a short retention time in vivo and low concentration at the lesion site. To address these issues, we prepared a composite hydrogel composed of sodium alginate and iECM and administered it via intrapericardial injection, forming a structure akin to cardiac patches within the pericardium. Compared with intramyocardial injection, intrapericardial injection avoids direct myocardial injury and ectopic tumor formation, offering less invasiveness and better biocompatibility. This study demonstrates that the sodium alginate/infusible extracellular matrix (SA/iECM) composite hydrogel can effectively prolong the local retention time of iECM in the heart, enhance electrical conduction between cardiomyocytes, promote angiogenesis at ischemic myocardial sites, inhibit apoptosis in the infarcted region, mitigate left ventricular remodeling postmyocardial infarction (MI), and improve cardiac function after infarction. Precise coordination of cardiomyocyte contraction and relaxation depends on the rhythmic occurrence of calcium-dependent action potentials. Cardiac dysfunction is partially attributed to the disruption of the excitation-contraction coupling (ECC) mechanism, which is associated with prolonged intracellular Ca2+ transients and alterations in contraction and relaxation Ca2+ levels. Our results show that the SA/iECM composite hydrogel improves electrical conduction, as evidenced by increased Cx43 expression and enhanced intercellular electrical connectivity. This research establishes that intrapericardial injection of a SA/iECM composite hydrogel is a safe and effective treatment modality, providing a theoretical basis for the use of biomaterials in MI therapy.

Cardiomyocyte βII spectrin plays a critical role in maintaining cardiac function by regulating mitochondrial respiratory function.

βII spectrin is a cytoskeletal protein known to be tightly linked to heart development and cardiovascular electrophysiology. However, the roles of βII spectrin in cardiac contractile function and pathological post-myocardial infarction remodeling remain unclear. Here, we investigated whether and how βII spectrin, the most common isoform of non-erythrocytic spectrin in cardiomyocytes, is involved in cardiac contractile function and ischemia/reperfusion (I/R) injury. We observed that the levels of serum βII spectrin breakdown products (βII SBDPs) were significantly increased in patients with acute myocardial infarction (AMI). Concordantly, βII spectrin was degraded into βII SBDPs by calpain in mouse hearts after I/R injury. Using tamoxifen-inducible cardiac-specific βII spectrin knockout mice, we found that deletion of βII spectrin in the adult heart resulted in spontaneous development of cardiac contractile dysfunction, cardiac hypertrophy and fibrosis at 5 weeks after tamoxifen treatment. Moreover, at 1 week after tamoxifen treatment, although spontaneous cardiac dysfunction in cardiac-specific βII spectrin knockout mice had not developed, deletion of βII spectrin in the heart exacerbated I/R-induced cardiomyocyte death and heart failure. Furthermore, restoration of βII spectrin expression via adenoviral small activating RNA (saRNA) delivery into the heart reduced I/R injury. Immunoprecipitation coupled with mass spectrometry (IP-LC-MS/MS) analyses and functional studies revealed that βII spectrin is indispensable for mitochondrial complex I activity and respiratory function. Mechanistically, βII spectrin promotes translocation of NADH:ubiquinone oxidoreductase 75 kDa Fe-S protein 1 (NDUFS1) from the cytosol to mitochondria by crosslinking with actin filaments (F-actin) to maintain F-actin stability. βII spectrin is an essential cytoskeletal element for preserving mitochondrial homeostasis and cardiac function. Defects in βII spectrin exacerbate cardiac I/R injury.

