神经干细胞迁移的研究进展

神经干细胞的定向迁移是胚胎神经系统发育的先决条件,同时在成体组织的许多生理、病理过程中也起着重要作用;研究发现,许多神经退行性疾病都与神经干细胞迁移的缺陷相关。近年来,越来越多的证据表明,无论是内源性的还是移植的神经干细胞都有向大脑损伤部位迁移的特性,显示出神经干细胞用于神经再生及损伤修复治疗的潜能。该文着重在神经干细胞的基本特性以及神经干细胞定向迁移的细胞与分子机制研究等方面进行了综述。     

MicroRNA-9 Coordinates Proliferation and Migration of Human Embryonic Stem Cell-Derived Neural Progenitors

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Highlights? miR-9 is expressed in hESC-derived early hNPCs and their progeny ? Loss of miR-9 inhibits early hNPC proliferation and delays maturation ? miR-9 knockdown promotes hNPC migration in vitro and in vivo ? Stathmin is a target of miR-9 and mediates its effects in early hNPCs     

Induced Pluripotent Stem Cell-Derived Neural Cells Survive and Mature in the Nonhuman Primate Brain

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Highlights? Autologous iPSC-derived neural progenitors survive in the monkey brain for 6 months ? Grafted cells differentiate into neurons, astrocytes, and oligodendrocytes ? Autologous transplantation elicits minimal immune and glial response     

RhoC Involved in the Migration of Neural Stem/Progenitor Cells

Alzheimer’s disease (AD) is characterized by deposition of beta-amyloid peptides (Aβ) and progressive loss of neurons. Neural stem/progenitor cells (NSPCs) can proliferate and produce immature neurons even in the brain of AD patients. However, Aβ₄₂ significantly decreased the expression of RhoC in NSPCs during the co-incubation (P < 0.01). Treating with RhoC siRNA prevented membrane from protrusion and led to a significant reduction in cell migration in responses to SDF-1. Compared with wild-type mice, the numbers of RhoC-immunoreactive cells in hippocampus and cortex were significantly down-regulated in APP/PS1 mice aged 9 months. The results suggest that Aβ₄₂ down-regulates the expression of RhoC in NSPCs in vitro and in vivo; down-regulated RhoC expression results in decreased migration of NSPCs.     

Susceptibility of Human Embryonic Stem Cell-Derived Neural Cells to Japanese Encephalitis Virus Infection

Pluripotent human embryonic stem cells (hESCs) can be efficiently directed to become immature neuroepithelial precursor cells (NPCs) and functional mature neural cells, including neurotransmitter-secreting neurons and glial cells. Investigating the susceptibility of these hESCs-derived neural cells to neurotrophic viruses, such as Japanese encephalitis virus (JEV), provides insight into the viral cell tropism in the infected human brain. We demonstrate that hESC-derived NPCs are highly vulnerable to JEV infection at a low multiplicity of infection (MOI). In addition, glial fibrillary acid protein (GFAP)-expressing glial cells are also susceptible to JEV infection. In contrast, only a few mature neurons were infected at MOI 10 or higher on the third day post-infection. In addition, functional neurotransmitter-secreting neurons are also resistant to JEV infection at high MOI. Moreover, we discover that vimentin intermediate filament, reported as a putative neurovirulent JEV receptor, is highly expressed in NPCs and glial cells, but not mature neurons. These results indicate that the expression of vimentin in neural cells correlates to the cell tropism of JEV. Finally, we further demonstrate that membranous vimentin is necessary for the susceptibility of hESC-derived NPCs to JEV infection.     

The Role of Genetic Variants of Stromal Cell-Derived Factor 1 in Pediatric HIV-1 Infection and Disease Progression

