Model Of MI Research Articles

Design, Synthesis, and Preclinical Evaluation of a High-Affinity 18F-Labeled Radioligand for Myocardial Growth Hormone Secretagogue Receptor Before and After Myocardial Infarction.

The peptide hormone ghrelin is produced in cardiomyocytes and acts through the myocardial growth hormone secretagogue receptor (GHSR) to promote cardiomyocyte survival. Administration of ghrelin may have therapeutic effects on post-myocardial infarction (MI) outcomes. Therefore, there is a need to develop molecular imaging probes that can track the dynamics of GHSR in health and disease to better predict the effectiveness of ghrelin-based therapeutics. We designed a high-affinity GHSR ligand labeled with 18F for imaging by PET and characterized its invivo properties in a canine model of MI. Methods: We rationally designed and radiolabeled with 18F a quinazolinone derivative ([18F]LCE470) with subnanomolar binding affinity to GHSR. We determined the sensitivity and invivo and ex vivo specificity of [18F]LCE470 in a canine model of surgically induced MI using PET/MRI, which allowed for anatomic localization of tracer uptake and simultaneous determination of global cardiac function. Uptake of [18F]LCE470 was determined by time-activity curve and SUV analysis in 3 regions of the left ventricle-area of infarct, territory served by the left circumflex coronary artery, and remote myocardium-over a period of 1.5 y. Changes in cardiac perfusion were tracked by [13N]NH3 PET. Results: The receptor binding affinity of LCE470 was measured at 0.33 nM, the highest known receptor binding affinity for a radiolabeled GHSR ligand. In vivo blocking studies in healthy hounds and ex vivo blocking studies in myocardial tissue showed the specificity of [18F]LCE470, and sensitivity was demonstrated by a positive correlation between tracer uptake and GHSR abundance. Post-MI changes in [18F]LCE470 uptake occurred independently of perfusion tracer distributions and changes in global cardiac function. We found that the regional distribution of [18F]LCE470 within the left ventricle diverged significantly within 1 d after MI and remained that way throughout the 1.5-y duration of the study. Conclusion: [18F]LCE470 is a high-affinity PET tracer that can detect changes in the regional distribution of myocardial GHSR after MI. In vivo PET molecular imaging of the global dynamics of GHSR may lead to improved GHSR-based therapeutics in the treatment of post-MI remodeling.

Salvia miltiorrhiza suppresses cardiomyocyte ferroptosis after myocardial infarction by activating Nrf2 signaling

Ethnopharmacological relevanceFerroptosis, a recently identified non-apoptotic form of cell death reliant on iron, is distinguished by an escalation in lipid reactive oxygen species (ROS) that are iron-dependent. This phenomenon has a strong correlation with irregularities in iron metabolism and lipid peroxidation. Salvia miltiorrhiza Bunge (DS), a medicinal herb frequently utilized in China, is highly esteemed for its therapeutic effectiveness in enhancing blood circulation and ameliorating blood stasis, particularly during the treatment of cardiovascular diseases (CVDs). Numerous pharmacological studies have identified that DS manifests antioxidative stress effects as well as inhibits lipid peroxidation. However, ambiguity persists regarding the potential of DS to impede ferroptosis in cardiomyocytes and subsequently improve myocardial damage post-myocardial infarction (MI). Aim of the studyThe present work focused on investigating whether DS could be used to prevent the ferroptosis of cardiomyocytes and improve post-MI myocardial damage. Materials and methodsIn vivo experiments: Through ligation of the left anterior descending coronary artery, we constructed both a wild-type (WT) and NF-E2 p45-related factor 2 knockout (Nrf2−/−) mouse model of MI. Effects of DS and ferrostatin-1 (Fer-1) on post-MI cardiomyocyte ferroptosis were examined through detecting ferroptosis and myocardial damage-related indicators as well as Nrf2 signaling-associated protein levels. In vitro experiments: Erastin was used for stimulating H9C2 cardiomyocytes to construct an in vitro ferroptosis cardiomyocyte model. Effects of DS and Fer-1 on cardiomyocyte ferroptosis were determined based on ferroptosis-related indicators and Nrf2 signaling-associated protein levels. Additionally, inhibitor and activator of Nrf2 were used for confirming the impact of Nrf2 signaling on DS's effect on cardiomyocyte ferroptosis. ResultsIn vivo: In comparison to the model group, DS suppressed ferroptosis in cardiomyocytes post-MI and ameliorated myocardial damage by inducing Nrf2 signaling-related proteins (Nrf2, xCT, GPX4), diminishing tissue ferrous iron and malondialdehyde (MDA) content. Additionally, it enhanced glutathione (GSH) levels and total superoxide dismutase (SOD) activity, effects that are aligned with those of Fer-1. Moreover, the effect of DS on alleviating cardiomyocyte ferroptosis after MI could be partly inhibited through Nrf2 knockdown. In vitro: Compared with the erastin group, DS inhibited cardiomyocyte ferroptosis by promoting the expression of Nrf2 signaling-related proteins, reducing ferrous iron, ROS, and MDA levels, but increasing GSH content and SOD activity, consistent with the effect of Fer-1. Additionally, Nrf2 inhibition increased erastin-mediated ferroptosis of cardiomyocytes through decreasing Nrf2 signaling-related protein expressions. Co-treatment with DS and Nrf2 activator failed to further enhance the anti-ferroptosis effect of DS. ConclusionMI is accompanied by cardiomyocyte ferroptosis, whose underlying mechanism is probably associated with Nrf2 signaling inhibition. DS possibly suppresses ferroptosis of cardiomyocytes and improves myocardial damage after MI through activating Nrf2 signaling.