Functional traits of the heart in post-infarction myocardial remodeling

The in vitro assessment of the functional peculiarities of heart failure (HF) linked to post-infarction remodeling of the myocardium in order to identify compensatory and decompensatory pathogenetic mechanisms. Material and methods. Myocardial infarction was reproduced in white laboratory rats by twice administration of isoproterenol (IMI). The functional state of the left ventricle (LV) of isolated heart was estimated at the end of the IMI model (initial) and after 4 weeks (the period of myocardial remodeling installing) in regard to following targets: study of myocardial inotropism to ET-1 action, including its effect on volume and resistance efforts, of myocardial tolerance to ischemia and reperfusion, as well as of coronary reactivity to various stimulations (eg, acetylcholine, bradykinin, adenosine, epoxyeicosatrienes). Results. Post-infarction remodeling of the myocardium was imposed by the reversal of ET-1 induced negative inotropic effect of the isolated heart to a positive response, manifested by increase in LV systolic pressure and cardiac output up to 10%. This improvement was associated with an increase of -dP/dTmax and +dP/dTmax values, indices of the isovolumic relaxation and contraction of the heart, by up to 9.3%, which led to a better hetero- and homeometric regulation of the heart, in particularly notable being the optimization of cardiac adaptation to resistance effort, including the condition of ET-1 premedication. The endothelium dependent coronary phenomenon Gregg was markedly improved such as the coronary functional reserve increased by up to 43% under the action of acetylcholine, adenosine and bradykinin. Remarkably, the post-infarction remodeling of the myocardium ensured a diminution of the B1-receptor mediated bradykinin induced coronary dilatation while the B2-receptors mediated bradykinin effect increased. Likewise, the increase of myocardium tolerance to ischemia (30 min) and reperfusion (45 min) was another disentangled benefit inherent to post-infarction remodeling, which was exhibited by significant lowered value of LV end-diastolic pressure. Conclusions. 1. The functional link of HF to post-infarction remodeling of the myocardium is outlined by the improvement of myocardial inotropism which led to appearance of the positive response to ET-1 manifested by the increase of LV systolic pressure and cardiac output. 2. Inotropic improvement was associated with an increase of isovolumic relaxation and contraction velocity, which contributed to the increased capacity of the homeometric regulation of the LV and of the heart adaptation to resistance effort as well. 3. An important pathophysiological hallmark of post-infarction HF is the increase of bradykinin induced coronary dilation mediated by B1 receptors, but its reduction in association with the increase of the coronary dilation mediated by B2 receptors is a prediction of a positive post-infarction remodeling of the myocardium and of HF evolution as well.

LIPCAR levels in plasma-derived extracellular vesicles is associated with left ventricle remodeling post-myocardial infarction

LIPCAR levels in plasma-derived extracellular vesicles is associated with left ventricle remodeling post-myocardial infarction

Cardiac Magnetic Resonance Evaluationof LV Remodeling Post-Myocardial Infarction: Prognosis, Monitoring and Trial Endpoints.

Adverse left ventricular remodeling (ALVR) and subsequent heart failure after myocardial infarction (MI) remain a major cause of patient morbidity and mortality worldwide. Overt inflammation has been identified as the common pathway underlying myocardial fibrosis and development of ALVR post-MI. With its ability to simultaneously provide information about cardiac structure, function, perfusion, and tissue characteristics, cardiac magnetic resonance (CMR) is well poised to inform prognosis and guide early surveillance and therapeutics in high-risk cohorts. Further, established and evolving CMR-derived biomarkers may serve as clinical endpoints in prospective trials evaluating the efficacy of novel anti-inflammatory and antifibrotic therapies. This review provides an overview of post-MI ALVR and illustrates how CMR may help clinical adoption of novel therapies via mechanistic or prognostic imaging markers.

АПОПТОЗ КАРДИОМИОЦИТОВ КАК ФАКТОР РАЗВИТИЯ ИШЕМИЧЕСКОЙ БОЛЕЗНИ СЕРДЦА

Introduction. Coronary heart disease is a common pathology, playing a key role in cardiovascular mortality. Damage of circulatory system affects people of all ages, including the active population, which provides an adverse impact on the socio-economic state of society. In this research, we analyzed the processes of cardiomyocyte apoptosis and their effects on myocardial ischemic damage. Aim was to identify the role of cardiomyocyte apoptosis in the development of coronary heart disease. Materials and Methods. A meta-analysis of 50 literary sources was performed in the PubMed database over the past 11 years. Results and Discussion. Meta-analysis has demonstrated that prevention of cardiomyocyte apoptosis is an extremely important therapeutic goal today. Ischemia/reperfusion, exercise- induced hypertrophy, and post-infarct myocardial remodeling are associated with myocyte apoptosis. This indicates that current treatments proven effective in these diseases may interfere with apoptosis. Conclusions. Studying apoptosis and its regulation is important for both understanding the pathogenesis of cardiovascular diseases and developing new therapeutic approaches. Apoptosis, i. e., controlled cell death, is of great importance in cardiac pathology. For instance, it plays a key role in ischemia/reperfusion, myocardial hypertrophy, and post-infarct remodeling. Key words: ischemic heart disease, apoptosis, cardiomyocytes.

