Mesenchymal stem cells reduce long-term cognitive deficits and attenuate myelin disintegration and microglia activation following repetitive traumatic brain injury

The underlying mechanisms for the beneficial effects exerted by bone marrow-mesenchymal stem cells (BM-MSCs) in treating repetitive traumatic brain injury (rTBI)-induced long-term sensorimotor/cognitive impairments are not fully elucidated. Herein, we aimed to explore whether BM-MSCs therapy protects against rTBI-induced long-term neurobehavioral disorders in rats via normalizing white matter integrity and gray matter microglial response. Rats were subjected to repeated mild lateral fluid percussion on day 0 and day 3. On the fourth day post-surgery, MSCs groups received MSCs (4 × 106 cells/ml/kg, intravenously) and were assessed by the radial maze, Y maze, passive avoidance tests, and modified neurological severity scores. Hematoxylin & eosin, and Luxol fast blue stainings were used to examine the histopathology and white matter thickness. At the same time, immunofluorescence staining was used to investigate the numbers of tumor necrosis factor-alpha (TNF-α)-containing microglia in gray matter. Three to nine months after neurotrauma, rats displayed sensorimotor and cognitive impairments, reduced thickness in white matter, and over-accumulation of TNF-α-containing microglia and cellular damage in gray matter. Therapy with BM-MSCs significantly attenuated the rTBI-induced sensorimotor and cognitive impairments and all their complications. Mesenchymal stem cell therapy might accelerate the recovery of sensorimotor and cognitive impairments in rats with rTBI via normalizing myelin integrity and microglia response.

Xyloketal derivative C53N protects against mild traumatic brain injury in mice

Purpose

Mild traumatic brain injury (mTBI), the most common type of TBI, can result in prolonged cognitive impairment, mood disorders, and behavioral problems. Reducing oxidative stress and inflammation can rescue the neurons from mTBI-induced cell death. Xyloketal B, a natural product from mangrove fungus, has shown good antioxidative and neuroprotective effects in several disease models. Here, we investigated the potential protection afforded by a xyloketal derivative, C53N, in a closed-skull mTBI model.

Materials and methods

Skulls of mice were thinned to 20–30 µm thickness, following which they were subjected to a slight compression injury to induce mTBI. One hour after TBI, mice were intraperitoneally injected with C53N, which was solubilized in 0.5% dimethyl sulfoxide in saline. In vivo two-photon laser scanning microscopy was used to image cell death in injured parenchyma in each mouse over a 12-hour period (at 1, 3, 6, and 12 hours). Water content and oxidation index, together with pathological analysis of glial reactivity, were assessed at 24 hours to determine the effect of C53N on mTBI.

Results

Cell death, oxidative stress, and glial reactivity increased in mTBI mice compared with sham-injured mice. Treatment with 40 or 100 mg/kg C53N 1 hour after mTBI significantly attenuated oxidative stress and glial reactivity and reduced parenchymal cell death at the acute phase after mTBI.

Conclusion

The present study highlights the therapeutic potential of the xyloketal derivative C53N for pharmacological intervention in mTBI.

Astragaloside IV protects blood-brain barrier integrity from LPS-induced disruption via activating Nrf2 antioxidant signaling pathway in mice

Endothelial cells of cerebral microvessels are one of the components of blood-brain-barrier (BBB), which are connected by tight junctions (TJs). BBB disruption in cerebral diseases such as ischemic stroke, Alzhemer's disease, multiple sclerosis and traumatic brain injury is implicated to exacerbate the disease progression. Astragaloside IV (ASIV) isolated from Astragalus membranaceus prevents BBB breakdown in rodents induced with cerebral edema and experimental autoimmune encephalomyelitis. However, its underlying molecular mechanism has not been elucidated yet. In present study, ASIV was found to prevent the leakage of BBB in LPS-induced mice, which was accompanied with increased zo-1 and occludin but reduced VCAM-1 in brain microvessels. Similarly, in brain endothelial cell line bEnd.3 cells, ASIV mitigated the increased permeability induced by LPS, as evidenced by increased TEER and reduced sodium fluorescein extravasation. ASIV also enhanced the expression of TJ proteins such as zo-1, occludin and claudin-5 in LPS stimulated bEnd.3 cells. Meanwhile, it inhibited the inflammatory responses and prevented the monocyte adhesion onto bEnd.3 cells upon LPS stimulation. Further study disclosed that ASIV could alleviate ROS level and activate Nrf2 antioxidant pathway in bEnd.3 cells. When Nrf2 was silenced, the protective effect of ASIV was abolished. In brain microvessels of LPS-induced mice, ASIV also enhanced the expression of Nrf2 antioxidant pathway related proteins. Collectively, our results demonstrated that ASIV protected the integrity of BBB in LPS-induced mice, the mechanism of which might be mediated via activating Nrf2 signaling pathway. The findings suggested that ASIV might be a potential neuroprotective drug acting on BBB.

