Single-cell analysis reveals T cell infiltration in old neurogenic niches.

Home at Last: Neural Stem Cell Niches Defined

Neurogenesis involves generation of new neurons through finely tuned multistep processes, such as neural stem cell (NSC) proliferation, migration, differentiation, and integration into existing neuronal circuitry in the dentate gyrus of the hippocampus and subventricular zone. Adult hippocampal neurogenesis is involved in cognitive functions and altered in various neurodegenerative disorders, including Alzheimer disease (AD). Ethosuximide (ETH), an anticonvulsant drug is used for the treatment of epileptic seizures. However, the effects of ETH on adult hippocampal neurogenesis and the underlying cellular and molecular mechanism(s) are yet unexplored. Herein, we studied the effects of ETH on rat multipotent NSC proliferation and neuronal differentiation and adult hippocampal neurogenesis in an amyloid β (Aβ) toxin-induced rat model of AD-like phenotypes. ETH potently induced NSC proliferation and neuronal differentiation in the hippocampus-derived NSC in vitro. ETH enhanced NSC proliferation and neuronal differentiation and reduced Aβ toxin-mediated toxicity and neurodegeneration, leading to behavioral recovery in the rat AD model. ETH inhibited Aβ-mediated suppression of neurogenic and Akt/Wnt/β-catenin pathway gene expression in the hippocampus. ETH activated the PI3K·Akt and Wnt·β-catenin transduction pathways that are known to be involved in the regulation of neurogenesis. Inhibition of the PI3K·Akt and Wnt·β-catenin pathways effectively blocked the mitogenic and neurogenic effects of ETH. In silico molecular target prediction docking studies suggest that ETH interacts with Akt, Dkk-1, and GSK-3β. Our findings suggest that ETH stimulates NSC proliferation and differentiation in vitro and adult hippocampal neurogenesis via the PI3K·Akt and Wnt·β-catenin signaling.

The eukaryotic expression vector containing full-length cDNA sequence of rate nerve growth factor (NGF) beta subunit was constructed and its effects on proliferation and differentiation of neural stem cells were observed. By using PCR, full-length cDNA sequence of NGF beta subunit in rats was cloned and ligated into the eukaryotic expression vector pEGFP-N1-NGF. The recombinant plasmid pEGFP-N1-NGF was transfected into the mesencephal neural stem cells of embryonic rats by Lipofectamin and transiently expressed. MTT method was used to determine the effects of NGF on proliferation of neural stem cells, and under phase-contrast microscopy, the effects of NGF on growth of nervous processes following differentiation of neural stem cells were observed. Sequence analysis indicated that the cloned full-length cDNA sequence of rat NGF beta was identical to that of published sequence encoding NGF in gene GeneBank. The transfection of recombinant plasmid pEGFP-N1-NGF into mesencephal neural stem cells of embryonic rats could obviously promote proliferation of neural stem cells and facilitate the growth of neural stem cells-derived nerve cells. It was suggested that neural stem cells could be used as a vehicle of gene transfer, and the expression of NGF beta subunit in the neural stem cells could promote the growth of nerve cells derived from neural stem cells.

EDITORIAL article Front. Cell. Neurosci., 19 January 2016Sec. Cellular Neurophysiology Volume 9 - 2015 | https://doi.org/10.3389/fncel.2015.00504

H3.3-K27M drives neural stem cell-specific gliomagenesis in a human iPSC-derived model.

