Metabolic and proteostatic differences in quiescent and active neural stem cells

Adult neural stem cells are neurogenesis progenitor cells that play an important role in neurogenesis.Therefore,neural regeneration may be a promising target for treatment of many neurological illnesses.The regenerative capacity of adult neural stem cells can be chara cterized by two states:quiescent and active.Quiescent adult neural stem cells are more stable and guarantee the quantity and quality of the adult neural stem cell pool.Active adult neural stem cells are chara cterized by rapid proliferation and differentiation into neurons which allow for integration into neural circuits.This review focuses on diffe rences between quiescent and active adult neural stem cells in nutrition metabolism and protein homeostasis.Furthermore,we discuss the physiological significance and underlying advantages of these diffe rences.Due to the limited number of adult neural stem cells studies,we refe rred to studies of embryonic adult neural stem cells or non-mammalian adult neural stem cells to evaluate specific mechanisms.

Autophagy in neural stem cells and glia for brain health and diseases

Autophagy is a multifaceted cellular process that not only maintains the homeostatic and adaptive responses of the brain but is also dynamically involved in the regulation of neural cell generation,maturation,and survival.Autophagy facilities the utilization of energy and the microenvironment for developing neural stem cells.Autophagy arbitrates structural and functional remodeling during the cell differentiation process.Autophagy also plays an indispensable role in the maintenance of stemness and homeostasis in neural stem cells during essential brain physiology and also in the instigation and progression of diseases.Only recently,studies have begun to shed light on autophagy regulation in glia(microglia,astrocyte,and oligodendrocyte)in the brain.Glial cells have attained relatively less consideration despite their unquestioned influence on various aspects of neural development,synaptic function,brain metabolism,cellular debris clearing,and restoration of damaged or injured tissues.Thus,this review composes pertinent information regarding the involvement of autophagy in neural stem cells and glial regulation and the role of this connexion in normal brain functions,neurodevelopmental disorders,and neurodegenerative diseases.This review will provide insight into establishing a concrete strategic approach for investigating pathological mechanisms and developing therapies for brain diseases.

Neurotrophins and neural stem cells in posttraumatic brain injury repair

Traumatic brain injury(TBI)is the main cause of disability,mental health disorder,and even death,with its incidence and social costs rising steadily.Although different treatment strategies have been developed and tested to mitigate neurological decline,a definitive cure for these conditions remains elusive.Studies have revealed that vari-ous neurotrophins represented by the brain-derived neurotrophic factor are the key regulators of neuroinflammation,apoptosis,blood-brain barrier permeability,neurite regeneration,and memory function.These factors are instrumental in alleviating neu-roinflammation and promoting neuroregeneration.In addition,neural stem cells(NSC)contribute to nerve repair through inherent neuroprotective and immunomodulatory properties,the release of neurotrophins,the activation of endogenous NSCs,and in-tercellular signaling.Notably,innovative research proposals are emerging to combine BDNF and NSCs,enabling them to synergistically complement and promote each other in facilitating injury repair and improving neuron differentiation after TBI.In this review,we summarize the mechanism of neurotrophins in promoting neurogen-esis and restoring neural function after TBI,comprehensively explore the potential therapeutic effects of various neurotrophins in basic research on TBI,and investigate their interaction with NSCs.This endeavor aims to provide a valuable insight into the clinical treatment and transformation of neurotrophins in TBI,thereby promoting the progress of TBI therapeutics.

Transplantation of fibrin-thrombin encapsulated human induced neural stem cells promotes functional recovery of spinal cord injury rats through modulation of the microenvironment

Recent studies have mostly focused on engraftment of cells at the lesioned spinal cord,with the expectation that differentiated neurons facilitate recovery.Only a few studies have attempted to use transplanted cells and/or biomaterials as major modulators of the spinal cord injury microenvironment.Here,we aimed to investigate the role of microenvironment modulation by cell graft on functional recovery after spinal cord injury.Induced neural stem cells reprogrammed from human peripheral blood mononuclear cells,and/or thrombin plus fibrinogen,were transplanted into the lesion site of an immunosuppressed rat spinal cord injury model.Basso,Beattie and Bresnahan score,electrophysiological function,and immunofluorescence/histological analyses showed that transplantation facilitates motor and electrophysiological function,reduces lesion volume,and promotes axonal neurofilament expression at the lesion core.Examination of the graft and niche components revealed that although the graft only survived for a relatively short period(up to 15 days),it still had a crucial impact on the microenvironment.Altogether,induced neural stem cells and human fibrin reduced the number of infiltrated immune cells,biased microglia towards a regenerative M2 phenotype,and changed the cytokine expression profile at the lesion site.Graft-induced changes of the microenvironment during the acute and subacute stages might have disrupted the inflammatory cascade chain reactions,which may have exerted a long-term impact on the functional recovery of spinal cord injury rats.

Long non-coding RNA H19 regulates neurogenesis of induced neural stem cells in a mouse model of closed head injury

Stem cell-based therapies have been proposed as a potential treatment for neural regeneration following closed head injury.We previously reported that induced neural stem cells exert beneficial effects on neural regeneration via cell replacement.However,the neural regeneration efficiency of induced neural stem cells remains limited.In this study,we explored differentially expressed genes and long non-coding RNAs to clarify the mechanism underlying the neurogenesis of induced neural stem cells.We found that H19 was the most downregulated neurogenesis-associated lnc RNA in induced neural stem cells compared with induced pluripotent stem cells.Additionally,we demonstrated that H19 levels in induced neural stem cells were markedly lower than those in induced pluripotent stem cells and were substantially higher than those in induced neural stem cell-derived neurons.We predicted the target genes of H19 and discovered that H19 directly interacts with mi R-325-3p,which directly interacts with Ctbp2 in induced pluripotent stem cells and induced neural stem cells.Silencing H19 or Ctbp2 impaired induced neural stem cell proliferation,and mi R-325-3p suppression restored the effect of H19 inhibition but not the effect of Ctbp2 inhibition.Furthermore,H19 silencing substantially promoted the neural differentiation of induced neural stem cells and did not induce apoptosis of induced neural stem cells.Notably,silencing H19 in induced neural stem cell grafts markedly accelerated the neurological recovery of closed head injury mice.Our results reveal that H19 regulates the neurogenesis of induced neural stem cells.H19 inhibition may promote the neural differentiation of induced neural stem cells,which is closely associated with neurological recovery following closed head injury.

