Mild Therapeutic Hypothermia Protects the Brain from Ischemia/Reperfusion Injury through Upregulation of iASPP

Inhibition of the cGAS-STING pathway: contributing to the treatment of cerebral ischemia-reperfusion injury

The cGAS-STING pathway plays an important role in ischemia-reperfusion injury in the heart, liver, brain, and kidney, but its role and mechanisms in cerebral ischemia-reperfusion injury have not been systematically reviewed. Here, we outline the components of the cGAS-STING pathway and then analyze its role in autophagy, ferroptosis, cellular pyroptosis, disequilibrium of calcium homeostasis, inflammatory responses, disruption of the blood-brain barrier, microglia transformation, and complement system activation following cerebral ischemia-reperfusion injury. We further analyze the value of cGAS-STING pathway inhibitors in the treatment of cerebral ischemia-reperfusion injury and conclude that the pathway can regulate cerebral ischemia-reperfusion injury through multiple mechanisms. Inhibition of the cGAS-STING pathway may be helpful in the treatment of cerebral ischemia-reperfusion injury.

Selective cerebral hypothermia alleviates focal cerebral ischemia/reperfusion injury via enhancing SUMO2/3 modification of Drp1 in rats

BACKGROUND

Selective Cerebral Hypothermia (SCH) has been demonstrated to potentiate SUMO2/3 modification, a native cellular safeguard against Cerebral Ischemia/Reperfusion Injury (CIRI). Dynamin-Related Protein 1 (Drp1), a pivotal regulator in the mitochondrial fission pathway, is an important substrate for SUMO2/3 modification. However, effects of SCH on SUMO2/3 modification of Drp1 remain undefined. Herein, the current study posits that SCH augments the SUMO2/3 modification of Drp1, thereby preserving mitochondrial integrity and mitigating CIRI.

METHODS

A focal CIRI model was established in Sprague-Dawley rats, with 20°C saline perfused via the transcarotid artery to induce SCH condition, and 37°C saline serving as a control. The modified Neurological Severity Score (mNSS) was used to quantitate the degree of neurological deficits. Staining of 2,3-5-triphenyltetrazolium chloride (TTC) was performed to detect cerebral infarction volume. Histological change of neurocyte was observed through Hematoxylin-eosin (HE) staining. Neurocyte apoptosis was evaluated using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) immunofluorescence staining. Western blot (WB) was utilized to evaluated the expressions of Drp1 and Cytochrome C. Co-immunoprecipitation was performed to evaluate the level of SUMO2/3 modification of Drp1. And transmission electron microscopy was used to observe the mitochondrial ultrastructure. The ratio of M-Drp1 to T-Drp1 and mitochondria morphological changes were observed under confocal microscopy.

RESULTS

Research data revealed that SCH significantly enhanced the SUMO2/3 modification of Drp1 when CIRI occurred. Concurrently, mNSSs, cerebral infarct volume, and apoptotic rates were notably attenuated in the SCH group, corroborating SCH's protective role. Expression levels of mitochondrial outer membrane Drp1 (M-Drp1), cytoplasmic cytochrome C (C-CytC), and ratio of M-Drp1 to T-Drp1 were reduced, and changes of mitochondrial ultrastructural and morphology were mitigated, underscoring SCH's inhibitory effect on mitochondrial fission. In contrast, 37°C saline displayed negligible protective impact while compare with 20°C saline perfusion.

CONCLUSIONS

The findings support that SCH amplifies SUMO2/3 modification of Drp1, curtails excessive mitochondrial fission, and consequently ameliorates focal CIRI in a rat model.

Hypothermia improves neuronal network recovery in a human-derived in vitro model of oxygen-deprivation