Stimulus specificity in combined action observation and motor imagery of typing.

Combined action observation and motor imagery (AO + MI) can improve movement execution (ME) in healthy adults and certain patient populations. However, it is unclear how the specificity of the observation component during AO + MI influences ME. As generalised observation could result in more flexible AO + MI rehabilitation programmes, this study investigated whether observing typing of target words (specific condition) or non-matching words (general condition) during AO + MI would have different effects on keyboard typing in healthy young adults. In Experiment 1, 51 students imagined typing a target word while watching typing videos that were either specific to the target word or general. There were no differences in typing execution between AO + MI conditions, though participants typed more slowly after both AO + MI conditions compared with no observation or imagery. Experiment 2 repeated Experiment 1 in 20 students, but with a faster stimulus speed in the AO + MI conditions and increased cognitive difficulty in the control condition. The results showed that the slowed typing after AO + MI was likely due to a strong influence of task-switching between imagery and execution, as well as an automatic imitation effect. Both experiments demonstrate that general and specific AO + MI comparably affect ME. In addition, slower ME following both AO + MI and a challenging cognitive task provides support for the motor-cognitive model of MI.

Abstract 15024: Immunomodulatory Effects of Human Embryonic Stem Cell-Derived Epicardial Cells in Myocardial Infarct Healing

Background: Acute myocardial infarction (AMI) causes excessive myocardium damage, including epicardium. Cell therapy by implantation of human pluripotent stem cell (hPSC)-derived cardiovascular cells has been tested in the infarcted hearts of preclinical models and clinical studies. However, whether hPSC-derived epicardial cells (hEPs) can be a therapeutic approach for infarcted hearts remains unclear. AMI induces inflammatory cascades, leading to multifaceted processes of myocardial injury and healing, whereas it is unknown whether hEPs regulate immune responses, especially macrophage plasticity at the acute phase of MI. Aims: to determine whether hEP implantation promotes myocardial infarct healing and modulates inflammatory response. Results: intramyocardial injection of hEPs at the acute phase of MI ameliorated functional worsening (p<0.001 vs. MI control) and scar formation of adult male NOD-SCID mouse hearts (p<0.05 vs. MI control) at day 28 post-MI, concomitantly with enhanced cardiomyocyte survival, angiogenesis, and lymphangiogenesis (p<0.05 vs. MI control). Mechanistically, hEPs suppressed AMI-induced increases of type I interferon (IFN-I) response, infiltration and cytokine-release of inflammatory cells, and promoted polarization of reparative macrophages. These effects were blocked by a IFN-I receptor agonist RO8191 in mouse model of MI. Moreover, hEP abundantly secreted intelectin 1 (ITLN1), which interacted with IFN-β and mimicked the effects of hEP-condition medium in the suppression of IFN-β-stimulated responses in macrophages and promotion of reparative macrophage polarization. However, ITLN1 downregulation in the hEPs canceled beneficial effects of hEPs in anti-inflammation and anti-IFN-I response, and in cardiac repair of infarcted hearts. Conclusions: our resutls demonstrate the reparative effects of hEP implantations in the infarcted hearts and reveal hEPs as an inflammatory modulator in promoting infarct healing via paracrine factor-mediated cell-cell communications. These findings provide new knowledges for the functions and mechanisms of hEPs for cardiac repair and suggest a therapeutic option of hEPs for ischemic myocardial repair.