Effects of Electronic Cigarette Vaping on Cardiac and Vascular Function, and Post-myocardial Infarction Remodeling in Rats

The effect of electronic cigarette (E-cig) vaping on cardiac and vascular function during the healing phase of myocardial infarction (MI), and post-MI remodeling was investigated. Sprague Dawley rats were subjected to left coronary artery ligation to induce MI. One week later, rats were randomized to receive either 12 weeks of exposure to purified air (n = 37) or E-cig vapor (15 mg/ml of nicotine) (n = 32). At 12 weeks, cardiac and vascular function, and post-MI remodeling were assessed. Baseline blood flow in the femoral artery did not differ between groups, but peak reperfusion blood flow was blunted in the E-cig group (1.59 ± 0.15 ml/min) vs. the air group (2.11 ± 0.18 ml/min; p = 0.034). Femoral artery diameter after reperfusion was narrower in the E-cig group (0.54 ± 0.02 mm) compared to the air group (0.60 ± 0.02 mm; p = 0.023). Postmortem left ventricular (LV) volumes were similar in the E-cig (0.69 ± 0.04 ml) and air groups (0.73 ± 0.04 ml; p = NS); and myocardial infarct expansion index did not differ between groups (1.4 ± 0.1 in E-cig group versus 1.3 ± 0.1 in air group; p = NS). LV fractional shortening by echo did not differ between groups at 12 weeks (E-cig at 29 ± 2% and air at 27 ± 1%; p = NS). Exposure to E-cig during the healing phase of MI was associated with altered vascular function with reduced femoral artery blood flow and diameter at reperfusion, but not with worsened LV dilation or worsened cardiac function.

Administration of N-acetylcysteine Attenuates Post-Myocardial Infarction Remodeling

Administration of N-acetylcysteine Attenuates Post-Myocardial Infarction Remodeling

Patterns of left ventricular remodeling post-myocardial infarction, determinants, and outcome.

Left ventricular remodeling (LVR) after myocardial infarction (MI) can lead to heart failure, arrhythmia, and death. We aim to describe adverse LVR patterns at 6 months post-MI and their relationships with subsequent outcomes and to determine baseline. A multicenter cohort of 410 patients (median age 57 years, 87% male) with reperfused MI and at least 3 akinetic LV segments on admission was analyzed. All patients had transthoracic echocardiography performed 4 days and 6 months post-MI, and 214 also had cardiac magnetic resonance imaging performed on day 4. To predict LVR, machine learning methods were employed in order to handle many variables, some of which may have complex interactions. Six months post-MI, echocardiographic increases in LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), and LV ejection fraction (LVEF) were 14.1% [interquartile range 0.0, 32.0], 5.0% [- 14.0, 25.8], and 8.7% [0.0, 19.4], respectively. At 6 months, ≥ 15% or 20% increases in LVEDV were observed in 49% and 42% of patients, respectively, and 37% had an LVEF < 50%. The rate of death or new-onset HF at the end of 5-year follow-up was 8.8%. Baseline variables associated with adverse LVR were determined best by random forest analysis and included stroke volume, stroke work, necrosis size, LVEDV, LVEF, and LV afterload, the latter assessed by Ea or Ea/Ees. In contrast, baseline clinical and biological characteristics were poorly predictive of LVR. After adjustment for predictive baseline variables, LV dilation > 20% and 6-month LVEF < 50% were significantly associated with the risk of death and/or heart failure: hazard ratio (HR) 2.12 (95% confidence interval (CI) 1.05-4.43; p = 0.04) and HR 2.68 (95% CI 1.20-6.00; p = 0.016) respectively. Despite early reperfusion and cardioprotective therapy, adverse LVR remains frequent after acute MI and is associated with a risk of death and HF. A machine learning approach identified and prioritized early variables that are associated with adverse LVR and which were mainly hemodynamic, combining LV volumes, estimates of systolic function, and afterload.

In-Hospital Levels of Circulating MicroRNAs as Potential Predictors of Left Ventricular Remodeling Post-Myocardial Infarction.

