Chuanming Luo

Enriched endogenous omega-3 fatty acids in mice protect against global ischemia injury

Transient global cerebral ischemia, one of the consequences of cardiac arrest and cardiovascular surgery, usually leads to delayed death of hippocampal cornu Ammonis1 (CA1) neurons and cognitive deficits. Currently, there are no effective preventions or treatments for this condition. Omega-3 (ω-3) PUFAs have been shown to have therapeutic potential in a variety of neurological disorders. Here, we report that the transgenic mice that express the fat-1 gene encoding for ω-3 fatty acid desaturase, which leads to an increase in endogenous ω-3 PUFAs and a concomitant decrease in ω-6 PUFAs, were protected from global cerebral ischemia injury. The results of the study show that the hippocampal CA1 neuronal loss and cognitive deficits induced by global ischemia insult were significantly less severe in fat-1 mice than in WT mice controls. The protection against global cerebral ischemia injury was closely correlated with increased production of resolvin D1, suppressed nuclear factor-kappa B activation, and reduced generation of pro-inflammatory mediators in the hippocampus of fat-1 mice compared with WT mice controls. Our study demonstrates that fat-1 mice with high endogenous ω-3 PUFAs exhibit protective effects on hippocampal CA1 neurons and cognitive functions in a global ischemia injury model.

Ginsenoside Rb1 Protects Rat Neural Progenitor Cells against Oxidative Injury

Ginseng, the root of Panax ginseng C.A. Meyer, has been used as a tonic to enhance bodily functions against various ailments for hundreds of years in Far Eastern countries without apparent adverse effects. Ginsenoside Rb1, one of the most active ingredients of ginseng, has been shown to possess various pharmacological activities. Here we report that Rb1 exhibits potent neuroprotective effects against oxidative injury induced by tert-butylhydroperoxide (t-BHP). Lactate dehydrogenase (LDH) assay demonstrated that incubation with 300 µm t-BHP for 2.5 h led to a significant cell loss of cultured rat embryonic cortex-derived neural progenitor cells (NPCs) and the cell viability was pronouncedly increased by 24 h pretreatment of 10 µm Rb1. TUNEL staining further confirmed that pretreatment of Rb1 significantly reduced the cell apoptosis in t-BHP-induced oxidative injury. Real time PCR revealed that pretreatment with Rb1 activated Nrf2 pathway in cultured NPCs and led to an elevated expression of HO-1. The results of the present study demonstrate that Rb1 shows a potent anti-oxidative effect on cultured NPCs by activating Nrf2 pathway.

Omega-3 Polyunsaturated Fatty Acids Protect Neural Progenitor Cells against Oxidative Injury

The omega-3 polyunsaturated fatty acids (ω-3 PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), derived mainly from fish oil, play important roles in brain development and neuroplasticity. Here, we reported that application of ω-3 PUFAs significantly protected mouse neural progenitor cells (NPCs) against H2O2-induced oxidative injury. We also isolated NPCs from transgenic mice expressing the Caenorhabditis elegans fat-1 gene. The fat-1 gene, which is absent in mammals, can add a double bond into an unsaturated fatty acid hydrocarbon chain and convert ω-6 to ω-3 fatty acids. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining showed that a marked decrease in apoptotic cells was found in fat-1 NPCs after oxidative injury with H2O2 as compared with wild-type NPCs. Quantitative RT-PCR and Western blot analysis demonstrated a much higher expression of nuclear factor erythroid 2-related factor 2 (Nrf2), a master transcriptional factor for antioxidant genes, in fat-1 NPCs. The results of the study provide evidence that ω-3 PUFAs resist oxidative injury to NPCs.