Abstract P1051: Minimally Invasive Delivery Of Synthetic Cardiac Stromal Cells In A Large Animal Model Of Myocardial Infarction

Cell therapies for cardiac tissue regeneration are commonly used for tissue remolding post-MI, however, due to viability, retention, and cost, acellular therapeutic components are being explored. Synthetic cardiac stromal cells (synCSCs) generated by encapsulating secreted factors from isolated human cardiac stromal cells were shown to promote cardiac repair after MI. Previously, synCSCs implantation required surgy. Reducing the risks of surgical complications is essential for translational research. It is beneficial to develop a minimally invasive approach such as intrapericardial cavity (iPC) injections. This pre-clinical study aims to elucidate the therapeutic effects of synCSC embedded in hyaluronic acid (HA) hydrogel on a large animal model of MI through iPC injection. HA hydrogel and synCSCs are fabricated according to previous studies. Video-assisted thoracoscopic surgery is performed for iPC injections in Yorkshire male pigs. Magnetic resonance imaging (MRI) and immunohistochemistry (IHC) data were collected for cardiac function analyses. This pre-clinical study aims to bridge the gap between the bench and bedside by using a minimally invasive approach of iPC injection of synCSCs embedded in the hydrogel. Figure 1 shows iPC injection of synCSCs in HA improved cardiac function and cardiomyocyte proliferation in the pig MI model. Single-cell RNA sequencing data is being analyzed to identify gene markers elevated by synCSC treatment and further uncover the molecular pathways activated by synCSC. iPC injection of synCSC provides a unique dataset in the field of cardiac tissue regeneration and offers another therapeutic option for patients suffering from MI.

Inflammation-Responsive Micellar Nanoparticles from Degradable Polyphosphoramidates for Targeted Delivery to Myocardial Infarction.

Nanoparticles that undergo a localized morphology change to target areas of inflammation have been previously developed but are limited by their lack of biodegradability. In this paper, we describe a low-ring-strain cyclic olefin monomer, 1,3-dimethyl-2-phenoxy-1,3,4,7-tetrahydro-1,3,2-diazaphosphepine 2-oxide (MePTDO), that rapidly polymerizes via ring-opening metathesis polymerization at room temperature to generate well-defined degradable polyphosphoramidates with high monomer conversion (>84%). Efficient MePTDO copolymerizations with norbornene-based monomers are demonstrated, including a norbornenyl monomer functionalized with a peptide substrate for inflammation-associated matrix metalloproteinases (MMPs). The resulting amphiphilic peptide brush copolymers self-assembled in aqueous solution to generate micellar nanoparticles (30 nm in diameter) which exhibit excellent cyto- and hemocompatibility and undergo MMP-induced assembly into micron-scale aggregates. As MMPs are upregulated in the heart postmyocardial infarction (MI), the MMP-responsive micelles were applied to target and accumulate in the infarcted heart following intravenous administration in a rat model of MI. These particles displayed a distinct biodistribution and clearance pattern in comparison to nondegradable analogues. Specifically, accumulation at the site of MI competed with elimination predominantly through the kidney rather than the liver. Together, these results suggest this as a promising new biodegradable platform for inflammation targeted delivery.

TDO2‐augmented fibroblasts secrete EVs enriched in immunomodulatory Y‐derived small RNA

AbstractMounting evidence implicates extracellular vesicles (EVs) factors as mediators of cell therapy. Cardiosphere‐derived cells are cardiac‐derived cells with tissue reparative capacity. Activation of a downstream target of wnt/β‐catenin signalling, tryptophan 2,3 dioxygenase (TDO2) renders therapeutically inert skin fibroblasts cardioprotective. Here, we investigate the mechanism by which concentrated conditioned media from TDO2‐augmented fibroblasts (TDO2‐CCM) exert cardioprotective effects. TDO2‐CCM is cardioprotective in a mouse model of MI compared to CCM from regular fibroblasts (HDF‐CCM). Transcriptomic analysis of cardiac tissue at 24 h demonstrates broad suppression of inflammatory and cell stress markers in animals given TDO2‐CCM compared to HDF‐CCM or vehicle. Sequencing analysis of TDO2‐EV RNA demonstrated abundance of a small Y‐derived small RNA dubbed ‘NT4’. Purification of TDO2‐EVs by size‐exclusion chromatography and RNAse protection assays demonstrated that NT4 is encapsulated inside EVs. Consistently with TDO2‐CCM, macrophages exposed to NT4 showed suppression of the inflammatory and cell stress mediators, particularly p21/cdkn1a. NT4‐depleted TDO2‐CCM resulted in diminished immunomodulatory capacity. Finally, administration of NT4 alone was cardioprotective in an acute model of myocardial infarction. Taken together, these findings elucidate the mechanism by which TDO2 augmentation mediates potency in secreted EVs through enrichment of NT4 which suppresses upstream cell stress mediators including p21/cdkn1a.