Background and Objectives: Biochemical and molecular regulation of both adaptive and pathological responses of heart tissue to ischemic injury is widely investigated. However, it is still not fully understood. Several biomarkers are tested as predictors of left ventricle (LV) remodeling after myocardial infarction (MI). The aim of this study was to assess the relationship between selected microRNAs (miRNAs) and LV function and morphology in patients after MI. Materials and Methods: Selected miRNAs related to heart failure were assessed in the acute phase of MI: miR-150-3p, miR-21-5p, miR-19b-3p, miR-155-5p, miR-22-5p. Echocardiography with 3D imaging was performed at baseline and after 6 months. Remodeling was defined as >20% increase in LV end-diastolic volume, whereas reverse remodeling was defined as >10% reduction in LV end-systolic volume. Results: Eighty patients entered the registry. Remodeling occurred in 26% and reverse remodeling was reported in 51% of patients. In the presented study, none of the analyzed miRNAs were found to be a significant LV remodeling predictor. The observed correlations between miRNAs and other circulating biomarkers of myocardial remodeling were relatively weak. Conclusions: Our analysis does not demonstrate an association between the analyzed miRNAs and LV remodeling in patients with MI.

LIPCAR levels in plasma-derived extracellular vesicles is associated with left ventricle remodeling post-myocardial infarction

BackgroundLong Intergenic noncoding RNA predicting CARdiac remodeling (LIPCAR) is a long noncoding RNA identified in plasma of patients after myocardial infarction (MI) to be associated with left ventricle remodeling (LVR). LIPCAR was also shown to be a predictor of early death in heart failure (HF) patients. However, no information regarding the expression of LIPCAR and its function in heart as well as the mechanisms involved in its transport to the circulation is known. The aims of this study are (1) to characterize the transporter of LIPCAR from heart to circulation; (2) to determine whether LIPCAR levels in plasma isolated-extracellular vesicles (EVs) reflect the alteration of its expression in total plasma and could be used as biomarkers of LVR post-MI.MethodsSince expression of LIPCAR is restricted to human species and the limitation of availability of cardiac biopsy samples, serum-free conditioned culture media from HeLa cells were first used to characterize the extracellular transporter of LIPCAR before validation in EVs isolated from human cardiac biopsies (non-failing and ischemic HF patients) and plasma samples (patients who develop or not LVR post-MI). Differential centrifugation at 20,000g and 100,000g were performed to isolate the large (lEVs) and small EVs (sEVs), respectively. Western blot and nanoparticle tracking (NTA) analysis were used to characterize the isolated EVs. qRT-PCR analysis was used to quantify LIPCAR in all samples.ResultsWe showed that LIPCAR is present in both lEVs and sEVs isolated from all samples. The levels of LIPCAR are higher in lEVs compared to sEVs isolated from HeLa conditioned culture media and cardiac biopsies. No difference of LIPCAR expression was observed in tissue or EVs isolated from cardiac biopsies obtained from ischemic HF patients compared to non-failing patients. Interestingly, LIPCAR levels were increased in lEVs and sEVs isolated from MI patients who develop LVR compared to patients who did not develop LVR.ConclusionOur data showed that large EVs are the main extracellular vesicle transporter of LIPCAR from heart into the circulation independently of the status, non-failing or HF, in patients. The levels of LIPCAR in EVs isolated from plasma could be used as biomarkers of LVR in post-MI patients.

Plac8 regulates the fibrogenic ability of cardiac fibroblasts in mice with myocardial infarction

Cardiac fibroblasts (CFs) are of vital importance for post-myocardial infarction (MI) remodeling. This study explored the role of Placenta specific 8 (Plac8) in MI on the basis of single-cell RNA-Seq (scRNA-Seq) data (GSE136088) and micro-array data (GSE153485). Through bioinformatics analysis, Plac8 was finally identified as a key gene related to fibroblasts. In addition, primary CFs of the neonatal mice were isolated, cultured and treated with hypoxia for in vitro cell model construction. Hydroxyproline assay demonstrated enhanced collagen production in hypoxic CFs, and qRT-PCR revealed increased relative contents of type I and type III collagen (Col1a1 and Col3a1). Western blot showed increased protein expression level of α-smooth muscle actin (α-SMA), and transwell assay and wound-healing assay collectively suggested enhanced cell migration. Moreover, Plac8 was found to be upregulated in hypoxic CFs. Then, after transfection with siNC or siPlac8, it was revealed that down-regulating Plac8 protein expression in hypoxic CFs reduced the levels of collagen secretion, the number of activated CFs and the degree of cell migration, indicating the regulation of Plac8 on hypoxic CFs’ transformation into myofibroblasts, cell migration and collagen deposition. Excessive myocardial fibrosis can cause adverse cardiac remodeling, leading to malignant arrhythmia and even heart failure.

