Rat Model Of Myocardial Infarction Research Articles

Transplanted allogeneic cardiac progenitor cells secrete GDF-15 and stimulate an active immune remodeling process in the ischemic myocardium

BackgroundDespite promising results in clinical studies, the mechanism for the beneficial effects of allogenic cell-based therapies remains unclear. Macrophages are not only critical mediators of inflammation but also critical players in cardiac remodeling. We hypothesized that transplanted allogenic rat cardiac progenitor cells (rCPCs) augment T-regulatory cells which ultimately promote proliferation of M2 like macrophages by an as-yet undefined mechanism.Methods and resultsTo test this hypothesis, we used crossover rat strains for exploring the mechanism of myocardial repair by allogenic CPCs. Human CPCs (hCPCs) were isolated from adult patients undergoing coronary artery bypass grafting, and rat CPCs (rCPCs) were isolated from male Wistar-Kyoto (WKY) rat hearts. Allogenic rCPCs suppressed the proliferation of T-cells observed in mixed lymphocyte reactions in vitro. Transplanted syngeneic or allogeneic rCPCs significantly increased cardiac function in a rat myocardial infarct (MI) model, whereas xenogeneic CPCs did not. Allogeneic rCPCs stimulated immunomodulatory responses by specifically increasing T-regulatory cells and M2 polarization, while maintaining their cardiac recovery potential and safety profile.Mechanistically, we confirmed the inactivation of NF-kB in Treg cells and increased M2 macrophages in the myocardium after MI by transplanted CPCs derived GDF15 and it’s uptake by CD48 receptor on immune cells.ConclusionCollectively, these findings strongly support the active immunomodulatory properties and robust therapeutic potential of allogenic CPCs in post-MI cardiac dysfunction.

Dexamethasone Alleviates Myocardial Injury in a Rat Model of Acute Myocardial Infarction Supported by Venoarterial Extracorporeal Membrane Oxygenation.

Myocardial ischemia causes myocardial inflammation. Research indicates that the venoarterial extracorporeal membrane oxygenation (VA ECMO) provides cardiac support; however, the inflammatory response caused by myocardial ischemia remains unresolved. Dexamethasone (Dex), a broad anti-inflammatory agent, exhibits a cardioprotective effect. This study aims to investigate the effect of Dex on a rat model of acute myocardial infarction (AMI) supported by VA ECMO. Male Sprague-Dawley rats (300–350 g) were randomly divided into three groups: Sham group (n = 5), ECMO group (n = 6), and ECMO + Dex group (n = 6). AMI was induced by ligating the left anterior descending (LAD) coronary artery. Sham group only thoracotomy was performed but LAD was not ligated. The ECMO and ECMO + Dex groups were subjected to 1 h of AMI and 2 h of VA ECMO. In the ECMO + Dex group, Dex (0.2 mg/kg) was intravenously injected into the rats after 1 h of AMI. Lastly, myocardial tissue and blood samples were harvested for further evaluation. The ECMO + Dex group significantly reduced infarct size and levels of cTnI, cTnT, and CK-MB. Apoptotic cells and the expression levels of Bax, Caspase3, and Cle-Caspase3 proteins were markedly lower in the ECMO + Dex group than that in the ECMO group. Neutrophil and macrophage infiltration was lower in the ECMO + Dex group than in the ECMO group. A significant reduction was noted in ICAM-1, C5a, MMP-9, IL-1β, IL-6, and TNF-α. In summary, our findings revealed that Dex alleviates myocardial injury in a rat model of AMI supported by VA ECMO.

MiR-214-3p Protects and Restores the Myocardial Tissue of Rat Myocardial Infarction Model by Targeting PTEN.

