The role of microRNAs in regulating myocardial ischemia reperfusion injury

The role of sirtuins in the regulation of reactive oxygen species in myocardial ischemia/reperfusion injury

Myocardial ischemia/reperfusion (I/R) injury has high morbidity and mortality rates, posing a significant burden on society. There is an urgent need to understand its pathogenesis and develop effective treatments. Reactive oxygen species (ROS) are crucial for the development of myocardial I/R injury, and inhibiting ROS overproduction is one of the most critical ways to delay myocardial I/R injury. Sirtuins are a group of nicotinic adenine dinucleotide ( +)-dependent histone deacetylases whose members can regulate ROS by modulating various biological processes. Numerous studies have shown that Sirtuins play an essential role in the progression of myocardial I/R injury by regulating ROS. This study focuses on the relationship between myocardial I/R injury and ROS, Sirtuins and ROS, discusses the role of Sirtuins in regulating ROS in myocardial I/R, and summarizes the therapeutic modalities aimed at targeting Sirtuins to modulate ROS in myocardial I/R injury, thereby guiding future research endeavors.

The Impact of Opioids on Epigenetic Modulation in Myocardial Ischemia and Reperfusion Injury: Focus on Non-coding RNAs

Myocardial ischemia-reperfusion injury (IRI) is a major issue in cardiovascular medicine, marked by tissue damage from the restoration of blood flow after ischemia. Opioids, known for their pain-relieving properties, have emerged as potential cardioprotective agents in IRI. Recent research suggests opioids influence epigenetic mechanisms-such as histone modifications and non-coding RNAs (ncRNAs)-which are essential for regulating gene expression and cellular responses during myocardial IRI. This review delves into how opioids like remifentanil affect histone modifications, DNA methylation, and ncRNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Remifentanil postconditioning (RPC) reduces apoptosis in cardiomyocytes through histone deacetylation, specifically downregulating histone deacetylase 3 (HDAC3). Similarly, opioids impact miRNAs such as miR- 206 - 3p and miR- 320 - 3p, and lncRNAs like TINCR and UCA1, which influence apoptosis, inflammation, and oxidative stress. Understanding these interactions highlights the potential for opioid-based therapies in mitigating IRI-induced myocardial damage.

Sevoflurane pretreatment alleviates hypoxia-reoxygenation-induced myocardial cell injury by upregulating miR-21-5p

Background

This study investigates the preventive benefits of sevoflurane against myocardial ischemia-reperfusion (I/R) injury, focusing on its effect on the modulation of miR-21-5p.

Methods

In the clinical study, patients with a history of myocardial ischemia or other conditions requiring surgery were enrolled. Before surgery, the patients were anesthetized with either sevoflurane or propofol. The expression levels of IMA, H-FABP, IL-1β, TNF-α, and IL-6 were also examined. Additionally, the expression of miR-21-5p and its relationships with IMA and H-FABP. A cardiomyocyte hypoxia/reoxygenation (H/R) cell model was created for the in vitro tests. The cells were treated with or without sevoflurane and then transfected with inhibitors of miR-21-5p or a negative control (NC). Evaluations were conducted on cell viability, apoptosis ratio, and oxidative stress indicators (MDA, SOD, and ROS). Furthermore, the expression levels of miR-21-5p, apoptotic markers (BCL-2, BAX), myocardial damage markers (IMA, H-FABP), and inflammatory agents (TNF-α, IL-1β, IL-6) were quantified.

Results

In patients with a history of myocardial ischemia, sevoflurane reduced myocardial I/R injury. These patients also showed upregulation of miR-21-5p, which expression positively linked with levels of IMA. Moreover, in H/R treated cardiac cells, sevoflurane markedly reduced the expression of BAX, MDA, ROS, SOD, inflammatory factor and the apoptotic ratio. Nevertheless, inhibition of miR-21-5p abolished these protective effects. Furthermore, in H/R myocardial cells, sevoflurane increased BCL-2 expression and cell survival; these effects were also countered by blocking miR-21-5p.

Conclusion

Mechanistically, we demonstrate for the first time that sevoflurane alleviates myocardial cell injury in myocardial I/R by upregulating miR-21-5p, thereby reducing inflammation, apoptosis, and oxidative stress in myocardial cells. This finding provides a potential therapeutic target for improving myocardial I/R.

miRNA-148a-3p targets to regulate the lipid metabolism gene SOCS3 to reduce myocardial ischemia/reperfusion injury

BACKGROUND

Acute myocardial infarction (AMI) is a major cause of death in cardiovascular patients. SOCS3's protective role in cardiac I/R-I is being explored, and miRNAs, particularly miRNA-148a-3p, are suspected to target SOCS3. To elucidate the role of miRNA-148a-3p targeting lipid metabolism gene SOCS3 in cardiac ischemia-reperfusion injury (I/R-I) in rats.

METHODS

Derived mRNA expression data GSE59867 from GEO, identified 558 lipid metabolism genes from KEGG and GSEA, and screened for differentially expressed genes in acute myocardial infarction (AMI). Predicted miRNA-148a-3p targeting SOCS3 using TargetScanHuman, validated binding via luciferase assay and 3'UTR mutation. Established a rat I/R-I model to assess miRNA-148a-3p and SOCS3 expression, and investigated SOCS3 regulation by miRNA-148a-3p overexpression. Analyzed expression of NF-κB p65, IL-1β, and TNF-α-related proteins, and evaluated cardiac hemodynamics post-SOCS3 regulation by miRNA-148a-3p.

RESULTS

In GSE59867, TSPO, SOCS3, LRP1, PLB1, CYP1B1, PPARG, ACSL1, and CYP27A1 were identified as differentially expressed lipid metabolism genes in AMI. The results of immune infiltration showed a close relationship between the differential lipid metabolism genes and the infiltration of immune cells such as macrophages and monocytes. The random forest algorithm identified SOCS3 as the key gene. The luciferase reporter gene demonstrated the participation of miRNA-148a-3p in the regulation of SOCS3 by binding to its 3'UTR. In vivo experiments revealed low expression of miRNA-148a-3p in myocardial I/R, while SOCS3 was highly expressed. Elevated miRNA-148a-3p expression led to a decrease in SOCS3, NF-κB p65, IL-1β, and TNF-α levels during cardiac I/R-I. Overexpression of miRNA-148a-3p enhanced the cardiac performance in rats experiencing cardiac I/R-I.

CONCLUSIONS

Overexpression of miRNA-148a-3p regulates NF-κB signaling pathway by targeting lipid metabolism gene SOCS3, reduces inflammatory response, and then reduces cardiac I/R-I in rats.

Profiling and bioinformatics analyses of circular RNAs in myocardial ischemia/reperfusion injury model in mice

BACKGROUND

Myocardial ischemia/reperfusion (I/R) injury, which is associated with high morbidity and mortality, is a main cause of unexpected myocardial injury after acute myocardial infarction. However, the underlying mechanism remains unclear. Circular RNAs (circRNAs), which are formed from protein-coding genes, can sequester microRNAs or proteins, modulate transcription and interfere with splicing. Authoritative studies suggest that circRNAs may play an important role in myocardial I/R injury.

AIM

To explore the role and mechanism of circRNAs in myocardial I/R injury.

METHODS

We constructed a myocardial I/R injury model using ligation of the left anterior descending coronary artery, and evaluated the success of the validated model using triphenyltetrazolium chloride and hematoxylin-eosin staining. Then, left ventricular samples from different groups were selected for mRNA-sequence, and differential gene screening was performed on the obtained results. The differentially obtained mRNAs were divided into up-regulated and down-regulated according to their expression levels, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analysis were performed, respectively. Then, the obtained circRNA and microRNA (miRNA) were paired for analysis, and the binding sites of miRNA and mRNA were virtual screened. Finally, the obtained circRNA, miRNA and mRNA were constructed by ceRNA mutual most useful network.

RESULTS

We used an RNA sequencing array to investigate the expression signatures of circRNAs in myocardial I/R injury using three samples from the I/R group and three samples from the sham group. A total of 142 upregulated and 121 downregulated circRNAs were found to be differentially expressed (fold change ≥ 2, P < 0.05). GO and KEGG functional analyses of these circRNAs were performed. GO analysis revealed that these circRNAs were involved mainly in cellular and intracellular processes. KEGG analysis demonstrated that 6 of the top 20 pathways were correlated with cell apoptosis. Furthermore, a circRNA-miRNA coexpression network and ceRNA network based on these genes were constructed, revealing that mmu-circ-0001452, mmu-circ-0001637, and mmu-circ-0000870 might be key regulators of myocardial I/R injury.

CONCLUSION

This research provides new insights into the mechanism of myocardial I/R, which mmu-circ-0001452, mmu-circ-0001637, and mmu-circ-0000870 are expected to be new therapeutic targets for myocardial I/R injury.

Circ_0001084/miR-181c-5p/PTPN4 Axis Mitigates Cardiomyocyte Injury by Modulating the TLR4/NF-κB Pathway: Insights into Therapeutic Potential for Myocardial Reperfusion Injury

Background

Myocardial ischemia/reperfusion (I/R) injury significantly impacts the recovery of ischemic heart disease patients. Non-coding RNAs, including miRNAs, have been increasingly recognized for their roles in regulating cardiomyocyte responses to hypoxia/reoxygenation (H/R) injury. miR-181c-5p, in particular, has been implicated in inflammatory and apoptotic processes, suggesting its potential involvement in exacerbating cellular damage.

