Jianbing Qin

Lycium barbarum polysaccharides prevent memory and neurogenesis impairments in scopolamine-treated rats.

Lycium barbarum is used both as a food additive and as a medicinal herb in many countries, and L. barbarum polysaccharides (LBPs), a major cell component, are reported to have a wide range of beneficial effects including neuroprotection, anti-aging and anticancer properties, and immune modulation. The effects of LBPs on neuronal function, neurogenesis, and drug-induced learning and memory deficits have not been assessed. We report the therapeutic effects of LBPs on learning and memory and neurogenesis in scopolamine (SCO)-treated rats. LBPs were administered via gastric perfusion for 2 weeks before the onset of subcutaneous SCO treatment for a further 4 weeks. As expected, SCO impaired performance in novel object and object location recognition tasks, and Morris water maze. However, dual SCO- and LBP-treated rats spent significantly more time exploring the novel object or location in the recognition tasks and had significant shorter escape latency in the water maze. SCO administration led to a decrease in Ki67- or DCX-immunoreactive cells in the dentate gyrus and damage of dendritic development of the new neurons; LBP prevented these SCO-induced reductions in cell proliferation and neuroblast differentiation. LBP also protected SCO-induced loss of neuronal processes in DCX-immunoreactive neurons. Biochemical investigation indicated that LBP decreased the SCO-induced oxidative stress in hippocampus and reversed the ratio Bax/Bcl-2 that exhibited increase after SCO treatment. However, decrease of BDNF and increase of AChE induced by SCO showed no response to LBP administration. These results suggest that LBPs can prevent SCO-induced cognitive and memory deficits and reductions in cell proliferation and neuroblast differentiation. Suppression of oxidative stress and apoptosis may be involved in the above effects of LBPs that may be a promising candidate to restore memory functions and neurogenesis.

IGF-1 Promotes Brn-4 Expression and Neuronal Differentiation of Neural Stem Cells via the PI3K/Akt Pathway

Our previous studies indicated that transcription factor Brn-4 is upregulated in the surgically denervated hippocampus in vivo, promoting neuronal differentiation of hippocampal neural stem cells (NSCs) in vitro. The molecules mediating Brn-4 upregulation in the denervated hippocampus remain unknown. In this study we examined the levels of insulin-like growth factor-1 (IGF-1) in hippocampus following denervation. Surgical denervation led to a significant increase in IGF-1 expression in vivo. We also report that IGF-1 treatment on NSCs in vitro led to a marked acceleration of Brn-4 expression and cell differentiation down neuronal pathways. The promotion effects were blocked by PI3K-specific inhibitor (LY294002), but not MAPK inhibitor (PD98059); levels of phospho-Akt were increased by IGF-1 treatment. In addition, inhibition of IGF-1 receptor (AG1024) and mTOR (rapamycin) both attenuated the increased expression of Brn-4 induced by IGF-1. Together, the results demonstrated that upregulation of IGF-1 induced by hippocampal denervation injury leads to activation of the PI3K/Akt signaling pathway, which in turn gives rise to upregulation of the Brn-4 and subsequent stem cell differentiation down neuronal pathways.

Therapeutic Effect of Human Umbilical Cord Mesenchymal Stem Cells on Neonatal Rat Hypoxic-Ischemic Encephalopathy

The therapeutic potential of umbilical cord blood mesenchymal stem cells has been studied in several diseases. However, the possibility that human umbilical cord Whartons jelly‐derived mesenchymal stem cells (hUCMSCs) can be used to treat neonatal hypoxic–ischemic encephalopathy (HIE) has not yet been investigated. This study focuses on the potential therapeutic effect of hUCMSC transplantation in a rat model of HIE. Dermal fibroblasts served as cell controls. HIE was induced in neonatal rats aged 7 days. hUCMSCs labeled with Dil were then transplanted into the models 24 hr or 72 hr post‐HIE through the peritoneal cavity or the jugular vein. Behavioral testing revealed that hUCMSC transplantation but not the dermal fibroblast improved significantly the locomotor function vs. vehicle controls. Animals receiving cell grafts 24 hr after surgery showed a more significant improvement than at 72 hr. More hUCMSCs homed to the ischemic frontal cortex following intravenous administration than after intraperitoneal injection. Differentiation of engrafted cells into neurons was observed in and around the infarct region. Gliosis in ischemic regions was significantly reduced after hUCMSC transplantation. Administration of ganglioside (GM1) enhanced the behavioral recovery on the base of hUCMSC treatment. These results demonstrate that intravenous transplantation of hUCMSCs at an early stage after HIE can improve the behavior of hypoxic–ischemic rats and decrease gliosis. Ganglioside treatment further enhanced the recovery of neurological function following hUCMSC transplantation.