Myocardial infarction (MI), which results in myocardial cell dysfunction and irreversible loss, is one of the most serious health threats today. This study was started with rats, by which the consequence of miRNA expression dysregulation to the occurrence and progression of cardiovascular diseases was explored. We first conducted miRNA sequencing on the myocardial tissues separately from myocardial infarction treatment and sham operation treatment to clarify those differently expressed miRNAs; then, our experiment of functional verification of those key miRNAs was initiated so as to dig out the molecular mechanism behind the miRNA's regulation in myocardial infarction. And it turned out that there were 32 upregulated miRNAs and 16 downregulated miRNAs according to our comparison from the myocardial infarction model group to the sham operation group; of all those upregulated, alteration in miR-214-3p expression was the most conspicuous. Overexpression of miR-214-3p greatly alleviated myocardial infarct area and ameliorated myocardial tissue structure, even reducing myocardial fibrosis and the devastation in the tissues. On the molecular level, miR-214-3p overexpression brought down both the apoptosis rate and cleaved caspase 3 expression. Besides that, we verified that PTEN is the target gene of miR-214-3p through a dual-luciferase assay. A cotransfection of miR-214-3p and PTEN brought about an obvious elevation in the myocardial infarct area, tissue damage, and fibrosis, even in the aspect of cellular apoptosis than a mere transfection of miR-214-3p. All the results above verified miR-214-3p′s effects in protecting myocardial tissues and reducing the infarct area, and it was reasonable to assume that those functions of miR-214-3p came into effect by targeting PTEN, which was then justified by the inversion to miR-214-3p′s protection via PTEN overexpression.

Effectiveness of exosome mediated miR-126 and miR-146a delivery on cardiac tissue regeneration.

Despite advances in the treatment of acute myocardial infarction, due to the non-proliferative nature of adult cardiomyocytes, the injured myocardium is mainly replaced by fibrotic tissue, which ultimately causes heart failure. To prevent heart failure, particularly after myocardial infarction, exosome-based therapy has emerged as one of the most promising strategies to regenerate cardiac function. Exosomes can carry microRNAs in support of neovascularization, anti-inflammatory, and endogenous cardiac regeneration. This study demonstrated that animal rat models' combination treatment with microRNA-126 and microRNA-146a mimics in exosomes is desirable for cardiac regeneration after myocardial infarction. The exosomes isolated from stem cells and loaded with microRNAs were characterized their impacts in cell migration, tube formation, and vascular endothelial growth factor degree. In the following, the usefulness of loaded microRNAs in exosomes and their encapsulation within alginate derivative hydrogel was analyzed in myocardial infarction for an animal model. Exosomes isolated and loaded with microRNAs showed the synergetic impact on cell migration, tube formation, and promoted vascular endothelial growth factor folding. Moreover, microRNAs loaded exosomes and encapsulated them in alginate hydrogel could help in reducing infarct size and improving angiogenesis in myocardial infarction. The angiogenesis markers including CD31 and connexion 43 upregulated for myocardial infarction models treated with alginate-based hydrogels loaded with exosomes and microRNAs-exosomes. Histological analysis indicated that myocardial infarction model rats treated with alginate hydrogel loaded with microRNAs-exosomes possessed lower and higher degrees of fibrosis and collagen fiber, respectively. These findings have important therapeutic implications for a myocardial infarction model through angiogenesis and vascular integrity regulation.

A dual crosslinked hydrogel-mediated integrated peptides and BMSC therapy for myocardial regeneration.

The efficacy of myocardial regeneration strategies for myocardial infarction (MI) is significantly compromised by the complex structure and microenvironment of the myocardium. Although tissue engineering strategies based on cell therapy and/or pro-angiogenesis can somewhat improve cardiac function, the lack of proper myocardial materials that can withstand sustained deformability and adaptable mechanical properties severely affects myocardial wall integrity, systolic-diastolic cycles, and regeneration. Herein, we developed an integrated single "all-in-one" in situ dual crosslinking conductive hydrogel with favorable treatment properties termed as MaHA/B-G-SH/Fe3+ by ionic interactions and chemical covalency based on modified hyaluronic acid (HA), gelatin (G), and Fe3+. The resulting dual crosslinking dynamic hydrogel not only provides self-healing and mechanical properties adapted to the myocardial systolic-diastolic cycle with simultaneous electrical signal transmission to fibrous islands and normal tissue, but also leads to significant increase of the myocardial wall thickness very close to that of normal myocardium upon one single injection with complete degradation within 28days. Notably, the hydrogel covalently conjugated with a tailored peptide sequence of GGR-KLT and encapsulated with bone mesenchymal stem cells (BMSCs) was further used for in situ injection in a rat MI model, which exhibited (i) efficient inhibition of excessive matrix degradation dependent on early MMP-2 expression, (ii) triggered on-demand release of KLT for at least 14days and significant promotion of angiogenesis, and (iii) synergistic BMSCs considerably enhanced myocardial regeneration within 28days. Taken together, the dual crosslinking conductive hydrogel-mediated synergistic peptide and cell therapy provides comprehensive recovery and regeneration of the structure and function of the injured myocardium, thus demonstrating great potential for clinical translations.