Stromal cell-Derived Factor 1 (SDF1) is the natural ligand of CXCR4, the coreceptor of HIV-1 X4 viruses. This study investigated the role of the single nucleotide polymorphism (SNP) rs1801157 ({"type":"entrez-nucleotide","attrs":{"text":"NM_000609.5","term_id":"291045299","term_text":"NM_000609.5"}}NM_000609.5:c.*519G>A) of the SDF1 gene in the natural history of mother-to-child transmission of HIV-1 and disease progression of HIV-1-infected children. The study was conducted in 428 children born to HIV-1-seropositive mothers, who had not undergone antiretroviral therapy (ART) during pregnancy, and in 120 HIV-1-infected children for whom the end-point was the onset of AIDS or the initiation of ART; 16 children developed early AIDS (<24 months of life), 13 from 24 to 84 months of age, and 14 had late AIDS (>84 months). The rs1801157 SNP was not associated with risk of perinatal infection in any genetic models tested. By contrast, this SNP influenced disease progression in a time-dependent manner. rs1801157 GA heterozygous children had a higher risk of late AIDS (HR = 6.3, 95%CI 1.9–20.7, p = 0.002) than children with the rs1801157 GG genotype. Children were studied for viral coreceptor usage at birth, after 84 months of age and/or at AIDS onset. While R5 viruses using CCR5 coreceptor were predominant at birth (94%) and at early AIDS (85%), viruses using CXCR4 coreceptor emerged during the course of infection and were detected in 49% of children older than 84 months and in 62% of late AIDS. The rs1801157 SNP did not influence the emergence of R5X4 viruses, but children with the rs1801157 GA genotype and R5X4 viruses were at significantly higher risk of late AIDS than children with rs1801157 GG genotype (OR = 8.0, 95% CI 1.2–52.2, p = 0.029). Our results indicate that the rs1801157 SNP does not influence perinatal infection, but impacts disease progression. This effect is time-dependent and linked to the coreceptor-usage of viral variants that undergo evolution during the course of HIV-1 infection.     

Human Induced Pluripotent Stem Cell-Derived Models to Investigate Human Cytomegalovirus Infection in Neural Cells

Human cytomegalovirus (HCMV) infection is one of the leading prenatal causes of congenital mental retardation and deformities world-wide. Access to cultured human neuronal lineages, necessary to understand the species specific pathogenic effects of HCMV, has been limited by difficulties in sustaining primary human neuronal cultures. Human induced pluripotent stem (iPS) cells now provide an opportunity for such research. We derived iPS cells from human adult fibroblasts and induced neural lineages to investigate their susceptibility to infection with HCMV strain Ad169. Analysis of iPS cells, iPS-derived neural stem cells (NSCs), neural progenitor cells (NPCs) and neurons suggests that (i) iPS cells are not permissive to HCMV infection, i.e., they do not permit a full viral replication cycle; (ii) Neural stem cells have impaired differentiation when infected by HCMV; (iii) NPCs are fully permissive for HCMV infection; altered expression of genes related to neural metabolism or neuronal differentiation is also observed; (iv) most iPS-derived neurons are not permissive to HCMV infection; and (v) infected neurons have impaired calcium influx in response to glutamate.     

Structure and Chromosomal Localization of the Human Stromal Cell-Derived Factor 1 (SDF1) Gene

Stromal cell-derived factors 1α and 1β are small cytokines belonging to the intercrine CXC subfamily and originally isolated from a murine bone-marrow stroma cell line by the signal sequence trap method. cDNA and genomic clones of human SDF1α and SDF1β (SDF1A and SDF1B) were isolated and characterized. cDNAs of SDF1α and SDF1β encode proteins of 89 and 93 amino acids, respectively. SDF1α and SDF1β sequences are more than 92% identical to those of the human counterparts. The genomic structure of the SDF1 gene revealed that human SDF1α and SDF1β are encoded by a single gene and arise by alternative splicing. SDF1α and SDF1β are encoded by 3 and 4 exons, respectively. Ubiquitous expression of the SDF1 gene, except in blood cells, was consistent with the presence of the GC-rich sequence in the 5′-flanking region of the SDF1 gene, as is often the case in the "housekeeping" genes. Although genes encoding other members of the intercrine family are localized on chromosome 4q or 17q, the human SDF1 gene was mapped to chromosome 10q by fluorescence in situ hybridization. Strong evolutionary conservation and unique chromosomal localization of the SDF1 gene suggest that SDF1α and SDF1β may have important functions distinct from those of other members of the intercrine family.     

The Roles of Hypoxia-Inducible Factors in Regulating Neural Stem Cells Migration to Glioma Stem Cells and Determinating Their Fates

The mortality of patients with malignant gliomas remains high despite the advancement in multi-modal therapy including surgery, radio- and chemotherapy. Glioma stem cells (GSCs), sharing some characteristics with normal neural stem cells (NSCs), contribute to the cellular origin for primary gliomas and the recurrence of malignant gliomas after current conventional therapy. Accordingly, targeting GSCs proves to be a promising avenue of therapeutic intervention. The specific tropism of NSCs to GSCs provides a novel platform for targeted delivery of therapeutic agents. Tropism and mobilization of NSCs are enhanced by hypoxia through upregulating chemotactic cytokines and activating several signaling pathways. Moreover, hypoxia-inducible factors (HIFs) produced under hypoxic microenvironment of the stem cell niche play critical roles in the growth and stemness phenotypes regulation of both NSCs and GSCs. However, the definite cellular and molecular mechanisms of HIFs involvement in the process remain obscure. In this review, we focus on the pivotal roles of HIFs in migration of NSCs to GSCs and potential roles of HIFs in dictating the fates of migrated NSCs and targeted GSCs.     