Enriched Endogenous Omega-3 Polyunsaturated Fatty Acids Protect Cortical Neurons from Experimental Ischemic Injury

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) exert therapeutic potential in a variety of neurological disorders, including ischemic stroke. However, the underlying mechanisms still lack investigation. Here, we report that cultured cortical neurons isolated from fat-1 mice with high endogenous n-3 PUFAs were tolerant to oxygen-glucose deprivation/reperfusion (OGD/R) injury. Fat-1 neurons exhibited significantly attenuated reactive oxygen species (ROS) activation induced by OGD/R injury, upregulated antiapoptotic proteins Bcl-2 and Bcl-xL, and reduced cleaved caspase-3. Exogenous administration of docosahexaenoic acid (DHA), a major component of the n-3 PUFA family, resulted in similar protective effects on cultured cortex neurons. We further verified the protective effects of n-3 PUFAs in vivo, using a mini ischemic model with a reproducible cortical infarct and manifest function deficits by occlusion of the distal branch of the middle cerebral artery with focused femtosecond laser pulses. The Fat-1 animals showed decreased ROS expression and higher level of glutathione in the injured brain, associated with improved functional recovery. We therefore provide evidence that n-3 PUFAs exert their protective effects against ischemic injury both in vitro and in vivo, partly through inhibiting ROS activation.

Omega-3 polyunsaturated fatty acids promote amyloid-β clearance from the brain through mediating the function of the glymphatic system

Impairment of amyloid‐β (Aβ) clearance leads to Aβ accumulation in the brain during the development of Alzheimers disease (AD). Strategies that can restore or improve the clearance function hold great promise in delaying or preventing the onset of AD. Here, we show that n‐3 polyunsaturated fatty acids (PUFAs), by use of fat‐1 transgenicmice andoral administration of fish oil, significantly promote interstitial Aβ clearance from theb rain and resist Aβ injury. Such beneficial effects were abolished in Aqp4‐knockout mice, suggesting that the AQP4‐ dependent glymphatic system is actively involved in the promoting the effects of n‐3 PUFAs on the clearance of extracellularAβ. Imaging on clarified brain tissues clearly displayed thatn‐3 PUFAsmarkedly inhibit the activation of astrocytes and protect the AQP4 polarization in the affected brain region after Aβ injection. The results of the present study prove a novelmechanism by which n‐3 PUFAs exert protective roles in reducingAβ accumulation via mediating the glymphatic system function.—Ren, H., Luo, C., Feng, Y., Yao, X., Shi, Z., Liang, F., Kang, J. X., Wan, J.‐B., Pei, Z., Su, H. Omega‐3 polyunsaturated fatty acids promote amyloid‐β clearance from the brain through mediating the function of the glymphatic system. FASEB J. 31, 282–293 (2017) www.fasebj.org

Deletion of aquaporin-4 is neuroprotective during the acute stage of micro traumatic brain injury in mice.

Micro traumatic brain injury (TBI) is the most common type of brain injury, but the mechanisms underlying it are poorly understood. Aquaporin-4 (AQP4) is a water channel expressed in astrocyte end-feet, which plays an important role in brain edema. However, little is known about the role of AQP4 in micro TBI. Here, we examined the role of AQP4 in the pathogenesis of micro TBI in a closed-skull brain injury model, using two-photon microscopy. Our results indicate that AQP4 deletion reduced cell death, water content, astrocyte swelling and lesion volume during the acute stage of micro TBI. Our data revealed that astrocyte swelling is a decisive pathophysiological factor in the acute phase of this form of micro brain injury. Thus, treatments that inhibit AQP4 could be used as a neuroprotective strategy for micro TBI.

Self-Assembling Peptide Nanofiber Scaffolds Enhance Dopaminergic Differentiation of Mouse Pluripotent Stem Cells in 3-Dimensional Culture