M6A methyltransferase METTL3 participated in sympathetic neural remodeling post-MI via the TRAF6/NF-κB pathway and ROS production

ObjectiveSudden cardiac death caused by ventricular arrhythmias (VAs) is the main cause of high mortality in patients with myocardial infarction (MI). Sympathetic neural remodeling caused by inflammation after MI is closely associated with the occurrence of VAs. METTL3, the earliest identified m6A methyltransferase, is critical in mediating inflammatory responses. Our aim was to investigate whether the m6A methyltransferase METTL3 was involved in sympathetic remodeling post-MI and its specific mechanism. Methods and resultsA rat MI model was established via left coronary artery ligation. The expression of METTL3, TRAF6, NOX2, and NF-κB increased at 3 days and remained elevated at 7 days after MI, as determined via Western blotting. METTL3 was primarily present in macrophages, as determined via immunofluorescence. Intramyocardial injection of lentivirus carrying METTL3-shRNA inhibited METTL3 expression in vivo. Methylated immunoprecipitation-qPCR determined the METTL3 knockdown inhibited the m6A level of TRAF6 mRNA 3′-UTR. The co-immunoprecipitation experiment proved that METTL3 combines with TRAF6. Western blotting showed that silencing METTL3 inhibited TRAF6 level, NF-κB activation, and ROS production; decreased cytokine release (TNF-α and IL-1β); and downregulated nerve growth factor expression. Finally, METTL3 knockdown reduced sympathetic remodeling after MI, as determined via immunofluorescence assays of tyrosine hydroxylase and growth-associated protein 43. Programmed electrical stimulation, renal sympathetic nerve activity recording, and haemodynamic measurements showed that METTL3 inhibition decreased sympathetic activity and improved cardiac function. ConclusionsDownregulation of METTL3 expression attenuated the excessive sympathetic neural remodeling induced by MI, further reducing the incidence of VAs and improving cardiac function. This was partly associated with the inhibition of the TRAF6/NF-κB pathway and ROS production.

Single-cell atlas of multilineage cardiac organoids derived from human induced pluripotent stem cells

Abstract Human induced pluripotent stem cell (hiPSC)-derived cardiac organoids can be used to model human heart development and cardiovascular disease, and provide therapeutic cells to repair the heart. We used single-cell transcriptome analysis to dissect the development of 3D mini-cardiac organoids (MCOs) consisting of hiPSC-derived cardiomyocytes, and endothelial and smooth muscle cells. We found that the 3D matrix-rich microenvironment significantly promoted the maturation of cardiomyocytes, and mixing endothelial and smooth muscle cells with cardiomyocytes led to the formation of cardiac fibroblast highly expressing DLK1. Modulation of DLK1 signaling affected immunomodulatory gene expression in 2D cultured cardiomyocytes. Transplantation of multilineage MCO into a rat model of myocardial infarction significantly improved cardiac function and reduced fibrosis in the infarcted area. Our single-cell analysis of MCO provided rich information about cell state and fate dynamics in the 3D multilineage microenvironment and brought new insight into the molecular mechanism that promotes cardiomyocyte maturation and heart repair.

Bone Marrow Mesenchymal Stem Cell-Derived Exosomal microRNA-29b-3p Promotes Angiogenesis and Ventricular Remodeling in Rats with Myocardial Infarction by Targeting ADAMTS16.