Methods

This study combined bioinformatic and experimental techniques to investigate myocardial injury. Gene expression data from the GEO database were analyzed, and HL-1 cardiomyocytes were used in a hypoxia/reoxygenation model to mimic reperfusion injury. Various molecular techniques have been applied to explore the underlying mechanisms, while statistical analyses have identified potential biomarkers and therapeutic targets.

Results

This study revealed significant upregulation of miR-181c-5p in cardiomyocyte H/R injury models, which inversely affected PTPN4 expression and activated the TLR4/NF-κB signaling pathway. Overexpression of PTPN4 inhibited this pathway. Notably, circ_0001084 was identified as absorbing miR-181c-5p, reducing its interaction with PTPN4 and subsequent pathway activation. This suggests a novel therapeutic pathway for myocardial I/R injury treatment, highlighting the interplay between non-coding RNAs and cellular stress responses.

Conclusion

circ_0001084 acts as a competing endogenous RNA for miR-181c-5p, enhancing PTPN4 expression and inhibiting the TLR4/NF-κB signaling pathway. These findings offer insights into the molecular mechanisms of myocardial I/R injury and potential therapeutic targets in ischemic heart disease.

Sevoflurane Affects Myocardial Autophagy Levels After Myocardial Ischemia Reperfusion Injury via the microRNA-542-3p/ADAM9 Axis

This research focused on investigating the effects of sevoflurane (Sev) on myocardial autophagy levels after myocardial ischemia reperfusion (I/R) injury via the microRNA-542-3p (miR-542-3p)/ADAM9 axis. Mice underwent 30 min occlusion of the left anterior descending coronary (LAD) followed by 2 h reperfusion. Cardiac infarction was determined by 2,3,5-triphenyltetrazolium chloride triazole (TTC) staining. Cardiac function was examined by echocardiography. Cardiac markers and oxidative stress factors were evaluated by ELISA. Autophagy-associated factors were detected by western blot. Relationship between miR-542-3p and ADAM9 was tested by dual-luciferase reporter gene assay, RT-qPCR, and western blot. Sev treatment ameliorated cardiac dysfunction, myocardial oxidative stress, and histopathological damages, decreased myocardial infarction size and myocardial apoptotic cells after myocardial I/R injury. Sev treatment elevated miR-542-3p expression and decreased ADAM9 expression in myocardial tissues after myocardial I/R injury. miR-542-3p overexpression could enhance the ameliorative effects of Sev on myocardial injury and myocardial autophagy in I/R mice. miR-542-3p targeted and negatively regulated ADAM9 expression. ADAM9 overexpression reversed the ameliorative effects of miR-542-3p up-regulation on myocardial injury and myocardial autophagy in Sev-treated I/R mice. Sev treatment could ameliorate myocardial injury and myocardial autophagy in I/R mice, mediated by mechanisms that include miR-542-3p up-regulation and ADAM9 down-regulation.

Overexpression of MiR-188-5p Downregulates IL6ST/STAT3/ NLRP3 Pathway to Ameliorate Neuron Injury in Oxygen-glucose Deprivation/Reoxygenation

BACKGROUND

CI/R, characterized by ischemic injury following abrupt reestablishment of blood flow, can cause oxidative stress, mitochondrial dysfunction, and apoptosis. We used oxygen-glucose deprivation/reoxygenation (OGD/R) induced injury in HT22 and primary mouse cortical neurons (MCN) as a model for CI/R.

OBJECTIVE

This study investigates the role of miR-188-5p in hippocampal neuron cell injury associated with Cerebral Ischemia-Reperfusion (CI/R).

METHODS

HT22 and MCN cells were induced by OGD/R to construct an in vitro model of CI/R. Cell apoptosis and proliferation were assessed using flow cytometry and the Cell Counting Kit-8 (CCK8). ELISA was conducted to measure the levels of IL-1β, IL-6, and TNF-α. Moreover, the interaction between miR-188-5p and IL6ST was investigated using dual luciferase assay, the expression of miR-188-5p, Bax, cleaved-caspase3, IL-6, Bcl-2, IL-1β, TNF-α, IL6ST, NFκB, NLRP3 and STAT3 was evaluated using RT-qPCR or Western blot, and immunofluorescence was used to analyze the co-expression of p-STAT3 and NLRP3 in neuronal cells.

RESULTS

OGD/R reduced proliferation and miR-188-5p levels and increased IL6ST expression, inflammation, and apoptosis in HT22 and MCN cells. Moreover, miR-188-5p was found to bind to IL6ST. Mimics of miR-188-5p reduced apoptosis, lowered the expression of cleaved-caspase3 and Bax proteins, and elevated Bcl-2 protein expression in cells treated with OGD/R. Overexpression of miR-188-5p decreased the levels of NLRP3 and p-STAT3 in the OGD/R group. Furthermore, the overexpression of miR-188-5p reduced IL6ST, p- NFκB/NFκB, p-STAT3/STAT3, and NLRP3 proteins in OGD/R, and these effects could be reversed by IL6ST overexpression.

CONCLUSION

Mimics of miR-188-5p were found to inhibit inflammation and the STAT3/NLRP3 pathway via IL6ST, thereby ameliorating injury in HT22 and MCN cells treated with OGD/R in the context of CI/R.

Nanocarriers for gene delivery to the cardiovascular system

Cardiovascular diseases have posed a great threat to human health. Fortunately, gene therapy holds great promise in the fight against cardiovascular disease (CVD). In gene therapy, it is necessary to select the appropriate carriers to deliver the genes to the target cells of the target organs. There are usually two types of carriers, viral carriers and non-viral carriers. However, problems such as high immunogenicity, inflammatory response, and limited loading capacity have arisen with the use of viral carriers. Therefore, scholars turned their attention to non-viral carriers. Among them, nanocarriers are highly valued because of their easy modification, targeting, and low toxicity. Despite the many successes of gene therapy in the treatment of human diseases, it is worth noting that there are still many problems to be solved in the field of gene therapy for the treatment of cardiovascular diseases. In this review, we give a brief introduction to the common nanocarriers and several common cardiovascular diseases (arteriosclerosis, myocardial infarction, myocardial hypertrophy). On this basis, the application of gene delivery nanocarriers in the treatment of these diseases is introduced in detail.

Myocardial ischemia-reperfusion injury; Molecular mechanisms and prevention

Cardiovascular diseases are one of the leading causes of mortality in developed countries. Among cardiovascular disorders, myocardial infarction remains a life-threatening problem predisposing to the development and progression of ischemic heart failure. Ischemia/reperfusion (I/R) injury is a critical cause of myocardial injury. In recent decades, many efforts have been made to find the molecular and cellular mechanisms underlying the development of myocardial I/R injury and post-ischemic remodeling. Some of these mechanisms are mitochondrial dysfunction, metabolic alterations, inflammation, high production of ROS, and autophagy deregulation. Despite continuous efforts, myocardial I/R injury remains a major challenge in medical treatments of thrombolytic therapy, heart disease, primary percutaneous coronary intervention, and coronary arterial bypass grafting. The development of effective therapeutic strategies to reduce or prevent myocardial I/R injury is of great clinical significance.

Dexmedetomidine alleviates myocardial ischemia-reperfusion injury by down-regulating miR-34b-3p to activate the Jagged1/Notch signaling pathway

BACKGROUND

Myocardial ischemia/reperfusion (I/R) injury is a fatal event that usually occurs after reperfusion therapy for myocardial infarction. Dexmedetomidine (Dex) has been shown to be beneficial in the treatment of myocardial infarction, however, its underlying mechanism for regulating I/R injury is unclear.

METHODS

H9c2 cell and rat models of I/R injury were established via oxygen-glucose deprivation reoxygenation (OGD/R) and occlusion of the left anterior descending branch of coronary artery, respectively. Flow cytometry, MTT, or DHE assay detected cell activity, ROS, or apoptosis, respectively. The expression levels of miR-34b-3p and related mRNAs were determined using qRT-PCR. Related protein expression levels were detected by Western blotting and ELISA test. The interaction between miR-34b-3p and Jagged1 was assessed by dual luciferase reporter and RIP assays. The morphology of cardiac tissue was examined by TTC, HE, and TUNEL labeling.

RESULTS

Dex markedly inhibited the inflammatory damage and apoptosis caused by OGD/R in H9c2 cells. MiR-34b-3p and Jagged1 levels were increased and decreased in myocardial I/R injury model, respectively, while Dex reversed this effect. Moreover, miR-34b-3p was firstly reported to directly bind and decrease Jagged1 expression, thereby inhibiting Notch signaling pathway. Transfection of agomiR-34b-3p or Jagged1 silencing eliminated Dex's defensive impact on OGD/R-induced cardiomyocytes damage. Dex relieved the myocardial I/R injury of rats via inhibiting miR-34b-3p and further activating Notch signaling pathway.

CONCLUSION

Dex protected myocardium from I/R injury via suppressing miR-34b-3p to activate Jagged1-mediated Notch signaling pathway. Our findings revealed a novel mechanism underlying of Dex on myocardial I/R injury.

Bone Marrow Mesenchymal Stem Cell Exosomal miR-345-3p Ameliorates Cerebral Ischemia-reperfusion Injury by Targeting TRAF6

INTRODUCTION

The purpose of this study was to investigate the effects of bone marrow mesenchymal stem cells (BMSCs) exosomal miR-345-3p and tumor necrosis factor receptorassociated factor 6 (TRAF6) on cerebral ischemia reperfusion (CIR) injury. Exosomes (Exos) derived from BMSCs were isolated and identified. PC12 (rat pheochromocytoma) cells were used to establish an oxygen and glucose deprivation/reoxygenation (OGD/R) model.