Mild therapeutic hypothermia showed potential neuroprotective properties during and after cerebral hypoxia or ischemia in experimental animal studies. However, in clinical trials, where hypothermia is mainly applied after reperfusion, results were divergent and neurophysiological effects unclear. In our current study, we employed human-derived neuronal networks to investigate how treatment with hypothermia during hypoxia influences neuronal functionality and whether it improves post-hypoxic recovery. We differentiated neuronal networks from human induced pluripotent stem cells on micro-electrode arrays (MEAs). We studied the effect of hypothermia (34°C)-as well hyperthermia (39°C) - on neuronal functionality during and after hypoxia using MEAs. We also studied the effects on the number of synaptic puncta and cell viability by immunocytochemistry. In comparison to neuronal networks under normothermia, we found that hypothermia during hypoxia improved functional neuronal network recovery, expressed as enhanced neuronal network activity. This was associated with prevention of synaptic loss during and after the hypoxic phase. Furthermore, hypothermia improved cell viability after the hypoxic phase. Instead, hyperthermia during hypoxia had detrimental effects, with an irreversible loss of neuronal network function, loss of synaptic puncta and decreased cell viability. Our results show potential neuroprotective properties of hypothermia occurring during hypoxia, indicating that administering hypothermia to bridge the time to reperfusion may be beneficial in clinical settings.

Mild therapeutic hypothermic protection activates the PI3K/AKT signaling pathway to inhibit TRPM7 and suppress ferroptosis induced by myocardial ischemia‑reperfusion injury

The present study aimed to investigate the role of PI3K‑mediated ferroptosis signaling induced by mild therapeutic hypothermia (MTH), which was defined as a temperature of 34˚C, in protecting against myocardial ischemia-reperfusion (I/R) injury (MIRI). To meet this aim, H9C2 cells underwent hypoxia‑reperfusion (H/R) and/or MTH. The MTT assay was used to assess cell viability, cytotoxicity was measured using a lactate dehydrogenase cytotoxicity assay, and Annexin V‑FITC/PI flow cytometric analysis was used to analyze early and late cell apoptosis. In addition, 84 healthy adult male Sprague‑Dawley rats were randomly divided into seven groups (n=12), and underwent I/R and various treatments. Hemodynamics were monitored, and the levels of myocardial injury marker enzymes and oxidative stress markers in myocardial tissue were measured using ELISA. The expression levels of PI3K, AKT, transient receptor potential cation channel subfamily M member 7 (TRPM7), glutathione peroxidase 4 (GPX4) and acyl‑CoA synthetase long chain family member 4 (ACSL4) in animals and cells were measured using western blot analysis. These experiments revealed that MTH could effectively reduce myocardial infarct size, improve hemodynamic performance following MIRI and suppress myocardial apoptosis, thereby contributing to the recovery from H/R injury. Mechanistically, MTH was revealed to be able to activate the PI3K/AKT signaling pathway in cells, upregulating GPX4, and downregulating the expression levels of TRPM7 and ACSL4. Treatment with 2‑aminoethoxydiphenyl borate (an inhibitor of TRPM7) could further strengthen the myocardial protective effects of MTH, whereas treatment with erastin (promoter of ferroptosis) and wortmannin (inhibitor of PI3K) led to the effective elimination of the myocardial protective effects of MTH. Compared with in the I/R group, the PI3K/AKT activation level and the expression levels of GPX4 were both significantly increased, whereas the expression levels of TRPM7 and ACSL4 were significantly decreased in the I/R + MTH group. Taken together, the results of the present study indicated that MTH may activate the PI3K/AKT signaling pathway to inhibit TRPM7 and suppress ferroptosis induced by MIRI.

Cold inducible RNA binding protein-regulated mitochondria associated endoplasmic reticulum membranes-mediated Ca2+ transport play a critical role in hypothermia cerebral resuscitation

Cardiac arrest is a global health issue causing more deaths than many other diseases. Hypothermia therapy is commonly used to treat secondary brain injury resulting from cardiac arrest. Previous studies have shown that CIRP is induced in specific brain regions during hypothermia and inhibits mitochondrial apoptotic factors. However, the specific mechanisms by which hypothermia-induced CIRP exerts its anti-apoptotic effect are still unknown. This study aims to investigate the role of Cold-inducible RNA-binding protein (CIRP) in mitochondrial-associated endoplasmic reticulum membrane (MAM)-mediated Ca2+ transport during hypothermic brain resuscitation.We constructed a rat model of cardiac arrest and resuscitation and hippocampal neuron oxygen-glucose deprivation/reoxygenation model. We utilized shRNA transfection to interfere the expression of CIRP and observe the effect of CIRP on the structure and function of MAM.Hypothermia induced CIRP can reduce the apoptosis of hippocampal neurons, and improve the survival rate of rats. Hypothermia induced CIRP can reduce the expressions of calcium transporters IP3R and VDAC1 in MAM, reduce the concentration of calcium in mitochondria, decrease the expression of ROS, and stabilize the mitochondrial membrane potential. Immunofluorescence and immunocoprecipitation showed that CIRP could directly interact with IP3R-VDAC1 complex, thereby changing the structure of MAM, inhibiting calcium transportation and improving mitochondrial function in vivo and vitro.Both in vivo and in vitro experiments have confirmed that hypothermia induced CIRP can act on the calcium channel IP3R-VDAC1 in MAM, reduce the calcium overload in mitochondria, improve the energy metabolism of mitochondria, and thus play a role in neuron resuscitation. This study contributes to understanding hypothermia therapy and identifies potential targets for brain injury treatment.