CXCL12 inhibits cortical neuron apoptosis by increasing the ratio of Bcl-2/Bax after traumatic brain injury

CXCL12 and its physiologic receptor CXCR4 are involved in controlling cell survival, proliferation and migration in adult tissues. This study aimed to investigate the effects of CXCL12 on cortical neuron apoptosis in rats after traumatic brain injury (TBI) and the potential mechanisms involved. At 3 days after TBI, in situ terminal transferase d-UTP nick-end labeling assay (TUNEL) showed that the apoptotic index (AI) deceased significantly in the CXCL12 treatment group compared with the control group (p < 0.05). Immunofluorescence double-labeled staining revealed that most of the TUNEL positive cells were NeuN positive neurons. The change trends of active caspase-3 expression were similar as those of the AI. The Bcl-2:Bax ratio was upregulated in the CXCL12 group compared with the control group. However, the effect of CXCL12 could be partially reverted by the additional use of AMD3100 (a kind of antagonist of CXCR4) (p < 0.05). Our results indicated that after TBI in rats CXCL12 combing CXCR4 receptors could inhibit the caspase-3 pathway by upregulating Bcl-2:Bax ratio, which protect neurons from apoptosis.

The denervated hippocampus provides proper microenvironment for the survival and differentiation of neural progenitors.

The fate of neural stem/progenitor cells (NSCs/NPCs) in vivo lies on the local microenvironment. Whether the denervated hippocampus provides a stimulative role on the survival and differentiation of the anterior subventricular zone (SVZa) progenitors was investigated in the present study. In vivo the SVZa progenitors were transplanted into the denervated hippocampus and the contralateral side, and were found migrating along the subgranular layer. More implanted cells were found survived and differentiated into the Neurofilament 200 (NF-200) or beta-Tubulin-III positive neurons in the denervated than in the normal hippocampus at all points studied. In vitro the extracts from the denervated and normal hippocampus were used to induce differentiation of the SVZa progenitors. More progenitors incubated with the denervated hippocampal extract differentiated significantly into the MAP-2 or AChE positive neurons than those incubated with the normal hippocampal extract (P<0.05). We concluded that the deafferented hippocampus provided proper microenvironment for the survival and neuronal differentiation of neural progenitors.

The controlled differentiation of human neural stem cells into TH-immunoreactive （ir） neurons in vitro

The expansion of human neural stem cells in vitro might overcome the poor donor supply of human fetal neural tissue in transplantation for Parkinsons disease. However, the differentiation of human neural stem cells into dopaminergic neurons has proven difficult. In the present study, we investigated the effects of cytokines, trophic factors of developmental striatum and Ginkgolide on differentiation of human neural stem cells (hNSCs) into TH-ir neurons. The immunoreactivity to tyrosine hydroxylase (TH), a distinctive marker for dopamine neurons was used to assess dopaminergic neuronal phenotype. We demonstrate that human neural stem cells expanded in vitro can efficiently differentiate into TH-ir neurons by induction. These stem cells might serve as a continuous, on-demand source of cells for therapeutic transplantation in patients with Parkinsons disease.

Proliferation, Migration, and Neuronal Differentiation of the Endogenous Neural Progenitors in Hippocampus after Fimbria Fornix Transection

ABSTRACT Neurogenesis in the hippocampus continues throughout adult life and can be regulated by the local microenvironment. To determine whether denervation stimulates neurogenesis in hippocampus, proliferation, migration, and differentiation of local neural stem cells (NSCs) in dentate gyrus was investigated after fimbria fornix transection. In the denervated hippocampus, NSCs proliferated markedly and migrated along the subgranular layer, and more newborn cells differentiated into neurons or astrocytes. After denervation, more newborn cells in the deafferented hippocampus expressed Brn-4 and differentiated into β-Tubulin III positive neurons. It is concluded that the local NSCs in hippocampus may proliferate and migrate into granule cell layer, in which changes in the deafferented hippocampus provided a suitable microenvironment for hippocampal neurogenesis and the increased Brn-4 in denervated hippocampus may be involved in this process.