METHODS

Cell counting kit-8, TUNEL staining, lactate dehydrogenase staining, RT-qPCR, and western blotting were utilized for analyzing the functions of miR-345-3p about PC12 cells. Dualluciferase reporter experiment was then to confirm the link between miR-345-3p and TRAF6. Finally, using male SD rats, the middle cerebral artery occlusion (MCAO) model was constructed. Regulation of I/R damage in MCAO rats of miR-345-3p and TRAF6 were further explored in the changes of modified neurological severity score, cerebral infarction pictures, relative infarct volume, and histopathological changes. After OGD/R treatment, neuronal apoptosis was dramatically increased. After treatment with exosomal miR-345-3p, OGD/R-induced neuroapoptosis was dramatically inhibited. Exosomal miR-345-3p inhibited OGD/R-induced neuroapoptosis by downregulating the expression of TRAF6. However, the miR-345-3p inhibitor aggravated the changes caused by OGD/R.

RESULTS

The corresponding regulations of miR-345-3p were reversed with TRAF6 overexpression. The animal experiments in vivo further verified that miR-345-3p ameliorated brain I/R injury in MCAO rats by targeting TRAF6.

CONCLUSION

This study found that BMSCs-exosomal miR-345-3p protected against CIR injury by decreasing TRAF6.

Celastrol assuages oxygen-glucose deprivation and reoxygenation-induced damage in human brain microvascular endothelial cells through the circDLGAP4/miR-6085/GDF11 pathway

The effect of Celastrol on cerebral ischemia-reperfusion remains unknown. The study aims to explore the role of circular RNA DLGAP4 (circDLGAP4) in cerebral ischemia-reperfusion and the underlying mechanism. Ischemia-reperfusion (I/R) injury of human brain microvascular endothelial cells (HBMECs) was induced by oxygen-glucose deprivation and reoxygenation (OGD/R). Reverse transcription quantitative real-time PCR (RT-qPCR) and western blotting analysis were performed to detect the expression of circDLGAP4, microRNA-6085 (miR-6085), growth differentiation factor 11 (GDF11), B-cell lymphoma-2 (BCL2) and BCL2-associated x protein (BAX). Cell viability, proliferation, and apoptosis were analyzed by cell counting kit-8, 5-Ethynyl-2'-deoxyuridine and flow cytometry analysis. Oxidative stress was analyzed by evaluating the levels of Malondialdehyde (MDA) and Reactive Oxygen Species (ROS) and the activity of Superoxide Dismutase (SOD). The associations among circDLGAP4, miR-6085 and GDF11 were identified by dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays. Celastrol reduced OGD/R-induced inhibition of circDLGAP4 expression in HBMECs. Celastrol treatment protected HBMECs from OGD/R-induced cell proliferation inhibition and apoptosis and oxidative stress promotion; however, circDLGAP4 depletion attenuated these effects. CircDLGAP4 acted as a sponge for miR-6085, and miR-6085 mimics restored circDLGAP4-mediated effects in OGD/R-stimulated HBMECs. In addition, GDF11 was identified as a targte of miR-6085, and participated in the regulation of miR-6085 to OGD/R-induced HBMEC damage. Further, circDLGAP4 absence inhibited GDF11 expression by interacting with miR-6085 under Celastrol treatment. Celastrol ameliorated OGD/R-induced HBMEC apoptosis and oxidative stress by circDLGAP4/miR-6085/GDF11 pathway, supporting the use of Celastrol as a therapeutic agent for cerebral infarction.

Research hotspots and development trends of microRNA in ischemia-reperfusion: network analysis of academic journals oriented by bibliometric and visualization

Background

Ischemia-reperfusion (IR) injury can occur in the heart, brain, liver, lung, kidney, and other important organs, and may greatly increase disease mortality. MicroRNAs (miRNAs) have a variety of functions, including regulating cell differentiation, proliferation, and apoptosis. In the past 10 years, many studies on miRNAs in IR have been conducted. This study involved a visual analysis of these studies, and a discussion of research hotspots, trends, and frontiers of this topic.

Methods

A total of 1,518 articles published between 2012 and 2022 on the topic of miRNA and IR and listed in the Web of Science database were analyzed visually using CiteSpace. Cooperative networks, literature citations, and keyword co-occurrence were analyzed.

Results

Of the 1,518 articles, most were published after 2018, and a rapid growth in numbers of publications was seen after 2019. Articles from China numbered the highest, followed by the United States and Canada. It has been found that many miRNAs are involved in the occurrence of IR, with various regulatory mechanisms and signaling pathways. The literature clustering generated by literature co-citation analysis and the keyword co-occurrence network showed that the previous miRNA research on IR had mainly focused on the following topics: myocardial infarction, ischemic stroke, acute kidney injury, oxidative stress, and inflammatory response. More attention has been paid to long noncoding RNA (lncRNA) and exosomes, with much exploration having been conducted in these areas.

Conclusions

Although miRNA is involved in the occurrence and development of IR, as a clinical intervention target for IR, further research is still needed.

Natural emodin reduces myocardial ischemia/reperfusion injury by modulating the RUNX1/miR‑142‑3p/DRD2 pathway and attenuating inflammation

Acute myocardial infarction is one of the leading causes of death worldwide. Although timely reperfusion could attenuate myocardial ischemia injury and reduce mortality, it causes severe secondary injury to the myocardium known as myocardial ischemia/reperfusion injury (MIRI) with unmet clinical needs. Emodin has a protective effect on MIRI in rodents. However, the precise mechanism underlying its pharmacological effect remains poorly understood. Accordingly, the present study used mRNA and microRNA (miRNA) sequencing based on MIRI mouse models to determine the mechanism involved. Emodin was found to prevent MIRI and attenuate the inflammation of myocardium in the MIRI model. In addition, by using an interdisciplinary approach, the present study uncovered that emodin suppressed the runt-related transcription factor 1 (RUNX1), which is a transcription factor of miR-142-3p, in either MIRI or the hypoxia/reoxygenation injury model. Furthermore, miR-142-3p can negatively regulate dopamine receptor D2 (DRD2), which acted as an anti-inflammatory factor to suppress NF-κB-dependent inflammation and prevent MIRI. These results were demonstrated by both cellular hypoxia/reoxygenation and mouse MIRI models. Overall, the present study provided an unrevealed molecular mechanism for emodin function. Emodin could inhibit NF-κB-triggered inflammation in MIRI by regulating the RUNX1/miR-142-3p/DRD2 pathway. Therefore, the RUNX1/miR-142-3p/DRD2 pathway presented a novel target for MIRI treatment, and the application of emodin in clinical practice may improve the treatment of MIRI.

Myocardial infarction from a tissue engineering and regenerative medicine point of view: A comprehensive review on models and treatments

In the modern world, myocardial infarction is one of the most common cardiovascular diseases, which are responsible for around 18 million deaths every year or almost 32% of all deaths. Due to the detrimental effects of COVID-19 on the cardiovascular system, this rate is expected to increase in the coming years. Although there has been some progress in myocardial infarction treatment, translating pre-clinical findings to the clinic remains a major challenge. One reason for this is the lack of reliable and human representative healthy and fibrotic cardiac tissue models that can be used to understand the fundamentals of ischemic/reperfusion injury caused by myocardial infarction and to test new drugs and therapeutic strategies. In this review, we first present an overview of the anatomy of the heart and the pathophysiology of myocardial infarction, and then discuss the recent developments on pre-clinical infarct models, focusing mainly on the engineered three-dimensional cardiac ischemic/reperfusion injury and fibrosis models developed using different engineering methods such as organoids, microfluidic devices, and bioprinted constructs. We also present the benefits and limitations of emerging and promising regenerative therapy treatments for myocardial infarction such as cell therapies, extracellular vesicles, and cardiac patches. This review aims to overview recent advances in three-dimensional engineered infarct models and current regenerative therapeutic options, which can be used as a guide for developing new models and treatment strategies.

miR-542-3p-Targeted PDE4D Regulates cAMP/PKA Signaling Pathway and Improves Cardiomyocyte Injury

Objective

To investigate the protective effect of miR-542-3p on cardiomyocyte injury and related mechanisms.

Methods

A cardiomyocyte hypoxia/reoxygenation model was established. The expression levels of miR-542-3p and PDE4D were detected using qRT-PCR; the luciferase reporter assay system was used to detect the targeting relationship between miR-542-3p and PDE4D; overexpressing miR-542-3p was transfected into cardiomyocytes, and ROS release was detected by immunofluorescence while cellular apoptosis was detected by TUNEL; and the western blot assay was applied to detect the expression of PDE4D, phosphorylated protein kinase A (p-PKA), and phosphorylated cyclic adenosine monophosphate (cAMP) response element-binding protein (p-CREB).

Results

Compared with the control group, the miR-542-3p expression level was decreased and the PDE4D expression level was increased in the cardiomyocyte hypoxia/reoxygenation model group. The dual-luciferase reporter assay system confirmed that miR-542-3p could target and regulate PDE4D; the transfection with cardiomyocytes using the overexpressing miR-542-3p could downregulate PDE4D expression, attenuate ROS release during cardiomyocyte injury, and reduce cellular apoptosis rate, while upregulating the expression of p-PKA and p-CREB.

Conclusion

The miR-542-3p can negatively regulate PDE4D protein expression and attenuate cardiomyocyte injury through a mechanism related to the activation of the cAMP/PKA signaling pathway.