Modulation of Feline Immunodeficiency Virus Infection by Stromal Cell-Derived Factor

The α-chemokine receptor CXCR4 has recently been shown to support syncytium formation mediated by strains of feline immunodeficiency virus (FIV) that have been selected for growth in the Crandell feline kidney cell line (CrFK-tropic virus). Given that both human and feline CXCR4 support syncytium formation mediated by FIV, we investigated whether human stromal cell-derived factor (SDF-1) would inhibit infection with FIV. Human SDF-1α and SDF-1β bound with a high affinity (K_Ds of 12.0 and 10.4 nM, respectively) to human cells stably expressing feline CXCR4, and treatment of CrFK cells with human SDF-1α resulted in a dose-dependent inhibition of infection by FIV_PET. No inhibitory activity was detected when the interleukin-2 (IL-2)-dependent feline T-cell line Mya-1 was used in place of CrFK cells, suggesting the existence of a CXCR4-independent mechanism of infection. Furthermore, neither the human β-chemokines RANTES, MIP-1α, MIP-1β, and MCP-1 nor the α-chemokine IL-8 had an effect on infection of either CrFK or Mya-1 cells with CrFK-tropic virus. Envelope glycoprotein purified from CrFK-tropic virus competed specifically for binding of SDF-1α to feline CXCR4 and CXCR4 expression was reduced in FIV-infected cells, suggesting that the inhibitory activity of SDF-1α in CrFK cells may be the result of steric hindrance of the virus-receptor interaction following the interaction between SDF and CXCR4. Prolonged incubation of CrFK cells with SDF-1α led to an enhancement rather than an inhibition of infection. Flow cytometric analysis revealed that this effect may be due largely to up-regulation of CXCR4 expression by SDF-1α on CrFK cells, an effect mimicked by treatment of the cells with phorbol myristate acetate. The data suggest that infection of feline cells with FIV can be mediated by CXCR4 and that, depending on the assay conditions, infection can be either inhibited or enhanced by SDF-1α. Infection with FIV may therefore prove a valuable model in which to study the development of novel therapeutic interventions for the treatment of AIDS.The initial stage in lentiviral infection involves the binding of the viral envelope glycoprotein (Env) to a molecule on the surface of the target cell. The primary high-affinity binding receptor for human immunodeficiency virus (HIV) is CD4 (9, 26), a member of the immunoglobulin supergene family of molecules. However, binding of the viral glycoprotein to CD4 is insufficient for infection to proceed (29); for virus-cell fusion to occur, the target cell must also express an accessory molecule or coreceptor. The principal coreceptors for HIV infection have now been identified as members of the seven-transmembrane domain (7TM) superfamily of molecules. Syncytium-inducing (SI) T-cell line-tropic strains of virus require coexpression of the α-chemokine receptor CXCR4 for infection (19), whereas non-syncytium-inducing (NSI) strains of virus require coexpression of the β-chemokine receptor CCR5 for infection (1, 6, 10, 13, 14). In addition, other chemokine receptors such as CCR2b and CCR3 (6, 13, 41, 48), the receptor encoded by human cytomegalovirus US28 (39, 41), and the orphan receptor STRL33 (28) can function as coreceptors for HIV infection. More recently, additional members of the 7TM superfamily have been identified as coreceptors for infection with simian immunodeficiency virus (SIV). Two of these receptors, termed Bonzo and BOB, support infection with not only SIV but also HIV type 2 (HIV-2) and macrophage-tropic or dualtropic (both macrophage- and T-cell-tropic) strains of HIV-1 (11). Bonzo has subsequently been identified as being identical to STRL33 (28), whereas BOB is identical to GPR15 (21). A subsequent