Purification, Visualization, and Molecular Signature of Neural Stem Cells

Comparison of effects of high- and low-frequency electromagnetic fields on proliferation and differentiation of neural stem cells

To compare the effects of high- (HF-EMF) and low-frequency electromagnetic fields (LF-EMF) on the proliferation and differentiation of neural stem cells (NSCs). NSCs were obtained from SD rat hippocampus and cultured in suspension and adherent differentiation media. NSCs were exposed to LF-EMF (5 m T, 50 Hz, 30 min daily), HF-EMF (maximum magnetic induction 2.5 T, 40 % MO, 50 Hz, 10 min daily) and no electromagnetic field. At 3 d, cell viability and quantity of NSCs in suspension were detected by CCK-8 assay and cell counting plate. Immunofluorescence staining and qRT-PCR were performed to detect the percentage of Tuj-1 and GFAP-positive NSCs and the expression of Tuj-1 and GFAP mRNA. The P3 NSCs were positive with Nestin and induced NSCs expressed Tuj-1, GFAP and oligodendrocyte markers (MBP). CCK-8 assay and cell counting showed that the OD value and quantity of LF-EMF group were significantly higher than those in other two groups (both P < 0.05). Compared with the control group, the OD value and quantity were significantly higher in the HF-EMF group (P < 0.05). Immunofluorescence staining and qRT-PCR revealed that the percentage of Tuj-1 positive cells and the expression of Tuj-1 mRNA of NSCs exposed to LF-EMF were the highest (both P < 0.05). The proportion of GFAP-positive NSCs and the expression of GFAP mRNA did not significantly differ among three groups (all P> 0.05). Both 50 Hz LF-EMF and HF-EMF can promote the proliferation of NSCs in vitro and LF-EMF can accelerate NSCs to differentiate into neurons.

Neuronal Hippo signaling: From development to diseases

Hippo signaling pathway is a highly conserved and familiar tissue growth regulator, primarily dealing with cell survival, cell proliferation, and apoptosis. The Yes-associated protein (YAP) is the key transcriptional effector molecule, which is under negative regulation of the Hippo pathway. Wealth of studies have identified crucial roles of Hippo/YAP signaling pathway during the process of development, including the development of neuronal system. We provide here, an overview of the contributions of this signaling pathway at multiple stages of neuronal development including, proliferation of neural stem cells (NSCs), migration of NSCs toward their destined niche, maintaining NSCs in the quiescent state, differentiation of NSCs into neurons, neuritogenesis, synaptogenesis, brain development, and in neuronal apoptosis. Hyperactivation of the neuronal Hippo pathway can also lead to a variety of devastating neurodegenerative diseases. Instances of aberrant Hippo pathway leading to neurodegenerative diseases along with the approaches utilizing this pathway as molecular targets for therapeutics has been highlighted in this review. Recent evidences suggesting neuronal repair and regenerative potential of this pathway has also been pointed out, that will shed light on a novel aspect of Hippo pathway in regenerative medicine. Our review provides a better understanding of the significance of Hippo pathway in the journey of neuronal system from development to diseases as a whole.

The distinct difference in azido sugar metabolic rate between neural stem cells and fibroblasts and its application for decontamination of chemically induced neural stem cells

In our report, we found a distinct difference in azido sugar metabolic rate between neural stem cells and fibroblasts, which can be used for selective removal of fibroblasts from neural stem cell mixtures. Chemically induced neural stem cells (ciNSCs) serve as a highly valuable source of NSCs. Incompletely induced fibroblasts could interfere with ciNSC differentiation and become tumorigenic. Herein, we applied our method for the decontamination of ciNSCs and it exhibited excellent selectivity for ciNSCs. The results demonstrate that the ciNSC population can be efficiently purified to 98.1%. As far as we know, this is the highest purity obtained so far. We envision that, in the future, our method could be used as a safe, effective, and chemically-defined tool for decontaminating ciNSCs in both fundamental research and clinical stem cell therapy.

Lewis X-Carrying Neoglycolipids Evoke Selective Apoptosis in Neural Stem Cells

N-glycans carrying the Lewis X trisaccharide [Galβ1-4 (Fucα1-3) GlcNAc] are expressed by neural stem cells (NSCs) exclusively before differentiation, and they actively contribute to the maintenance of stemness of these cells. To address the functional roles of the Lewis X-mediated molecular interactions in NSCs, we created a series of synthetic neoglycolipids that contained a Lewis X-carrying glycan connected to an acyl chain through an amide bond. The neoglycolipids formed aqueous micelles displaying functional Lewis X glycotopes. Surprisingly, the neoglycolipid micelles evoked selective apoptosis in undifferentiated NSCs, whereas their differentiated cells remained unaffected. The apoptotic activity depended on the structural integrity of the Lewis X glycotopes and also on the length of the acyl chain, with an optimum length of C18. We propose hypothetical functional mechanisms of the neoglycolipid, which involves selective NSC targeting with Lewis X glycan and apoptotic signaling by the intracellular release of fatty acids. This serendipitous finding may offer a new strategy for controlling neural cell fates using artificial glycoclusters.

Differential miRNA expression analysis during late stage terminal hindgut development in fetal rats

BACKGROUND

Terminal hindgut deformity is the leading digestive tract malformation, however, the etiology and pathogenesis remained unknown. To date, gene expression abnormalities were considered the primary cause of these diseases. miRNAs have been found to play an important role in regulating the expression of genes.