Inhibitor of apoptosis stimulating protein of p53 protects against MPP+-induced neurotoxicity of dopaminergic neurons

Inhibitor of apoptosis stimulating protein of p53 (iASPP) is related to the pathogenesis of several neurological disorders by affecting the oxidative stress and survival of neurons. However, whether iASPP has a role in Parkinson disease (PD) remains to be determined. This work explored the potential regulatory effect of iASPP in an in vitro model of PD based on 1-methyl-4-phenylpyridinium (MPP+)-evoked neurotoxicity of dopaminergic neurons in culture. MN9D neurons were treated with MPP+ at 200 µM in the culture media for 24 h to induce neurotoxicity. Overexpression and silencing of iASPP in neurons were achieved by infecting recombinant adenovirus expressing iASPP and sh-iASPP, respectively. Protein expression was examined by immunoblotting. MPP+-evoked neurotoxicity of dopaminergic neurons was determined by cell viability, TUNEL, and flow cytometric assays. The transcriptional activity of nuclear erythroid factor 2-like 2 (Nrf2) was assessed by luciferase reporter assay. Kelch-like ECH-associated protein 1 (Keap1)-knockout neurons were generated by lentiCRISPR/Cas9-Keap1 constructs. Expression levels of iASPP declined in MPP+-stimulated neurons. Overexpression of iASPP in neurons exhibited inhibitory effects on MPP+-evoked apoptosis, α-synuclein accumulation, and oxidative stress, while iASPP-deficient neurons were more sensitive to MPP+-induced neurotoxicity. Overexpression of iASPP led to an enhancing effect on Nrf2 activation in MPP+-stimulated neurons. Mechanism research revealed that iASPP may contribute to the activation of Nrf2 by competing with Nrf2 in binding with Keap1. Notably, the regulatory effect of iASPP on Nrf2 was diminished in Keap1-knockout neurons. The chemical inhibition of Nrf2 or knockdown of Nrf2 abrogated the protective effects of iASPP on MPP+-induced neurotoxicity. To conclude, iASPP protects dopaminergic neurons against MPP+-induced neurotoxicity through modulation of the Keap1/Nrf2 axis. Therefore, iASPP may play a crucial role in mediating the loss of dopaminergic neurons in PD, and targeting the iASPP-Nrf2 axis could be a promising strategy for treating PD.

Role of PERK-mediated pathway in the effect of mild hypothermia after cerebral ischaemia/reperfusion

BACKGROUND

Hypothermia is an effective method of reducing brain injury caused by a variety of neurological insults. It is aimed to elucidate whether a change in the expression of PERK-mediated pathway proteins is an indicator of the neuroprotective effect of mild hypothermia after cerebral ischaemia/reperfusion.

METHODS

One hundred and ninety-two male C57BL/6 mice were randomly divided into three groups: a sham group, a cerebral normothermic ischaemia/reperfusion (I/R) group and a cerebral hypothermic I/R group. A cerebral ischaemia model was established by ligating the bilateral common carotid artery for 15 min. Mice in the hypothermia group stayed in a cage that was set at 33°C, sprayed with a spray of 70% ethanol, and blown with two high-speed fans. The state of neurons was assessed on micropreparations stained with haematoxylin-eosin and TUNEL. The expressions of GRP78, p-perk, p-eif2α, ATF4 and CHOP were measured by western blot analysis 6, 12, 24 and 72 h after reperfusion.

