Olfactory three needle regulates the proliferation of olfactory bulb neural stem cells and ameliorates brain injury after subarachnoid hemorrhage by regulating Wnt/β-catenin signaling

Background

Subarachnoid hemorrhage (SAH) is a serious cerebrovascular emergency. The incidence of SAH and hazard ratio of death increase with age.

Objective

In this study, we aimed to observe the effects and potential mechanisms of olfactory three needle (OTN) on cognitive impairment, neuronal activity, and neural stem cell differentiation in SAH rats.

Methods

Sprague-Dawley (SD) rats were randomly divided into five groups: Sham, SAH group, SAH + Nimodipine (NMP) group, and SAH + OTN group. The rats in the SAH + OTN group received the OTN electroacupuncture treatment. For treatment with recombinant DKK1 (a Wnt/β-catenin inhibitor), mice were injected with DKK1.

Results

Our results found that OTN improved cognitive impairment and hippocampal neuron damage in SAH rats. Furthermore, OTN promoted the proliferation of neural stem cells in SAH rats. Mechanistically, OTN activated Wnt/β-catenin signaling in SAH rats, as indicated by the increased expression levels of Wnt1, β-Catenin, LMNB1, and p-GSK-3β. DKK1 reversed the improvement effect of OTN on cognitive impairment and neuronal damage in SAH rats. Meanwhile, DKK1 blocked the promoting effect of OTN on the proliferation of NSCs in SAH rats.

Conclusions

OTN electroacupuncture may be an effective therapeutic strategy for SAH.

GCN5/KAT2A contributes to axon growth and neurogenesis

Posttranslational modification (PTM) of tubulin proteins is involved in microtubule dynamics. Acetylation, an important alpha-tubulin PTM, which is regarded as a hallmark event of stable microtubules, often occurs in neurogenesis and axon outgrowth. GCN5/KAT2A is a well-known histone acetyltransferase and has also been reported to hold the activity of nonhistone acetyltransferases, such as acetylated tubulin (Ace-tubulin). In this study, we investigated the role of GCN5/KAT2A in axon growth and neurogenesis. E18 cortical neurons obtained from day 18 embryos of pregnant Sprague-Dawley (SD) rats were cultured and transfected with GCN5 siRNA or treated with the GCN5 inhibitor MB-3. Neural stem cells (NSCs) derived from the cerebral cortexes of E14 SD rats were cultured and differentiated. During differentiation, MB-3 was applied to investigate the effect of GCN5 dysfunction on neurogenesis. The axonal length and the ratio and distribution of acetylated and tyrosinated tubulin (Tyr-tubulin) were evaluated by immunostaining assay. The expression levels of Nestin, Tuj1, acetylated tubulin, and tyrosinated tubulin proteins were analyzed by Western blotting assays. In primary neurons, both GCN5 siRNA and MB-3 treatment reduced acetylated tubulin protein, changed the ratio of acetylated and tyrosinated tubulin, and decreased axonal length. During NSC differentiation, MB-3 application reduced axon outgrowth, decreased acetylated tubulin and altered the distribution of acetylated tubulin and tyrosinated tubulin. This study revealed for the first time that the acetyltransferase GCN5/KAT2A could contribute to axon outgrowth by altering the ratio and distribution of acetylated tubulin.

Differential Network Analysis Reveals Regulatory Patterns in Neural Stem Cell Fate Decision

Deciphering regulatory patterns of neural stem cell (NSC) differentiation with multiple stages is essential to understand NSC differentiation mechanisms. Recent single-cell transcriptome datasets became available at individual differentiation. However, a systematic and integrative analysis of multiple datasets at multiple temporal stages of NSC differentiation is lacking. In this study, we propose a new method integrating prior information to construct three gene regulatory networks at pair-wise stages of transcriptome and apply this method to investigate five NSC differentiation paths on four different single-cell transcriptome datasets. By constructing gene regulatory networks for each path, we delineate their regulatory patterns via differential topology and network diffusion analyses. We find 12 common differentially expressed genes among the five NSC differentiation paths, with one common regulatory pattern (Gsk3b_App_Cdk5) shared by all paths. The identified regulatory pattern, partly supported by previous experimental evidence, is essential to all differentiation paths, but it plays a different role in each path when regulating other genes. Together, our integrative analysis provides both common and specific regulatory mechanisms for each of the five NSC differentiation paths.

Polyaniline-polycaprolactone fibers for neural applications: Electroconductivity enhanced by pseudo-doping

Replenishing neurons in patients with neurodegenerative diseases is one of the ultimate therapies for these progressive, debilitating and fatal diseases. Electrical stimulation can improve neuron stem cell differentiation but requires a reliable nanopatterned electroconductive substrate. Potential candidate substrates are polycaprolactone (PCL) - polyaniline:camphorsulfonic acid (PANI:CSA) nanofibers, but their nanobiophysical properties need to be finetuned. The present study investigates the use of the pseudo-doping effect on the optimization of the electroconductivity of these polyaniline-based electrospun nanofibers. This was performed by developing a new solvent system that comprises a mixture of hexafluoropropanol (HFP) and trifluoroethanol (TFE). For the first time, an electroconductivity so high as 0.2 S cm^-1 was obtained for, obtained from a TFE:HFP 50/50 vol% solution, while maintaining fiber biocompatibility. The physicochemical mechanisms behind these changes were studied. The results suggest HFP promotes changes on PANI chains conformations through pseudo-doping, leading to the observed enhancement in electroconductivity. The consequences of such change in the nanofabrication of PCL-PANI fibers include an increase in fiber diameter (373 ± 172 nm), a decrease in contact angle (42 ± 3°) and a decrease in Young modulus (1.6 ± 0.5 MPa), making these fibers interesting candidates for neural tissue engineering. Electrical stimulation of differentiating neural stem cells was performed using AC electrical current. Positive effects on cell alignment and gene expression (DCX, MAP2) are observed. The novel optimized platform shows promising applications for (1) building in vitro platforms for drug screening, (2) interfaces for deep-brain electrodes; and (3) fully grown and functional neurons transplantation.