An increasing amount of evidence has suggested that microRNA (miR) plays a role in myocardial infarction (MI). Our study aimed to discuss the impact of exosomal miR-29b-3p in MI by regulating A Disintegrin and Metalloproteinase with Thrombospondin Motifs 16 (ADAMTS16). Exosomes were extracted from bone marrow mesenchymal stem cells (BMSCs). In a rat model of MI, myocardial angiogenesis and ventricular remodeling-related factors, as well as myocardial fibrosis, collagen volume fraction (CVF), capillary density, level of vascular endothelial growth factor (VEGF), and apoptosis of cardiomyocytes, were tested. ADAMTS16 and miR-29b-3p levels in the myocardial tissue of MI rats were tested. miR-29b-3p expression was decreased and ADAMTS16 expression was increased in the myocardial tissue of MI rats. ADAMTS16 was a target gene of miR-29b-3p. Upregulated miR-29b-3p delivered by BMSC-derived exosomes improved myocardial angiogenesis and ventricular remodeling, reduced myocardial fibrosis and CVF, increased capillary density and VEGF expression, and suppressed apoptosis of cardiomyocytes in MI rats. ADAMTS16 overexpression accelerated MI in rats, and ADAMTS16 upregulation reversed the protective effects of miR-29b-3p upregulation on MI rats. Our study provides evidence that upregulated miR-29b-3p delivered by BMSC-secreted exosomes can improve myocardial angiogenesis and ventricular remodeling in rats with MI by targeting ADAMTS16.

Anchored-PKA regulates connexin-43 gap junction communication in the heart

Cardiac connexin-43 (Cx43) forms gap junction (GJ) channels at the intercalated discs (ID) of cardiomyocytes ensuring anisotropic action potential (AP) propagation. This process is essential for sequential and coordinated contraction of the heart. Stimulation of β-adrenergic receptors activates protein kinase A (PKA), which in turn increases electrical conduction velocity. Myocardial infarction (MI) is characterized by a prolonged ischemia leading to irreversible ventricular cardiomyocytes death and impaired cardiac function. To compensate this loss, chronic activation of PKA signaling is established. In addition, post-MI, Cx43 subcellular localization is altered affecting GJ communication and AP propagation leading to uncoordinated contractions and fatal arrhythmias. Considering the key role of Cx43 and PKA signaling in AP propagation, we investigated the potential regulation of GJ communication by PKA under cardiac physiological condition and post-MI. First, we assessed Cx43 phosphorylation with PKA specific inhibition and with a peptide displacing PKA anchoring from A-Kinase Anchoring Protein (AKAPs). Then, we identified the ezrin as the AKAP mediated the regulation of Cx43 phosphorylation by immunoprecipitation, immunofluorescence and siRNA mediated knockdown experiments. We assessed by functional GAP-FLIP experiments the key role of ezrin-PKA complex in the regulation of intercellular communication. Finally, we generated a left anterior descending coronary artery model of MI in rats to evaluate by proximity ligation assay and western blot experiments the Cx43-ezrin-PKA complex localization and expression. We point that ezrin forms a supramolecular complex with PKA and Cx43 at the ID of cardiomyocytes. Ezrin regulates Cx43 phosphorylation and GJ communication in cardiomyocytes. Interestingly, post-MI we noticed a significant reduction in Cx43 level and phosphorylation associated with a decrease in proximity with ezrin at the ID. Our data identified a cardiac PKA-ezrin-Cx43 complex regulating Cx43 phosphorylation, and therefore, GJ communication. In addition, we reported a loss of proximity between ezrin and Cx43 post-MI. We proposed that this may explain partly an impaired AP propagation leading to uncoordinated contractions post MI.

A1 and A2b adenosine receptors regulate GPX4 against ferroptosis of cardiomyocytes in myocardial infarction rat model and in vitro

AimThe regulation of GPX4 by A1AR and A2bAR was investigated, and whether the inhibition of A1AR and A2bAR on ferroptosis of myocardial cell is related to GPX4 was also discussed. Methodswe constructed a rat model of myocardial ischemia and reperfusion (MIR) model and hypoxia/reoxygenation (H/R) model of H9C2 cells, and MIR rats were intraperitoneally injected with A1AR and A2bAR agonists and antagonists. TTC staining, DHE, TUNEL, western blot experiments, immunohistochemistry assay were implemented to analyze the influence of A1AR and A2bAR on ferroptosis and potential role of GPX4. To further authenticate the result of non-specific agonists and antagonists, we transfected siRNA interference or overexpression vectors into cells. CCK8, flow cytometry and western blot were performed to evaluate cell proliferation and apoptosis, and the expression of GPX4 and ferroptosis-related proteins. ResultsThe experimental results showed that reduced expression of A1AR, A2bAR and GPX4 was found after MIR. A1AR and A2bAR activation by agonists increased GPX4 expression and decreased production of lipid ROS, further inhibiting apoptosis of cardiomyocytes. In addition, we also analyzed the effect of A1AR and A2bAR on ferroptosis-related proteins. We found that expression of FIH1 protein increased and expression of ACSL4 and NOX1 proteins decreased. Consistent with results in vivo, cellular data also indicated that A1AR and A2bAR overexpression could increase proliferation ability of H9C2, and inhibit apoptosis and ROS production, upregulate GPX4 and FIH1, and downregulate ACSL4 and NOX1. ConclusionA1AR and A2bAR could regulate GPX4, thereby affecting ferroptosis of cardiomyocytes in a rat model of MIR.

