hUC-MSC-EV-miR-24 enhances the protective effect of dexmedetomidine preconditioning against myocardial ischemia-reperfusion injury through the KEAP1/Nrf2/HO-1 signaling

The cardioprotective effect of microRNAs (miRNAs) on myocardial ischemic-reperfusion (I/R) injury has been documented. Here, we aim to decipher the mechanism of miR-24 delivered by human umbilical cord mesenchymal stem cell-derived extracellular vesicles (hUC-MSC-EVs) in myocardial I/R injury after dexmedetomidine (DEX) preconditioning. We collected and identified hUC-MSCs and extracted EVs, which were co-cultured with DEX-preconditioned hypoxia/reoxygenation (H/R) cardiomyocyte models or injected into I/R mouse models. The cardiomyocytes and myocardial injury were evaluated by molecular biology experiments. miR-24 was highly expressed in hUC-MSC-EVs. hUC-MSC-EVs could transfer miR-24 into cardiomyocytes where miR-24 augmented cell viability and inhibited cell apoptosis after DEX preconditioning. In the co-culture system of RAW264.7 macrophages with hUC-MSC-EVs, miR-24 promoted M2-type polarization of macrophages and reduced M1-type macrophage polarization. Mechanistically, miR-24 targeted KEAP1 and inhibited its expression, resulting in disruption of the Nrf2/HO-1 signaling. In vivo data confirmed that miR-24 delivered by hUC-MSC-EVs enhanced the suppressing effect of DEX preconditioning on inflammation and apoptosis in rats following myocardial I/R injury. Overall, miR-24 delivered by hUC-MSC-EVs can promote M2 polarization of macrophages and enhance the protective effect of DEX preconditioning on myocardial I/R injury by down-regulating the KEAP1/Nrf2/HO-1 signaling axis.

Large animal models of cardiac ischemia-reperfusion injury: Where are we now?

Large animal models of cardiac ischemia-reperfusion are critical for evaluation of the efficacy of cardioprotective interventions prior to clinical translation. Nonetheless, current cardioprotective strategies/interventions formulated in preclinical cardiovascular research are often limited to small animal models, which are not transferable or reproducible in large animal models due to different factors such as: (i) complex and varied features of human ischemic cardiac disease (ICD), which are challenging to mimic in animal models, (ii) significant differences in surgical techniques applied, and (iii) differences in cardiovascular anatomy and physiology between small versus large animals. This article highlights the advantages and disadvantages of different large animal models of preclinical cardiac ischemic reperfusion injury (IRI), as well as the different methods used to induce and assess IRI, and the obstacles faced in using large animals for translational research in the settings of cardiac IR.

Mechanistic Role of Methanolic Extract of Taraxacum officinale Roots as Cardioprotective Against Ischemia-Reperfusion Injury-Induced Myocardial Infarction in Rats

Taraxacum officinale play an important role in the prophylaxis and treatment of cardiovascular disease (CVD). Taraxacum officinale is proven as promising antioxidant in earlier studies and one of its constituent "cichoric acid" is shown to have vasorelaxant property. Therefore, present study mainly designed to investigate the cardioprotective effects of Taraxacum officinale against ischemia-reperfusion injury (I/R injury)-induced myocardial dysfunction in rats. This study not only explored the overall cardioprotective potential but also tried to explore its molecular mechanism using pharmacological inhibition via L-NAME and glibenclamide. Pretreatment of methanolic extract of Taraxacum officinale significantly attenuated (p < 0.001) increased levels of lactate dehydrogenase (LDH), creatine kinase (CK), infarct size, and thiobarbituric acid reactive substance (TBARS), while it increased the reduced levels of protein content, glutathione (GSH), and catalase (CAT) activity. Results showed that pretreatment with methanolic extract of Taraxacum officinale provides cardioprotection against I/R induced myocardial dysfunction, at least, may be mediated through the endogenous release of nitric oxide.

Effect of the Ligation and Reperfusion Timeframe on Maximal Ischemia-Reperfusion Injury in Diverse Rat Models

Background

Little is known about the effect that different time sequences for coronary ligation and reperfusion have on ischemic-reperfusion (IR) injury.