GSDMD-mediated pyroptosis dominantly promotes left ventricular remodeling and dysfunction in post-myocardial infarction: a comparison across modes of programmed cell death and mitochondrial involvement

BackgroundMyocardial infarction (MI) has recently accounted for more than one-third of global mortality. Multiple molecular pathological pathways, such as oxidative stress, inflammation, and mitochondrial dysfunction, have been recognized as possible mechanisms in the development of MI. Furthermore, different phases of ischemic injury following the progression of MI were also associated with multiple types of programmed cell death (PCDs), including apoptosis, necroptosis, ferroptosis, and pyroptosis. However, it remains unknown whether which types of PCDs play the most dominant role in post-myocardial infarction (post-MI).MethodIn this study, we used a preclinical rat model of MI induced by permanent left anterior descending coronary artery (LAD) ligation (n = 6) or a sham operated rat model (n = 6). After a 5-week experiment, cardiac function and morphology, mitochondrial studies, and molecular signaling analysis of PCDs were determined.ResultsHerein, we demonstrated that post-MI rats had considerably impaired cardiac geometry, increased oxidative stress, myocardial injuries, and subsequently contractile dysfunction. They also exhibited worsened cardiac mitochondrial function and dynamic imbalance. More importantly, we found that post-MI mediated abundant myocardial cell death through multiple PCDs, including apoptosis, necroptosis, and pyroptosis, but not ferroptosis.ConclusionIn this study, we provide the first insights into the mechanism of PCDs by pyroptosis, which is leveraged as the most dominant mode of cell death after MI.

Growth differentiation factor 11 promotes macrophage polarization towards M2 to attenuate myocardial infarction via inhibiting Notch1 signaling pathway

Abstract Background Myocardial infarctions (MI) is a major threat to human health especially in people exposed to cold environment. The polarization of macrophages towards different functional phenotypes (M1 macrophages and M2 macrophages) is closely related to MI repairment. The growth differentiation factor 11 (GDF11) has been reported to play a momentous role in inflammatory associated diseases. In this study, we examined the regulatory role of GDF11 in macrophage polarization and elucidated the underlying mechanisms in MI. Methods In vivo, the mice model of MI was induced by permanent ligation of the left anterior descending coronary artery (LAD), and mice were randomly divided into the sham group, MI group, and MI+GDF11 group. The protective effect of GDF11 on myocardial infarction and its effect on macrophage polarization were verified by echocardiography, triphenyl tetrazolium chloride staining and immunofluorescence staining of heart tissue. In vitro, based on the RAW264.7 cell line, the effect of GDF11 in promoting macrophage polarization toward the M2 type by inhibiting the Notch1 Signaling pathway was validated by qRT-PCR, Western blot, and flow cytometry. Results We found that GDF11 was significantly downregulated in the cardiac tissue of MI mice. And GDF11 supplementation can improve the cardiac function. Moreover, GDF11 could reduce the proportion of M1 macrophages and increase the accumulation of M2 macrophages in the heart tissue of MI mice. Furthermore, the cardioprotective effect of GDF11 on MI mice was weakened after macrophage clearance. At the cellular level, application of GDF11 could inhibit the expression of M1 macrophage (classically activated macrophage) markers iNOS, interleukin (IL)-1β, and IL-6 in a dose-dependent manner. In contrast, GDF11 significantly increased the level of M2 macrophage markers including IL-10, CD206, arginase 1 (Arg1), and vascular endothelial growth factor (VEGF). Interestingly, GDF11 could promote M1 macrophages polarizing to M2 macrophages. At the molecular level, GDF11 significantly down-regulated the Notch1 signaling pathway, the activation of which has been demonstrated to promote M1 polarization in macrophages. Conclusions GDF11 promoted macrophage polarization towards M2 to attenuate myocardial infarction via inhibiting Notch1 signaling pathway.

Hypoxic preconditioned aged BMSCs accelerates MI injury repair by modulating inflammation, oxidative stress and apoptosis

The benefits of autologous cell therapy for cardiac repair are diminished in aged individuals due to the limited quality and poor tolerance of aged stem cells in the ischemic micro-environment. The safe and efficient methods to improve the therapeutic effect of aged stem cells are needed to treat the increasing number of aged patients with cardiac diseases. In the present study, we aimed to determine whether hypoxic preconditioning can improve the therapeutic effect of aged stem cells even if the responsiveness of aged MSCs is poor, and to seek the underlying mechanism. Using a murine model of MI, our results showed that hypoxic preconditioning promoted the therapeutic effect of aged BMSCs, which was expressed in improved cardiac function, decreased scar size and alleviated cardiac remodeling in vivo. This in vivo effect of hypoxic preconditioned aged BMSCs was associated with alleviated inflammation, oxidative stress and apoptosis in infarcted heart. In vitro studies confirmed that hypoxic preconditioned aged BMSCs exert cytoprotective impacts on H9C2 cells against lethal hypoxia injury via attenuating oxidative stress and apoptosis. Our data support the promise of hypoxic preconditioning as a potential strategy to improve autologous stem cell therapy for ischemic heart injury in aged individuals.