Objective To investigate the effect of gene of phosphate and tension homology deleted on chromsome ten (PTEN) inhibitor bpV (pic) on the proliferation and differentiation of neural stem cells (NSCs). Methods Stem cell suspension was prepared from the cerebral cortex of the 16 days of fetal rat. The cells were divided into2 groups: group A (control group): no treatment, group B (experimental group): bpV treatment group (culture medium containing bpV). The number of stem cell spheres was observed by immunofluorescence staining, the proliferation of NSCs was detected by cell counting kit一8 (CCK-8) test, the differentiation of NSCs was detected by immunofluorescence staining, and the expression of PTEN and the mammalian target of rapamycin (mTOR) genes was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) on the fifth day. Results In the experimental group, the number of stem cells per low field (×50) in the experimental group was 60±5, which was significantly higher than that in the control group (40±3, P 0.05). The expression of PTEN in experimental NSCs was 2.13 times higher than that in control NSCs (P<0.01), while the expression of mTOR in experimental NSCs was 3.62 times higher than that in control NSCs (P<0.01). Conclusion PTEN inhibitor bpV (pic) can promote the proliferation of neural stem cells and promote the differentiation of neural stem cells into neurons to a certain extent. Key words: Gene of phosphate and tension homology deleted on chromsome ten; Tumor suppressor gene; Neural stem cells; Proliferation; Differentiation

SummaryThe consequences of DNA damage generation in mammalian somatic stem cells, including neural stem cells (NSCs), are poorly understood despite their potential relevance for tissue homeostasis. Here, we show that, following ionizing radiation-induced DNA damage, NSCs enter irreversible proliferative arrest with features of cellular senescence. This is characterized by increased cytokine secretion, loss of stem cell markers, and astrocytic differentiation. We demonstrate that BMP2 is necessary to induce expression of the astrocyte marker GFAP in irradiated NSCs via a noncanonical signaling pathway engaging JAK-STAT. This is promoted by ATM and antagonized by p53. Using a SOX2-Cre reporter mouse model for cell-lineage tracing, we demonstrate irradiation-induced NSC differentiation in vivo. Furthermore, glioblastoma assays reveal that irradiation therapy affects the tumorigenic potential of cancer stem cells by ablating self-renewal and inducing astroglial differentiation.

Patient-derived iPSC-cerebral organoid modeling of the 17q11.2 microdeletion syndrome establishes CRLF3 as a critical regulator of neurogenesis.

Objective To explore the effect of olfactory ensheathing cells (OECs) on the proliferation and differentiation of neural stem cells (NSCs). Methods The cells from the embryonic rat brain were primarily cultured and identified by immunofluorescence and immunocytochemistry. NSCs in the experimental group shared medium with OECs were cultured and induced to differentiate. Simultaneously, NSCs in the control group were cultured alone. The effect of OECs on the proliferation and differentiation of NSCs was observed by immunocytochemistry. Results Nerve growth factor receptor (P75NGFR) was observed in the primarily cultured OECs; nestin was expressed in the primarily cultured neurosphere and the cells differentiated from the neurosphere expressed neurofilament 200 (NF200) and glial fibrillary acidic protein (GFAP). Compared with that in the control group, the number of NSCs in the experimental group was significantly increased (P<0.05). On the 4~(th) and 7~(th) day of differentiation, the percentage of NF200-positive cell was higher in the experimental group than that in the control group (P<0.05), indicating that the appearance of OECs increased the differentiation of NSCs into NF200-positive cells. Conclusion OECs can promote the proliferation of NSCs and induce the differentiation of NSCs into neurons. Key words: Olfactory ensheathing cells; Neural stem cells; Cell proliferation; Cell differentiation