Objective

To investigate the relationship between the extent of IR injury and the timeframe for coronary ligation/reperfusion in three animal models.

Methods

Three rat models were used: normal Sprague-Dawley rats, diabetes mellitus (DM) rats, and fat rats. The rats in each model were divided into four groups based on the coronary ligation period (L): 30, 60, 120, and 180 min, and then divided into seven sub-groups based on the reperfusion period (R): 0, 30, 60, 120, 180, 270, and 360 min. R0 was the IR injury baseline for each sub-group. The hearts were harvested and stained with Evans blue and 2,3,5-triphenyl tetrazolium chloride dye to distinguish the different myocardial injury areas: area at risk (AAR) and myocardial necrosis. The difference between each subgroup and baseline (R0) for the necrotic area/AAR was calculated.

Results

In the normal rats, the highest IR injury differences compared with the baseline group occurred at L120, with a reperfusion time of > 180 min. The highest IR injury difference compared to the baseline group occurred at L30, with a reperfusion time of > 180 min in the DM rats and at L60R270, L120R180 in the fat rats.

Conclusions

IR injury, as induced by different coronary ligation and reperfusion time intervals, had diverse expression profiles in the different animal models. Optimal animal models with optimal coronary ligation/reperfusion protocols to achieve maximal IR injury will affect the results and interpretation of future studies.

Intestinal Microbiota in Experimental Acute Kidney Injury

Recent studies have demonstrated an important role played by gut microbiota in maintaining intestinal homeostasis and host immune system function. Gut microbiota have been studied in experimental acute kidney injury (AKI) using different mice and rat models exposed to either ischemia or cisplatin-mediated tubular injury. Differences in inflammatory markers and severity of AKI have been observed between germ-free mice, wild-type mice, and mice treated with antibiotics or specific bacteria. Interventions modifying the gut microbiota after experimental AKI have had either beneficial or harmful effects on kidney tubular injury and recovery. These findings provide strong evidence for a modulatory role of gut microbiota during AKI. Ischemic and cis-platin-induced AKI have distinct stool microbial signatures based on 16s sequencing. Future in-depth studies exploring the mechanisms of how the microbiota influence AKI and development of feasible therapeutic options have the potential to improve outcomes in clinical AKI.

The Effect of Perioperative N-acetylcysteine on the Short and Long Term Outcomes in Pediatrics Undergoing Living-Donor Liver Transplantation

BACKGROUND

Ischemia-reperfusion injury during transplantation can cause post-operative graft dysfunction.

OBJECTIVE

To assess the efficacy of N-acetylcysteine in preventing hepatic ischemia-reperfusion injury and post-transplant outcomes.

METHODS

In this retrospective study on pediatrics undergoing living-donor (from one of their parents) liver transplantation, N-acetylcysteine was administered to one group (n=20) after induction in the donors until graft harvest, and in the recipients during implantation, which was maintained for 19 hours. The second group (n=20) did not receive NAC. Early allograft dysfunction was determined in the presence of alanine aminotransferase or aspartate aminotransferase ≥2000 IU/L and bilirubin ≥10 mg/dL within the first 7 days, and an international normalized ratio ≥1.6 on day 7. Data were collected from a retrospectively maintained database.

RESULTS

The incidence of post-reperfusion syndrome was lower in N-acetylcysteine group compared with the other group (5% vs. 30%, p=0.037). Serum creatinine level was significantly (p=0.04) different in the N-acetylcysteine group during the second post-operative week (0.14 vs. 0.15 mg/dL). There was no significant difference in the incidence of early allograft dysfunction (21% vs. 14%, p=0.327), and the survival rate (p=0.409).

CONCLUSION

Peri-operative infusion of N-acetylcysteine in both donor and recipient would effectively prevent post-reperfusion syndrome and renal insufficiency. However, it might not affect the early allograft dysfunction, ICU stay, and mortality. NAC increases the chance of re-operation due to non-surgical bleeding in the first post-operative day.

Neuroprotective effects of Tiliacora triandra leaf extract in a mice model of cerebral ischemia reperfusion

OBJECTIVE

The present study investigated possible neuroprotective effects of ethanolic extract of Tiliacora triandra leaf against cerebral ischemic-reperfusion injury in mice.

