Chondroitin sulfate proteoglycan represses neural stem/progenitor cells migration via PTPσ/α-actinin4 signaling pathway.

Neural stem/progenitor cells (NSPCs) are a promising candidate for the cell-replacement therapy after central nervous system (CNS) injury. However, the short of sufficient NSPCs migration and integration into the lesions is an essential challenge for cell-based therapy after CNS injury due to the disturbance of local environmental homeostasis. Chondroitin sulfate proteoglycan (CSPG) is obviously accumulated at the lesions and destroyed local homeostasis after CNS injury. The previous study has demonstrated that the CSPG is a dominating ingredient inhibiting axonal regrowth of newly born neurons after CNS injury. NSPCs, a strain of special neural subtypes, hold the capacity of leading processes formation to regulate NSPCs migration, which has the same mechanism as axonal regrowth. Hence, it is worth investigating the effect of CSPG on NSPCs migration and its underlying mechanism. Here, different concentration of CSPG was used to evaluate its effect on NSPCs migration. The results showed that the CSPG suppressed NSPCs migration in a dose-dependent manner from 10 to 80 µg/mL with phase-contrast microscopy after 24 hours. Meanwhile, transwell assays were performed to certify the above results. Our data indicated that the 40 µg/mL CSPG obviously suppressed NSPCs migration via decreasing filopodia formation using immunofluorescence staining. Furthermore, data indicated that the 40 µg/mL CSPG upregulated protein tyrosine phosphatase receptor σ (PTPσ) expression and decreased α-actinin4 (ACTN4) expression through immunofluorescence, reverse transcription polymerase chain reaction, and Western blot assays. While the inhibitory effect was attenuated using PTPσ-specific small interfering RNA. In addition, data demonstrated that the 40 µg/mL CSPG facilitated NSPCs differentiation into glial fibrillary acidic protein-positive cells and inhibited NSPCs directing into MAP2- and MBP-positive cells. Collectively, these data demonstrated that the CSPG suppressed NSPCs migration through PTPσ/ACTN4 signaling pathway. Meanwhile, CSPG facilitated NSPCs differentiation into astrocytes and inhibited NSPCs directing into neurons and oligodendrocytes.

A three-dimensional matrix system containing melatonin and neural stem cells repairs damage from traumatic brain injury in rats.

Brain lesions can cause neural stem cells to activate, proliferate, differentiate, and migrate to the injured area. However, after traumatic brain injury, brain tissue defects and microenvironment changes greatly affect the survival and growth of neural stem cells; the resulting reduction in the number of neural stem cells impedes effective repair of the injured area. Melatonin can promote the survival, proliferation, and differentiation of neural stem cells under adverse conditions such as oxidative stress or hypoxia that can occur after traumatic brain injury. Therefore, we investigated the therapeutic effects of melatonin combined with neural stem cells on traumatic brain injury in rats. First, in vitro studies confirmed that melatonin promoted the survival of neural stem cells deprived of oxygen and glucose. Then, we established a three-dimensional Matrigel-based transplantation system containing melatonin and neural stem cells and then used it to treat traumatic brain injury in rats. We found that treatment with the Matrigel system containing melatonin and neural stem cells decreased brain lesion volume, increased the number of surviving neurons, and improved recovery of neurological function compared with treatment with Matrigel alone, neural stem cells alone, Matrigel and neural stem cells combined, and Matrigel and melatonin combined. Our findings suggest that the three-dimensional Matrigel-based transplantation system containing melatonin and neural stem cells is a potential treatment for traumatic brain injury.

Neuroprotection by cattle encephalon glycoside and ignotin beyond the time window of thrombolysis in ischemic stroke.

Cattle encephalon glycoside and ignotin (CEGI) injection is known as a multi-target neuroprotective drug that contains numerous liposoluble molecules, such as polypeptides, monosialotetrahexosyl ganglioside (GM-1), free amino acids, hypoxanthine and carnosine. CEGI has been approved by the Chinese State Food and Drug Administration and widely used in the treatments of various diseases, such as stroke and Alzheimer's disease. However, the neuroprotective effects of CEGI beyond the time window of thrombolysis (within 4.5 hours) on acute ischemic stroke remain unclear. This study constructed a rat middle cerebral artery occlusion model by suture-occluded method to simulate ischemic stroke. The first daily dose was intraperitoneally injected at 8 hours post-surgery and the CEGI treatments continued for 14 days. Results of the modified five-point Bederson scale, beam balance test and rotameric test showed the neurological function of ischemic stroke rats treated with 4 mL/kg/d CEGI improved significantly, but the mortality within 14 days did not change significantly. Brain MRI and 2,3,5-triphenyltetrazolium chloride staining confirmed that the infarct size in the 4 mL/kg/d CEGI-treated rats was significantly reduced compared with ischemic insult only. The results of transmission electron microscopy and double immunofluorescence staining showed that the hippocampal neuronal necrosis in the ischemic penumbra decreased whereas the immunopositivity of new neuronal-specific protein doublecortin and the percentage of Ki67/doublecortin positive cells increased in CEGI-treated rats compared with untreated rats. Our results suggest that CEGI has an effective neuroprotective effect on ischemic stroke when administered after the time window of thrombolysis. The study was approved by the Animal Ethics Committee of The Third Military Medical University, China.

Iron chelation suppresses secondary bleeding after intracerebral hemorrhage in angiotensin II-infused mice.