METHODS

A total of 24 pregnant rats were randomly divided into two groups. The experimental group (n=12) received 1% ethylenethiourea (125mg/kg) by gavage on gestational day 11, while the control group (n=12) received the same volume of distilled water. From each group, fetal rats were obtained by cesarean section on gestational day 16. For the extraction of total RNA, 1 cm rectum samples were obtained from four fetal rats that had similar weights. Chip hybridization was conducted after poly(A) and biotin were added to the RNA samples, and this was followed by washing, dyeing, and scanning of the chip. Differences identified in the miRNA expression profiles and the target gene analysis results were further analyzed to identify potential regulators of terminal hindgut development.

RESULTS

Compared with the control group, 111 miRNAs expressed in the terminal hindgut of the experimental group were up-regulated on gestational day 16, while 117 miRNAs were down-regulated. The ten miRNAs with the greatest differential expression profiles between the experimental and control samples were selected for target gene prediction, pathway analysis, and gene ontology analysis. A subset of these miRNAs was found to be closely related to rat fetus terminal hindgut growth and development. In addition, target gene analysis showed that miR-193 may have an important role in regulating a key gene in anorectal development, Hoxd13. This role was confirmed in a dual luciferase reporter assay when miR-193 was able to inhibit expression of a reporter gene under the control of the 3' untranslated region of the Hoxd13 gene in the human embryonic kidney cell line, 293T. Real-time PCR and Western blotting experiments further showed that the expression of Hoxd13 was significantly lower when miR-193 was highly expressed in rat intestinal epithelial cells. The differences in both sets of experiments were statistically significant compared with the negative control group (P<0.05).

CONCLUSION

These data support an important regulatory role for miRNAs in the expression of target genes during terminal hindgut development in fetal rats. In particular, miR-193-mediated inhibition of Hoxd13 was found to be significant in rat intestinal epithelial cells.

Formyl peptide receptors promotes neural differentiation in mouse neural stem cells by ROS generation and regulation of PI3K-AKT signaling

This study aimed to determine whether formyl peptide receptors (FPRs) regulated the differentiation of neural stem cells (NSCs). FPRs promote the migration of NSCs both in vitro and in vivo. However, the role of FPRs during differentiation of NSCs is unknown. Analysis by Western blot showed significantly increased expression of FPR1 and FPR2 during differentiation of NSCs. The activation of FPRs promotes NSCs to differentiate into neurons with more primary neurites and branch points and longer neurites per cell. Meanwhile, this activation also inhibits the differentiation of NSC into astrocytes. This bidirectional effect can be inhibited by the FPRs-specific inhibitor. Moreover, it was found that the activation of FPRs increased the generation of reactive oxygen species (ROS) and phosphorylation of AKT in the NSCs, while N-acetylcysteine and LY294002 inhibited the FPRs-stimulated increase in ROS generation and AKT phosphorylation, and blocked the FPRs-stimulated neural differentiation into neurons. Therefore, FPRs-stimulated neural differentiation was mediated via ROS and PI3K-AKT signaling pathways. Collectively, the present findings provided a novel insight into the functional role of FPRs in neurogenesis, with important implications for its potential use as a candidate for treating brain or spinal cord injury.

Transcriptional and Genomic Targets of Neural Stem Cells for Functional Recovery after Hemorrhagic Stroke

Hemorrhagic stroke is a life-threatening disease characterized by a sudden rupture of cerebral blood vessels, and it is widely believed that neural cell death occurs after exposure to blood metabolites or subsequently damaged cells. Neural stem cells (NSCs), which maintain neurogenesis and are found in subgranular zone and subventricular zone, are thought to be an endogenous neuroprotective mechanism for these brain injuries. However, due to the complexity of NSCs and their microenvironment, current strategies cannot satisfactorily enhance functional recovery after hemorrhagic stroke. It is well known that transcriptional and genomic pathways play important roles in ensuring the normal functions of NSCs, including proliferation, migration, differentiation, and neural reconnection. Recently, emerging evidence from the use of new technologies such as next-generation sequencing and transcriptome profiling has provided insight into our understanding of genomic function and regulation of NSCs. In the present article, we summarize and present the current data on the control of NSCs at both the transcriptional and genomic levels. Using bioinformatics methods, we sought to predict novel therapeutic targets of endogenous neurogenesis and exogenous NSC transplantation for functional recovery after hemorrhagic stroke, which could also advance our understanding of its pathophysiology.

Enumeration of Neural Stem Cells Using Clonal Assays

Neural stem cells (NSCs) have the ability to self-renew and generate the three major neural lineages — astrocytes, neurons and oligodendrocytes. NSCs and neural progenitors (NPs) are commonly cultured in vitro as neurospheres. This protocol describes in detail how to determine the NSC frequency in a given cell population under clonal conditions. The protocol begins with the seeding of the cells at a density that allows for the generation of clonal neurospheres. The neurospheres are then transferred to chambered coverslips and differentiated under clonal conditions in conditioned medium, which maximizes the differentiation potential of the neurospheres. Finally, the NSC frequency is calculated based on neurosphere formation and multipotency capabilities. Utilities of this protocol include the evaluation of candidate NSC markers, purification of NSCs, and the ability to distinguish NSCs from NPs. This method takes 13 days to perform, which is much shorter than current methods to enumerate NSC frequency.