Role of miRNA-1 and miRNA-21 in Acute Myocardial Ischemia-Reperfusion Injury and Their Potential as Therapeutic Strategy

Coronary artery disease remains the leading cause of death. Acute myocardial infarction (MI) is characterized by decreased blood flow to the coronary arteries, resulting in cardiomyocytes death. The most effective strategy for treating an MI is early and rapid myocardial reperfusion, but restoring blood flow to the ischemic myocardium can induce further damage, known as ischemia-reperfusion (IR) injury. Novel therapeutic strategies are critical to limit myocardial IR injury and improve patient outcomes following reperfusion intervention. miRNAs are small non-coding RNA molecules that have been implicated in attenuating IR injury pathology in pre-clinical rodent models. In this review, we discuss the role of miR-1 and miR-21 in regulating myocardial apoptosis in ischemia-reperfusion injury in the whole heart as well as in different cardiac cell types with special emphasis on cardiomyocytes, fibroblasts, and immune cells. We also examine therapeutic potential of miR-1 and miR-21 in preclinical studies. More research is necessary to understand the cell-specific molecular principles of miRNAs in cardioprotection and application to acute myocardial IR injury.

Construction and Analysis of the lncRNA-miRNA-mRNA Network Based on Competing Endogenous RNA in Atrial Fibrillation

Background

Accumulated studies have revealed that long non-coding RNAs (lncRNAs) play critical roles in human diseases by acting as competing endogenous RNAs (ceRNAs). However, functional roles and regulatory mechanisms of lncRNA-mediated ceRNA in atrial fibrillation (AF) remain unknown. In the present study, we aimed to construct the lncRNA-miRNA-mRNA network based on ceRNA theory in AF by using bioinformatic analyses of public datasets.

Methods

Microarray data sets of GSE115574 and GSE79768 from the Gene Expression Omnibus database were downloaded. Twenty-one AF right atrial appendage (RAA) samples and 22 sinus rhythm (SR) subjects RAA samples were selected for subsequent analyses. After merging all microarray data and adjusting for batch effect, differentially expressed genes were identified. Gene Ontology (GO) categories and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were carried out. A ceRNA network was constructed.

Result

A total of 8 lncRNAs and 43 mRNAs were significantly differentially expressed with fold change >1.5 (p < 0.05) in RAA samples of AF patients when compared with SR. GO and KEGG pathway analysis showed that cardiac muscle contraction pathway were involved in AF development. The ceRNA was predicted by co-expressing LOC101928304/ LRRC2 from the constructional network analysis, which was competitively combined with miR-490-3p. The expression of LOC101928304 and LRRC were up-regulated in myocardial tissue of patients with AF, while miR-490-3p was down-regulated.

Conclusion

We constructed the LOC101928304/miR-490-3p/LRRC2 network based on ceRNA theory in AF in the bioinformatic analyses of public datasets. The ceRNA network found from this study may help improve our understanding of lncRNA-mediated ceRNA regulatory mechanisms in the pathogenesis of AF.

Exosomal microRNA-150-5p from bone marrow mesenchymal stromal cells mitigates cerebral ischemia/reperfusion injury via targeting toll-like receptor 5

MicroRNA (miR)-150-5p has been investigated in many studies, while the role of exosomal miR-150-5p from bone arrow mesenchymal stromal cells (BMSCs) on cerebral ischemia/reperfusion (I/R) injury is not fully explored. This research aims to probe the effects of exosomal miR-150-5p from BMSCs on cerebral I/R injury via regulating B-cell translocation gene 2 (TLR5). Bone marrow mesenchymal stem cell-derived exosomes (BMSCs-Exo) were isolated and identified. The middle cerebral artery occlusion (MCAO) rat model was established and treated by BMSCs-Exo. Then, functional assays were conducted to explore neurological function, pathological changes, neuron apoptosis and inflammatory factors in MCAO rats. miR-150-5p and TLR5 expression in rat brain tissues were detected. Then, gain and loss-function assays were conducted to determine the impact of exosomes, miR-150-5p and TLR5 on neurological function, pathological changes, neuron apoptosis and inflammatory factors of MCAO rats. The binding relation between miR-150-5p and TLR5 was validated. It was found that miR-150-5p expression was decreased while TLR5 level was augmented in MCAO rats. BMSCs-Exo could improve neurological function, pathological changes, decelerate neuron apoptosis and reduce inflammatory factors in MCAO rats. Enriched miR-150-5pcould enhance the protective effects of BMSCs-Exo on cerebral I/R injury. The elevated TLR5 reversed the impacts of elevated exosomal miR-150-5p on cerebral I/R injury. TLR5 was targeted by miR-150-5p. This research manifested that exosomal miR-150-5p from BMSCs exerts protective effects on cerebral I/R injury via repressing TLR5. This study provided novel therapeutic targets for the treatment of cerebral I/R injury.

Overexpression of miR-1298 attenuates myocardial ischemia-reperfusion injury by targeting PP2A

Previous studies reported that microRNA-1298 was abnormally expressed in the myocardium of rat hearts after hypoxia/normoxia injury. This study aims to investigate the function and specific mechanism of miR-1298 in myocardial ischemia/reperfusion (IR) injury. Neonatal rat cardiomyocytes (NRCMs) were isolated from neonatal rat hearts and subjected to oxygen/glucose deprivation/reperfusion (OGD/R) to induce I/R injury. The rat model with I/R injury was induced by ligating the proximal left anterior descending artery (LAD). MiR-1298 expression was detected by qRT-PCR. The levels of PP2A, Bcl-2, Bax, and AMPK signaling members (p-AMPK, p-GSK3β) was detected by Western blot. Cell apoptosis was evaluated by TUNEL staining assay and flow cytometry. The infarct size of rat hearts was assessed by TTC staining assay. Premature and mature MiR-1298 were significantly downregulated while PP2A was significantly upregulated during I/R injury both in vitro and in vivo. The prediction of Starbase suggested that PP2A was a potential target of miR-1298. MiR-1298 overexpression significantly reduced cardiomyocyte apoptosis in vitro, and its protective effect was obviously attenuated by PP2A overexpression. Luciferase reporter assay showed that miR-1298 targeted PP2A directly. In addition, miR-1298 overexpression significantly reduced infarct size and cardiomyocyte apoptosis in the hearts of rats received with I/R injury in vivo. Moreover, miR-1298 overexpression significantly elevated the levels of Bcl-2 and AMPK signaling members (p-AMPK, p-GSK3β) while decreased Bax level, and these effects were partially reversed by PP2A overexpression. MiR-1298 participated in myocardial I/R injury by targeting the PP2A/AMPK/GSK3β signaling pathway, suggesting that miR-1298 might be a potential therapeutic target for myocardial I/R injury.

Isoflurane and low-level carbon monoxide exposures increase expression of pro-survival miRNA in neonatal mouse heart

Anesthetics such as isoflurane are known to cause apoptosis in the developing mammalian brain. However, isoflurane may have protective effects on the heart via relieving ischemia and downregulating genes related to apoptosis. Ischemic preconditioning, e.g. through the use of low levels of carbon monoxide (CO), has promise in preventing ischemia-reperfusion injury and cell death. However, it is still unclear how it either triggers the stress response in neonatal hearts. For this reason, thirty-three microRNAs (miRNAs) known to be differentially expressed following anesthesia and/or ischemic or hypoxic heart damage were investigated in the hearts from neonatal mice exposed to isoflurane or low level of CO, using an air-exposed control group. Only miR-93-5p increased with isoflurane exposure, which may be associated with the suppression of cell death, autophagy, and inflammation. By contrast, twelve miRNAs were differentially expressed in the heart following CO treatment. Many miRNAs previously shown to be responsible for suppressing cell death, autophagy, and myocardial hypertrophy were upregulated (e.g., 125b-3p, 19-3p, and 21a-5p). Finally, some miRNAs (miR-103-3p, miR-1a-3p, miR-199a-1-5p) which have been implicated in regulating energy balance and cardiac contraction were also differentially expressed. Overall, this study demonstrated that CO-mediated miRNA regulation may promote ischemic preconditioning and cardioprotection based on the putative protective roles of the differentially expressed miRNAs explored herein and the consistency of these results with those that have shown positive effects of CO on heart viability following anesthesia and ischemia-reperfusion stress.

Silencing of SNHG6 alleviates hypoxia/reoxygenation-induced cardiomyocyte apoptosis by modulating miR-135a-5p/HIF1AN to activate Shh/Gli1 signalling pathway

OBJECTIVES

To examine the effects of small nucleolar RNA host gene 6 (SNHG6) on apoptosis during myocardial ischemic/reperfusion (I/R) injury and its potential molecular mechanisms.

METHODS

In vitro model of I/R was built through exposing mouse HL-1 cardiomyocytes to hypoxia/reoxygenation (H/R) treatment. Quantitative real-time polymerase chain reaction assays were performed to determine gene expression. Cell Counting Kit-8, flow cytometric and western blot assays were conducted to detect cell viability, apoptosis and protein expression. Lactate dehydrogenase (LDH) activity was examined by a commercial detection kit. Dual-luciferase gene reporter and RNA immunoprecipitation experiments were applied for determining the interaction between the molecules.