RESULTS

The number of surviving cells was significantly higher in the hypothermia group than in the group without hypothermia (p < .05). The GRP78 expression in the hypothermia group was statistically higher (p < .05) than in the ischaemia/reperfusion group. Optical densities of p-perk, p-eif2α and ATF4 in hippocampus CA1 neurons ischaemia were statistically significantly lower in the hypothermia group than in the ischaemia/reperfusion group (p < .05). The CHOP expression in the hypothermia group was statistically lower (p < .05) than in the ischaemia/reperfusion group.

CONCLUSION

Mild hypothermia for 6 h promoted moderate neuroprotection by mediating the expression of GRP78, p-PERK, p-eIF2α, ATF4 and CHOP.

A novel extract from Ginkgo biloba inhibits neuroinflammation and maintains white matter integrity in experimental stroke

Ginkgo biloba L. leaf extract (GBE) has been added in many commercial herbal formulations such as EGb 761 and Shuxuening Injection to treat cardiovascular diseases and stroke worldwide. However, the comprehensive effects of GBE on cerebral ischemia remained unclear. Using a novel GBE (nGBE), which consists of all the compounds of traditional (t)GBE and one new compound, pinitol, we investigated its effect on inflammation, white matter integrity, and long-term neurological function in an experimental stroke model. Both transient middle cerebral artery occlusion (MCAO) and distal MCAO were conducted in male C57/BL6 mice. We found that nGBE significantly reduced infarct volume at 1, 3, and 14 days after ischemia. Sensorimotor and cognitive functions were superior in nGBE treated mice after MCAO. nGBE inhibited the release of IL-1β in the brain, promoted microglial ramification, and regulated the microglial M1 to M2 phenotype shift at 7 days post injury. In vitro analyses showed that nGBE treatment reduced the production of IL-1β and TNFα in primary microglia. Administration of nGBE also decreased the SMI-32/MBP ratio and enhanced myelin integrity, thus exhibiting improved white matter integrity at 28 days post stroke. These findings demonstrate that nGBE protects against cerebral ischemia by inhibiting microglia-related inflammation and promoting white matter repair, suggesting that nGBE is a promising therapeutic strategy for long-term recovery after stroke.

Pro-fibrotic and apoptotic activities of circARAP1 in myocardial ischemia-reperfusion injury

Reperfusion modality can cause damage to cardiomyocytes, known as myocardial ischemia-reperfusion injury (MI/RI). Circular RNAs (circRNAs) are fundamental regulators associated with many cardiac diseases, including MI/RI. However, their functional impact on cardiomyocyte fibrosis and apoptosis remains elusive. Therefore, this study aimed to explore possible molecular mechanisms of circARPA1 in animal models and in hypoxia/reoxygenation (H/R)-treated cardiomyocytes. GEO dataset analysis showed that has_circ_0023461 (circARPA1) was differentially expressed in myocardial infarction samples. Real-time quantitative PCR further supported that circARPA1 was expressed at high levels in animal models and in H/R-triggered cardiomyocytes. Then, loss-of-function assays were performed to show that circARAP1 suppression effectively ameliorated cardiomyocyte fibrosis and apoptosis in MI/RI mice. Mechanistic experiments showed that miR-379-5p, KLF9 and Wnt signaling pathways were associated with circARPA1. circARPA1 can sponge miR-379-5p to regulate KLF9 expression, thereby activating the wnt/β-catenin pathway. Finally, gain-of-function assays revealed that circARAP1 aggravated MI/RI in mice and H/R-induced cardiomyocyte injury by regulating the miR-379-5p/KLF9 axis to activate Wnt/β-catenin signaling.

Mild hypothermia alleviates oxygen−glucose deprivation/reperfusion-induced apoptosis by inhibiting ROS generation, improving mitochondrial dysfunction and regulating DNA damage repair pathway in PC12 cells

