Exosomes Derived from Mesenchymal Stem Cells Rescue Myocardial Ischaemia/Reperfusion Injury by Inducing Cardiomyocyte Autophagy Via AMPK and Akt Pathways

Background/Aims: Microvascular obstruction (MVO), an undesirable complication of percutaneous coronary intervention, is independently associated with adverse left ventricle remodeling and poor prognosis after acute myocardial infarction. Hypoxia and oxidative stress major roles in the pathophysiology of MVO. Pim1 serves an important protective role in the ischemic myocardium, but the underlying mechanisms remain poorly defined. Autophagy in early hypoxia or during moderate oxidative stress has been demonstrated to protect the myocardium. In this study, we investigated the association between the protective effect of Pim1 and autophagy after hypoxia and oxidative stress. Methods: Ventricular myocytes from neonatal rat heart (NRVMs) were isolated. NRVMs were exposed to hypoxia and H₂O₂. Rapamycin and 3-methyladenine (3-MA) were used as an activator and inhibitor of autophagy, respectively. pHBAd-Pim1 was transfected into NRVMs. We assessed cardiomyocyte apoptosis by Annexin V-FITC/PI flow cytometry. Autophagy was evaluated by mRFP-GFP-LC3 adenovirus infection by confocal microscopy. Western blotting was used to quantify apoptosis or autophagy protein (caspase-3, LC3, P62, AMPK, mTOR, ATG5) concentrations. Results: Autophagy and apoptosis in NRVMs significantly increased and peaked at 3 h and 6 h, respectively, after exposure to hypoxia and H₂O₂. The mTOR inhibitor rapamycin induced autophagy and decreased cardiomyocyte apoptosis, but the autophagy inhibitor 3-MA decreased autophagy and increased apoptosis at 3 h after exposure to hypoxia and H₂O₂. Pim1 levels in NRVMs increased at 3 h and decreased gradually after exposure to hypoxia and H₂O₂. Pim1 overexpression enhanced autophagy and decreased apoptosis. Pim1-induced promotion of autophagy is partly the result of activation of the AMPK/mTOR/ATG5 pathway after exposure to hypoxia and H₂O₂. Conclusion: Our results revealed that Pim1 overexpression prevented NRVMs from apoptosis via upregulating autophagy after exposure to hypoxia and oxidative stress, partly through activation of the AMPK/mTOR/ATG5 autophagy pathway.

Section: Cellular Physiology and Biochemistrymentioning

confidence: 68%

Pim1 Overexpression Prevents Apoptosis in Cardiomyocytes After Exposure to Hypoxia and Oxidative Stress via Upregulating Cell Autophagy

Zhu¹,

Wang²,

Sun³

et al. 2018

“…Exosomes (Exos) derived from MSCs have been described as a novel pathway of cell-to-cell interaction and a crucial point in signal regulation [21][22][23]. These membranous structures which deliver exogenous functional mRNA and miRNA sequences to target cells contribute to disease progression and can help to treat diseases.…”

Section: Introductionmentioning

confidence: 99%

Exosomes from MiR-30d-5p-ADSCs Reverse Acute Ischemic Stroke-Induced, Autophagy-Mediated Brain Injury by Promoting M2 Microglial/Macrophage Polarization

Jiang

Wang

Jin

et al. 2018

243

191

Background/Aims: Recent studies have indicated that exosomes secreted from adipose-derived stem cells (ADSCs) have important effects in the treatment of ischemic injury. However, the treatment mechanism is unclear. This study aimed to investigate whether ADSC-derived exosomes enriched with microRNA (miR)-30d-5p have a protective effect on acute ischemic stroke (AIS). Methods: In the current study, inflammatory factors and miR-30d-5p expression were assessed in 70 subjects with AIS and 35 healthy controls. Exosomes were characterized by transmission electron microscopy and further examined using nanoparticle tracking analyses. A rat model of AIS and an in vitro model of oxygen- and glucose-deprived (OGD) primary microglia were established to study the protective mechanism of exosomes from miR-30d-5p-overexpressing ADSCs in ischemia-induced nerve injury. Results: The results showed that following AIS, the expression of inflammatory cytokines increased, while the anti-inflammatory cytokines IL-4, IL-10, and miR-30d-5p decreased both in patients and in animal models. Moreover, in vitro studies demonstrated that suppression of autophagy significantly reduced the OGD-induced inflammatory response. In addition, exosome treatment was more effective in suppressing the inflammatory response by reversing OGD-induced and autophagy-mediated microglial polarization to M1. Furthermore, in vivo studies showed that exosomes derived from ADSCs significantly decreased the cerebral injury area of infarction by suppressing autophagy and promoting M2 microglia/macrophage polarization. Conclusions: Our results suggest that miR-30d-5p-enhanced ADSC-derived exosomes prevent cerebral injury by inhibiting autophagy-mediated microglial polarization to M1.

“…Adenosine monophosphate-activated protein kinase (AMPK) has emerged as a master regulator of metabolic energy, and is a cellular adaptive mechanism activated during metabolic stress to boost energy production and so that to salvage the failing myocardium [13, 14] and myocardial IR injury [15]. Of note, AMPK activation has been verified to confer cardioprotection against myocardial IR injury in diabetes by limiting cardiac apoptosis through attenuation of endoplasmic reticulum stress [14, 16].…”

Section: Introductionmentioning

confidence: 99%

AMPK Contributes to Cardioprotective Effects of Pterostilbene Against Myocardial Ischemia- Reperfusion Injury in Diabetic Rats by Suppressing Cardiac Oxidative Stress and Apoptosis

Kosuru

Cai

Kandula³

et al. 2018

Background/Aims: Pterostilbene (PT) exerts antidiabetic effects by decreasing blood glucose and modulating lipid metabolism and has been shown to attenuate myocardial ischemia-reperfusion (IR) injury in non-diabetic subjects. However, whether PT can protect against myocardial IR injury in diabetes is unknown. AMPK stimulation is indispensable in offering cardioprotection against myocardial IR injury in diabetes by limiting cardiac apoptosis. Thus, we hypothesized that PT may confer protection against myocardial IR injury in diabetes via AMPK activation. Methods: Sprague-Dawley rats at eight weeks of diabetes induction (induced by an intravenous dose of 65 mg/kg streptozotocin) were administered with vehicle or PT (20 and 40 mg/kg/day, p.o.) for four weeks (starting from week 9 to 12). At the end of week 12, myocardial IR injury was induced by subjecting the diabetic rats to 30 minutes of coronary artery ligation and followed by 2 hours of reperfusion. In in vitro studies, rat primary cardiomyocytes were incubated with low glucose (LG, 5.5 mM) or high glucose (HG, 30 mM) and exposed to 45 minutes hypoxia and 2 hours reoxygenation in the presence or absence of PT (0.5 µM) or the AMPK inhibitor compound C (CC, 5 µM). Results: PT significantly reduced post-ischemic cardiac infarct size, oxidative stress, plasma lactate dehydrogenase (LDH), creatine kinase-MB levels and apoptosis in diabetic rats. In cardiomyocytes, PT decreased hypoxia/ reoxygenation-induced oxidative stress, attenuated LDH and cleaved caspase3/caspase3 ratio and increased Bcl-2/Bax ratio and AMPK phosphorylation. However, CC administration blunted the cardioprotective effects of PT both in vivo and in vitro. Conclusion: Suppressing cardiac oxidative stress and apoptosis via AMPK stimulation may represent a primary mechanism whereby pterostilbene attenuates diabetic myocardial IR injury.