The Effects of Chunghyul-Dan, an Agent of Korean Medicine, on a Mouse Model of Traumatic Brain Injury

Chunghyul-Dan (CHD) is the first choice agent for the prevention and treatment of stroke at the Kyung Hee Medical Hospital. To date, CHD has been reported to have beneficial effects on brain disease in animals and humans, along with antioxidative and anti-inflammatory effects. The aim of this study was to evaluate the pharmacological effects of CHD on a traumatic brain injury (TBI) mouse model to explore the possibility of CHD use in patients with TBI. The TBI mouse model was induced using the controlled cortical impact method. CHD was orally administered twice a day for 5 d after TBI induction; mice were assessed for brain damage, brain edema, blood-brain barrier (BBB) damage, motor deficits, and cognitive impairment. Treatment with CHD reduced brain damage seen on histological examination and improved motor and cognitive functions. However, CHD did not reduce brain edema and BBB damage. In conclusion, CHD could be a candidate agent in the treatment of patients with TBI. Further studies are needed to assess the exact mechanisms of the effects during the acute-subacute phase and pharmacological activity during the chronic-convalescent phase of TBI.

A positive correlation exists between neurotrauma and TGF-β1-containing microglia in rats

BACKGROUND

Transforming growth factor-beta 1 (TGF-β1) regulates many processes after traumatic brain injury (TBI). Both Neuro AiD™ (MLC601) and astragaloside (AST) attenuate microglia activation in rats with TBI. The purpose of this study was to investigate whether MLC601 or AST improves output of TBI by affecting microglial expression of TGF-β1.

MATERIALS AND METHODS

Adult male Sprague-Dawley rats (120 in number) were used to investigate the contribution of TGF-β1-containing microglia in the MLC601-mediated or the AST-mediated neuroprotection in the brain trauma condition using lateral fluid percussion injury.

RESULTS

Pearson correlation analysis revealed that there was a positive correlation between brain injury (evidenced by both brain contused volume and neurological severity score) and the cortical numbers of TGF-β1-containing microglia for the rats (n = 12) 4 days post-TBI. MLC601 or AST significantly (P < 0·05) attenuated TBI-induced brain contused volume (119 ± 14 mm³ or 108 ± 11 mm³ vs. 160 ± 21 mm³ ), neurological severity score (7·8 ± 0·3 or 8·1 ± 0·4 vs. 10·2 ± 0·5) and numbers of TGF-β1-containing microglia (6% ± 2% or 11% ± 3% vs. 79% ± 7%) for the rats 4 days post-TBI.

CONCLUSIONS

There was a positive correlation between TBI and cortical numbers of TGF-β1-containing microglia which could be significantly attenuated by astragaloside or NeuroAiD™ (MLC601) in rats.

Astragaloside IV inhibits microglia activation via glucocorticoid receptor mediated signaling pathway

Inhibition of microglia activation may provide therapeutic treatment for many neurodegenerative diseases. Astragaloside IV (ASI) with anti-inflammatory properties has been tested as a therapeutic drug in clinical trials of China. However, the mechanism of ASI inhibiting neuroinflammation is unknown. In this study, we showed that ASI inhibited microglia activation both in vivo and in vitro. It could enhance glucocorticoid receptor (GR)-luciferase activity and facilitate GR nuclear translocation in microglial cells. Molecular docking and TR-FRET GR competitive binding experiments demonstrated that ASI could bind to GR in spite of relative low affinity. Meanwhile, ASI modulated GR-mediated signaling pathway, including dephosphorylation of PI3K, Akt, I κB and NF κB, therefore, decreased downstream production of proinflammatory mediators. Suppression of microglial BV-2 activation by ASI was abrogated by GR inhibitor, RU486 or GR siRNA. Similarly, RU486 counteracted the alleviative effect of ASI on microgliosis and neuronal injury in vivo. Our findings demonstrated that ASI inhibited microglia activation at least partially by activating the glucocorticoid pathway, suggesting its possible therapeutic potential for neuroinflammation in neurological diseases.