Objective To investigate the effects of functional electrical stimulation (FES) on endogenous proliferation of the neural stem cells within the brain and the behaviors in rats with acute cerebral infarction and explore the FES therapeutic mechanism on improving the neural function after the cerebral infarction. Methods Fifty-four SD adult male rats were randomly allocated into FES treatment group, placebo stimulation group and sham-operated group (n=18). Focal cerebral infarction models were induced by the performent of middle cerebral artery occlusion (MCAO) in rats; the FES treatment group began receiving the FES (10 min/d, once dairy) and the placebo stimulation group did not give any special treatment since the 3rd day of the successful model inducement. The expression of nestin positive cells in the hippocampus subgranular zone and subventricular zone was examined by immunohistochemistry staining and the expression of nestin protein at ischemia side was detected by Western blot analysis on the 3rd, 7th and 14th d after MCAO; meanwhile, the behavior functions of rats at various time points were evaluated. Results The number of nestin positive cells in the hippocampus subgranular zone and subventricular zone and the expression of nestin protein from ischemia side brain in the FES treatment group significantly increased than those in the placebo stimulation group on the 7th and 14th d after MCAO (P<0.05). And statistical difference was noted on the 14th d on the behavior functional evaluation between the FES treatment group and the placebo stimulation group (P<0.05). Conclusion FES may enhance the endogenous proliferation of the neural stem cells within the brain in rats with acute cerebral infarction and improve the behavior function in rats, which may be one of the mechanisms of FES on improving the neural function after cerebral infarction. Key words: Functional electrical stimulation; Neural stem cell; Cerebral infarction; Nestin

The effect of the dosage of NT-3/chitosan carriers on the proliferation and differentiation of neural stem cells

Neural stem cells in the adult brain possess the ability to remain quiescent until needed in tissue homeostasis or repair. It was previously shown that traumatic brain injury (TBI) stimulated neural stem cell (NSC) proliferation in the adult hippocampus, indicating an innate repair mechanism, but it is unknown how TBI promotes NSC proliferation. In the present study, we observed dramatic activation of mammalian target of rapamycin complex 1 (mTORC1) in the hippocampus of mice with TBI from controlled cortical impact (CCI). The peak of mTORC1 activation in the hippocampal subgranular zone, where NSCs reside, is 24–48 h after trauma, correlating with the peak of TBI-enhanced NSC proliferation. By use of a Nestin-GFP transgenic mouse, in which GFP is ectopically expressed in the NSCs, we found that TBI activated mTORC1 in NSCs. With 5-bromo-2′-deoxyuridine labeling, we observed that TBI increased mTORC1 activation in proliferating NSCs. Furthermore, administration of rapamycin abolished TBI-promoted NSC proliferation. Taken together, these data indicate that mTORC1 activation is required for NSC proliferation postinjury, and thus might serve as a therapeutic target for interventions to augment neurogenesis for brain repair after TBI.

The ginkgo biloba extract EGb761 improves memory loss and cognitive impairments in patients with senile dementia. It also promotes proliferation of neural stem cells in the subventricular zone in Parkinson's disease model mice and in the hippocampal zone of young epileptic rats. However, it remains unclear whether EGb761 enhances proliferation of endogenous neural stem cells in the brain of rats with vascular dementia. In this study, a vascular dementia model was established by repeatedly clipping and reperfusing the bilateral common carotid arteries of rats in combination with an intraperitoneal injection of a sodium nitroprusside solution. Seven days after establishing the model, rats were intragastrically given EGb761 at 50 mg/kg per day. Learning and memory abilities were assessed using the Morris water maze and proliferation of endogenous neural stem cells in the subventricular zone and dentate gyrus were labeled by 5-bromo-2-deoxyuridine immunofluorescence in all rats at 15 days, and 1, 2, and 4 months after model establishment. The escape latencies in Morris water maze tests of rats with vascular dementia after EGb761 treatment were significantly shorter than the model group. Immunofluorescence staining showed that the number and proliferation of 5-bromo-2-deoxyuridine-positive cells in the subventricular zone and dentate gyrus of the EGb761-treated group were significantly higher than in the model group. These experimental findings suggest that EGb761 enhances proliferation of neural stem cells in the subventricular zone and dentate gyrus, and significantly improves learning and memory in rats with vascular dementia.