The brain ischemia/reperfusion (I/R) injury has a great impact on human life and property safety. As far as we know, mild hypothermia (MH) is an effective measure to reduce neuronal injury after I/R. However, the precise mechanism is not extremely clear. The purpose of this study was to investigate whether mild therapeutic hypothermia can play a protective role in nerve cells dealing with brain I/R injury and explore its specific mechanism in vitro. A flow cytometer, cell counting kit-8 (CCK-8) assay and lactate dehydrogenase (LDH) release assay were performed to detect apoptotic rate of cells, cell viability and cytotoxicity, respectively, reactive oxygen species (ROS) assay kit, JC-1 fluorescent methods, immunofluorescence and western blot were used to explore ROS, mitochondrial transmembrane potential (^Δψm), mitochondrial permeability transition pore (MPTP) and protein expression, respectively. The result indicated that the cell activity was decreased, while the cytotoxicity and apoptosis rate were increased after treating with oxygen-glucose deprivation/reperfusion (OGD/R) in PC12 cells. However, MH could antagonize this phenomenon. Interestingly, treating with OGD/R increased the release of ROS and the transfer of Cytochrome C (Cyt-C) from mitochondria to cytoplasm. In addition, it up-regulated the expression of γH2AX, Bax and Clv-caspase3, down-regulated the expression of PCNA, Rad51 and Bcl-2, and inhibited the function of mitochondria in PC12 cells. Excitingly, the opposite trend was observed after MH treatment. Therefore, our results suggest that MH protects PC12 cells against OGD/R-induced injury with the mechanism of inhibiting cell apoptosis by reducing ROS production, improving mitochondrial function, reducing DNA damage, and enhancing DNA repair.

Low technology, mild controlled hypothermia for necrotizing enterocolitis treatment: an initiative to improve healthcare to preterm neonates

Necrotizing enterocolitis (NEC) treatment remains unchanged for years. Data suggest that mild controlled hypothermia could potentially improve NEC outcomes. Our units presented unfavourable outcomes on NEC. The aim was to assess our experience with low technology, mild controlled hypothermia on NEC outcomes, and improve preterm infants' healthcare. This was a single-center quality improvement study with retrospective cohort design at the neonatal intensive care unit in the university hospital. Forty-three preterm infants with NEC (Modified Bell's Stage II/III) were included: 19 in the control group (2015-2018) and 24 in the hypothermia group (2018-2020). The control group received standard treatment (fasting, abdominal decompression, and broad-spectrum antibiotics). The hypothermia group underwent cooling to 35.5 °C for 48 h after NEC diagnosis, along with conventional treatment. The primary outcomes are intestinal perforation, need for surgery, duration of parenteral nutrition, death, and extensive resection of the small intestine. There was no statistical difference in the NEC score. The hypothermia group required less surgery (aRR 0.40; 95% CI 0.19-0.85), presented less bowel perforation (aRR 0.39; 95% CI 0.18; 0.83), had a shorter duration of parenteral nutrition (aHR 5.28; 95% CI 1.88-14.89), did not need extensive intestinal resection, (0 vs 15.7%), and did not experience any deaths (0 vs 31.6%).Conclusions: In our experience, low technology, mild controlled hypothermia was feasible, not related to adverse effects, and effective treatment for NEC Modified Bell's Stage II/III. It avoided surgery, bowel perforation, and extensive intestinal resection; reduced mortality; and shortened parenteral nutrition duration. What is Known: • New approaches have been proposed to avoid enterocolitis incidence; however, the treatment of enterocolitis stage 2 has been the same for decades, and unfavourable outcomes remain despite conventional management. • Studies suggest that hypothermia can be an alternative to enterocolitis treatment. What is New: • Mild controlled hypothermia can be an additional practice to treat enterocolitis stage 2, is feasible, and is not related to adverse effects to preterm infants. • It can decrease surgery needs, duration of parenteral nutrition, and death and avoids extensive intestinal resection in preterm infants.

Upregulation of iASPP ameliorates hypoxia/reoxygenation-induced apoptosis and oxidative stress in cardiomyocytes by upregulating Nrf2 signaling

The inhibitor of apoptosis-stimulating protein of p53 (iASPP) acts as a key modulator of cellular protection against oxidative stress. In the present work, we assessed the role of iASPP in the regulation of cardiomyocyte injury induced by hypoxia/reoxygenation (H/R). We found that H/R-exposed cardiomyocytes expressed decreased levels of iASPP. The upregulation of iASPP repressed H/R-induced injury by decreasing levels of apoptosis and reactive oxygen species production. The upregulation of iASPP increased nuclear factor (erythroid-derived 2)-like 2 (Nrf2) nuclear translocation and enhanced Nrf2 activation. The overexpression of Kelch-like ECH-associated protein 1 reversed iASPP-mediated promotion of Nrf2 activation. Nrf2 inhibition abrogated iASPP-mediated cardioprotective effects in H/R-exposed cardiomyocytes. Our work demonstrates that the upregulation of iASPP ameliorates H/R-induced apoptosis and oxidative stress in cardiomyocytes via potentiating Nrf2 signaling via modulation of Keap1.