MATERIALS AND METHODS

Forty male Institute of Cancer Research (ICR) mice were randomly divided into five groups: (1) Sham + 10% Tween 80, (2) bilateral common carotid artery occlusion (BCCAO) + 10% Tween 80, (3) BCCAO + T. triandra 300 mg/kg, (4) BCCAO + T. triandra 600 mg/kg and (5) BCCAO + quercetin 10 mg/kg. Cerebral ischemic-reperfusion (IR) was induced by 30 min of BCCAO followed by 45 min of reperfusion. After IR induction, total brain protein, calcium, malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), and reduced glutathione (GSH), as well as brain infraction and histopathological changes in vulnerable brain areas, such as the cerebral cortex and hippocampus, were evaluated.

RESULTS

The results showed that 2 weeks of pretreatment with T. triandra leaf extract at doses of 300 and 600 mg/kg significantly reduced calcium and MDA, but increased GSH and SOD and CAT activities. The extract significantly attenuated brain infarction and neuronal death in the cerebral cortex and hippocampus.

CONCLUSION

We demonstrated the neuroprotective effects of T. triandra leaf extract against cerebral IR injury in mice.

Protein kinases are involved in the cardioprotective effects activated by platelet glycoprotein IIb/IIIa inhibitor tirofiban at reperfusion in rats in vivo

The thrombolytic effect of platelet glycoprotein IIb/IIIa inhibitors (GP IIb/IIIa inhibitors) in myocardial infarction has been well established. Nevertheless, data on the mechanism of the cardioprotective effect of GP IIb/IIIa inhibitors in ischemic-reperfusion injury (IR) are lacking. Sprague-Dawley rats received 120 min of coronary ischemia and 180 min of reperfusion. A GP IIb/IIIa inhibitor was given via continuous intravenous infusion at a rate of 2 μg/kg/min 30 min prior to reperfusion with/without inhibitors of PKCε (chelerythrine), PI3 kinase and Akt (wortmannin), p38 MAPK (SB203582), p42/44 MAPK (PD98059) and ERK1/2 (u0126) 15 min prior to the GP IIb/IIIa inhibitor. Protein isolation and analysis were performed by Western blot analysis. The cardioprotective effects were measured as the ratio of myocardial necrotic area to the area at risk (AAR) and the apoptotic index (AI) calculated as the percentage of myocytes positive for terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling of all myocytes stained by 4', 6-diamidino-2-phenylindole. The GP IIb/IIIa inhibitor reduced the ratio of myocardial necrotic area to AAR and AI, and also exerted an immediate cardioprotective effect by activating multiple signaling pathways including phosphorylation and activation of PKCε, PI3 kinase, Akt, p38 MAPK, p42/44 MAPK and ERK1/2. However, there were no significant increases in the phosphorylation of Raf and MEK1/2. We concluded that the GP IIb/IIIa inhibitor reduced the extent of cardiac IR and significantly ameliorate the apoptosis of myocytes in the rats. In addition, the cardioprotective effect was mediated through the activation of multiple signal transduction pathways.

Klotho Reduces Necroptosis by Targeting Oxidative Stress Involved in Renal Ischemic-Reperfusion Injury

BACKGROUND/AIMS

Klotho is a multifunctional protein expressed predominantly in kidney tubular epithelium. Here, we investigated the protective effects of Klotho on necroptosis in renal ischemic-reperfusion injury (IRI) and the role of oxidative stress in this process.

METHODS

Mice were subjected to bilateral renal pedicle clamping. Mouse renal tubular epithelial (TCMK-1) cells were exposed to hypoxia/reoxygenation (H/R) or H2O2. Kidney samples from acute kidney injury (AKI) patients and controls were examined by immunofluorescence. Klotho protein and N-acetyl-L-cysteine (NAC) were used to define their roles in mediating necroptosis. Necroptosis was assessed by TUNEL staining, immunoblotting, and real-time PCR. Oxidative stress was studied via ELISA, immunoblotting, colorimetric, and thiobarbituric acid reactive substances assays.