Brn-4 is upregulated in the deafferented hippocampus and promotes neuronal differentiation of neural progenitors in vitro

Fimbria‐fornix (FF), the septo‐hippocampal pathway, was transected to model Alzheimers disease (AD), which is characterized by loss of cholinergic afferent fibers in hippocampus. Various alternations may happen in the deafferented hippocampus. In this study, we determined the expression of Brn‐4 in hippocampus after FF lesion. RT‐PCR and Western blot showed that mRNA transcription and protein of Brn‐4 increased significantly and reached to the peak at day 14 after FF lesion. Hybridization and immunohistochemistry indicated that Brn‐4 signals in hippocampus and dentate gyrus (DG) of the deafferented side were significantly stronger than the normal side. More Brn‐4 positive cells were identified in the DG of deafferented hippocampus. In the pyramidal and granular cells, Brn‐4 positive cells were all NeuN positive neurons, whereas in the neurogenic area, subgranular zone (SGZ), only a part of Brn‐4 positive cells were NeuN positive, and these Brn‐4/NeuN double positive neurons in SGZ and hilus of DG increased significantly after the trauma induced by FF lesion. In vitro Brn‐4 antibody attenuated the role of extract from deafferented hippocampus in promoting differentiation of hippocampal progenitors into MAP‐2 positive neurons. This study demonstrated that after FF lesion, Brn‐4 in the deafferented hippocampus was upregulated and might play an important role in inducing local progenitors to differentiate into neurons, which may compensate for the loss of cholinergic afferent fibers or other dysfunctions.

Identification of neonatal rat hippocampal radial glia cells in vitro

The role of radial glia cells (RGCs) as neural progenitors and as guides for migrating neurons is well established, whereas their precise contribution to adult hippocampal neurogenesis remains less understood. To precisely study the properties of hippocampal RGCs under normal conditions in vitro, here we acquired the hippocampal RGCs of postnatal 1 d rats under adherent conditions in vitro, identified their astroglia and stem/progenitor properties. We found that the neonatal rat hippocampal RGCs had longer processes than the RGCs from fetal cerebral cortices, and these cells could be double-labeled by BLBP, GFAP, Vimentin with Nestin and expressed some stem/progenitor genes, these cells also presented multiple differentiation potentialities, albeit the ability of gliogenesis far exceeded the neurogenesis under normal culture conditions in vitro. Taken together, we acquired and identified some properties of the RGCs from neonatal rat hippocampi in vitro.

Brn4 and TH synergistically promote the differentiation of neural stem cells into dopaminergic neurons

Neural stem cells (NSCs) are pluripotent cells capable of differentiation into dopaminergic (DA) neurons, which are the major cell types damaged in Parkinsons disease (PD). Therefore, NSCs are considered the most promising cell source for cell replacement therapy of PD. However, the poor differentiation and maturation of DA neurons and decreased cell survival after transplantation are a challenge. We have previously demonstrated that Brn4, a member of the POU domain family of transcription factors, induced the differentiation of NSCs into neurons and promoted their maturation. In this study, we directly transduced tyrosine hydroxylase (TH), the rate-limiting enzyme in dopamine biosynthesis, into NSCs to induce DA neuronal differentiation. However, these DA neurons were morphologically immature and seldom expressed dopamine transporter (DAT), a late marker of mature DA neurons. In contrast, TH co-transfected with Brn4 generated increased number of mature DA neurons. Furthermore, Brn4 significantly induced the expression of glial cell line-derived neurotrophic factor (GDNF) with its receptors GFRα-1 and Ret, which may contribute to the maturation and survival of differentiated DA neurons. Our findings may be of future importance for the use of NSCs in cell replacement therapy of PD.