Autologous Bone Marrow Mononuclear Cells (BMMC)-Associated Anti-Inflammatory Nanoparticles for Cardiac Repair after Myocardial Infarction.

To investigate the effect of transplantation of stem cells from the bone marrow mononuclear cells (BMMC) associated with 15d-PGJ2-loaded nanoparticles in a rat model of chronic MI. Chronic myocardial infarction (MI) was induced by the ligation of the left anterior descending artery in 40 male Wistar rats. After surgery, we transplanted bone marrow associated with 15d-PGJ2-loaded nanoparticle by intramyocardial injection (106 cells/per injection) seven days post-MI. Myocardial infarction was confirmed by echocardiography, and histological analyses of infarct morphology, gap junctions, and angiogenesis were obtained. Our results from immunohistochemical analyses demonstrated the presence of angiogenesis identified in the transplanted region and that there was significant expression of connexin-43 gap junctions, showing a more effective electrical and mechanical integration of the host myocardium. This study suggests that the application of nanoparticle technology in the prevention and treatment of MI is an emerging field and can be a strategy for cardiac repair.

Extracellular vesicles derived from human bone marrow mesenchymal stem cells protect rats against acute myocardial infarction-induced heart failure

Extracellular vesicles (EVs) derived from human bone marrow mesenchymal stem cells (BMSCs) are suggested to promote angiogenesis in a rat model of acute myocardial infarction (AMI). This study aimed to explore the underlying mechanism of BMSCs-EVs in AMI-induced heart failure (HF). BMSCs were isolated and verified, and EVs were purified and identified. After establishment of AMI-induced HF models, rats were treated with BMSCs-EVs and/or overexpressing (ov)/knocking down (kd) bone morphogenetic protein 2 (BMP2). Cardiac function, myocardial histopathological changes, angiogenesis, and vascular regeneration density were measured. Levels of pro-angiogenesis factors and cardiomyocyte apoptosis were detected. The viability and angiogenesis of hypoxic human umbilical vein endothelial cells (HUVECs) were measured. After BMSCs-EV treatment, the cardiac function of HF rats was improved, myocardial fibrosis and inflammatory cell infiltration were decreased, angiogenesis was increased, and cardiomyocyte apoptosis was inhibited. BMP2 was significantly upregulated in themyocardium. Ov-BMP2-BMSCs-EVs alleviated myocardial fibrosis and inflammatory cell infiltration, and promoted angiogenesis of HF rats, and improved the activity and angiogenesis of hypoxic HUVECs, while kd-BMP2-BMSCs-EVs showed limited protection against AMI-induced HF. BMSCs-EVs deliver BMP2 to promote angiogenesis and improve cardiac function of HF rats.

Targeting Circulating lncRNA ENST00000538705.1 Relieves Acute Coronary Syndrome via Modulating ALOX15

Objective Acute coronary syndrome (ACS) is the most dangerous and deadly form of coronary heart disease. Herein, we aimed to explore ACS-specific circulating lncRNAs and their regulatory mechanisms. Methods This study collected serum samples from ACS patients and healthy controls for microarray analysis. Dysregulated circulating lncRNAs and mRNAs were determined with |log2fold − change| > 1 and p < 0.05. lncRNA-mRNA coexpression analysis was carried out. ENST00000538705.1 and ALOX15 expression was further verified in serum specimens. In human coronary artery endothelial cells (HCAECs), ENST00000538705.1 and ALOX15 were knocked out through transfecting specific siRNAs. Thereafter, proliferation and migration were investigated with CCK-8 and wound-healing assays. Myocardial infarction rat models were established and administrated with siRNAs against ENST00000538705.1 or ALOX15. Myocardial damage was investigated with H&E staining, and serum TC, LDL, and HDL levels were measured. Results Microarray analysis identified 353 dysregulated circulating lncRNAs and 441 dysregulated circulating mRNAs in ACS. Coexpression analysis indicated the interaction between ENST00000538705.1 and ALOX15. RT-qPCR confirmed the remarkable upregulation of circulating ENST00000538705.1 and ALOX15 in ACS patients. In HCAECs, ENST00000538705.1 knockdown lowered the expression of ALOX15 but ALOX15 did not alter the expression of ENST00000538705.1. Silencing ENST00000538705.1 or ALOX15 weakened the proliferation and migration of HCAECs. Additionally, knockdown of ENST00000538705.1 or ALOX15 relieved myocardial damage, decreased serum TC and LDL levels, and elevated HDL levels in myocardial infarction rats. Conclusion Collectively, our findings demonstrate that circulating ENST00000538705.1 facilitates ACS progression through modulating ALOX15, which provide potential targets for ACS treatment.

