Treatment Of Hypoxic-ischemic Brain Injury Research Articles

A Human Brain Model Mimicking Umbilical Cord Mesenchymal Stem Cells for the Treatment of Hypoxic-Ischemic Brain Injury.

We used an in vitro model of the human brain immune microenvironment to simulate hypoxic-ischemic brain injury (HIBI) and treatment with human umbilical cord mesenchymal stem cells (hUMSCs) to address the transformation barriers of gene differences between animals and humans in preclinical research. A co-culture system, termed hNAME, consisted of human hippocampal neurons (N), astrocytes (A), microglia (M), and brain microvascular endothelial cells (E). Flow cytometry measured the apoptosis rates of neurons and endothelial cells. hNAME-neurons and endothelial cells experienced more severe damage than monolayer cells, particularly after 48 h and 24 h of reoxygenation (OGD48/R24). Western blotting identified neuroinflammatory response markers, including HIF-1α, C1q, C3, TNF-α, and iNOS. Inflammatory factors originated from the glial chamber rather than the neurons and vascular endothelial chambers. A gradual increase in the release of inflammatory factors was observed as the OGD and reoxygenation times increased, peaking at OGD48/R24. The hNAME value was confirmed in human umbilical cord mesenchymal stem cells (hUMSCs). Treatment with hUMSCs resulted in a notable decrease in the severity of neuronal and endothelial cell damage in hNAME. The hNAME is an ideal in vitro model for simulating the immune microenvironment of the human brain because of the interactions between neurons, vessels, astrocytes, and microglia.

Combination treatments with therapeutic hypothermia for hypoxic‐ischemic neuroprotection

Therapeutic hypothermia is now proven to reduce death or disability in term and near-term born infants with moderate to severe hypoxic-ischemic encephalopathy. Nevertheless, many infants still survive with disability, despite treatment with hypothermia. Recent preclinical and clinical studies suggest that current protocols for therapeutic hypothermia are near-optimal. The obvious strategy, in addition to improving early initiation of therapeutic hypothermia after birth, is to combine hypothermia with other neuroprotective agents. We review evidence that the mechanisms of action of many promising agents overlap with the anti-excitotoxic, anti-apoptotic, and anti-inflammatory mechanisms of hypothermia, leading to a lack of benefit from combination treatment. Moreover, even apparently beneficial combinations have failed to translate in clinical trials. These considerations highlight the need for preclinical studies to test clinically realistic protocols of timing and duration of treatment, before committing to large randomized controlled trials.

Treatment and new progress of neonatal hypoxic-ischemic brain damage.

Neonatal hypoxic ischemia (HI) results in different extents of brain damage, and immature brain tissue is particularly sensitive to the stimulation of HI. Hypoxic-ischemic brain damage (HIBD) is a common and serious nervous system disease in neonates, for both full-term infants and preterm infants, and is one of the main causes of neonatal death. The surviving infants are often associated with cerebral palsy, mental retardation, and other sequelae, which severely affect quality of life. For term infants, hypoxia and ischemia mainly affect gray matter, whereas in preterm infants, the white matter. However, up to now, inadequate standards and specific measures that can be used to treat hypoxic-ischemic brain injury are available. Recently, in addition to supportive therapy and symptomatic treatment, research on the treatment of hypoxic-ischemic brain injury has focused on the following aspects: hypothermia therapy, stem cell therapy, neuroprotective agents, ibuprofen, and combination therapy. In this review, we will summarize the treatment of HIBD and make suggestions for the future treatment direction.