Detrimental and Beneficial Effect of Autophagy and a Potential Therapeutic Target after Ischemic Stroke

Autophagy, a physiologic mechanism that promotes energy recycling and orderly degradation through self-regulated disassembly of cellular components, helps maintain homeostasis. A series of evidences suggest that autophagy is activated as a response to ischemia and has been well-characterized as a therapeutic target. However, the role of autophagy after ischemia remains controversial. Activated-autophagy can remove necrotic substances against ischemic injury to promote cell survival. On the contrary, activation of autophagy may further aggravate ischemic injury, causing cell death. Therefore, the present review will examine the current understanding of the precise mechanism and role of autophagy in ischemia and recent neuroprotective therapies on autophagy, drug therapies, and nondrug therapies, including electroacupuncture (EA).

A preclinical randomized controlled study of ischemia treated with Ginkgo biloba extracts: Are complex components beneficial for treating acute stroke?

The rigorous design of preclinical experimental studies of candidate neuroprotectants for the treatment of acute ischemic stroke is crucial for the success of subsequent randomized clinical trials. The efficacy of Ginkgo biloba extracts (GBEs) in complex mixtures for the treatment of acute ischemic stroke remains unclear. In this preclinical randomized controlled trail (pRCT), the effects of a novel (n)GBE containing pinitol versus traditional (t)GBE without pinitol were evaluated on the mouse models of acute transient and permanent stroke, separately. The sample size, an important aspect of study design, was calculated based on our experimental data. Mice with ischemia that were induced by transient middle cerebral artery occlusion (tMCAO) or permanent distal middle cerebral artery occlusion (pdMCAO), were treated with vehicle, nGBE, tGBE, or pinitol alone by tail-vein injection. Our results showed that nGBE significantly reduced infarct size in mice with tMCAO compared with vehicle-treated control mice. Both nGBE and tGBE significantly reduced infarct size in mice with pdMCAO compared with the vehicle-treated controls. None of the three treatments rescued weight loss or prevented the neurological deficits in either the tMCAO- or pdMCAO-model mice. These findings suggest that nGBE, which includes all of the components of tGBE and pinitol, is neuroprotective in two ischemic stroke models. Additional studies of complex GBE mixtures for stroke treatment compared to single component medications are undergoing evaluation.

Increases of iASPP-Keap1 interaction mediated by syringin enhance synaptic plasticity and rescue cognitive impairments via stabilizing Nrf2 in Alzheimer's models

Oxidative stress is an important pathogenic manifestation of Alzheimer's disease (AD) that contributes to synaptic dysfunction, which precedes Aβ accumulation and neurofibrillary tangle formation. However, the molecular machineries that govern the decline of antioxidative defence in AD remains to be elucidated, and effective candidate for AD treatment is limited. Here, we showed that the decreases in the inhibitor of apoptosis-stimulating protein of p53 (iASPP) was associated with the vulnerability to oxidative stress in the amyloid precursor protein (APP)/presenilin 1 (PS1) mouse brain. Treatment with an antioxidant, syringin, could ameliorate AD-related pathologic and behavioural impairments. Interestingly, syringin treatment resulted in an upregulation of iASPP and the increase in the interaction of iASPP with Kelchlike ECH-associating protein 1 (Keap1). Syringin reduced neuronal apoptosis independently of p53. We confirmed that syringin-induced enhancement of antioxidant defenses involved the stabilization of Nrf2 in overexpressing human Swedish mutant APP (APPswe) cells in vitro. Syringin-mediated Nrf2 nuclear translocation facilitated the activation of the Nrf2 downstream genes via iASPP/Nrf2 axis. Our results demonstrate that syringin-mediated increases of iASPP-Keap1 interaction restore cellular redox balance. Further study on the syringin-iASPP interactions may help in understanding the regulatory mechanism and designing novel potent modulators for AD treatment.