Integrin alpha 11 is cardioprotective post myocardial infarction, regulating infarct formation and collagen organization

Abstract Background Post Myocardial Infarction (MI), fibrosis and in particular collagen production is an important response in order to replace apoptotic cells within the injured area and stabilize the heart wall1. Cardiac fibroblasts in and around the infarct region under mechanical and biochemical stress transform into myofibroblasts, secreting collagen to help stabilize the infarct segment2. In the short term this is an appropriate response to avoid rupture and death3. However, Long term collagen deposition will increase ventricular stiffness reducing compliance leading to further cardiac dysfunction and heart failure4. Mechanical activation of collagen production and fibrosis is understood to be a significant mediator of cardiac fibrosis, yet the mechanisms controlling mechanical activation of fibrosis are not well understood5,6. Purpose Here, we sort to investigate the role of Integrin α11 in cardiac remodelling post MI, a collagen binding integrin which preferentially binds to type I collagen and, is significantly upregulated post MI4,7. Methods Fibroblast Conditional α11 knockout (KO) and Wildtype Littermates (WT) underwent either SHAM or left anterior descending aorta (LAD) ligation surgery. Cardiac function was assessed with echocardiography and pressure volume loops. Ventricle samples were processed for FFPE histological/immunohistochemical analysis with hematoxylin/eosin, Collagen I &amp; III antibodies. Finally, Second Harmonic generation microscopy was undertaken to identify collagen organisation with previously validated CurveAlign and CT-Fire algorithms. Results α11KO and WT mice demonstrated similar cardiac function. There was evidence of basal structural differences as Collagen I (P&amp;lt;0.05) and III (P&amp;lt;0.0001) deposition was reduced along with cardiac myocyte size (P&amp;lt;0.0001) in α11KO mice. In response to LAD ligation α11KO mice had significantly worse mortality (∼57% v’s ∼22%, P&amp;lt;0.05) which, correlated with an increased MI size (WT=∼39%, α11KO=∼64% P&amp;lt;0.05). Cardiac function 2 days following ligation measured by echo demonstrated that Fractional Area Change (FAC) (23%±2 v’s 16%±2 P&amp;lt;0.05) and Cardiac Output (8.5ml±1 v’s 5ml±0.7, P&amp;lt;0.05) were significantly worse in α11 KO compared to WT mice. The reduced function persisted 4 weeks post ligation as FAC was significantly worse in α11KO mice (∼9%±2%, P&amp;lt;0.0001) compared to WT (∼19%±1%). Moreover, α11KO mice that survived MI had significantly more collagen I (P&amp;lt;0.0001) content in the remote, peri-infarct and infarct zone’s than that of WT along with a lack of hypertrophic response. Finally, Collagen alignment measured using SHG images with CurveAlign demonstrated collagen fibres had significantly less structural alignment in α11KO mice (P&amp;lt;0.05). Conclusion We demonstrate a cardioprotective role for Integrin α11 post myocardial infarction. Where, the lack of α11 leads to worsened mortality, larger MI, worsened cardiac function and impaired collagen organisation in the infarct post MI.

Cardioprotective potential of exosomes derived from blood outgrowth endothelial cells in ischemic cardiomyopathy