RETRACTED ARTICLE:Bone mesenchymal stemcell-derived exosomal microRNA-29b-3p prevents hypoxic-ischemic injury in rat brain byactivating the PTEN-mediated Akt signaling pathway

BackgroundMesenchymal stem cells (MSCs) are suspected to exert neuroprotectiveeffects in brain injury, in part through the secretion of extracellular vesicleslike exosomes containing bioactive compounds. We now investigate the mechanismby which bone marrow MSCs (BMSCs)-derived exosomes harboring the smallnon-coding RNA miR-29b-3p protect against hypoxic-ischemic brain injury inrats.MethodsWe established a rat model of middle cerebral artery occlusion(MCAO) and primary cortical neuron or brain microvascular endothelial cell(BMEC) models of oxygen and glucose deprivation (OGD). Exosomes were isolatedfrom the culture medium of BMSCs. We treated the MCAO rats with BMSC-derivedexosomes in vivo, and likewise the OGD-treated neurons and BMECs in vitro. Wethen measured apoptosis- and angiogenesis-related features using TUNEL and CD31immunohistochemical staining and in vitro Matrigel angiogenesis assays.ResultsThe dual luciferase reporter gene assay showed that miR-29b-3ptargeted the protein phosphatase and tensin homolog (PTEN). miR-29b-3p wasdownregulated and PTEN was upregulated in the brain of MCAO rats and inOGD-treated cultured neurons. MCAO rats and OGD-treated neurons showed promotedapoptosis and decreased angiogenesis, but overexpression of miR-29b-3p orsilencing of PTEN could reverse these alterations. Furthermore, miR-29b-3p couldnegatively regulate PTEN and activate the Akt signaling pathway. BMSCs-derivedexosomes also exerted protective effects against apoptosis of OGD neurons andcell apoptosis in the brain samples from MCAO rats, where we also observedpromotion of angiogenesis.ConclusionBMSC-derived exosomal miR-29b-3p ameliorates ischemic brain injuryby promoting angiogenesis and suppressing neuronal apoptosis, a finding whichmay be of great significance in the treatment of hypoxic-ischemic braininjury.

Hypoxic postconditioning improves behavioural deficits at 6 weeks following hypoxic-ischemic brain injury in neonatal rats

Hypoxic-ischemic (HI) brain injury in newborns is associated with high morbidity and mortality, with many babies suffering neurological deficits. Recently, we showed that hypoxic postconditioning (PostC) immediately post injury can protect against HI up to one week in neonatal rats. Here, we aimed to examine whether long term functional deficits were also improved by PostC. Sprague-Dawley rats were assigned to control (C) or HI group on postnatal day 7 (P7). The HI group underwent unilateral carotid artery occlusion followed by hypoxia (7% oxygen, 3h). Half of each group were randomly assigned to the PostC group (8% oxygen, 1h/day for 5days post-injury), or normoxic group, where animals were kept under ambient conditions. Righting reflex and negative geotaxis tests were performed on P8 and P14. On P42, rats underwent further behavioural tests of motor function and memory (forelimb grip strength, grid walking and novel object recognition tasks). Brain injury was assessed using histological scoring of brain sections. At P14, PostC reduced the righting reflex deficit compared to HI alone. Long-term (6 weeks) behavioural deficits were observed in grid walking and novel object recognition tests after HI alone, with both functions improved following PostC. Following HI, there was an increase in brain injury assessed by histological scoring compared to control, and this damage was reduced by PostC. This novel finding of long-term histological neuroprotection accompanied by functional improvements by PostC further demonstrates the clinical potential of mild hypoxia for the treatment of HI brain injury.

Neuroprotective Role of Exogenous Brain-Derived Neurotrophic Factor in Hypoxia-Hypoglycemia-Induced Hippocampal Neuron Injury via Regulating Trkb/MiR134 Signaling.

Hypoxic-ischemic brain injury is an important cause of neonatal mortality and morbidity. Brain-derived neurotrophic factor (BDNF) has been reported to play a neuroprotective role in hypoxic-ischemic brain injury; however, the specific effects and mechanism of BDNF on hypoxic-hypoglycemic hippocampal neuron injury remains unknown. The current study investigated the action of BDNF in regulating cerebral hypoxic-ischemic injury by simulating hippocampal neuron ischemia and hypoxia. We found that BDNF, p-Trkb, and miR-134 expression levels decreased, and that exogenous BDNF increased survival and reduced apoptosis in hypoxic-hypoglycemic hippocampal neurons. The results also show that BDNF inhibits MiR-134 expression by activating the TrkB pathway. Transfection with TrkB siRNA and pre-miR-134 abrogated the neuroprotective role of BDNF in hypoxic-hypoglycemic hippocampal neurons. Our results suggest that exogenous BDNF alleviates hypoxic-ischemic brain injury through the Trkb/MiR-134 pathway. These findings may help to identify a potential therapeutic agent for the treatment of hypoxic-ischemic brain injury.