OTUD7B (Cezanne) ameliorates fibrosis after myocardial infarction via FAK-ERK/P38 MAPK signaling pathway

Fibrosis is one of the crucial reasons for cardiac dysfunction after myocardial infarction (MI). Understanding the underlying molecular mechanism that causes fibrosis is crucial to developing effective therapy. Recently, OUT domain-containing 7B (OTUD7B), also called Cezanne, a multifunctional deubiquitylate, has been found to play various roles in cancer and vascular diseases and control many important signaling pathways, including inflammation, proliferation, and so on. However, whether OTUD7B plays a role in fibrosis caused by MI remains unclear. Our study aimed to explore the function of OTUD7B in cardiac fibrosis and investigate the underlying mechanism. We found that the expression of OTUD7B was downregulated in the MI rat model and cultured cardiac fibroblasts (CFs) in hypoxic conditions and after TGF-β1 treatment. In vitro, silencing OTUD7B using small interfering RNA (siRNA) increased α-SMA (smooth muscle actin α) and collagen Ⅰ levels in CFs, whereas the overexpression of OTUD7B using adenovirus decreased their expression. Mechanistically, OTUD7B could regulate the phosphorylation of focal adhesion kinase (FAK), a non-receptor tyrosine kinase that has been proved to act as a potential mediator of fibrosis, and ERK/P38 MAPK was involved in this regulation process. In vitro, overexpression of OTUD7B downregulated the phosphorylation level of FAK and then inhibited ERK/P38 phosphorylation, thus leading to decreased α-SMA and collagen Ⅰ expressions, while OTUD7B knockdown showed an opposite result. These findings suggest that OTUD7B could become a potentially effective therapeutic strategy against fibrosis after MI.

Pre-transplantation of Bone Marrow Mesenchymal Stem Cells Amplifies the Therapeutic Effect of Ultrasound-Targeted Microbubble Destruction-Mediated Localized Combined Gene Therapy in Post-Myocardial Infarction Heart Failure Rats.

Although stem cell transplantation and single-gene therapy have been intensively discussed separately as treatments for myocardial infarction (MI) hearts and have exhibited ideal therapeutic efficiency in animal models, clinical trials turned out to be disappointing. Here, we deliver sarcoplasmic reticulum Ca2+-ATPase 2a (SERCA2a) and connexin 43 (Cx43) genes simultaneously via an ultrasound-targeted microbubble destruction (UTMD) approach to chronic MI hearts that have been pre-treated with bone marrow mesenchymal stem cells (BMSCs) to amplify cardiac repair. First, biotinylated microbubbles (BMBs) were fabricated, and biotinylated recombinant adenoviruses carrying the SERCA2a or Cx43 gene were conjugated to the surface of self-assembled BMBs to form SERCA2a-BMBs, Cx43-BMBs or dual gene-loaded BMBs. Then, the general characteristics of these bubbles, including particle size, concentration, contrast signal and gene loading capacity, were examined. Second, a rat myocardial infarction model was created by ligating the left anterior descending coronary artery and injecting BMSCs into the infarct and border zones. Four weeks later, co-delivery of SERCA2a and Cx43 genes to the infarcted heart were delivered together to the infarcted heart using the UTMD approach. Cardiac mechano-electrical function was determined 4 wk after gene transfection, and the infarcted hearts were collected for myocardial infarct size measurement and detection of expression of SERCA2a, Cx43 and cardiac-specific markers. Finally, to validate the role of BMSC transplantation, MI rats transplanted or not with BMSCs were transfected with SERCA2a and Cx43, and the cardiac mechano-electrical function of these two groups of rats was recorded and compared. General characteristics of the self-assembled gene-loaded BMBs were qualified, and the gene loading rate was satisfactory. The self-assembled gene-loaded BMBs were in microscale and exhibit satisfactory dual-gene loading capacity. High transfection efficiency was achieved under ultrasound irradiation in vitro. In addition, rats in which SERCA2a and Cx43 were overexpressed simultaneously had the best contractile function and electrical stability among all experimental groups. Immunofluorescence assay revealed that the levels of SERCA2a and/or Cx43 proteins were significantly elevated, especially in the border zone. Moreover, compared with rats that did not receive BMSCs, rats pre-treated with BMSCs have better mechano-electrical function after transfection with SERCA2a and Cx43. Collectively, we report a promising cardiac repair strategy for post-MI hearts that exploits the providential advantages of stem cell therapy and UTMD-mediated localized co-delivery of specific genes.