Bone mesenchymal stem cell-conditioned medium decreases the generation of astrocytes during the process of neural stem cells differentiation

OBJECTIVES

The aim of this study was to investigate the effect of bone mesenchymal stem cell (BMSC) conditioned medium (CM) and Bone morphogenetic protein-4 (BMP-4) on the generation of astrocytes during the process of NSCs differentiation.

DESIGN

Neural stem cells (NSCs) were grown under different culture conditions.

SETTING

The First Affiliated Hospital of Anhui Medical University, Hefei, China.

OUTCOME MEASURES

The study consisted of four groups: NSCs cultured under control conditions (group 1) or with the addition of BMSC-CM (group 2);(BMP-4) (group 3) or both (group 4).The expression of glial fibrillary acidic protein (GFAP) was detected by immunocytochemical staining and Western blotting.

RESULTS

The expression of GFAP was higher in Group3 and lower in Group 2 compared to that in Group 1. The expression of GFAP in Group 4 was intermediate between that of Group 2 and Group 3.

CONCLUSIONS

These results suggest that BMSC-CM can decrease the generation of astrocytes and that the inhibition of the (BMP-4) /Smad1/5/8 signaling pathway may be the underlying mechanism. This phenomenon may be mediated by increasing the expression of Smad6.

The therapeutic contribution of nanomedicine to treat neurodegenerative diseases via neural stem cell differentiation

The discovery of adult neurogenesis drastically changed the therapeutic approaches of central nervous system regenerative medicine. The stimulation of this physiologic process can increase memory and motor performances in patients affected by neurodegenerative diseases. Neural stem cells contribute to the neurogenesis process through their differentiation into specialized neuronal cells. In this review, we describe the most important methods developed to restore neurological functions via neural stem cell differentiation. In particular, we focused on the role of nanomedicine. The application of nanostructured scaffolds, nanoparticulate drug delivery systems, and nanotechnology-based real-time imaging has significantly improved the safety and the efficacy of neural stem cell-based treatments. This review provides a comprehensive background on the contribution of nanomedicine to the modulation of neurogenesis via neural stem cell differentiation.

Genome-wide copy number profiling of mouse neural stem cells during differentiation

There is growing evidence that gene amplifications were present in neural stem and progenitor cells during differentiation. We used array-CGH to discover copy number changes including gene amplifications and deletions during differentiation of mouse neural stem cells using TGF-ß and FCS for differentiation induction. Array data were deposited in GEO (Gene Expression Omnibus, NCBI) under accession number GSE35523. Here, we describe in detail the cell culture features and our TaqMan qPCR-experiments to validate the array-CGH analysis. Interpretation of array-CGH experiments regarding gene amplifications in mouse and further detailed analysis of amplified chromosome regions associated with these experiments were published by Fischer and colleagues in Oncotarget (Fischer et al., 2015). We provide additional information on deleted chromosome regions during differentiation and give an impressive overview on copy number changes during differentiation induction at a time line.

Postnatal age governs the extent of differentiation of hippocampal CA1 and CA3 subfield neural stem/progenitor cells into neurons and oligodendrocytes

While neural stem/progenitor cells (NSCs) in the dentate gyrus of the hippocampus have been extensively characterized, the behavior of NSCs in the CA1 and CA3 subfields of the hippocampus is mostly unclear. Therefore, we compared the in vitro behavior of NSCs expanded from the micro-dissected CA1 and CA3 subfields of postnatal day (PND) 4 and 12 Fischer 344 rats. A small fraction (∼1%) of dissociated cells from CA1 and CA3 subfields of both PND 4 and 12 hippocampi formed neurospheres in the presence of EGF and FGF-2. A vast majority of neurosphere cells expressed NSC markers such as nestin, Sox-2 and Musashi-1. Differentiation assays revealed the ability of these NSCs to give rise to neurons, astrocytes, and oligodendrocytes. Interestingly, the overall neuronal differentiation of NSCs from both subfields decreased with age (23-28% at PND4 to 5-10% at PND12) but the extent of oligodendrocyte differentiation from NSCs increased with age (24-32% at PND 4 to 45-55% at PND 12). Differentiation of NSCs into astrocytes was however unchanged (40-48%). Furthermore, NSCs from both subfields gave rise to GABA-ergic neurons including subclasses expressing markers such as calbindin, calretinin, neuropeptide Y and parvalbumin. However, the fraction of neurons that expressed GABA decreased between PND4 (59-67%) and PND 12 (25-38%). Additional analyses revealed the presence of proliferating NSC-like cells (i.e. cells expressing Ki-67 and Sox-2) in different strata of hippocampal CA1 and CA3 subfields of both PND4 and PND 12 animals. Thus, multipotent NSCs persist in both CA1 and CA3 subfields of the hippocampus in the postnatal period. Such NSCs also retain their ability to give rise to both GABA-ergic and non-GABA-ergic neurons. However, their overall neurogenic potential declines considerably in the early postnatal period.