KEY FINDINGS

SNHG6 expression was increased in H/R-challenged cardiomyocytes. Depletion of SNHG6 protected against H/R-induced cardiomyocytes apoptosis. SNHG6 could sponge miR-135a-5p to inhibit its expression. Down-regulation of miR-135a-5p reversed the anti-apoptotic effect caused by SNHG6 knockdown in H/R-induced cardiomyocytes. Hypoxia inducible factor 1 subunit alpha inhibitor (HIF1AN) was identified as a direct target of miR-135a-5p, and knockdown of HIF1AN relieved H/R-induced cardiomyocytes apoptosis. Silencing of SNHG6 activated Shh/Gli1 signalling pathway by regulating miR-135a-5p/HIF1AN. Furthermore, inactivation of Shh/Gli signalling abolished the anti-apoptotic effects of SNHG6 knockdown in H/R-induced cardiomyocytes.

CONCLUSIONS

SNHG6 serves as a sponge for miR-135a-5p to promote HIF1AN expression and inactivate Shh/Gli1 signalling, eventually aggravating H/R-induced apoptosis in cardiomyocytes.

miR-362-3p Targets Orosomucoid 1 to Promote Cell Proliferation, Restrain Cell Apoptosis and Thereby Mitigate Hypoxia/Reoxygenation-Induced Cardiomyocytes Injury

This study aimed to investigate the mechanism of how miR-362-3p/orosomucoid 1 (ORM1) involved in hypoxia/reoxygenation (H/R)-induced cardiomyocytes injury. Based on data obtained from Gene Expression Omnibus (GEO) database, we revealed that ORM1 was highly expressed and positively correlated with the expression of inflammatory factors (MAPK1, MAPK3, IL1B and CASP9). miR-362-3p was identified as an upstream regulatory miRNA of ORM1 and negatively modulated the mRNA and protein expression levels of ORM1 in H/R-injured cardiomyocytes. Moreover, we found that miR-362-3p was downregulated in cardiomyocytes injured by H/R. The promoting influence of miR-362-3p mimic on the proliferation and the inhibitory effect of miR-362-3p mimic on the apoptosis of H/R-stimulated cardiomyocytes were eliminated by overexpression of ORM1. Furthermore, miR-362-3p affected the expression of MAPK1, MAPK3, IL1B and CASP9 in H/R-injured cardiomyocytes through targeting ORM1. Our outcomes illustrated that miR-362-3p exhibited a protective influence on H/R-induced cardiomyocytes through targeting ORM1.

MiR-21 mediates the protection of kaempferol against hypoxia/reoxygenation-induced cardiomyocyte injury via promoting Notch1/PTEN/AKT signaling pathway

Kaempferol, a natural flavonoid compound, possesses potent myocardial protective property in ischemia/reperfusion (I/R), but the underlying mechanism is not well understood. The present study was aimed to explore whether miR-21 contributes to the cardioprotective effect of kaempferol on hypoxia/reoxygenation (H/R)-induced H9c2 cell injury via regulating Notch/phosphatase and tensin homologue (PTEN)/Akt signaling pathway. Results revealed that kaempferol obviously attenuates H/R-induced the damages of H9c2 cells as evidence by the up-regulation of cell viability, the down-regulation of lactate dehydrogenase (LDH) activity, the reduction of apoptosis rate and pro-apoptotic protein (Bax) expression, and the increases of anti-apoptotic protein (Bcl-2) expression. In addition, kaempferol enhanced miR-21 level in H9c2 cells exposed to H/R, and inhibition of miR-21 induced by transfection with miR-21 inhibitor significantly blocked the protection of kaempferol against H/R-induced H9c2 cell injury. Furthermore, kaempferol eliminated H/R-induced oxidative stress and inflammatory response as illustrated by the decreases in reactive oxygen species generation and malondialdehyde content, the increases in antioxidant enzyme superoxide dismutase and glutathione peroxidase activities, the decreases in pro-inflammatory cytokines interleukin (IL)-1β, IL-8 and tumor necrosis factor-alpha levels, and an increase in anti-inflammatory cytokine IL-10 level, while these effects of kaempferol were all reversed by miR-21 inhibitor. Moreover, results elicited that kaempferol remarkably blocks H/R-induced the down-regulation of Notch1 expression, the up-regulation of PTEN expression, and the reduction of P-Akt/Akt, indicating that kaempferol promotes Notch1/PTEN/AKT signaling pathway, and knockdown of Notch1/PTEN/AKT signaling pathway induced by Notch1 siRNA also abolished the protection of kaempferol against H/R-induced the damage of H9c2 cells. Notably, miR-21 inhibitor alleviated the promotion of kaempferol on Notch/PTEN/Akt signaling pathways in H9c2 cells exposed to H/R. Taken together, these above findings suggested thatmiR-21 mediates the protection of kaempferol against H/R-induced H9c2 cell injuryvia promoting Notch/PTEN/Akt signaling pathway.

MicroRNA‑494 suppresses hypoxia/reoxygenation‑induced cardiomyocyte apoptosis and autophagy via the PI3K/AKT/mTOR signaling pathway by targeting SIRT1

Acute myocardial infarction can be caused by ischemia/reperfusion (I/R) injury; however, the mechanism underlying I/R is not completely understood. The present study investigated the functions and mechanisms underlying microRNA (miR)-494 in I/R-induced cardiomyocyte apoptosis and autophagy. Hypoxia/reoxygenation (H/R)-treated H9c2 rat myocardial cells were used as an in vitro I/R injury model. Apoptosis and autophagy were analyzed by Cell Counting Kit-8 assay, Lactic dehydrogenase and superoxide dismutase assay, flow cytometry, TUNEL staining and western blotting. Reverse transcription-quantitative PCR demonstrated that, H9c2 cells treated with 12 h hypoxia and 3 h reoxygenation displayed significantly downregulated miR-494 expression levels compared with control cells. Compared with the corresponding negative control (NC) groups, miR-494 mimic reduced H/R-induced cell apoptosis and autophagy, whereas miR-494 inhibitor displayed the opposite effects. Silent information regulator 1 (SIRT1) was identified as a target gene of miR-494. Furthermore, miR-494 inhibitor-mediated effects on H/R-induced cardiomyocyte apoptosis and autophagy were partially reversed by SIRT1 knockdown. Moreover, compared with si-NC, SIRT1 knockdown significantly increased the phosphorylation levels of PI3K, AKT and mTOR in H/R-treated and miR-494 inhibitor-transfected H9c2 cells. Collectively, the results indicated that miR-494 served a protective role against H/R-induced cardiomyocyte apoptosis and autophagy by directly targeting SIRT1, suggesting that miR-494 may serve as a novel therapeutic target for myocardial I/R injury.

Down-regulating miR-217-5p Protects Cardiomyocytes against Ischemia/Reperfusion Injury by Restoring Mitochondrial Function via Targeting SIRT1

Downregulating miR-217-5p could protect cardiomyocytes against ischemia/reperfusion (I/R) injury, but its role in restoring mitochondrial function of I/R-injured cardiomyocytes remained unclear. H9C2 cardiomyocyte-derived cell line with I/R injury was established in vitro on the basis of hypoxia/reperfusion (H/R) model. Cell viability and apoptosis were respectively detected by MTT assay and flow cytometry. Contents of lactate dehydrogenase (LDH) and adenosine triphosphate (ATP) were determined. Flow cytometry was performed to measure the production of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP). Target gene and potential binding sites between miR-217-5p and Sirtuin1 (SIRT1) were predicted by TargetScan and confirmed by dual-luciferase reporter assay. Relative SIRT1 and expressions of autophagy-related and apoptosis-related genes were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. After I/R treatment, the viability of H9C2 cardiomyocyte-derived cell line and ATP contents were reduced, but LDH and ROS contents were increased, at the same time, cell apoptosis and the expressions of miR-217-5p, p62 and cleaved caspase-3 were increased, whereas the expressions of SIRT1, LC3 (light chain 3), PINK1 (PTEN-induced kinase 1), Parkin, Bcl-2, and c-IAP (inhibitor of apoptosis protein) were reduced. However, downregulating miR-217-5p expression reversed the effects of I/R. SIRT1 was predicted and verified to be the target of miR-217-5p, and silencing SIRT1 reversed the effects of downregulating miR-217-5p on I/R-injured cells. Downregulating miR-217-5p could help restore mitochondrial function via targeting SIRT1, so as to protect cardiomyocytes against I/R-induced injury.

Inhibition of Rho-kinase is involved in the therapeutic effects of atorvastatin in heart ischemia/reperfusion

The aim of the present study was to investigate the effects of atorvastatin against heart ischemia/reperfusion (I/R) injury and its potential underlying mechanism. Rats were allocated into the following groups: Sham, I/R, atorvastatin (10 mg/kg daily), fasudil (10 mg/kg daily) and atorvastatin + fasudil in combination. Drugs were administered for 2 weeks prior to I/R injury. I/R was established by ligating the left anterior descending branch (LAD) for 30 min and releasing the ligature for 180 min. The I/R group was found to have increased myocardial infarct size, cardiomyocyte apoptosis, levels of plasma interleukin (IL)-6 and tumor necrosis factor (TNF)-α, superoxide dismutase (SOD) activity, malondialdehyde (MDA) levels and Rho-kinase activity compared with the other treatment groups (P<0.05). Moreover, pretreatment with atorvastatin significantly attenuated Rho-kinase activity, myocardial infarct size, cardiomyocyte apoptosis, levels of plasma IL-6 and TNF-α, SOD activity and MDA levels, and upregulated nitric oxide production. It was also indicated that the specific Rho-kinase inhibitor, fasudil, had the same effects as atorvastatin in I/R. Therefore, the present results suggested atorvastatin may lead to cardiovascular protection, which may be mediated by Rho-kinase inhibition in heart I/R injury.