Abstract Introduction Blood outgrowth endothelial cell (BOEC)-derived exosomes can effectively induce vascular network formation in vitro and mediate therapeutic neovascularization in a skin wound healing model. We hypothesized that BOEC-derived exosomes can enhance myocardial repair in mice after ischemia-reperfusion (I/R) injury. Methods BOECs were isolated and culture-expanded from peripheral blood of patients with severe ischemic cardiomyopathy (ICMP) in normoxic and hypoxic (1% O2) conditions. Exosomes were isolated from the medium by differential ultracentrifugation, and their size, number, and surface markers were determined by nano tracking analysis (NTA) and immunoblot analysis. Myocardial infarction (MI) was induced via transient LAD ligation for 60 min followed by reperfusion. BOEC-derived exosomes and were resuspended in small fractions (120x10^8 particles per 10 µl) 2.5 µl 4 aliquots were injected under direct vision into the epicardial wall of the peri-infarct region. One month later, left ventricular (LV) structure and function were analyzed using a 7T Bruckner MRI with commercial software Segment in mice that received exosome injections or placebo injections (n=10 and n=8, respectively). Results Quantification of exosomes by NTA showed higher concentrations in the medium of BOECs cultured in hypoxia. Immunoblot analysis confirmed robust expression of exosome markers TSG101 and Flotilin-1. One month after intramyocardial exosome injections, heart rate, LV volumes or LV ejection fraction were similar between mice receiving myocardial exosomes injections (n=10) in the border zone as compared to those receiving placebo (n=8). However, in vivo exosome transfer mediated favorable structural remodeling after MI with lower LV mass indices (p=0.01) and better preserved regional wall thickness in all 4 segments receiving exosomes aliquots (p&amp;lt;0.05) (Figure). Conclusions Our results suggest that BOEC-derived exosomes have favorable post-infarction myocardial structural remodeling. Exosomes may constitute an attractive cell-free therapeutic modality.Figure

Enhancing autophagic flux via FYCO1 confers protection against adverse cardiac remodeling in response to myocardial ischemia

Abstract Background Dysregulation of autophagy is known to have detrimental effects on cardiac function. Yet, the autophagy-lysosome pathway in the context of ischemia is still widely unexplored. Fyco1 is highly expressed in the heart and facilitates transport of autophagosomes in cardiomyocytes, thereby enhancing global autophagic flux. Purpose The purpose of our study was to study the potentially beneficial effects of activation of autophagy via FYCO1 on cardiac remodeling post myocardial infarction. Methods FYCO1-Tg mice were crossbred with RFP-EGFP-LC3-Tg reporter mice (FYCO1-TGxRGFP) to enable analysis of autophagic flux in vivo using confocal microscopy. Myocardial ischemia was induced by permanent ligation of left anterior descending artery (LAD). Mice were analyzed 3 and 30 days post LAD ligation. Cardiac function (ejection fraction, EF) was measured by echocardiography. Fibrosis and Infarct size (%) were assessed in Masson’s Trichrome staining. Autophagy activity was analysed by Western blot for p62 and LC3 II. Furthermore, Evans blue/TTC staining was performed to assess the area at risk and to define perfused, ischemic and necrotic area post LAD ligation. Results Under conditions of FYCO1 overexpression isolated cardiomyocytes were capable to remain a status of activated autophagy in hypoxia; presented with significantly increased protein levels of p62 (ctrl: 1±0,02; OE: 3,1±0,4) and LC3 II (ctrl: 1±0,05; OE: 5,5±0,4). In FYCO1-TGxRGFP mice we observed an overall increased autophagic flux demonstrated by significantly increased p62 expression (WT LAD: 2,9±0,4; TG LAD:4,0±0,5) and LC3 II protein levels (WT LAD: 1,6±0,2; TG LAD:14,0±1,4) post LAD ligation. While WT mice revealed accumulation of autolysosomes 30 days post LAD ligation as assessed by confocal microscopy (WT autophagosomes: 1±0,4; WT autolysosomes: 38,6±3,8), in FYCO1-TGxRGFP mice the ratio between autophagosomes and autolysosomes remained even (TG autophagosomes:43,3±5,1; TG autolysosomes: 73,5±12,4), suggesting preservation of adequate autophagic flux. In Evans blue/TTC staining, FYCO1-TGxRGFP mice demonstrated comparable ischemic but a markedly decreased necrotic area (ischemic: 1,9±1,8%; necrotic: 37,1±11,5%) of the LV as compared to WT (ischemic: 2,1±1,9%; necrotic: 53,4±31,4%). Fibrosis (WT: 19,6±1,8%; TG: 10,6±1,6%) and infarct size (WT: 34,5 ±3,9%; TG: 5,5±2%) was found significantly decreased in FYCO1-TGxRGFP-mice. Importantly, global heart function of FYCO1-TGxRGFP-mice was significantly improved post LAD compared to WT (EF WT: 36,7±6,3%; TG: 46,3±18,3%). Conclusion Our study demonstrates that activation of autophagy via FYCO1 protects against accumulation of autolysosomes and therefore protects against adverse cardiac remodeling and improves cardiac function post myocardial ischemia. These findings may offer translational potential in enhancing autophagic flux in the context of myocardial ischemia.

