Therapeutic Effect of Rapamycin on TDP-43-Related Pathogenesis in Ischemic Stroke.

Stroke is a major cause of death and disability across the world, and its detrimental impact should not be underestimated. Therapies are available and effective for ischemic stroke (e.g., thrombolytic recanalization and mechanical thrombectomy); however, there are limitations to therapeutic interventions. Recanalization therapy has developed dramatically, while the use of adjunct neuroprotective agents as complementary therapies remains deficient. Pathological TAR DNA-binding protein (TDP-43) has been identified as a major component of insoluble aggregates in numerous neurodegenerative pathologies, including ALS, FTLD and Alzheimer's disease. Here, we show that increased pathological TDP-43 fractions accompanied by impaired mitochondrial function and increased gliosis were observed in an ischemic stroke rat model, suggesting a pathological role of TDP-43 in ischemic stroke. In ischemic rats administered rapamycin, the insoluble TDP-43 fraction was significantly decreased in the ischemic cortex region, accompanied by a recovery of mitochondrial function, the attenuation of cellular apoptosis, a reduction in infarct areas and improvements in motor defects. Accordingly, our results suggest that rapamycin provides neuroprotective benefits not only by ameliorating pathological TDP-43 levels, but also by reversing mitochondrial function and attenuating cell apoptosis in ischemic stroke.

Neuroprotective Effects of Emodin against Ischemia/Reperfusion Injury through Activating ERK-1/2 Signaling Pathway.

BACKGROUND: Stroke is one of the leading causes of death and disability worldwide and places a heavy burden on the economy in our society. Current treatments, such as the use of thrombolytic agents, are often limited by a narrow therapeutic time window. However, the regeneration of the brain after damage is still active days, even weeks, after stroke occurs, which might provide a second window for treatment. Emodin, a traditional Chinese medicinal herb widely used to treat acute hepatitis, has been reported to possess antioxidative capabilities and protective effects against myocardial ischemia/reperfusion injury. However, the underlying mechanisms and neuroprotective functions of Emodin in a rat middle cerebral artery occlusion (MCAO) model of ischemic stroke remain unknown. This study investigates neuroprotective effects of Emodin in ischemia both in vitro and in vivo. METHODS: PC12 cells were exposed to oxygen-glucose deprivation to simulate hypoxic injury, and the involved signaling pathways and results of Emodin treatment were evaluated. The therapeutic effects of Emodin in ischemia animals were further investigated. RESULTS: Emodin reduced infarct volume and cell death following focal cerebral ischemia injury. Emodin treatment restored PC12 cell viability and reduced reactive oxygen species (ROS) production and glutamate release under conditions of ischemia/hypoxia. Emodin increased Bcl-2 and glutamate transporter-1 (GLT-l) expression but suppressed activated-caspase 3 levels through activating the extracellular signal-regulated kinase (ERK)-1/2 signaling pathway. CONCLUSION: Emodin induced Bcl-2 and GLT-1 expression to inhibit neuronal apoptosis and ROS generation while reducing glutamate toxicity via the ERK-1/2 signaling pathway. Furthermore, Emodin alleviated nerve cell injury following ischemia/reperfusion in a rat MCAO model. Emodin has neuroprotective effects against ischemia/reperfusion injury both in vitro and in vivo, which may be through activating the ERK-1/2 signaling pathway.

Efficient Labeling Of Mesenchymal Stem Cells For High Sensitivity Long-Term MRI Monitoring In Live Mice Brains.

BACKGROUND: Regenerative medicine field is still lagging due to the lack of adequate knowledge regarding the homing of therapeutic cells towards disease sites, tracking of cells during treatment, and monitoring the biodistribution and fate of cells. Such necessities require labeling of cells with imaging agents that do not alter their biological characteristics, and development of suitable non-invasive imaging modalities. PURPOSE: We aimed to develop, characterize, and standardize a facile labeling strategy for engineered mesenchymal stem cells without altering their viability, secretion of FGF21 protein (neuroprotective), and differentiation capabilities for non-invasive longitudinal MRI monitoring in live mice brains with high sensitivity. METHODS: We compared the labeling efficiency of different commercial iron oxide nanoparticles towards our stem cells and determined the optimum labeling conditions using prussian blue staining, confocal microscopy, transmission electron microscopy, and flow cytometry. To investigate any change in biological characteristics of labeled cells, we tested their viability by WST-1 assay, expression of FGF21 by Western blot, and adipogenic and osteogenic differentiation capabilities. MRI contrast-enhancing properties of labeled cells were investigated in vitro using cell-agarose phantoms and in mice brains transplanted with the therapeutic stem cells. RESULTS: We determined the nanoparticles that showed best labeling efficiency and least extracellular aggregation. We further optimized their labeling conditions (nanoparticles concentration and media supplementation) to achieve high cellular uptake and minimal extracellular aggregation of nanoparticles. Cell viability, expression of FGF21 protein, and differentiation capabilities were not impeded by nanoparticles labeling. Low number of labeled cells produced strong MRI signal decay in phantoms and in live mice brains which were visible for 4 weeks post transplantation. CONCLUSION: We established a standardized magnetic nanoparticle labeling platform for stem cells that were monitored longitudinally with high sensitivity in mice brains using MRI for regenerative medicine applications.