Non-coding RNAs and Ischemic Cardiovascular Diseases

The Ischemic Heart Disease (IHD) is considered a clinical condition characterized by myocardial ischemia causing an imbalance between myocardial blood supply and demand, leading to morbidity and mortality across the worldwide. Prompt diagnostic and prognostic represents key factors for the treatment and reduction of the mortality rate. Therefore, one of the newest frontiers in cardiovascular research is related to non-coding RNAs (ncRNAs), which prompted a huge interest in exploring ncRNAs candidates for utilization as potential therapeutic targets for diagnostic and prognostic and/or biomarkers in IHD. However, there are undoubtedly many more functional ncRNAs yet to be discovered and characterized. Here we will discuss our current knowledge and we will provide insight on the roles and effects elicited by some ncRNAs related to IHD.

Non-coding RNAs participate in the ischemia-reperfusion injury

Ischemia, being defined as blood supply deficiency is involved in the pathogenesis of a number of life-threatening conditions such as myocardial infarction and cerebral stroke. Assessment of the molecular pathology of these conditions has led to identification of the role of reperfusion in induction and aggravation of tissue injury and necrosis. Thus, the term "ischemia/ reperfusion (I/R) injury" has been introduced. This process involves aberrant regulation of the mitochondrial function, apoptotic and autophagic pathways and signal transducers. More recently, non-coding RNAs including long non-coding RNAs (lncRNAs) ad microRNAs (miRNAs) have been shown to influence I/R injury. Animal studies and clinical investigations have shown up-/down-regulation of tens of lncRNAs and miRNAs in this process. In the current study, we summarize the role of these transcripts in the pathophysiology of I/R injury and their potential as biomarkers for detection of extent of tissue injury.

Targeting the MicroRNA-490-3p-ATG4B-Autophagy Axis Relieves Myocardial Injury in Ischemia Reperfusion

We investigated the potential role of miR-490-3p in ischemia reperfusion (IR) injury. We first determined the expression of miR-490-3p and autophagy-related 4B cysteine (ATG4B) in IR. Then, to explore whether miR-490-3p would affect autophagy, apoptosis, and IR injury, we evaluated apoptosis, autophagy, and infarct size via gain- and loss-of-function experiments. Furthermore, we used adenovirus to enhance or inhibit the expression of ATG4B, and then measured autophagy, apoptosis, and IR injury. miR-490-3p was downregulated in the hearts during the process of IR, while ATG4B was upregulated. The inhibition of miR-490-3p or overexpression of ATG4B could promote the expression of LC3II, increase the autolysosomes, inhibit the expression of p62, and reduce infarct size. On all accounts, the inhibition of miR-490-3p could promote autophagy to reduce myocardial IR injury by upregulating ATG4B, a finding that provides new insights for the protective mechanism of autophagy in IR. Graphical Abstract.

Rno-microRNA-30c-5p promotes myocardial ischemia reperfusion injury in rats through activating NF-κB pathway and targeting SIRT1

Background

This study aimed to investigate the regulatory effect of rno-microRNA-30c-5p (rno-miR-30c-5p) on myocardial ischemia reperfusion (IR) injury in rats and the underlying molecular mechanisms.

Methods

A rat model of myocardial IR injury was established. The infarct size was detected by 2,3,5-triphenyltetrazolium chloride staining. The pathologic changes of myocardial tissues were detected by hematoxylin-eosin staining. The apoptosis of myocardial cells was measured by TUNEL staining and flow cytometry. The mRNA expression of rno-miR-30c-5p and Sirtuin 1 (SIRT1) was detected by quantitative real-time PCR. The levels of IL-1β, IL-6 and TNF-α were detected by enzyme linked immunosorbent assay. The protein expression of Bax, Bcl-2, caspase-3, p-IκBα, IκBα, p-NF-κB p65, NF-κB p65 and SIRT1 was detected by Western blot. The interaction between rno-miR-30c-5p and SIRT1 was predicted by TargetScan, and further identified by dual luciferase reporter gene and RNA immunoprecipitation assay.

Results

The myocardial IR injury model was successfully established in rats. IR induced the myocardial injury in rats and increased the expression of rno-miR-30c-5p. Overexpression of rno-miR-30c-5p enhanced the inflammation, promoted the apoptosis, and activated NF-κB pathway in IR myocardial cells. SIRT1 was the target gene of rno-miR-30c-5p. Silencing of SIRT1 reversed the effects of rno-miR-30c-5p inhibitor on the apoptosis and NF-κB pathway in IR myocardial cells.

Conclusions

Rno-miR-30c-5p promoted the myocardial IR injury in rats through activating NF-κB pathway and down-regulating SIRT1.

The Role of Non-coding RNAs in Ischemic Myocardial Reperfusion Injury

MicroRNAs (miRNA) are non-coding RNAs that regulate gene expression in up to 90% of the human genome through interactions with messenger RNA (mRNA). The expression of miRNAs varies and changes in diseased and healthy states, including all stages of myocardial ischemia-reperfusion and subsequent ischemia-reperfusion injury (IRI). These changes in expression make miRNAs an attractive potential therapeutic target. Herein, we review the differences in miRNA expression prior to ischemia (including remote ischemic conditioning and ischemic pre-conditioning), the changes during ischemia-reperfusion, and the changes in miRNA expression after IRI, with an emphasis on inflammatory and fibrotic pathways. Additionally, we review the effects of manipulating the levels of certain miRNAs on changes in infarct size, inflammation, remodeling, angiogenesis, and cardiac function after either ischemia-reperfusion or permanent coronary ligation. Levels of target miRNA can be increased using molecular mimics ("agomirs"), or can be decreased by using "antagomirs" which are antisense molecules that act to bind and thus inactivate the target miRNA sequence. Other non-coding RNAs, including long non-coding RNAs and circular RNAs, also regulate gene expression and have a role in the regulation of IRI pathways. We review the mechanisms and downstream effects of the miRNAs that have been studied as therapy in both permanent coronary ligation and ischemia-reperfusion models.

Exosome Derived from Coronary Serum of Patients with Myocardial Infarction Promotes Angiogenesis Through the miRNA-143/IGF-IR Pathway

Purpose

Myocardial ischemia-reperfusion injury primarily causes myocardial infarction (MI), which is manifested by cell death. Angiogenesis is essential for repair and regeneration in cardiac tissue after MI. In this study, we aimed to investigate the effect of exosomes derived from the serum of MI patients in angiogenesis and its related mechanism.

Patients and Methods

Exosomes, isolated from serum, were collected from MI (MI-exosome) and control (Con-exosome) patients. After coculturing with human umbilical vein endothelial cells, MI-exosome promoted cell proliferation, migration, and tube formation.

Results

The results revealed that the production and release of MI-exosome were associated with cardiomyocytes. Moreover, microarray assays demonstrated that miRNA-143 was significantly decreased in MI-exosome. Meanwhile, the overexpression and knockdown of miRNA-143 could inhibit and enhance angiogenesis, respectively. Furthermore, the effect of exosomal miRNA-143 on angiogenesis was mediated by its targeting gene, insulin-like growth factor 1 receptor (IGF-IR), and was associated with the production of nitric oxide (NO).

Conclusion

Taken together, exosomes derived from the serum of patients with MI promoted angiogenesis through the IGF-IR/NO signaling pathway. The results provide novel understanding of the function of exosomes in MI.

Role of miR-92a-3p, oxidative stress, and p38MAPK/NF-κB pathway in rats with central venous catheter related thrombosis

BACKGROUND

miR-92a-3p and oxidative stress are reportedly associated with venous thrombosis. However, the role of miR-92a-3p and oxidative stress in catheter-related thrombosis (CRT) remains ambiguous. Herein, we studied the roles of miR-92a-3p, oxidative stress, and p38-mitogen-activated protein kinase/nuclear factor kappa-B (MAPK/NF-κB) pathway in CRT.

METHODS

Forty-five male rats were randomly and equally divided into control, sham operation, and CRT groups. The rats were sacrificed after 10 days. Reactive oxygen species (ROS), superoxide dismutase (SOD), and malondialdehyde (MDA) levels in the serum were determined by enzyme-linked immunosorbent assay (ELISA). The expression levels of miR-92a-3p, heme oxygenase-1 (HO-1), NF-κB p65, and p38 MAPK in the venous tissues were detected with quantitative polymerase chain reaction (qPCR) and Western blot.

RESULTS

Thrombosis was observed only in the CRT group. Compared with the levels in the control and sham operation groups, ROS and MDA significantly increased in the CRT group, but SOD significantly decreased. qPCR and Western blot results showed that miR-92a-3p, HO-1, p38 MAPK, and NF-κB p65 expression was significantly upregulated in the venous tissues of the CRT group. Moreover, miR-92a-3p was positively correlated with HO-1, which was positively correlated with p38 MAPK and NF-κB p65.

CONCLUSION

miR-92a-3p was correlated with oxidative stress in CRT. miR-92a-3p and oxidative stress contributed to endothelial dysfunction and simultaneously was associated with CRT.

MiR-433 Regulates Myocardial Ischemia Reperfusion Injury by Targeting NDRG4 Via the PI3K/Akt Pathway

BACKGROUND AND PURPOSE

Myocardial ischemia reperfusion (IR) injury is a serious issue in the treatment of myocardial infarction. MiR-433 is upregulated in myocardial IR injury, but its specific effects remain unclear. In this study, we explored the effect and mechanism of miR-433 in myocardial IR injury.