study has demonstrated that an additional molecule, designated GPR1 (30), can function as a coreceptor for SIV (18). Thus, a diverse range of 7TM molecules which can support infection with primate lentiviruses have now been identified.The selective usage of chemokine receptors as coreceptors for infection by HIV and SIV is borne out by the sensitivity of the viruses to inhibition by chemokines. Infection with viruses which use CCR5 can be inhibited by the β-chemokines RANTES, MIP-1α, and MIP-1β (7, 14), whereas those which use CXCR4 can be inhibited by stromal cell-derived factor (SDF-1) (3, 36). Although infection of primary macrophages by certain primary NSI viruses is not inhibited reproducibly by the β-chemokines RANTES, MIP-1α, and MIP-1β (14, 33, 44), analogs of the β-chemokines such as AOP-RANTES that inhibit HIV infection with an increased potency, inhibit infection of both peripheral blood mononuclear cells (PBMC) and primary macrophages, and do not trigger signalling via G proteins coupled to the chemokine receptor have been developed (47). Therefore, with the development of SDF-1 derivatives analogous to AOP-RANTES, it may be possible to generate therapeutic agents that are effective at inhibiting not only the NSI strains of HIV found in early infection but also the SI strains of virus which appear late in infection with the progression to AIDS.Feline immunodeficiency virus (FIV) induces an AIDS-like illness in its natural host, the domestic cat (38). A proportion of primary isolates of FIV can be readily adapted to grow and form syncytia in the Crandell feline kidney (CrFK) cell line (45), analagous to the isolation of SI variants of HIV. Sequencing of the env gene from CrFK-tropic viruses would suggest that the principal determinant of CrFK tropism is an increase in charge of the V3 loop of the envelope glycoprotein (45, 51), further strengthening the analogy between CrFK-tropic strains of FIV and SI strains of HIV. While the primary high-affinity binding receptor for FIV remains elusive, recent studies have demonstrated a role for the feline homolog of CXCR4 in infection with CrFK-tropic strains of FIV (53, 56). Given that the appearance of CXCR4-dependent SI variants of HIV in the peripheral blood of HIV-infected individuals accompanies the progression to AIDS (8), the ability to study the role of such CXCR4-dependent strains of virus in disease pathogenesis is of obvious interest. Moreover, as it appears that several strains of SIV show preferential usage of CCR5 and not CXCR4 for infection (5, 11, 18), then FIV infection of the domestic cat is the only animal model described to date in which the contribution of CXCR4-dependent viruses to the pathogenesis of AIDS may be studied in the natural host of the virus.In this study, we investigated the nature of the interaction between FIV and the chemokine receptor CXCR4. Given the high degree of amino acid sequence homology between human and feline CXCR4 (56), we examined the interaction between human SDF-1 and feline CXCR4. We have found that human SDF-1 binds specifically to feline CXCR4 and inhibits infection with FIV. We demonstrate that SDF-1 can upregulate CXCR4 expression with a corresponding enhancement of infection and that this effect can be mimicked by treatment of the cells with the phorbol ester phorbol myristate acetate (PMA). Moreover, infection of interleukin-2 (IL-2)-dependent T cells with FIV was resistant to the inhibitory effects of SDF-1, suggesting the existence of a CXCR4-independent mechanism of infection in these cells. These data suggest that the mechanism of infection with FIV bears striking similarities to infection with HIV and that the study of FIV infection of the domestic cat may provide a valuable insight into the pathogenesis of AIDS.     