RESULTS

Renal IRI induced Klotho deficiency in the serum and kidney, but an increase in the urine. The levels of the necroptotic markers receptor-interacting protein kinase (RIP) 1, RIP3, IL-1β, and TUNEL-positive cells increased after IRI; all increases were ameliorated by Klotho. In TCMK-1 cells, Klotho and NAC attenuated the elevation in RIP1, RIP3, and LDH release induced by H/R or H2O2. Moreover, Klotho decreased the levels of oxidative stress biomarkers and elevated superoxide dismutase 2 expression in both in vivo and in vitro experiments. Studies in human samples further confirmed the Klotho deficiency and increased formation of RIP3 puncta in AKI kidneys.

CONCLUSION

Klotho protects tubular epithelial cells from IRI and its anti-necroptotic role may be associated with oxidative stress inhibition.

The effect of asafoetida essential oil on myocardial ischemic-reperfusion injury in isolated rat hearts

OBJECTIVE

Previous studies reported that asafetida from Ferula assa-foetida Linn. species and its essential oil (AEO) have antioxidant effects. In the present study, the effect of AEO was evaluated on ischemic-reperfusion injury in isolated rat hearts.

MATERIALS AND METHODS

Forty-eight male Wistar rats were divided into 6 groups: 1) control group, 2) vehicle group, 3-5) AEO groups and, 6) carvedilol group. In the control group, hearts were only subjected to 30-min global ischemia followed by 120-min reperfusion. Hearts in other groups were perfused with vehicle (Tween 0.1%), AEO (0.125, 0.25 or 0.50 µL/g heart) or carvedilol (10 µM) for 5 min immediately before the induction of ischemia.

RESULTS

Compared to the control group, myocardial dysfunction was significantly more severe only in group 5 in which a significant increase in left ventricular end diastolic pressure and a significant decrease in left ventricular developed pressure and ± dp/dt. Also, the activities of lactate dehydrogenase and creatine kinase as the markers of myocardial injury were significantly higher only in group 5 compared to control group. The size of infarct and the incidence of irreversible fibrillation did not show any significant differences between the control group and groups 3-5.

CONCLUSION

These results showed that perfusion of isolated rat hearts with AEO 0.5 µL/g heart, but not at lower concentrations, might worsen myocardial ischemic-reperfusion injury.

C5a/C5aR pathway accelerates renal ischemia-reperfusion injury by downregulating PGRN expression

Recent reports indicate that the complement C5a/C5aR pathway and progranulin (PGRN) deficiency both contribute to ischemia-reperfusion (IR)-induced acute kidney injury. However, the underlying relationship between the C5a/C5aR signaling pathway and PGRN expression during acute kidney injury is poorly understood. In this study, we showed that C5aR expression was significantly upregulated after renal IR, and that C5aR deficiency led to a marked increase in PGRN expression and a significant reduction in tubular damage and production of inflammatory cytokines. In accordance with these results, recombinant C5a caused downregulation of PGRN protein and mRNA levels in renal tubular epithelial cells (HK-2 cells), which could be negated by disruption of C5a/C5aR signaling by the C5aR antagonist, as confirmed by immunofluorescence, western blotting, and quantitative real-time PCR. Moreover, C5aR deficiency resulted in attenuated NF-κB expression 24h after IR, and recombinant C5a potentiated TNFα-induced NF-κB activation in HK-2 cells. Inhibition of NF-κB activation reversed C5a-induced downregulation of PGRN expression. Our results show for the first time that the complement C5a/C5aR pathway aggravates IR-induced acute kidney injury by suppressing PGRN expression and confirm that suppression of PGRN expression is associated with increased NF-κB activation induced by C5a.

Cell membrane integrity and revascularization: The possible functional mechanism of ischemic preconditioning for skeletal muscle protection against ischemic-reperfusion injury

BACKGROUND

The purpose of this paper was to evaluate whether ischemic preconditioning (IPC) could make protective effects against skeletal muscle injuries induced by ischemic-reperfusion (I/R).

METHODS

Eighteen rats were randomly divided into three groups of 6 subjects each: control group, I/R group, and IPC group. Thigh root ischemia of rats in the I/R group was induced by 3h ischemia and 24h reperfusion. IPC was applied by 3 periods of 15min ischemia/15min reperfusion prior to ischemia. Morphological changes in skeletal muscle cells induced by I/R and IPC were observed by hematoxylin and eosin (HE) staining and electron microscopy. In addition, angiogenesis was evaluated by immunolabeling of CD31.