Vitexin protects against hypoxic-ischemic injury via inhibiting Ca2+/Calmodulin-dependent protein kinase II and apoptosis signaling in the neonatal mouse brain.

Neonatal hypoxic-ischemic is a major cause of death and disability in neonates. In this study, we suggest for the first time that pretreatment with vitexin may suppress a pro-apoptotic signaling pathway in hypoxic-ischemic neuronal injury in neonates by inhibition of the phosphorylation of Ca2+/Calmodulin-dependent protein kinase II. Here we found that vitexin pretreatment reduced brain infarct volume in a dose-dependent manner. In addition, vitexin decreased the number of TUNEL-positive cells and brain atrophy. Furthermore, vitexin improved neurobehavioral outcomes. Vitexin also reduced oxygen glucose deprivation-induced neuronal injury and calcium entry. Vitexin pretreatment increased the Bcl-2/Bax protein ratio and decreased phosphorylation of Ca2+/Calmodulin-dependent protein kinase II and NF-κB, cleaved caspase-3 protein expression 24 hours after injury. Our data indicate that pretreatment with vitexin protects against neonatal hypoxic-ischemic brain injury and thus has potential as a treatment for hypoxic-ischemic brain injury.

Tideglusib, a chemical inhibitor of GSK3β, attenuates hypoxic-ischemic brain injury in neonatal mice

BackgroundHypoxia-ischemia is an important cause of brain injury and neurological morbidity in the newborn infants. The activity of glycogen synthase kinase-3β (GSK-3β) is up-regulated following neonatal stroke. Tideglusib is a GSK-3β inhibitor which has neuroprotective effects against neurodegenerative diseases in clinical trials. However, the effect of tideglusib on hypoxic-ischemic (HI) brain injury in neonates is still unknown. MethodsPostnatal day 7 (P7) mouse pups subjected to unilateral common carotid artery ligation followed by 1h of hypoxia or sham surgery was performed. HI animals were administered tideglusib (5mg/kg) or vehicle intraperitoneally 20min prior to the onset of ischemia. The brain infarct volume and whole brain images, were used in conjunction with Nissl staining to evaluate the protective effects of tideglusib. Protein levels of glial fibrillary acidic protein (GFAP), Notch1, cleaved caspase-3/9, phosphorylated signal transducer and activator of transcription 3 (STAT3), GSK-3β and protein kinase B (Akt) were detected to identify potentially involved molecules. ResultsTideglusib significantly reduced cerebral infarct volume at both 24h and 7days after HI injury. Tideglusib also increased phosphorylated GSK-3β(Ser9) and Akt(Ser473), and reduced the expression of GFAP and p-STAT3(Tyr705). In addition, pretreatment with tideglusib also enhanced the protein level of Notch1. Moreover, tideglusib reduced the cleavage of pro-apoptotic signal caspase proteins, including caspase 3 and caspase 9 following HI. ConclusionThese results indicate that tideglusib shows neuroprotection against hypoxic-ischemic brain injury in neonatal mice. General significanceTideglusib is a potential compound for the prevention or treatment of hypoxic-ischemic brain injury in neonates.

Multipotent adult progenitor cells for hypoxic-ischemic injury in the preterm brain.