AIMS: Secondary bleeding and further hematoma expansion (HE) aggravate brain injury after intracerebral hemorrhage (ICH). The majority of HE results from hypertensive ICH. Previous study reported higher iron content in the brains of hypertensive patients. Iron overload exacerbates the risk of hemorrhagic transformation in thromboembolic stroke mice. Whether iron overload during the process of hypertension participates in secondary bleeding of hypertensive ICH remains unclear. METHODS: Hypertension was induced by continuous infusion of angiotensin II (Ang II) with an osmotic pump into C57BL/6 mice. ICH was simulated by intrastriatal injection of the liquid polymer Onyx-18. Iron chelation and iron overload was achieved by deferoxamine mesylate or iron dextran injection. Secondary bleeding was quantified by measuring the hemoglobin content in the ipsilateral brain hemisphere. RESULTS: Ang II-induced hypertensive mice showed increased iron accumulation in the brain and expanded secondary hemorrhage after ICH modeling. Moreover, iron chelation suppressed while iron overload aggravated secondary bleeding. Mechanistically, iron exacerbated the loss of contractile cerebral vascular smooth muscle cells (VSMCs), aggravated blood-brain barrier (BBB) leakage in Ang II-induced hypertensive mice, and increased glial and MMP9 accumulation after ICH. CONCLUSION: Iron overload plays a key role in secondary bleeding after ICH in Ang II-induced hypertensive mice. Iron chelation during the process of Ang II-induced hypertension suppresses secondary bleeding after ICH.

G protein-coupled estrogen receptor 1 negatively regulates the proliferation of mouse-derived neural stem/progenitor cells via extracellular signal-regulated kinase pathway.

G protein-coupled estrogen receptor 1 (GPER1, also known as GPR30) has been reported to play a wide range of function in the central nervous system (CNS). However, whether GPER1 is expressed by neural stem/progenitor cells (NSPCs) and its role has not been established. Here, we found the expression of GPER1 in mouse-derived NSPCs via western blot and immunofluorescent staining. Moreover, we revealed that specific activation of GPER1 by the agonist G1 decreased the proliferation of NSPCs in a dose-dependent manner. The neurosphere formation assay and Ki67 staining further demonstrated that activation of GPER1 inhibited the proliferation of NSPCs. Additionally, the inhibitory effect of G1 on the proliferation of NSPCs could be blocked by the specific GPER1 antagonist G15. Intriguingly, ERK pathway was involved in the negative effect of GPER1 on the proliferation of NSPCs, because the phosphorylation level of ERK in NSPCs was remarkably decreased during G1 treatment. However, the antagonist G15 reversed the down-regulated level of p-ERK. Knock-down GPER1 also reversed the inhibitory effect of G1 on NSPCs proliferation. Together, our results provide the first evidence that GPER1 is expressed by NSPCs and its activation negatively modulates the proliferation of NSPCs, highlighting the importance of GPER1 in regulating NSPC behaviors.

An organic NIR-II nanofluorophore with aggregation-induced emission characteristics for in vivo fluorescence imaging.

Background: In vivo fluorescence imaging in the second near-infrared (NIR-II, 1000-1700 nm) window using organic fluorophores has great advantages, but generally suffers from a relatively low fluorescence quantum yield (mostly less than 2%). In this study, organic nanoparticles (L1013 NPs) with a high fluorescence quantum yield (9.9%) were systhesized for in vivo imaging. Methods: A molecule (BTPPA) with donor-acceptor-donor structure and aggregation-induced emission enabling moieties was prepared. BTPPA molecules were then encapsulated into nanoparticles (L1013 NPs) using a nanoprecipitation method. The L1013 NPs were intravenously injected into the mice (including normal, stroke and tumor models) for vascular and tumor imaging. Results: L1013 NPs excited at 808 nm exhibit NIR-II emission with a peak at 1013 nm and an emission tail extending to 1400 nm. They have a quantum yield of 9.9% and also show excellent photo/colloidal stabilities and negligible in vitro and in vivo toxicity. We use L1013 NPs for noninvasive real-time visualization of mouse hindlimb and cerebral vessels (including stroke pathology) under a very low power density (4.6-40 mW cm‒2) and short exposure time (40-100 ms). Moreover, L1013 NPs are able to localize tumor pathology, with a tumor-to-normal tissue ratio of 11.7±1.3, which is unusually high for NIR-II fluorescent imaging through passive targeting strategy. Conclusion: L1013 NPs demonstrate the potential for a range of clinical applications, especially for tumor surgery.

Ischemic postconditioning protects against ischemic brain injury by up-regulation of acid-sensing ion channel 2a.

Ischemic postconditioning renders brain tissue tolerant to brain ischemia, thereby alleviating ischemic brain injury. However, the exact mechanism of action is still unclear. In this study, a rat model of global brain ischemia was subjected to ischemic postconditioning treatment using the vessel occlusion method. After 2 hours of ischemia, the bilateral common carotid arteries were blocked immediately for 10 seconds and then perfused for 10 seconds. This procedure was repeated six times. Ischemic postconditioning was found to mitigate hippocampal CA1 neuronal damage in rats with brain ischemia, and up-regulate acid-sensing ion channel 2a expression at the mRNA and protein level. These findings suggest that ischemic postconditioning up-regulates acid-sensing ion channel 2a expression in the rat hippocampus after global brain ischemia, which promotes neuronal tolerance to ischemic brain injury.

A rare fatal case of a novel bunyavirus-associated hemophagocytic lymphohistiocytosis.

Herein we describe a rare fatal case of a novel bunyavirus-associated hemophagocytic lymphohistiocytosis (HLH) in a 62-year-old female patient. The novel bunyavirus infects patients with or without HLH who have similar clinical features such as fever, thrombocytopenia, and leukocytopenia. Therefore, the diagnosis of HLH can be easily missed. When HLH occurs, the disease worsens and the fatality rate rises. Our finding highlights the importance of bone marrow biopsy performed as soon as possible for patients suspected of having a novel bunyavirus infection and showing marked cytopenia in three cell lines.