TPT1 Supports Proliferation of Neural Stem/Progenitor Cells and Brain Tumor Initiating Cells Regulated by Macrophage Migration Inhibitory Factor (MIF)

Neurochemical Research - One of the key areas in stem cell research is the identification of factors capable of promoting the expansion of Neural Stem Cell/Progenitor Cells (NSPCs) and...     

BRCA-1 基因与神经干细胞

乳腺癌易感基因(Breast cancer susceptibility gene,Brca-1)是肿瘤抑制基因家族中的一员,它是乳腺癌特异性抑癌基因,1994年Miki等[1]采用定位克隆方法首次将Brca-1分离出来。Brca-1能防止细胞过快地或失去控制地生长和分化,在调节细胞进程、DNA损伤修复、细胞生长与凋亡及转录活化和抑制等多种生物学途径都发挥重要作用,Korhonen等2003年报道Brca-1基因可促进体外培养的大鼠来源的神经干细胞的增殖。     

Suppression of Th1-Mediated Autoimmunity by Embryonic Stem Cell-Derived Dendritic Cells

We herein demonstrate the immune-regulatory effect of embryonic stem cell-derived dendritic cells (ES-DCs) using two models of autoimmune disease, namely non-obese diabetic (NOD) mice and experimental autoimmune encephalomyelitis (EAE). Treatment of pre-diabetic NOD mice with ES-DCs exerted almost complete suppression of diabetes development during the observation period for more than 40 weeks. The prevention of diabetes by ES-DCs was accompanied with significant reduction of insulitis and decreased number of Th1 and Th17 cells in the spleen. Development of EAE was also inhibited by the treatment with ES-DCs, and the therapeutic effect was obtained even if ES-DCs were administrated after the onset of clinical symptoms. Treatment of EAE-induced mice with ES-DCs reduced the infiltration of inflammatory cells into the spinal cord and suppressed the T cell response to the myelin antigen. Importantly, the ES-DC treatment did not affect T cell response to an exogenous antigen. As the mechanisms underlying the reduction of the number of infiltrating Th1 cells, we observed the inhibition of differentiation and proliferation of Th1 cells by ES-DCs. Furthermore, the expression of VLA-4α on Th1 cells was significantly inhibited by ES-DCs. Considering the recent advances in human induced pluripotent stem cell-related technologies, these results suggest a clinical application for pluripotent stem cell-derived dendritic cells as a therapy for T cell-mediated autoimmune diseases.     

Two Factor Reprogramming of Human Neural Stem Cells into Pluripotency

Background

Reprogramming human somatic cells to pluripotency represents a valuable resource for the development of in vitro based models for human disease and holds tremendous potential for deriving patient-specific pluripotent stem cells. Recently, mouse neural stem cells (NSCs) have been shown capable of reprogramming into a pluripotent state by forced expression of Oct3/4 and Klf4; however it has been unknown whether this same strategy could apply to human NSCs, which would result in more relevant pluripotent stem cells for modeling human disease.

Methodology and Principal Findings

Here, we show that OCT3/4 and KLF4 are indeed sufficient to induce pluripotency from human NSCs within a two week time frame and are molecularly indistinguishable from human ES cells. Furthermore, human NSC-derived pluripotent stem cells can differentiate into all three germ lineages both in vitro and in vivo.

Conclusions/Significance

We propose that human NSCs represent an attractive source of cells for producing human iPS cells since they only require two factors, obviating the need for c-MYC, for induction into pluripotency. Thus, in vitro human disease models could be generated from iPS cells derived from human NSCs.     

Roles of ES Cell-Derived Gliogenic Neural Stem/Progenitor Cells in Functional Recovery after Spinal Cord Injury

Transplantation of neural stem/progenitor cells (NS/PCs) following the sub-acute phase of spinal cord injury (SCI) has been shown to promote functional recovery in rodent models. However, the types of cells most effective for treating SCI have not been clarified. Taking advantage of our recently established neurosphere-based culture system of ES cell-derived NS/PCs, in which primary neurospheres (PNS) and passaged secondary neurospheres (SNS) exhibit neurogenic and gliogenic potentials, respectively, here we examined the distinct effects of transplanting neurogenic and gliogenic NS/PCs on the functional recovery of a mouse model of SCI. ES cell-derived PNS and SNS transplanted 9 days after contusive injury at the Th10 level exhibited neurogenic and gliogenic differentiation tendencies, respectively, similar to those seen in vitro. Interestingly, transplantation of the gliogenic SNS, but not the neurogenic PNS, promoted axonal growth, remyelination, and angiogenesis, and resulted in significant locomotor functional recovery after SCI. These findings suggest that gliogenic NS/PCs are effective for promoting the recovery from SCI, and provide essential insight into the mechanisms through which cellular transplantation leads to functional improvement after SCI.     

Function of Mouse Embryonic Stem Cell-Derived Supporting Cells in Neural Progenitor Cell Maturation and Long Term Cxpansion

Background

In the differentiation of mouse embryonic stem (ES) cells into neurons using the 5-stage method, cells in stage 4 are in general used as neural progenitors (NPs) because of their ability to give rise to neurons. The choice of stage 4 raises several questions about neural progenitors such as the type of cell types that are specifically considered to be neural progenitors, the exact time when these progenitors become capable of neurogenesis and whether neurogenesis is an independent and autonomous process or the result of an interaction between NP cells and the surrounding cells.

Methodology/Principal Findings

In this study, we found that the confluent monolayer cells and neural sphere like cell clusters both appeared in the culture of the first 14 days and the subsequent 6 weeks. However, only the sphere cells are neural progenitors that give rise to neurons and astrocytes. The NP cells require 14 days to mature into neural lineages fully capable of differentiation. We also found that although the confluent monolayer cells do not undergo neurogenesis, they play a crucial role in the growth, differentiation, and apoptosis of the sphere cells, during the first 14 days and long term culture, by secreted factors and direct cell to cell contact.

Conclusions/Significance

The sphere cells in stage 4 are more committed to developing into neural progenitors than monolayer cells. Interaction between the monolayer cells and sphere cells is important in the development of stage 4 cell characteristics.