Dopaminergic differentiation of embryonic stem cells (ESCs) gains more and more attention worldwide owing to its potential use for neurorestorative therapy for the treatment of Parkinson’s disease. The conventional 2D cell culture on petri dishes with various animal derived substrata such as collagen gels, laminin, and Matrigel is widely used to induce dopaminergic differentiation and it may limit the efficiency in the generation of dopaminergic neurons from ESCs and prevent their application for human therapies. Here, we reported that a self-assembling peptide made from natural amino acids has a property to generate a true 3D environment for dopaminergic differentiation. Mouse ESCs (R1) and mouse iPSCs (TTF-1) embedded in RADA16-I peptide-derived nanofiber scaffolds led to a marked increase in dopaminergic differentiation compared to the laminin-coated 2D culture or Matrigel-encapsulated 3D culture. These differentiated neurons expressed specific dopaminergic markers and produced appropriate patterns of action potential firing. Consistent with the increase in the number of dopaminergic neurons differentiated from R1 or TTF-1 in the self-assembling peptide nanofiber scaffold (SAPNS), both the expression levels of genes that involve in dopaminergic differentiation and maturation and the dopamine release in SAPNS culture were significantly elevated. The results of the study suggest that SAPNS provides a promising 3D culture system for dopaminergic differentiation.

Allopurinol protects against ischemic insults in a mouse model of cortical microinfarction.

Microinfarcts are common in patients with cognitive decline and dementia. Allopurinol (ALLO), a xanthine oxidase (XO) enzyme inhibitor, has been found to reduce proinflammatory molecules and oxidative stress in the vasculature. We here examined the effect of pre-treatment with allopurinol on the cortical microinfarction. C57BL/6J mice were subjected to a permanent single penetrating arteriole occlusion induced by two-photon laser irradiation. Infarction volume, the activation of glial cells and nitrosative stress in the ischemic brain was assessed using immunohistochemistry. Pre-treatment with ALLO achieved 42% reduction of infarct volume and significantly reduced microglia infiltration, astrocyte proliferation and nitrosative stress in the ischemic brain. These data indicate that ALLO protects against microinfarcts possibly through inhibition of nitrosative stress and attenuation of microglia infiltration as well as astrocytes reactivation.

Paravascular pathways contribute to vasculitis and neuroinflammation after subarachnoid hemorrhage independently of glymphatic control

Subarachnoid hemorrhage (SAH) is a devastating disease with high mortality. The mechanisms underlying its pathological complications have not been fully identified. Here, we investigate the potential involvement of the glymphatic system in the neuropathology of SAH. We demonstrate that blood components rapidly enter the paravascular space following SAH and penetrate into the perivascular parenchyma throughout the brain, causing disastrous events such as cerebral vasospasm, delayed cerebral ischemia, microcirculation dysfunction and widespread perivascular neuroinflammation. Clearance of the paravascular pathway with tissue-type plasminogen activator ameliorates the behavioral deficits and alleviates histological injury of SAH. Interestingly, AQP4−/− mice showed no improvements in neurological deficits and neuroinflammation at day 7 after SAH compared with WT control mice. In conclusion, our study proves that the paravascular pathway dynamically mediates the pathological complications following acute SAH independently of glymphatic control.

Reprogramming somatic cells to cells with neuronal characteristics by defined medium both in vitro and in vivo

BackgroundCurrently, direct conversion from somatic cells to neurons requires virus-mediated delivery of at least one transcriptional factor or a combination of several small-molecule compounds. Delivery of transcriptional factors may affect genome stability, while small-molecule compounds may require more evaluations when applied in vivo. Thus, a defined medium with only conventional growth factors or additives for cell culture is desirable for inducing neuronal trans-differentiation.ResultsHere, we report that a defined medium (5C) consisting of basic fibroblast growth factor (bFGF), N2 supplement, leukemia inhibitory factor, vitamin C (Vc), and β-mercaptoethanol (βMe) induces the direct conversion of somatic cells to cells with neuronal characteristics. Application of 5C medium converted mouse embryonic fibroblasts (MEFs) into TuJ+ neuronal-like cells, which were capable of survival after being transplanted into the mouse brain. The same 5C medium could convert primary rat astrocytes into neuronal-like cells with mature electrophysiology characteristics in vitro and facilitated the recovery of brain injury, possibly by inducing similar conversions, when infused into the mouse brain in vivo. Crucially, 5C medium could also induce neuronal characteristics in several human cell types.ConclusionsIn summary, this 5C medium not only provides a means to derive cells with neuronal characteristics without viral transfection in vitro but might also be useful to produce neurons in vivo for neurodegenerative disease treatment.