BackgroundPreterm infants are at risk for hypoxic-ischemic encephalopathy. No therapy exists to treat this brain injury and subsequent long-term sequelae. We have previously shown in a well-established pre-clinical model of global hypoxia-ischemia (HI) that mesenchymal stem cells are a promising candidate for the treatment of hypoxic-ischemic brain injury. In the current study, we investigated the neuroprotective capacity of multipotent adult progenitor cells (MAPC®), which are adherent bone marrow-derived cells of an earlier developmental stage than mesenchymal stem cells and exhibiting more potent anti-inflammatory and regenerative properties.MethodsInstrumented preterm sheep fetuses were subjected to global hypoxia-ischemia by 25 min of umbilical cord occlusion at a gestational age of 106 (term ~147) days. During a 7-day reperfusion period, vital parameters (e.g., blood pressure and heart rate; baroreceptor reflex) and (amplitude-integrated) electroencephalogram were recorded. At the end of the experiment, the preterm brain was studied by histology.ResultsSystemic administration of MAPC therapy reduced the number and duration of seizures and prevented decrease in baroreflex sensitivity after global HI. In addition, MAPC cells prevented HI-induced microglial proliferation in the preterm brain. These anti-inflammatory effects were associated with MAPC-induced prevention of hypomyelination after global HI. Besides attenuation of the cerebral inflammatory response, our findings showed that MAPC cells modulated the peripheral splenic inflammatory response, which has been implicated in the etiology of hypoxic-ischemic injury in the preterm brain.ConclusionsIn a pre-clinical animal model MAPC cell therapy improved the functional and structural outcome of the preterm brain after global HI. Future studies should establish the mechanism and long-term therapeutic effects of neuroprotection established by MAPC cells in the developing preterm brain exposed to HI. Our study may form the basis for future clinical trials, which will evaluate whether MAPC therapy is capable of reducing neurological sequelae in preterm infants with hypoxic-ischemic encephalopathy.

Marine compound xyloketal B reduces neonatal hypoxic-ischemic brain injury.

Neonatal hypoxic-ischemic encephalopathy causes neurodegeneration and brain injury, leading to sensorimotor dysfunction. Xyloketal B is a novel marine compound isolated from a mangrove fungus Xylaria species (no. 2508) with unique antioxidant effects. In this study, we investigated the effects and mechanism of xyloketal B on oxygen-glucose deprivation-induced neuronal cell death in mouse primary cortical culture and on hypoxic-ischemic brain injury in neonatal mice in vivo. We found that xyloketal B reduced anoxia-induced neuronal cell death in vitro, as well as infarct volume in neonatal hypoxic-ischemic brain injury model in vivo. Furthermore, xyloketal B improved functional behavioral recovery of the animals following hypoxic-ischemic insult. In addition, xyloketal B significantly decreased calcium entry, reduced the number of TUNEL-positive cells, reduced the levels of cleaved caspase-3 and Bax proteins, and increased the level of Bcl-2 protein after the hypoxic-ischemic injury. Our findings indicate that xyloketal B is effective in models of hypoxia-ischemia and thus has potential as a treatment for hypoxic-ischemic brain injury.

Change of blood brain barrier permeability and mechanisms after cerebral hypoxia-ischemia

The blood brain barrier(BBB) is a barrier system between the blood and brain tissue,which can maintain relatively stable of internal environment in the central nervous system (CNS).Cerebral hypoxiaischemia and other conditions can lead to the change of the permeability of BBB.This paper reviews the latest research for the structural basis and function of BBB,and for the scope,time and mechanism of the change of BBB structure and function during hypoxic-ischemic brain injury.This theory in the regulation of BBB may play an important role in the treatment of hypoxic-ischemic brain injury and underlying diseases of CNS. Key words: Hypoxia-ischemia; Blood brain barrier; Permeability

Therapeutic effects of a reducible poly (oligo- d-arginine) carrier with the heme oxygenase-1 gene in the treatment of hypoxic-ischemic brain injury