An integrative approach to uncover the components, mechanisms, and functions of traditional Chinese medicine prescriptions on male infertility.

Male infertility is a major and growing health problem with an estimated global prevalence of 4.2%. The current therapy is limited by the unknown etiology of MI, emphasizing the critical requirement forward to a more efficient method or medication. Through thousands of years, Traditional Chinese Medicine (TCM) has been shown to be effective in treating MI effectively. However, the components, mechanisms and functions of TCM prescriptions on MI are still obscure, severely limiting its clinical application. In order to discover the molecular mechanism of TCM against MI, our study presents a comprehensive approach integrated data mining, network pharmacology, molecular docking, UHPLC-Q-Orbitrap HRMS, and experimental validation. Here, we begin to acquire 289 clinical TCM prescriptions for MI from a TCM hospital’s outpatient department. Then, Core Chinese Materia Medica (CCMM) was then retrieved from the TCM Inheritance Support System (TCMISS), which was utilized to discover the underlying rules and connections in clinical prescriptions. After that, 98 CCMM components and 816 MI targets were obtained from ten distinct databases. Additionally, the network pharmacology methods, including network construction, GO and KEGG pathway enrichment, PPI analysis, were utilized to reveal that kaempferol, quercetin, isorhamnetin, and beta-sitosterol are the core components of CCMM in treating MI. The mechanisms and functions of CCMM against MI are hormone regulation, anti-apoptosis, anti-oxidant stress, and anti-inflammatory. Furthermore, the strong connections between four core components and six key targets were verified using a molecular docking method. Following that, the core components of the CCMM extract were identified using UHPLC-Q-Orbitrap HRMS analysis. Finally, in vivo experiments demonstrated that CCMM and four core components could improve the density, motility, viability of sperm, lecithin corpuscle density, decrease the rate of sperm malformation and testis tissue damage, and regulate the protein expressions of AKT1, MAPK3/1, EGFR, and TNF-α in a mouse model of MI. UHPLC-Q-Orbitrap HRMS analysis and in vivo experiments further validated the results of data mining, network pharmacology, and molecular docking. Our study could uncover the components, mechanisms, and functions of TCM prescriptions against MI and develop a new integrative approach to demonstrate TCM’s multi-component, multi-target, and multi-pathway approach to disease treatment.

LncRNA-HOTAIR Inhibits H9c2 Apoptosis After Acute Myocardial Infarction via miR-206/FN1 Axis.

Although previous studies showed that long non-coding RNAs (lncRNAs) have critical roles in the pathogenesis of acute myocardial infarction (AMI), the underlying molecular mechanism that lncRNAs participate in MI remains unclear. Herein, we explored the expression of lncRNA HOX antisense non-coding RNA (HOTAIR) in the serum of MI patients and mouse model of AMI. Biological functions of HOTAIR in hypoxic H9c2 cells, the in vitro model of MI, were also assessed. RT-qPCR results showed that HOTAIR expression was downregulated in the serum of AMI patients and AMI mice. HOTAIR overexpression promoted H9c2 cell viability and inhibited cell apoptosis under hypoxic conditions. Mechanically, HOTAIR was regulated by miR-206 and FN1 was the direct target of miR-206. More importantly, miR-206 overexpression or FN1 knockdown reversed the effect of HOTAIR overexpression on H9c2 cell viability and apoptosis under hypoxic conditions. Therefore, targeting the HOTAIR/miR-206/FN1 axis may be a promising therapeutic method for MI.

Adipose Tissue-derived Cardiomyocytes for Enhancing Cardiac Remodeling in a Rat Model of Acute Myocardial Infarction

This investigation was directed towards addressing the pivotal role of adipose tissue-derived cardiomyocytes seeded onto nanofiber (NF) in repairing the deteriorated cardiac tissue in a model of MI. Molecular analysis for MEF2C and Actn expression was attained to ensure the differentiation of ADMSCs into cardiomyocytes in vitro. The in vivo study was conducted on forty adult rats assigned into four groups: (1) control; (2) MI; (3) MI treated with adipose tissue-derived cardiomyocytes; (4) MI treated with adipose tissue-derived cardiomyocytes seeded onto NF. Treatment of MI-challenged rats with adipose tissue-derived cardiomyocytes modulates ST height, heart rate, RR, PR, QTc, QRS intervals and P duration as manifested in the ECG. The biochemical parameters corroborated the ECG outcomes as they displayed significant inhibition in serum LDH and CK-MB enzymes activity as well as significant suppression in cardiac cTnT level paralleled with significant elevations in cardiac Cx43 and Actn levels in the treated groups. Molecular analysis of GATA4 and NKX2.5 gene expression levels declared significant downregulation in the treated groups. Photomicrographs of cardiac tissue sections of rats in the treated groups showed great renovation in the cardiac microarchitecture. Conclusively, this study delivers a futuristic approach for treatment of MI by applying differentiated cardiomyocytes systematically.