A transient wave of Bhlhe41+ resident macrophages enables remodeling of the developing infarcted myocardium

The immune system plays a critical role during myocardial injury, contributing to repair and remodeling post myocardial infarction (MI). The myocardial infarct and border zone exhibit high heterogeneity, in turn leading to reconstructing macrophage subsets and specific functions. Here we use a combination of single-cell RNA sequencing, spatial transcriptomes, and reporter mice to characterize temporal-spatial dynamics of cardiac macrophage subtype in response to MI. We identify that transient appearance of monocyte-derived Bhlhe41+ Mφs in the "developing" infarct zone peaked at day 7, while other monocyte-derived macrophages are identified in "old" infarct zone. Functional characterization by co-culture of Bhlhe41+ Mφs with cardiomyocytes and fibroblasts or depletion of Bhlhe41+ Mφs unveils a crucial contribution of Bhlhe41+ Mφs in suppression of myofibroblast activation. This work highlights the importance of Bhlhe41+ Mφ phenotype and plasticity in preventing excessive fibrosis and limiting the expansion of developing infarct area.

NKRF in Cardiac Fibroblasts Protects against Cardiac Remodeling Post-Myocardial Infarction via Human Antigen R.

Myocardial infarction (MI) remains the leading cause of death worldwide. Cardiac fibroblasts (CFs) are abundant in the heart and are responsible for cardiac repair post-MI. NF-κB-repressing factor (NKRF) plays a significant role in the transcriptional inhibition of various specific genes. However, the NKRF action mechanism in CFs remains unclear in cardiac repair post-MI. This study investigates the NKRF mechanism in cardiac remodeling and dysfunction post-MI by establishing a CF-specific NKRF-knockout (NKRF-CKO) mouse model. NKRF expression is downregulated in CFs in response to pathological cardiac remodeling in vivo and TNF-α in vitro. NKRF-CKO mice demonstrate worse cardiac function and survival and increased infarct size, heart weight, and MMP2 and MMP9 expression post-MI compared with littermates. NKRF inhibits CF migration and invasion in vitro by downregulating MMP2 and MMP9 expression. Mechanistically, NKRF inhibits human antigen R (HuR) transcription by binding to the classical negative regulatory element within the HuR promoter via an NF-κB-dependent mechanism. This decreases HuR-targeted Mmp2 and Mmp9 mRNA stability. This study suggests that NKRF is a therapeutic target for pathological cardiac remodeling.

Cardiac patches made of brown adipose-derived stem cell sheets and conductive electrospun nanofibers restore infarcted heart for ischemic myocardial infarction.

Cell sheet engineering has been proven to be a promising strategy for cardiac remodeling post-myocardial infarction. However, insufficient mechanical strength and low cell retention lead to limited therapeutic efficiency. The thickness and area of artificial cardiac patches also affect their therapeutic efficiency. Cardiac patches prepared by combining cell sheets with electrospun nanofibers, which can be transplanted and sutured to the surface of the infarcted heart, promise to solve this problem. Here, we fabricated a novel cardiac patch by stacking brown adipose-derived stem cells (BADSCs) sheet layer by layer, and then they were combined with multi-walled carbon nanotubes (CNTs)-containing electrospun polycaprolactone/silk fibroin nanofibers (CPSN). The results demonstrated that BADSCs tended to generate myocardium-like structures seeded on CPSN. Compared with BADSCs suspension-containing electrospun nanofibers, the transplantation of the CPSN-BADSCs sheets (CNBS) cardiac patches exhibited accelerated angiogenesis and decreased inflammation in a rat myocardial infarction model. In addition, the CNBS cardiac patches could regulate macrophage polarization and promote gap junction remodeling, thus restoring cardiac functions. Overall, the hybrid cardiac patches made of electrospun nanofibers and cell sheets provide a novel solution to cardiac remodeling after ischemic myocardial infarction.