Non-viral carriers for gene therapy have been developed to minimize carrier cytotoxicity and to enhance transfection efficiency. Previously, we synthesized a 9-arginine-based reducible high molecular weight peptide for gene delivery. For the reducible poly(oligo- d-arginines) (rPOA), 9-arginine oligopeptides are connected by internal disulfide linkages to produce a high molecular weight peptide. In this study, rPOA was evaluated as a carrier of the heme oxygenase-1 (HO-1) gene for the treatment of ischemia/reperfusion (I/R) -induced brain stroke. An in vitro transfection assay showed that rPOA had higher transfection efficiency and lower toxicity than polyethylenimine (PEI). For in vivo evaluation, I/R rat models were produced by middle cerebral artery occlusion (MCAO). rPOA/HO-1 expression plasmid (pHO-1) polyplexes were injected into the brain at 1 h before MCAO, and HO-1 expression levels in the brain were then measured by ELISA. The results indicated that rPOA/pHO-1 polyplexes had higher transfection efficiencies than PEI/pHO-1 polyplexes. The rPOA/pHO-1 polyplexes significantly reduced infarct volumes. In addition, tumor necrosis factor-alpha (TNF-α) was reduced in the rPOA/pHO-1 polyplex injection group, suggesting that HO-1 had an anti-inflammatory effect, while the PEI/pHO-1 polyplex did not show this effect. These results suggest that rPOA is a potential non-viral vector for HO-1 gene therapy to protect brain cells from I/R-related neuronal injury including stroke.

Treating Neonatal Brain Injury - Promise and Inherent Research Challenges

In this review we discuss current challenges faced by researchers and clinician-scientists in the pursuit of therapeutics to treat hypoxic-ischemic (HI) brain injury in term infants. At present, there is an absence of neuroprotective drugs that are safe and effective for the protection of neonates from neurological sequels after HI. We discuss secondary neurotoxic processes elicited by HI that may be targets for therapeutic interventions with a specific focus on inflammatory mechanisms. Advances in research to unravel these cellular processes and molecular mechanisms that drive injurious processes after HI have traditionally been plagued by conflicting results when assessing different times for intervention, different models for brain injury, and the adult versus neonate brain. We attribute impeded drug development in part to such disparate results and general difficulties to conduct a stringent, comprehensive analysis of candidate drugs prior to clinical trials. It will be imperative to implement changes in the clinic and laboratory in order for future drug initiatives to achieve success. We also provide a brief discussion on the pursuit of anti-inflammatory molecules and monitoring methods that are the focus of current patents and that, in our opinion, may lead to important new developments in the treatment of HI brain injury in newborn infants.

Platelet-activating factor antagonist (ABT-491) decreases neuronal apoptosis in neonatal rat model of hypoxic ischemic brain injury

Hypoxic ischemic brain injury (HIBI) is a common cause of neonatal mortality and morbidity. To date, no study has investigated the role of platelet-activating factor (PAF) antagonists on neuronal apoptosis in neonatal rat model of HIBI. In the present study, we evaluated the effect of a highly potent and selective PAF antagonist (ABT-491) on neuronal apoptosis in neonatal rat model of HIBI. Seven-day-old Wistar rat pups were subjected to right common carotid artery ligation and hypoxia (92% nitrogen and 8% oxygen) for 2 h. They were treated with ABT-491 or saline either immediately before or after hypoxia. In sham group animals, neither ligation, nor hypoxia was performed. Neuronal apoptosis was evaluated by the terminal-transferase mediated dUTP biotin nick-end-labeling (TUNEL) and caspase-3 staining methods. Administration of ABT-491 either before or after hypoxia resulted in significant reduction of the numbers of apoptotic cells in both hemispheres, when compared to saline treatment group. The numbers of apoptotic cells in right hemispheres in all groups were significantly higher than that in the left hemispheres. These results suggested that ABT-491, a highly potent and selective PAF antagonist, administration either before or after hypoxia reduces apoptosis and we propose that ABT-491 may be a novel approach in the treatment of HIBI.