A novel soluble epoxide hydrolase vaccine protects murine cardiac muscle against myocardial infarction

Myocardial infarction is still a life-threatening disease, even though its prognosis has been improved through the development of percutaneous coronary intervention and pharmacotherapy. In addition, heart failure due to remodeling after myocardial infarction requires lifelong management. The aim of this study was to develop a novel treatment suppressing the myocardial damage done by myocardial infarction. We focused on inhibition of soluble epoxide hydrolase to prolong the activation of epoxyeicosatrienoic acids, which have vasodilatory and anti-inflammatory properties. We successfully made a new vaccine to inactivate soluble epoxide hydrolase, and we have evaluated the effect of the vaccine in a rat myocardial infarction model. In the vaccinated group, the ischemic area was significantly reduced, and cardiac function was significantly preserved. Vaccine treatment clearly increased microvessels in the border area and suppressed fibrosis secondary to myocardial infarction. This soluble epoxide hydrolase vaccine is a novel treatment for improving cardiac function following myocardial infarction.

PM2.5 Exposure Lowers Mitochondrial Endurance During Cardiac Recovery in a Rat Model of Myocardial Infarction.

Many studies have reported the negative effect of PM2.5exposure on heart function which is likely to impair postcardiac surgery rehabilitation that is involved in recovery and wound healing, yet the direct effects ofPM2.5from diesel exhaust (DPM)on cardiac recovery is unknown.To study the impact ofDPM on cardiac recovery and repair, we utilized isoproterenol induced myocardial infarction (MI) model where female rats were exposed to DPM prior and after MI induction. The experimental groups comprise of normal, ISO control, DPM control (42days of exposure), DPM exposed prior (21days) and after (21days) MI induction (D + I + D) and DPM exposed (21days) after MI (I + D). Post-MI rat hearts from D + I + D group exhibited higher fibrosis, elevated cardiac injury and altered electrophysiology, where this pathology was also observed in I + D group animals which was mild.Loss of mitochondrial quality was evidentin DPM exposed animals with and without MI, where severe mitochondrial damage persisted in D + I + D group. In addition, these animals showed strikingdecline in ETC enzyme activity, ATP levels, mitochondrial copy number and down regulation of PGC1-α, TFAM and POLGalong with thegenes involved in mitophagy and mitofusion. Besides, the MI associated inactivation of cardio protective signalling pathways like PI3K and Akt were persistent in D + I + D group. In fact, I + D group animals also showed a similar pattern of change, but in a mild form. Taken together, exposure to PM2.5increases the risk, frequency or progression of MI by impairing the recovery potential of the myocardium.

Effect of TLR4/MyD88/NF-kB axis in paraventricular nucleus on ventricular arrhythmias induced by sympathetic hyperexcitation in post-myocardial infarction rats.