METHODS

The expression of miR-433 was measured by qRT-PCR. H9c2 cells were transfected with miR-433 mimic and inhibitor after exposure to HR, respectively. Cell viability was detected by MTT. Cell apoptosis was measured by flow cytometry. Protein expression was assessed by western blot. Dual-luciferase reporter assay was performed to assess the target reaction between miR-433 and NDRG4. In vivo rat model of IR was used, and antagomiR-433 was injected to IR rats.

RESULTS

The qRT-PCR results showed that miR-433 expression increased in H9c2 cardiomyocytes after exposure to HR. Transfection with miR-433 inhibitor significantly increased cell viability, reduced LDH and apoptosis, downregulated Bax level, and upregulated Bcl-2 level. In contrast, the miR-433 mimic significantly augmented the HR-induced effects. Dual-luciferase reporter assay and western blot analysis suggested that miR-433 directly targeted NDRG4. NDRG4 silencing abrogated the protection of miR-433 inhibition on HR injury in H9c2 cells. It also reversed PI3K/Akt pathway activation that was induced by miR-433 inhibition. MiR-433 inhibition significantly decreased CK-MB and LDH serum level in IR rats. And NDRG4, p-PI3K, and p-Akt protein expression was elevated by antagomiR-433 injection in vivo.

CONCLUSION

MiR-433 regulated myocardial IR injury by targeting NDRG4 and modulating PI3K/Akt signal pathway.

Intracoronary compared with intravenous bolus tirofiban on the microvascular obstruction in patients with STEMI undergoing PCI: a cardiac MR study

To investigate the potential effect of intracoronary administration of the glycoprotein IIb/IIIa inhibitor tirofiban on the microvascular obstruction (MVO) assessed by cardiac magnetic resonance (CMR) imaging compared to the intravenous route in patients with ST-segment-elevation myocardial infarction undergoing primary percutaneous coronary intervention (PCI). Two hundred eight patients were randomized into two groups (tirofiban i.v. and tirofiban i.c.). CMR was completed within 3-7 days after ST-segment-elevation myocardial infarction. One hundred thirty-two patients had a follow-up CMR at 6 months after discharge. The primary end point was the CMR measurements including myocardium strain, myocardial perfusion index, final infarct size, prevalence and extent of MVO, and the change of left ventricular end-diastolic volume (LVEDV) at six months follow-up. The second endpoint was major adverse cardiovascular events (composite of all-cause death, nonfatal reinfarction and congestive heart failure) in one year. The MVO prevalence and extent [56% versus 36%, p = 0.004; 2.08 (IQR: 1.18-5.07) g versus 1.68 (IQR: 0.30-3.28) g, p = 0.041] showed a significant difference between the intravenous and intracoronary groups. Global left ventricular peak longitudinal strain was significantly different in intracoronary groups compared to intravenous groups, - 12.5 [IQR: - 13.4 to - 10.9] versus - 12.3 [IQR: - 13.4 to - 10.4], respectively (P = 0.042). Infarcted myocardial perfusion index was significantly different in intracoronary groups compared to intravenous groups, 0.11 [IQR: 0.08 to 0.15] versus 0.09 [IQR: 0.07 to 0.14], respectively (P = 0.026). Intracoronary tirofiban was associated with a higher change in LVEDV compared with intravenous group (- 10.2% [IQR: - 13.7% to - 2.6%] versus 1.3% [IQR: - 5.6% to 6.1%], p < 0.001). Intracoronary tirofiban application showed no benefit on the occurrence of major adverse cardiovascular events during follow-up compared to intravenous administration. This CMR study in ST-segment-elevation myocardial infarction patients showed a benefit in MVO and left ventricular remodeling for intracoronary tirofiban administration compared to intravenous administration in patients undergoing PCI.

Hsa_circ_0011385 accelerates the progression of thyroid cancer by targeting miR-361-3p

Background

Thyroid cancer is an endocrine malignancy that is growing in incidence worldwide. Despite progress in diagnostics and treatment of thyroid cancer, prognosis remains poor. Emerging research has shown that circular RNAs (circRNAs) have crucial regulatory roles in cancers. However, the possible functions and mechanisms of hsa_circ_0011385 remain undetermined.

Materials and methods

Expression levels of hsa_circ_0011385 and miR-361-3p were evaluated by qRT-PCR assay. The interaction between hsa_circ_0011385 and miR-361-3p was verified by dual-luciferase reporter assay. Effects of hsa_circ_0011385 or miR-361-3p on cell viability, proliferation, cell cycle, apoptosis, migration and invasion were confirmed by cell counting kit-8 (CCK-8), carboxyfluoresceinsuccinimidyl ester (CFSE), flow cytometry, and Transwell assays in vitro. The effect of hsa_circ_0011385 on thyroid cancer progression was also determined by in vivo tumor formation assay. Target genes of miR-361-3p were predicted by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and the expression of apoptosis- and metastasis-related proteins were assessed by Western blot assay.

Results

Hsa_circ_0011385 upregulated in thyroid cancer; hsa_circ_0011385 knockdown inhibited thyroid cancer cell proliferation, migration and invasion, and promoted cell cycle arrest and apoptosis. In addition, hsa_circ_0011385 could negatively regulate miR-361-3p by functioning as a sponge. Hsa_circ_0011385 promoted thyroid cancer cell proliferation, migration and invasion and suppressed cell cycle arrest and apoptosis by targeting miR-361-3p in vitro. We also found that hsa_circ_0011385 knockdown dramatically inhibited thyroid cancer growth in vivo. Furthermore, hsa_circ_0011385 regulated expression of apoptosis and metastasis-related proteins in thyroid cancer.

Conclusions

Hsa_circ_0011385facilitated thyroid cancer cell proliferation, invasion and migration, and inhibited thyroid cancer cell cycle arrest and apoptosis by targeting miR-361-3p, suggesting that the hsa_circ_0011385/miR-361-3p axis might be a promising therapeutic target for thyroid cancer.

Inhibition of miR-217 Protects Against Myocardial Ischemia-Reperfusion Injury Through Inactivating NF-κB and MAPK Pathways

PURPOSE

Recent studies have demonstrated that miRNAs play a vital role in regulating myocardial ischemia/reperfusion injury (MIRI). MiR-217 has been proven to be implicated in cardiac diseases such as chronic heart failure and cardiac myxoma. However, the role of miR-217 in MIRI is not clear.

METHODS

A mouse MIRI model was established and the myocardial infarct size was evaluated by TTC staining. The expression level of miR-217 in I/R group was determined by real-time polymerase chain reaction. Subsequently, MIRI mice and H9C2 cells were administrated with miR-217 inhibitor in vivo and in vitro, respectively. The levels of TNF-α and IL-6 were measured by commercially available ELISA kits. Blood and cell samples were collected for the measurement of lactate dehydrogenase (LDH) level and caspase-3 activity. Cell viability was assessed with the CCK-8 assay. We then explored the detailed molecular mechanisms by TargetScan 7.1 database and further studies were performed to prove the prediction by dual-luciferase reporter assay.

RESULTS

Larger stainless infarct areas were observed in the MIRI group, accompanied by inceased serum LDH activity, indicating the mouse MIRI model was successfully established. MiR-217 was up-regulated in MIRI mice and hypoxia/reoxygenation-treated H9C2 cells. MiR-217 knockdown alleviated the MIRI in MIRI mouse model, and also attenuated the myocardial hypoxia/reoxygenation injury in H9C2 cells. Moreover, dual specificity protein phosphatase 14 (DUSP14) was proved to be a target of miR-217. Besides, further study indicated that inhibition of miR-217 protected against MIRI through inactivating NF-κB and MAPK pathways via targeting DUSP14.

CONCLUSIONS

MiR-217 inhibition protected against MIRI through inactivating NF-κB and MAPK pathways by targeting DUSP14. This study may provide valuable diagnostic and factors and therapeutic agents for MIRI.

MicroRNA-146a protects against myocardial ischaemia reperfusion injury by targeting Med1

BACKGROUND

Myocardial ischaemia reperfusion injury (MIRI) is a difficult problem in clinical practice, and it may involve various microRNAs. This study investigated the role that endogenous microRNA-146a plays in myocardial ischaemia reperfusion and explored the possible target genes.

METHODS

MIRI models were established in microRNA-146a deficient (KO) and wild type (WT) mice. MicroRNA-146a expression was evaluated in the myocardium of WT mice after reperfusion. The heart function, area of myocardium infarction and in situ apoptosis were compared between the KO and WT mice. Microarray was used to explore possible target genes of microRNA-146a, while qRT-PCR and dual luciferase reporter assays were used for verification. Western blotting was performed to detect the expression levels of the target gene and related signalling molecules. A rescue study was used for further testing.

RESULTS

MicroRNA-146a was upregulated 1 h after reperfusion. MicroRNA-146a deficiency decreased heart function and increased myocardial infarction and apoptosis. Microarray detected 19 apoptosis genes upregulated in the KO mice compared with the WT mice. qRT-PCR and dual luciferase verified that Med1 was one target gene of microRNA-146a. TRAP220, encoded by Med1 in the KO mice, was upregulated, accompanied by an amplified ratio of Bax/Bcl2 and increased cleaved caspase-3. Inhibition of microRNA-146a in H9C2 cells caused increased TRAP220 expression and more apoptosis under the stimulus of hypoxia and re-oxygenation, while knockdown of the increased TRAP220 expression led to decreased cell apoptosis.