Treatment of Hypoxic-Ischemic Brain Injury in Newborn Rats with TPCK 3 h after Hypoxia Decreases Caspase-9 Activation and Improves Neuropathologic Outcome

N-Tosyl-L-phenylalanyl-chloromethyl ketone (TPCK) reduces apoptosis in vitro. Pretreatment with TPCK reduces brain injury. Would treatment after injury reduce damage? Seven-day-old rats had the right carotid artery ligated and were subjected to 2.5 h of 8% oxygen and were treated intraperitoneally 3 h after hypoxia with 10 mg/kg of TPCK or vehicle. Brain damage was measured 22 days after injury. bcl-2, bax, and cytochrome c where measured by Western blot 24 h after injury. Caspase-9 and caspase-3 activity were measured enzymatically 24 h after injury. Treatment with TPCK reduced the loss of the right hemisphere caused by injury from 27.6 ± 2.8% SEM (vehicle, n = 56) to 19.8 ± 2.8% (TPCK, n = 61, p < 0.05). Hypoxic ischemia increased cytosolic cytochrome c from 0.25 ± 0.04 to 0.4 ± 0.04 optical density (OD; p < 0.05), but TPCK had no effect (0.31 ± 0.03 OD). TPCK reduced caspase-9 activity from 72 ± 30 to 43 ± 5 fluorescence units/h/mg (p < 0.05 vs. vehicle), and caspase-3 activity from 66 ± 10 to 39 ± 3.7 fluorescence units/h/mg (p < 0.05 vs. vehicle). Treatment with TPCK 3 h after hypoxic ischemia reduced brain infarct size. TPCK may act by reducing caspase-9 activation by cytochrome c.

Platelet-Activating Factor Is an Important Mediator in Hypoxic Ischemic Brain Injury in the Newborn Rat

Hypoxic-ischemic encephalopathy is still a very important cause of neonatal mortality and morbidity. Recently, platelet-activating factor (PAF) has been accused of being responsible for the neuronal damage in hypoxic-ischemic brain. We investigated tissue PAF concentrations in hypoxic-ischemic brain injury in immature rats. Endogenous PAF concentration in brain tissue showed a marked increase in hypoxic-ischemic pups (85.6 ± 15.5 pg/mg protein) when compared to that of control (9.05 ± 3.1 pg/mg protein). In addition, we examined the effects of flunarizine, a selective calcium channel blocker, and Ginkgo biloba extract (EGb 761) on endogenous PAF concentration in hypoxic-ischemic brain injury. Endogenous PAF concentrations in both flunarizine-pretreated (16.6 ± 4.8 pg/mg protein) and EGb 761-pretreated (33.5 ± 8.9 pg/mg protein) pups were significantly lower than the untreated group. These results indicate that PAF is an important mediator in immature rat model of cerebral hypoxic-ischemic injury. The suppressor effect of flunarizine and EGb 761 on PAF production may open new insight into the treatment of hypoxic-ischemic brain injury.

The effect of L-carnitine on platelet activating factor concentration in the immature rat model of hypoxic-ischemic brain injury.

Recent data suggested that platelet-activating factor (PAF) could play a pathophysiologically important role in the progression of hypoxic-ischemic brain injury. We investigated brain tissue PAF concentration in the hypoxic-ischemic brain of immature rats. Endogenous PAF concentration in brain tissue showed a marked increase in hypoxic-ischemic pups (Group 1, 85.6 +/- 15.5 pg/mg protein) when compared to that of the control (9.1 +/- 3.1 pg/mg protein). In addition, we studied the effects of pretreatment with L-carnitine (5 days and 2 h before the hypoxia) on endogenous PAF concentration in the hypoxic-ischemic brain. Endogenous PAF concentration in the short-term pretreatment group (Group 2, 81.6 +/- 9.7 pg/mg protein) was not different than in Group 1 rat pups. However, a significantly decreased PAF concentration was found in the group of pups that received carnitine pretreatment for 5 days (Group 3, 30.5 +/- 11.0 pg/mg protein). These results indicate that PAF is an important mediator in the immature rat model of cerebral hypoxic-ischemic injury. The suppressor effect of L-carnitine on PAF production may give new insight into the treatment of hypoxic-ischemic brain injury.