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Poor expression of iASPP is associated with the serious accumulation of β-amyloid.

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Syringin reduces Aβ production and mitigates cognitive deficits by amending redox.

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Syringin-caused increases of iASPP facilitate the activation of NADPH and γGCL-C.

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Syringin protects neuronal cells against oxidative stress via iASPP/Nrf2 axis.

The Development of Stem Cell-Based Treatment for Acute Ischemic Cerebral Injury

Acute ischemic brain injury is a serious disease that severely endangers the life safety of patients. Such disease is hard to predict and highly lethal with very limited effective treatments currently. Although currently, there exist treatments like drug therapy, hyperbaric oxygen therapy, rehabilitation therapy and other treatments in clinical practice, these are not significantly effective for patients when the situation is severe. Thus scientists must explore more effective treatments. Stem cells are undifferentiated cells with a strong potential of self-renewal and differentiate into various types of tissues and organs. Their emergence has brought new hopes for overcoming difficult diseases, further improving medical technology and promoting the development of modern medicine. Some combining therapies and genetically modified stem cell therapy have also been proven to produce obvious neuroprotective function for acute ischemic brain injury. This review is an introduction to the current research findings and discusses the definition, origin and classification of stem cells, as well as the future prospects of the stem cell-based treatment for acute ischemic cerebral injury.

Neuroprotection by mesenchymal stem cell (MSC) administration is enhanced by local cooling infusion (LCI) in ischemia

OBJECTIVE

The present study aimed to determine if hypothermia augments the neuroprotection conferred by MSC administration by providing a conducive micro-environment.

METHODS

Sprague-Dawley rats were subjected to 1.5 h middle cerebral artery occlusion (MCAO) followed by 6 or 24 h of reperfusion for molecular analyses, as well as 1, 14 and 28 days for brain infarction or functional outcomes. Rats were treated with either MSC (1 × 10⁵), LCI (cold saline, 0.6 ml/min, 5 min) or both. Brain damage was determined by Infarct volume and neurological deficits. Long-term functional outcomes were evaluated using foot-fault and Rota-rod testing. Human neural SHSY5Y cells were investigated in vitro using 2 h oxygen-glucose deprivation (OGD) followed by MSC with or without hypothermia (HT) (34 °C, 4 h). Mitochondrial transfer was assessed by confocal microscope, and cell damage was determined by cell viability, ATP, and ROS level. Protein levels of IL-1β, BAX, Bcl-2, VEGF and Miro1 were measured by Western blot following 6 h and 24 h of reperfusion and reoxygenation.

RESULTS

MSC, LCI, and LCI + MSC significantly reduced infarct volume and deficit scores. Combination therapy of LCI + MSC precipitated better long-term functional outcomes than monotherapy. Upregulation of Miro1 in the combination group increased mitochondrial transfer and lead to a greater increase in neuronal cell viability and ATP, as well as a decrease in ROS. Further, combination therapy significantly decreased expression of IL-1β and BAX while increasing Bcl-2 and VEGF expression.

CONCLUSION

Therapeutic hypothermia upregulated Miro1 and enhanced MSC mitochondrial transfer-mediated neuroprotection in ischemic stroke. Combination of LCI with MSC therapy may facilitate clinical translation of this approach.

Hypoxia, hibernation and Neuroprotection: An Experimental Study in Mice

Hibernation is a unique physiological state that evolved to survive periods of food shortages. It is characterized by profound decreases in metabolic rate, body temperature and physiological functions. Studies have shown that animals in hibernation can resist neurological damage. Here, we aimed to study whether hypoxia can induce a hibernation-like state in a traditionally non-hibernating animal and whether it is neuroprotective. All procedures were conducted according to international guidelines on laboratory animal safety. Mice C57BL/6 (19-21g) were placed into a 125 mL jar with fresh air and the jar was sealed with a rubber plug. For each run, the tolerance limit was judged by the animals' appearance for "air hunger". The animal was removed from the jar as soon as its first gasping breath appeared and was moved to another fresh-air-containing jar of similar volume. This procedure was performed in four runs. The hypoxia exposure significantly decreased oxygen (O2) consumption, carbon dioxide (CO2) production, respiratory rate and heart rate. Meanwhile, rectal temperature reached a minimum of 12.7±2.56°C, which is lower than a wide range of ambient temperatures. The mimicked hibernation decreased the infarct size in a focal cerebral ischemia mouse model. Our findings suggest the possibility of inducing suspended animation-like hibernation states for medical applications post injury.