Protective role of emodin in rats with post-myocardial infarction heart failure and influence on extracellular signal-regulated kinase pathway

ABSTRACT We aimed to explore the effects of emodin on the energy metabolism of myocardial cells in rats with post-myocardial infarction (MI) heart failure (HF) and the extracellular signal-regulated kinase (ERK) pathway. The model of MI was established by ligation of the left anterior descending branch. After 4 weeks, the rats with left ventricular ejection fraction (LVEF) of ≤45% were used aspost-MI HF model animals and randomly divided into model, low-dose, middle-dose, high-dose and control groups (n=10). Low-, middle- and high-dose groups were gavaged with 20 mg/kg, 40 mg/kg and 60 mg/kg emodin daily, respectively. After administration for 14 d, the changes in LVEF, left ventricular end-systolic diameter (LVESD), left ventricular end-diastolic diameter (LVEDD) and interventricular septum thickness (IVS) were analyzed. The apoptosis rate of myocardial cells was detected by TUNEL staining. The levels of serum cardiac troponin I (cTnI) and peroxisome proliferator-activated receptor-γ coactivator-1 (PGC-1) were determined using ELISA, and the expressions of mitochondrial respiratory chain complex I protein and phosphorylated-ERK (p-ERK) in myocardial tissues were determined by Western blotting. Compared with model group, LVEDD, LVESD, apoptosis rate of myocardial cells, levels of serum cTnI and PGC-1, and expressions of complex I and p-ERK in myocardial tissues significantly decreased, while LVEF and IVS increased in low-dose, middle-dose, high-dose and control groups (P<0.05). The changes in the above indices were significantly dependent on the dose of emodin (P<0.05).Emodin can significantly relieve post-MI HF, reduce the apoptosis rate of myocardial tissues, and ameliorate the cardiac function of rats.

Acute regional changes in myocardial strain may predict ventricular remodelling after myocardial infarction in a large animal model

To identify predictors of left ventricular remodelling (LVR) post-myocardial infarction (MI) and related molecular signatures, a porcine model of closed-chest balloon MI was used along with serial cardiac magnetic resonance imaging (CMRI) up to 5–6 weeks post-MI. Changes in myocardial strain and strain rates were derived from CMRI data. Tissue proteomics was compared between infarcted and non-infarcted territories. Peak values of left ventricular (LV) apical circumferential strain (ACS) changed over time together with peak global circumferential strain (GCS) while peak GLS epicardial strains or strain rates did not change over time. Early LVR post-MI enhanced abundance of 39 proteins in infarcted LV territories, 21 of which correlated with LV equatorial circumferential strain rate. The strongest associations were observed for D-3-phosphoglycerate dehydrogenase (D-3PGDH), cysteine and glycine-rich protein-2, and secreted frizzled-related protein 1 (sFRP1). This study shows that early changes in regional peak ACS persist at 5–6 weeks post-MI, when early LVR is observed along with increased tissue levels of D-3PGDH and sFRP1. More studies are needed to ascertain if the observed increase in tissue levels of D-3PGDH and sFRP1 might be casually involved in the pathogenesis of adverse LV remodelling.

L-carnitine protects cardiac damage by reducing oxidative stress and inflammatory response via inhibition of tumor necrosis factor-alpha and interleukin-1beta against isoproterenol-induced myocardial infarction

Brief introductionMyocardial infarction (MI) is a common manifestation of certain cardiac diseases where oxidative stress and fibrosis aggravate the condition markedly. Main objective of the studyInvestigation of L-carnitine’s cardioprotective roles and mechanism of action in a rat model of MI. MethodsTo develop a MI animal model, Isoproterenol (ISO) was administered in male Long Evans rats where animals were divided into five groups (six rats/group). The oxidative stress and antioxidant enzyme activities were determined by different biochemical tests. The real-time PCR was performed to determine the expression of TNF-α and Il-1β. Histopathological observations by hematoxylin-eosin and Masson trichrome were made to observe the tissue damage and fibrosis in heart and kidney. Significant findings from the studyThe ISO-treated rats showed increased levels of troponin I and lipid peroxidation and lower antioxidant enzyme activity in heart and kidney tissues. The levels of TNF-α and IL-1β were also increased in ISO-rats. Co-administration of L-carnitine with ISO reversed all these parameters. The elevated levels of uric acid and creatinine kinase and ALP, AST and ALT activities in ISO-rats were also significantly reduced by L-carnitine administration. L-carnitine markedly decreased the infiltration of inflammatory cells and improved the tissue architecture in heart and kidney. Control animals did not show any appreciable response upon L-carnitine administration. Relevant contribution to knowledgeThese results suggest that L-carnitine plays a defensive role against cardiac and renal damage in ISO-treated MI rat model via suppressing oxidative stress and increasing antioxidant enzyme functions through inhibition of TNF-α and IL-1β.