Sympathetic activation after myocardial infarction (MI) leads to ventricular arrhythmias (VAs), which can result in sudden cardiac death (SCD). The toll‐like receptor 4 (TLR4)/myeloid differentiation primary response 88 (MyD88)/nuclear factor‐kappa B (NF‐kB) axis within the hypothalamic paraventricular nucleus (PVN), a cardiac‐neural sympathetic nerve centre, plays an important role in causing VAs. An MI rat model and a PVN‐TLR4 knockdown model were constructed. The levels of protein were detected by Western blotting and immunofluorescence, and localizations were visualized by multiple immunofluorescence staining. Central and peripheral sympathetic activation was visualized by immunohistochemistry for c‐fos protein, renal sympathetic nerve activity (RSNA) measurement, heart rate variability (HRV) analysis and norepinephrine (NE) level detection in serum and myocardial tissue measured by ELISA. The arrhythmia scores were measured by programmed electrical stimulation (PES), and cardiac function was detected by the pressure–volume loop (P‐V loop). The levels of TLR4 and MyD88 and the nuclear translocation of NF‐kB within the PVN were increased after MI, while sympathetic activation and arrhythmia scores were increased and cardiac function was decreased. However, inhibition of TLR4 significantly reversed these conditions. PVN‐mediated sympathetic activation via the TLR4/MyD88/NF‐kB axis ultimately leads to the development of VAs after MI.

Serum proteomic analysis reveals the cardioprotective effects of Shexiang Baoxin Pill and Suxiao Jiuxin Pill in a rat model of acute myocardial infarction

Ethnopharmacological relevanceShexiang Baoxin Pill (SBP) and Suxiao Jiuxin Pill (SJP) are traditional Chinese medicines used to treat cardiovascular disease (CVD) in China. However, the mechanism of their therapeutic effect on CVD has not been clearly elucidated yet. AimsThe aim of this study is to investigate the cardioprotective effect of SBP and SJP in the treatment of acute myocardial infarction (AMI) model rats by applying serum proteomic approach. Materials and methodsThe rat model of AMI was generated by ligating the left anterior descending coronary artery. 42 rats were randomly divided into four groups: sham-operating (Sham, n = 10) group, model (Mod, n = 8) group, Shexiang Baoxin pills pretreatment (SBP, n = 12) group and Suxiao Jiuxin pills pretreatment (SJP, n = 12) group. Data Independent Acquisition (DIA) proteomic approach was utilized to investigate the serum proteome from the rat individuals. The differentially expressed proteins were subsequently obtained with bioinformatic analysis. ResultsDIA-MS identified 415 proteins within 42 samples, and 84 differentially expressed proteins may contribute to the therapeutic effects of SBP and SJP. GOBP and KEGG pathway analysis of 84 differentially expressed proteins revealed that the proteins were mainly involved in platelet activation and adhesion processes. All 84 differentially expressed proteins presented the same changing tendency in the SBP and SJP groups when compared with the Mod group. Among these 84 proteins, 25 proteins were found to be related to CVD. Among these 25 proteins, ACTB, ACTG1, FGA, FGB, FGG, PF4 and VWF were found to be involved in platelet aggregation and activation. FN1, HSPA5 and YWHAZ were associated with adhesion. ConclusionsThe results of our study suggest that the cardioprotective effects of SBP and SJP are achieved through the modulation of focal adhesion, platelet activation pathways.

V1-Cal hydrogelation enhances its effects on ventricular remodeling reduction and cardiac function improvement post myocardial infarction.

Myocardial infarction (MI) is a major cause of disability and mortality worldwide. A cell permeable peptide V1-Cal has shown remarkable therapeutic effects on ML However, using V1-Cal to improve long-term cardiac function after MI is presently limited by its short half-life. Herein, we co-assembled V1-Cal with a well-known hydrogelator Nap-Phe-Phe-Tyr (NapFFY) to obtain a new supramolecular hydrogel V1-Cal/NapFFY. We found that the hydrogel could significantly enhance the therapeutic effects of V1-Cal on ventricular remodeling reduction and cardiac function improvement in a myocardial infarction rat model. In vitro experiments indicated that co-assembly of V1-Cal with NapFFY significantly increased mechanic strength of the hydrogel, enabling a sustained release of V1-Cal for more than two weeks. In vivo experiments supported that sustained release of V1-Cal from V1-Cal/NapFFY hydrogel could effectively decrease the expression and activation of TRPV1, reduce apoptosis and the release of inflammatory factors in a MI rat model. In particular, V1-Cal/NapFFY hydrogel significantly decreased infarct size and fibrosis, while improved cardiac function 28 days post MI. We anticipate that V1-Cal/NapFFY hydrogel could be used clinically to treat MI in the near future.