Myocardial-Targeting Tannic Cerium Nanocatalyst Attenuates Ischemia/Reperfusion Injury

Ischemic heart disease (IHD) is one of the leading causes of death worldwide. Medications or surgery have been considered as effective protocols to treat IHD for decades. Yet the reperfusion of the blood flow frequently leads to the generation of excessive reactive oxygen species (ROS), causing prominent and irreversible damage to the cardiomyocytes. In the present work, tannic acid-assembled tetravalent cerium (TA-Ce) nanocatalysts with appealing cardiomyocyte-targeting and antioxidation capability have been synthesized and applied for the effective and biocompatible ischemia/reperfusion injury therapeutics. TA-Ce nanocatalysts could effectively rescue the cardiomyocytes from oxidative stress induced by H2 O2 challenge as well as oxygen-glucose deprivation in vitro. In the murine ischemia/reperfusion model, cardiac accumulation and intracellular ROS scavenging could be achieved against the pathology, substantially reducing the myocardial infarct area and recovering heart functionality. This work illuminates the design of nanocatalytic metal complexes and their therapeutic prospects in ischemic heart diseases with high effectiveness and biocompatibility, paving the way for the clinical translation from bench to bedside.

Inhibition of LncRNA-HRIM Increases Cell Viability by Regulating Autophagy Levels During Hypoxia/Reoxygenation in Myocytes

Backgrund/Aims: Ischemia reperfusion (I/R) promotes the severity of cardiomyocyte injury. Long noncoding RNAs (LncRNAs) are key regulators in cardiovascular diseases. However, the association between LncRNAs and myocardial I/R injury has not been thoroughly characterized to date. We attempted to clarify the potential biological role of a LncRNA (E230034O05Rik), which we named hypoxia/reoxygenation (H/R) injury-related factor in myocytes (HRIM), by investigating the differential expression of LncRNAs between groups of myocytes exposed to either a normal level of oxygen or to H/R.

METHODS

Microarray analysis was used to determine analyze the global differential expression of LncRNAs in H9c2 myocytes exposed either to a normal level of oxygen or to H/R. Target LncRNA levels were further verified in vitro and ex vivo by real-time polymerase chain reaction (qPCR). Cell viability was analyzed using the Cell Counting Kit-8 assay. Autophagy levels were confirmed by Western blotting, transmission electron microscopy, and autophagic double-labeled (mRFP-GFP-LC3) adenovirus analyses.

RESULTS

Gene expression profiling revealed that 797 LncRNAs and 1898 mRNAs were differentially expressed in the H/R group compared with the normal oxygen group. Among these LncRNAs and mRNAs, 6 upregulated LncRNAs and 2 downregulated LncRNAs in the H/R group were selected and further validated by qPCR in vitro and ex vivo. Additionally, LncRNA-HRIM was inhibited by specific siRNAs in H9c2 myocytes exposed to H/R. The inhibition of LncRNA-HRIM by siRNA prevented cell death by suppressing excessive autophagic activity in myocytes, This finding suggests a detrimental role of LncRNA-HRIM in the regulation of I/R injury.

CONCLUSIONS

LncRNAs are involved in H/R injury of H9c2 myocytes. Inhibition of LncRNA-HRIM increased cell viability by reducing autophagy in myocytes during H/R.

Large Animal Models: The Key to Translational Discovery in Digestive Disease Research

Gastrointestinal disease is a prevalent cause of morbidity and mortality and the use of animal models have been instrumental in studying mechanisms of digestive pathophysiology. As investigators attempt to translate the wealth of basic science information developed from rodent, models, large animal models provide a number of translational advantages. The pig, in particular, is arguably one of the most powerful models of human organ systems, including the gastrointestinal tract. The pig has provided important tools and insight into intestinal ischemia/reperfusion injury, intestinal mucosal repair, as well as new insights into esophageal injury and repair. Porcine model development has taken advantage of the size of the animal, allowing increased surgical and endoscopic access. In addition, cellular tools such as the intestinal porcine epithelial cell line and porcine enteroids are providing the methodology to translate basic science findings using in-depth mechanistic analyses. Further opportunities in porcine digestive disease modeling include developing additional transgenic pig strains. Collectively, porcine models hold great promise for the future of clinically relevant digestive disease research.