Abstract MP219: Hnrnpa2b1-dependent Selective Sorting Of Mir-486a-5p Into Msc-derived Exosomes Contributes To Cardioprotection

Exosomes (Exo) are a class of extracellular vesicles and involvement of stem cell-derived Exo in cardiac repair and cardioprotection is thought to be an important in the heart. Our HYPOTHESIS Is that specific microRNAs (miRs) from mesenchymal stem cell (MSC)-derived exosomes are actively and selectively sorted into Exo by RNA binding proteins and motifs on the miR, to serve specific functions of the Exo, including Cardioprotection. Methods: We characterized the miR populations of parental MSCs and their Exo via RNA Seq and confirmed by QRT-PCR the subpopulation of miRs that is increased in Exo vs . MSC cells. We then used Multiple Em for Motif Elicitation (MEME) Version 5.3.3 and determined the predicted conserved motifs. From these, we predicted RNA binding protein sites from the literature. In parallel, we performed mass spectrometry and western blot analyses to determine RNA binding proteins in MSC and Exo. Predicting that hnRNPA2B1 was a likely RNA binding protein for the new motif, we knocked out the cognate gene (CRISPR) in MSC and evaluated the KO Exo vs. the WT Exo by RNA Seq and QRT-PCR. We performed protein and RNA pulldowns, and EMSA to validate binding of hnRNPA2B1 to several of the miRs, and investigated the effects of these miRs on cell survival after simIR and in an in vivo mouse model of MI. Results: We found a set of eight miRs that are selectively concentrated in the MSC Exo. MEME software predicted a conserved binding motif of gAGu, which is close to canonical sites for binding of hnRNPA2B1 and hnRNPA1. We determined hnRNPA2B1 was in MSC and Exo and showed KO hnRNPA2B1 cells and Exo had no compensatory perturbation of other RNA binding proteins. The KO MSC Exo show reduction of the selective sorting of the miRs of interest. Pulldowns and binding assay results verify binding of hnRNPA2B1 to both miR-486a-5p and miR-122a. Finally, we showed that miR-486a-5p is protective in H9C2 cells submitted to simIR and results in significant 68% reduction of infarct size (n=7, P=0.0175) in vivo in association with repression of PDCD4 expression and apoptosis. Conclusions: We determined that a set of miRs is selectively concentrated in MSC Exo and demonstrated the necessity of hnRNPA2B1 in that process. This appears to involve a conserved RNA sequence motif (mutational analysis underway). A major miR affected is miR-486a-5p, which is strongly cardioprotective. Our results support that miR-486a-5p is selectively concentrated in MSC Exo and contributes to cardioprotection by reducing PDCD4 activity in apoptosis.

Therapeutic effects of CXCR4+ subpopulation of transgene‐free induced cardiosphere‐derived cells on experimental myocardial infarction

ObjectivesMyocardial infarction (MI) is the most predominant type of cardiovascular diseases with high mortality and morbidity. Stem cell therapy, especially cardiac progenitor cell therapy, has been proposed as a promising approach for cardiac regeneration and MI treatment. Previously, we have successfully generated cardiac progenitor‐like cells, induced cardiosphere (iCS), via somatic reprogramming. However, the genome integration characteristic of virus‐based reprogramming approach hampered their therapeutic applications due to the risk of tumour formation. In the current study, we aim to establish a safer iCS generation strategy with transgene‐free approaches.Materials and MethodsFour transgene‐free approaches for somatic reprogramming, including episome, minicircle, self‐replicative RNA, and sendai virus, were compared, from the perspective of cardiac progenitor marker expression, iCS formation, and cardiac differentiation. The therapeutic effects were assessed in the mouse model of MI, from the perspective of survival rate, cardiac function, and structural alterations.ResultsThe self‐replicative RNA approach produced more iCS, which had cardiomyocyte differentiation ability and therapeutic effects on the mouse model of MI with comparable levels with endogenous cardiospheres and iCS generated with retrovirus. In addition, the CXCR4 (C‐X‐C chemokine receptor 4) positive subpopulation of iCS derived cells (iCSDC) delivered by intravenous injection was found to have similar therapeutic effects with intramyocardial injection on the mouse model of MI, representing a safer delivery approach.ConclusionThus, the optimized strategy for iCS generation is safer and has more therapeutic potentials.