CONCLUSIONS

MicroRNA-146a exerts a protective effect against MIRI, which might be partially mediated by the target gene Med1 and related to the apoptosis signalling pathway.

miRNA-145-5p induces apoptosis after ischemia-reperfusion by targeting dual specificity phosphatase 6

Disorders mainly caused by ischemia-reperfusion (I/R), including stroke and myocardial infarction, is linked to debilitating health conditions and death. Recent research indicates that microRNAs (miRNAs) mediate the process of ischemic pathology. This study investigated the effects of miR-145-5p in regulating myocardial ischemic injury. The I/R models were established in rat cardiomyocytes H9C2 and rats. Western blot analysis and quantitative polymerase chain reaction was performed to analyze protein expression. Annexin V-FITC/PI staining was conducted to evaluate cell apoptosis. The application of miR-145-5p mimics and inhibitor revealed that miR-145-5p promoted apoptosis in cardiomyocytes. Furthermore, we found that miR-145-5p directly inhibited dual specificity phosphatase 6 (DUSP6) by luciferase reporter assay. The results indicated that DUSP6 was beneficial against I/R injury through inhibiting c-Jun N-terminal kinase pathways. In conclusion, the essential roles of miR-145-5p and DUSP6 in I/R provide a novel therapeutic target to develop future intervention strategies.

miR-202-5p protects rat against myocardial ischemia reperfusion injury by downregulating the expression of Trpv2 to attenuate the Ca 2+ overload in cardiomyocytes

BACKGROUND

This study was aimed to unveil micro RNA (miRNA) expression profiles in myocardial ischemia-reperfusion (MI/R) rats and explore whether and how dysregulated miRNAs were involved in the initiation and progression of MI/R in a calcium-dependent manner.

METHOD AND RESULTS

Rat model of MI/R was established and cardiomyocytes isolated from neonatal rats cardiomyocytes were induced. Both miRNA and messenger RNA expression profiles were analyzed by Microarray. Quantitative reverse-transcription polymerase chain reaction, immunoblotting, bioinformatics analysis, dual-luciferase reporter gene assay, hematoxylin and eosin, Evans blue, and triphenyl tetrazolium chloride were also used in this study. Serum concentrations of myocardial enzymes (phosphocreatine kinase [CK], creatine kinase [CK-MB], lactate dehydrogenase [LDH]), cardiomyocytes loadage of Ca²⁺ , as well as the expression level of inositol 1,4,5-trisphosphate receptors (IP3R) and sarcoplasmic reticulum Ca²⁺ -ATPase 2a (SERCA2a) were measured, respectively. Effects of upregulation or downregulation of miR-202-5p or Trpv2 on these indicators were investigated in vivo and in vitro. In MI/R rats and hypoxia/reoxygenation-induced NCMs, miR-202-5p was downregulated, while Trpv2 was upregulated. Trpv2 was a promising target of miR-202-5p and negatively regulated by miR-202-5p. Upregulation of miR-202-5p or downregulation of Trpv2 significantly reduced the serum concentration of myocardial enzymes, as well as cardiomyocyte-produced reactive oxygen species, but inhibition of miR-202-5p or overexpression of Trpv2 brought the worsening situation for these indicators. Besides, upregulation of miR-202-5p upregulation or downregulation of Trpv2 also inhibited Ca²⁺ overload in cardiomyocytes, accompanied with the increase of SERCA2a and suppression of IP3R. The reduced damage degree and infarct size in myocardial tissue were contrarily worsened by miR-202-5p inhibitor.

CONCLUSION

Overexpression of miR-202-5p or downregulation of its downstream Trpv2 presented the cardioprotective effects to MI/R rats.

MicroRNA-23 inhibition protects the ischemia/reperfusion injury via inducing the differentiation of bone marrow mesenchymal stem cells into cardiomyocytes

Recently, miRNA-23 has been illustrated to play an important role in causing myocardial ischemia/reperfusion injury (MIRI), indicated that inhibition of miR-23 could protect the cardiomyocyte from MIRI. However, the underlying mechanism of miR-23 inhibition in alleviating the reperfusion-induced myocardial damage is unclear. Recognizing that the bone marrow mesenchymal stem cells (BMSCs) have the potential for pluripotent differentiation into myocardial cells, we therefore hypothesis that the BMSCs are involved in the process of miR-23 alleviating IRI. For verification, the BMSCs was established firstly and confirmed by the immunofluorescence assay and flow cytometry analysis. As results revealed that BMSCs were positive for CD44 which was known for BMSC markers, and negative expression for CD45, indicating that the BMSCs was successfully established in our work. Subsequently, we have investigated the effect of miR-23 on the expression of hyaluronan synthase-2 (Has2), a critical gene during heart morphogenesis. Results obtained by the Western-blot and qRT-PCR assay displayed that the levels of Has2 in the BMSCs treated by miR-23 inhibitor was significantly up-regulated than that of control group. Furthermore, the effect of miR-23 on promoting the transformation of BMSCs into myocardial cells was investigated. As demonstrated by the results that the expression level of the cardiac markers in BMSCs transfected with miR-23 inhibitor was remarkably elevated, indicating that inhibition of miR-23 exactly facilitated to the transformation of BMSCs into myocardial cells. The underlying mechanisms experiments showed that the Wnt1, TCF4, and the β-catenin could be significantly elevated by treating with miR-23 inhibitor, suggesting that the activation of Wnt pathway has played a significant role in that process. Finally, the in vivo IRI antagonism effect of miR-23 inhibition was studied and results displayed that the myocardium lesions of these IR rats could be significantly recovered by treating with miR-23 inhibitor.

Targeting autophagy in cardiac ischemia/reperfusion injury: A novel therapeutic strategy

Acute myocardial infarction (AMI) is one of the leading causes of morbidity worldwide. Myocardial reperfusion is known as an effective therapeutic choice against AMI. However, reperfusion of blood flow induces ischemia/reperfusion (I/R) injury through different complex processes including ion accumulation, disruption of mitochondrial membrane potential, the formation of reactive oxygen species, and so forth. One of the processes that gets activated in response to I/R injury is autophagy. Indeed, autophagy acts as a "double-edged sword" in the pathology of myocardial I/R injury and there is a controversy about autophagy being beneficial or detrimental. On the basis of the autophagy effect and regulation on myocardial I/R injury, many studies targeted it as a therapeutic strategy. In this review, we discuss the role of autophagy in I/R injury and its targeting as a therapeutic strategy.

Inhibition of Smurf2 translation by miR-322/503 protects from ischemia-reperfusion injury by modulating EZH2/Akt/GSK3β signaling

Myocardial ischemia-reperfusion (I/R) is a common and lethal disease that threatens people's life worldwide. The underlying mechanisms are under intensive study and yet remain unclear. Here, we explored the function of miR-322/503 in myocardial I/R injury. We used isolated rat perfused heart as an in vivo model and H9c2 cells subjected with the oxygen and glucose deprivation followed by reperfusion as in vitro model to study myocardial I/R injury. 2,3,5-Triphenyltetrazolium chloride (TTC) staining was used to measure the infarct size, and terminal deoxynucleotidyl transferase dUTP-mediated nick-end label (TUNEL) staining was used to examine apoptosis. Quantitative RT-PCR and Western blot were used to determine expression levels of miR-322/503, Smad ubiquitin regulatory factor 2 (Smurf2), enhancer of zeste homolog 2 (EZH2), p-Akt, and p-GSK3β. Overexpression of miR-322/503 decreased infarct size, inhibited cell apoptosis, and promoted cell proliferation through upregualtion of p-Akt and p-GSK3β. Thus the expression of miR-322/503 was reduced during I/R process. On the molecular level, miR-322/503 directly bound Smurf2 mRNA and suppressed its translation. Smurf2 ubiquitinated EZH2 and degraded EZH2, which could activate Akt/GSK3β signaling. Our study demonstrates that miR-322/503 plays a beneficial role in myocardial I/R injury. By inhibition of Smurf2 translation, miR-322/503 induces EZH2 expression and activates Akt/GSK3β pathway, thereby protecting cells from ischemia reperfusion injury.

Troxerutin attenuates myocardial cell apoptosis following myocardial ischemia-reperfusion injury through inhibition of miR-146a-5p expression

The aim of the current study was to investigate the effects and the underlying mechanisms of troxerutin on myocardial cell apoptosis during ischemia-reperfusion (I/R) injury. Hypoxia/reoxygenation (H/R) model in neonatal rat cardiomyocytes, and I/R model in rats, were established following troxerutin preconditioning. The quantitative real-time polymerase chain reaction analysis was performed to examine the messenger RNA miR-146a-5p expression in cardiomyocytes and myocardial tissues. Hemodynamic parameters and serum creatine kinase, lactate dehydrogenase, tumor necrosis factor-α, and interleukin-10 were evaluated. Infarct size was examined by 2,3,5-triphenyltetrazolium chloride staining. Besides, myocardial apoptosis was detected by terminal deoxynucleotidyl transferase (dUTP) nick end labeling (TUNEL) assay. Western blot analysis was performed to determine the protein levels of caspase-3, Bax, and Bcl-2. The results showed that, troxerutin decreased rat cardiomyocyte apoptosis during H/R injury. Furthermore, the antiapoptotic effect of troxerutin against I/R injury was mediated by miR-146a-5p downregulation. In vivo experiments suggested that troxerutin alleviated myocardial I/R injury in rats via inhibition of miR-146a-5p. In conclusion, troxerutin exerted cardioprotective effects during I/R injury by downregulating miR-146a-5p.