Objective To investigate the effects of melatonin on the proliferation of neural stem cells (NSCs) in cerebral ischemia reperfusion (IR) rats, and to explore the possible mechanisms. Methods Seventy-two rats were randomly divided into the normal control group (n=12), model group (n=30) and melatonin group (n=30) according to the random number table. The rats in the model group and melatonin group were divided into four subgroups: 6 h, 24 h, 72 h and 7 d subgroups according to the time after IR. The morphological changes of the subventricular zone (SVZ) were examined by HE staining; the effects of melatonin on NSCs proliferation were examined by immunofluorescence staining; the effects of melatonin on toll-like receptor 4 (TLR4) and nuclear factor (NF) -κB p65 protein were examined by immunohistochemistry staining and Western blotting analysis. The correlation between the proliferating NSCs and TLR4 protein or the NF-κB p65 protein was analyzed by linear regression analysis. Results HE staining showed that the cells in the SVZ of rats in the model group were in disorder and irregular in shape. In the melatonin group, the cells in the SVZ of the injured side were relatively well arranged. Immunofluorescence staining showed that the number of proliferating cell nuclear antigen (PCNA)+Nestin+4′,6-diamidino-2-phenylindole (DAPI)+ cells in the SVZ of the model (498.47±26.44/mm2) and melatonin groups (623.10±39.70/mm2) increased gradually, and reached a higher level after IR for 7 days, which were significantly higher than the normal control group (203.91±32.23/mm2) (F=35.193, 170.344, 277.536, 285.947, all P<0.01). The number of PCNA+Nestin+DAPI+ cells in the melatonin group rats at each time points was significantly higher than that in the model group (F=102.561, 91.244, 168.502, 38.013, all P<0.01). Immunohistochemistry staining showed that the numbers of TLR4+ and NF-κB p65+ cells in the SVZ of the model (740.02±31.63/mm2; 710.01±26.59/mm2) and melatonin groups (555.57±25.28/mm2; 528.85±30.60/mm2) increased gradually, and reached a higher level 7 d after IR, which were significantly higher than the normal control group (107.97±12.84/mm2; 109.80±13.89/mm2) (F=21.413, 263.059, 873.691, 1 037.098, all P<0.01; F=26.374, 372.940, 854.826, 929.018, all P<0.01). There were less TLR4+ (F=7.641, 25.135, 66.094, 103.753, all P<0.05) and NF-κB p65+ cells (F=18.612, 69.597, 113.113, 119.814, all P<0.01) in the melatonin group as compared with those in the model group at each time points. Western blotting analysis showed that the expression of TLR4 (0.87±0.08; 0.68±0.06) and NF-κB p65 (0.72±0.05; 0.58±0.05) protein was higher in the model and melatonin groups as compared with the normal control group (0.35±0.04, 0.31±0.03; F=107.43, F=132.51, both P<0.01). The expression of the TLR4 and NF-κB p65 protein was lower in the melatonin group as compared with that in the model group (P<0.01). Linear regression analysis showed that the differences of PCNA+Nestin+DAPI+ cells were all negatively correlated with that of the TLR4+ cells and NF-κB p65+ cells in the melatonin group (r2=0.838, r2=0.813, both P<0.01). Conclusion Melatonin can inhibit the expression of TLR4 and NF-κB p65 protein, thus promote the proliferation of endogenous NSCs in cerebral ischemia reperfusion rats. Key words: Brain ischemia; Reperfusion injury; NF-kappa B; Neural stem cells

SummaryThe systemic regulation of stem cells ensures that they meet the needs of the organism during growth and in response to injury. A key point of regulation is the decision between quiescence and proliferation. During development, Drosophila neural stem cells (neuroblasts) transit through a period of quiescence separating distinct embryonic and postembryonic phases of proliferation. It is known that neuroblasts exit quiescence via a hitherto unknown pathway in response to a nutrition-dependent signal from the fat body. We have identified a population of glial cells that produce insulin/IGF-like peptides in response to nutrition, and we show that the insulin/IGF receptor pathway is necessary for neuroblasts to exit quiescence. The forced expression of insulin/IGF-like peptides in glia, or activation of PI3K/Akt signaling in neuroblasts, can drive neuroblast growth and proliferation in the absence of dietary protein and thus uncouple neuroblasts from systemic control.