A Steroid Receptor Coactivator Stimulator MCB-613 Attenuates Adverse Remodeling After Myocardial Infarction

Previous work from ours and other laboratories have shown that steroid receptor coactivators (SRCs) are involved in heart development and in mitigating cardiac dysfunction in cardiac injury models. Members of the p160 SRC family, SRC-1 (NCOA1), SRC-2 (NCOA2/TIF2/GRIP1) and SRC-3 (NCOA3/AIB1/ACTR/pCIP), interact with nuclear receptors and other transcription factors to drive target gene expression by assembling transcriptional coactivator complexes to increase transcription. This indicates a potential for SRC targeting drugs pertinent to cell migration, proliferation and survival-promoting paracrine interactions in cardiac tissue injury responses. We have identified a small molecule activator of SRCs (MCB-613) that selectively and reversibly binds to SRCs as shown by surface plasmon resonance and is a potent SRC stimulator that acts to greatly enhance SRC transcriptional activity with no apparent toxicity in mice. We postulated that MCB-613 could enable wound repair and preservation of cardiac function after an acute MI by reducing the extent of injury-related fibrosis and the subsequent chronic loss of cardiac function associated with non-contracting scar tissue. We thus tested the effect of MCB-613 on the cardiac injury response by administering MCB-613 two hours after ischemic injury in a mouse model of MI. Along with measurements of functional cardiac output and damage, we sought to identify the cell-type specific responses responsible for MCB-613’s cardio-protective effects by utilizing single cell transcriptomics of cardiac interstitial cells to characterize the effects of SRC stimulation on cardiac function post-MI. We show that MCB-613, a potent small molecule stimulator of steroid receptor coactivators (SRCs) attenuates pathological remodeling post-MI. MCB-613 decreases infarct size, apoptosis, hypertrophy, and fibrosis while maintaining significant cardiac function. MCB-613, when given within hours post-MI, induces lasting protection from adverse remodeling concomitant with: (i) inhibition of macrophage inflammatory signaling and IL-1 signaling which attenuates the acute inflammatory response, (ii) attenuation of fibroblast differentiation, and (iii) promotion of Tsc22d3 expressing macrophages - all of which may limit inflammatory damage. Our results indicate MCB-613 controls the cellular interstitial cardiac repair response to ischemia. Distinct molecular and cellular mechanisms related to stimulation of SRC-3 have been identified that pave the way for the further exploration of SRCs as drug targets that can be engaged to improve the management of myocardial injury response outcomes. SRC stimulation with MCB-613 (and derivatives) is a potential novel therapeutic approach for inhibiting cardiac dysfunction after MI.

Adipolin/C1q/Tnf-related protein 12 prevents adverse cardiac remodeling after myocardial infarction.

BackgroundMyocardial infarction (MI) is a leading cause of death worldwide. We previously identified adipolin, also known as C1q/Tnf-related protein 12, as an anti-inflammatory adipokine with protective features against metabolic and vascular disorders. Here, we investigated the effect of adipolin on myocardial remodeling in a mouse model of MI.MethodsMale adipolin-knockout (APL-KO) and wild-type (WT) mice were subjected to the permanent ligation of the left anterior descending coronary artery to create MI.ResultsAPL-KO mice exhibited increased ratios of heart weight/body weight and lung weight/body weight after MI compared with WT mice. APL-KO mice showed increased left ventricular diastolic diameter and decreased fractional shortening after MI compared with WT mice. APL-KO mice exhibited increased expression of pro-inflammatory mediators and enhanced cardiomyocyte apoptosis in the post-MI hearts compared with WT mice. Systemic administration of adenoviral vectors expressing adipolin to WT mice after MI surgery improved left ventricular contractile dysfunction and reduced cardiac expression of pro-inflammatory genes. Treatment of cultured cardiomyocytes with adipolin protein reduced lipopolysaccharide-induced expression of pro-inflammatory mediators and hypoxia-induced apoptosis. Treatment with adipolin protein increased Akt phosphorylation in cardiomyocytes. Inhibition of PI3 kinase/Akt signaling reversed the anti-inflammatory and anti-apoptotic effects of adipolin in cardiomyocytes.ConclusionOur data indicate that adipolin ameliorates pathological remodeling of myocardium after MI, at least in part, by its ability to reduce myocardial inflammatory response and apoptosis.