Synergistically Induced Hypothermia and Enhanced Neuroprotection by Pharmacological and Physical Approaches in Stroke

Hypothermia is considered as a promising neuroprotective treatment for ischemic stroke but with many limitations. To expand its clinical relevance, this study evaluated the combination of physical (ice pad) and pharmacological [transient receptor potential vanilloid channel 1 (TRPV1) receptor agonist, dihydrocapsaicin (DHC)] approaches for faster cooling and stronger neuroprotection. A total of 144 male Sprague Dawley rats were randomized to 7 groups: sham (n=16), stroke only (n=24), stroke with physical hypothermia at 31ºC for 3 h after the onset of reperfusion (n=24), high-dose DHC (H-DHC)(1.5 mg/kg, n=24), low-dose DHC (L-DHC)(0.5 mg/kg, n=32) with (n=8) or without (n=24) external body temperature control at ~38 ºC (L-DHC, 38 ºC), and combination therapy (L-DHC+ ice pad, n=24). Rats were subjected to middle cerebral artery occlusion (MCAO) for 2 h. Infarct volume, neurological deficits and apoptotic cell death were determined at 24 h after reperfusion. Expression of pro- and anti-apoptotic proteins was evaluated by Western blot. ATP and reactive oxygen species (ROS) were detected by biochemical assays at 6 and 24 h after reperfusion. Combination therapy of L-DHC and ice pad significantly improved every measured outcome compared to monotherapies. Combination therapy achieved hypothermia faster by 28.6% than ice pad, 350% than L-DHC and 200% than H-DHC alone. Combination therapy reduced (p<0.05) neurological deficits by 63% vs. 26% with L-DHC. No effect was observed when using ice pad or H-DHC alone. L-DHC and ice pad combination improved brain oxidative metabolism by reducing (p<0.05) ROS at 6 and 24 h after reperfusion and increasing ATP levels by 42.9% compared to 25% elevation with L-DHC alone. Finally, combination therapy decreased apoptotic cell death by 48.5% vs. 24.9% with L-DHC, associated with increased anti-apoptotic protein and reduced pro-apoptotic protein levels (p<0.001). Our study has demonstrated that combining physical and pharmacological hypothermia is a promising therapeutic approach in ischemic stroke, and warrants further translational investigations.

Mild therapeutic hypothermia protects against cerebral ischemia/reperfusion injury by inhibiting miR-15b expression in rats

OBJECTIVE

Mild hypothermia has a protective effect on ischemic stroke, but the mechanisms remain elusive. Here, we investigated microRNA (miRNA) profiles and the specific role of miRNAs in ischemic stroke treated with mild hypothermia.

MATERIALS AND METHODS

Male adult Sprague Dawley rats were subjected to focal transient cerebral ischemia. Mild hypothermia was induced by applying ice packs around the neck and head of the animals. miRNAs expression profiles were detected in ischemic stroke treated with mild therapeutic hypothermia through miRNA chips. Reverse transcription-polymerase chain reaction (RT-PCR) was used to verify the change of miRNA array. Western blot and adenosine triphosphate (ATP) assay kits were used to detect the changes of protein expression and ATP levels, respectively. miR-15b mimic and its control were injected into the right lateral ventricle 60 min before the induction of ischemia.

RESULTS

The results showed that mild hypothermia affected miRNAs profiles expression. We verified the expression of miR-15b and miR-598-3p by miRNA RT-PCR. miR-15b mimic inhibited the expression of its target, ADP ribosylation factor-like 2 (Arl2) protein, and decreased ATP levels in PC12 cells. Compared with the control, miR-15b mimic increased the infarct volume and aggravated the neurological function under normothermia or hypothermia treatment. Furthermore, the expression of Arl2 was decreased in the miR-15b mimic group under normothermia or hypothermia treatment.

CONCLUSIONS

Mild therapeutic hypothermia affected miRNA profiles and protected against cerebral ischemia/reperfusion by inhibiting miR-15b expression in rats. miR-15b may be a potential target for therapeutic intervention in stroke.