Hyperbaric Oxygen Therapy Suppresses Apoptosis and Promotes Renal Tubular Regeneration After Renal Ischemia/Reperfusion Injury in Rats

BACKGROUND

Renal ischemia/reperfusion (I/R) injury remains a major cause of acute kidney injury (AKI), in addition to I/R injury-induced tissue inflammation, necrosis and apoptosis. Hyperbaric oxygen therapy (HBO) is defined as a treatment in which a patient is intermittently exposed to 100% oxygen pressurized to a pressure above sea level (> 2.0 atmospheres absolute (ATA), 1.0 ATA = 760 mmHg). It has been used in a number of medical conditions with a proven efficacy in a limited number of disorders. However, the effects of HBO therapy on apoptosis and proliferative activity after I/R injury have not been fully understood.

OBJECTIVES

We studied the possible beneficial effects of HBO therapy on apoptosis and tubular cell regeneration after renal I/R injury in rats.

MATERIALS AND METHODS

Sprague-Dawley (SD) rats were randomized into three groups: Sham (Sham-operated rats); I/R (animals submitted to I/R); and I/R + HBO (I/R rats exposed to HBO). Tubular cell apoptosis was confirmed by DNA laddering and the terminal deoxynucleotidyl transferase-mediated uridine triphosphate nick end labeling (TUNEL) assay. Cellular proliferation activity was determined using the anti-Ki-67 antibody.

RESULTS

A significant decrease in apoptotic cells and increase in proliferative reaction were observed in the I/R + HBO group compared to the I/R group.

CONCLUSIONS

We demonstrated that HBO suppressed apoptosis, which caused inflammation after renal I/R, and promoted tubular cell regeneration. HBO has protective effects against AKI caused by renal I/R through the inhibition of apoptosis.

Effect of HEMADO on Level of CK-MB and LDH Enzymes after Ischemia/Reperfusion Injury in Isolated Rat Heart

INTRODUCTION

Ischemia/Reperfusion (IR) injury mainly causes the increase of enzymes involved in myocytes injury including CK-MB (creatine kinase-MB) isoenzyme and LDH (lactate dehydrogenase). Leakage of CK-MB isoenzyme and LDH from myocardial tissues to blood is indicator of acute myocardial infarction. The aim of this study was to assess the effect of HEMADO on IR injury and its relationship with mitochondrial ATP-sensitive K+ channels (mitoKATP) in rat heart.

METHODS

Twenty eight male Wistar rats (250-300g) were divided into four groups (seven members in each group): control (without ischemia), I/R (with ischemia+without HEMADO), ischemia received HEMADO (HEMADO), ischemia received HEMADO and 5-HD (5-hydroxydecanoate, specific mitoKATP channel blocker) (HEMADO+5-HD). The animals were anesthetized and the hearts were quickly removed and mounted on Langendorff apparatus and perfused by Krebs-Henseleit solution under constant pressure and temperature of 37ºC. After 20 minutes of stabilization, ischemic groups were exposed to 40 minutes of global ischemia and consecutive 90 minutes of reperfusion.

RESULTS

IR injury increased the level of LDH and CK-MB in the collected coronary flow during 5 minutes since start of reperfusion. HEMADO reduced the enzymes' levels and using 5-HD abolished the effect of HEMADO.

CONCLUSION

Our findings indicated that HEMADO could protect the heart against ischemia-reperfusion injury by decreasing the CK-MB and LDH levels. The cardioprotective effect of HEMADO may be mediated in part by mitoKATP.