RESULTS

IPC could prevented morphological alternations induced by ischemia, including myofilament, cell membrane, cell matrix, nucleus, mitochondria, and sarcoplasmic reticulum damage in skeletal muscle cells. The CD31 immunolabeling showed that neovascularization was observed in the IPC group but not in the I/R group. IPC could protect skeletal muscle cells from necrosis, apoptosis, and morphological damages induced by I/R injury.

CONCLUSION

Revascularization may play a key role in the mechanism underlying the protective effects of IPC in vivo.

β-Caryophyllene Pretreatment Alleviates Focal Cerebral Ischemia-Reperfusion Injury by Activating PI3K/Akt Signaling Pathway

β-Caryophyllene (BCP) has been reported to be protective against focal cerebral ischemia-reperfusion (I/R) injury by its anti-oxidative and anti-inflammatory features. Recent study demonstrates that the BCP exhibits potential neuroprotection against I/R injury induced apoptosis, however, the mechanism remains unknown. Therefore, we investigate the underlying anti-apoptotic mechanism of BCP pretreatment in I/R injury. Sprague-Dawley rats (pretreated with BCP suspensions or solvent orally for 7 days) were subjected to transient Middle Cerebral Artery Occlusion (MCAO) for 90 min, followed by 24 h reperfusion. Results showed that BCP pretreatment improved the neurologic deficit score, lowered the infarct volume and decreased number of apoptotic cells in the hippocampus. Moreover, in western blot and RT-qPCR detections, BCP pretreatment down-regulated the expressions of Bax and p53, up-regulated the expression of Bcl-2, and enhanced the phosphorylation of Akt on Ser473. Blockage of PI3K activity by wortmannin not only abolished the BCP-induced decreases in infarct volume and neurologic deficit score, but also dramatically abrogated the enhancement of AKt phosphorylation. Our results suggested that BCP pre-treatment protects against I/R injury partly by suppressing apoptosis via PI3K/AKt signaling pathway activation.

Vagus nerve stimulation initiated late during ischemia, but not reperfusion, exerts cardioprotection via amelioration of cardiac mitochondrial dysfunction

BACKGROUND

We previously reported that vagus nerve stimulation (VNS) applied immediately at the onset of cardiac ischemia provides cardioprotection against cardiac ischemic-reperfusion (I/R) injury.

OBJECTIVE

This study aimed to determine whether VNS applied during ischemia or at the onset of reperfusion exerts differential cardioprotection against cardiac I/R injury.

METHODS

Twenty-eight swine (25-30 kg) were randomized into 4 groups: Control (sham-operated, no VNS), VNS-ischemia (VNS applied during ischemia), VNS-reperfusion (VNS applied during reperfusion), and VNS-ischemia+atropine (VNS applied during ischemia with 1 mg/kg atropine administration). Ischemia was induced by left anterior descending (LAD) coronary artery occlusion for 60 minutes, followed by 120 minutes of reperfusion. VNS was applied either 30 minutes after LAD coronary artery occlusion or at the onset of reperfusion and continued until the end of reperfusion. Cardiac function, infarct size, myocardial levels of connexin 43, cytochrome c, tumor necrosis factor α, and interleukin 4, and cardiac mitochondrial function were determined.

RESULTS

VNS applied 30 minutes after LAD coronary artery occlusion, but not at reperfusion, markedly reduced ventricular fibrillation incidence and infarct size (~59%), improved cardiac function; attenuated cardiac mitochondrial reactive oxygen species production, depolarization, swelling, and cytochrome c release; and increased the amount of phosphorylated connexin 43 and interleukin 4 as compared with the Control group. These beneficial effects of VNS were abolished by atropine.

CONCLUSION

VNS could provide significant cardioprotective effects even when initiated later during ischemia, but was not effective after reperfusion. These findings indicate the importance of timing of VNS initiation and warrant the potential clinical application of VNS in protecting myocardium at risk of I/R injury.