Ethanol changes Nestin-promoter induced neural stem cells to disturb newborn dendritic spine remodeling in the hippocampus of mice

Adolescent binge drinking leads to long-lasting disorders of the adult central nervous system,particularly aberrant hippocampal neurogenesis.In this study,we applied in vivo fluorescent tracing using NestinCreERT2::Rosa26-tdTomato mice and analyzed the endogenous neurogenesis lineage progression of neural stem cells(NSCs)and dendritic spine formation of newborn neurons in the subgranular zone of the dentate gyrus.We found abnormal orientation of tamoxifen-induced tdTomato+(tdTom^(+))NSCs in adult mice 2 months after treatment with EtOH(5.0 g/kg,i.p.)for 7 consecutive days.EtOH markedly inhibited tdTom^(+)NSCs activation and hippocampal neurogenesis in mouse dentate gyrus from adolescence to adulthood.EtOH(100 mM)also significantly inhibited the proliferation to 39.2%and differentiation of primary NSCs in vitro.Adult mice exposed to EtOH also exhibited marked inhibitions in dendritic spine growth and newborn neuron maturation in the dentate gyrus,which was partially reversed by voluntary running or inhibition of the mammalian target of rapamycinenhancer of zeste homolog 2 pathway.In vivo tracing revealed that EtOH induced abnormal orientation of tdTom+NSCs and spatial misposition defects of newborn neurons,thus causing the disturbance of hippocampal neurogenesis and dendritic spine remodeling in mice.

Neural stem cells promote neuroplasticity: a promising therapeutic strategy for the treatment of Alzheimer’s disease

Recent studies have demonstrated that neuroplasticity,such as synaptic plasticity and neurogenesis,exists throughout the normal lifespan but declines with age and is significantly impaired in individuals with Alzheimer’s disease.Hence,promoting neuroplasticity may represent an effective strategy with which Alzheimer’s disease can be alleviated.Due to their significant ability to self-renew,differentiate,and migrate,neural stem cells play an essential role in reversing synaptic and neuronal damage,reducing the pathology of Alzheimer’s disease,including amyloid-β,tau protein,and neuroinflammation,and secreting neurotrophic factors and growth factors that are related to plasticity.These events can promote synaptic plasticity and neurogenesis to repair the microenvironment of the mammalian brain.Consequently,neural stem cells are considered to represent a potential regenerative therapy with which to improve Alzheimer’s disease and other neurodegenerative diseases.In this review,we discuss how neural stem cells regulate neuroplasticity and optimize their effects to enhance their potential for treating Alzheimer’s disease in the clinic.

Induced neural stem cells regulate microglial activation through Akt-mediated upregulation of CXCR4 and Crry in a mouse model of closed head injury

Microglial activation that occurs rapidly after closed head injury may play important and complex roles in neuroinflammation-associated neuronal damage and repair.We previously reported that induced neural stem cells can modulate the behavior of activated microglia via CXCL12/CXCR4 signaling,influencing their activation such that they can promote neurological recovery.However,the mechanism of CXCR4 upregulation in induced neural stem cells remains unclear.In this study,we found that nuclear factor-κB activation induced by closed head injury mouse serum in microglia promoted CXCL12 and tumor necrosis factor-αexpression but suppressed insulin-like growth factor-1 expression.However,recombinant complement receptor 2-conjugated Crry(CR2-Crry)reduced the effects of closed head injury mouse serum-induced nuclear factor-κB activation in microglia and the levels of activated microglia,CXCL12,and tumor necrosis factor-α.Additionally,we observed that,in response to stimulation(including stimulation by CXCL12 secreted by activated microglia),CXCR4 and Crry levels can be upregulated in induced neural stem cells via the interplay among CXCL12/CXCR4,Crry,and Akt signaling to modulate microglial activation.In agreement with these in vitro experimental results,we found that Akt activation enhanced the immunoregulatory effects of induced neural stem cell grafts on microglial activation,leading to the promotion of neurological recovery via insulin-like growth factor-1 secretion and the neuroprotective effects of induced neural stem cell grafts through CXCR4 and Crry upregulation in the injured cortices of closed head injury mice.Notably,these beneficial effects of Akt activation in induced neural stem cells were positively correlated with the therapeutic effects of induced neural stem cells on neuronal injury,cerebral edema,and neurological disorders post–closed head injury.In conclusion,our findings reveal that Akt activation may enhance the immunoregulatory effects of induced neural stem cells on microglial activation via upregulation of CXCR4 and Crry,thereby promoting induced neural stem cell–mediated improvement of neuronal injury,cerebral edema,and neurological disorders following closed head injury.

New insights into the biological roles of immune cells in neural stem cells in post-traumatic injury of the central nervous system

Traumatic injuries in the central nervous system,such as traumatic brain injury and spinal cord injury,are associated with tissue inflammation and the infiltration of immune cells,which simultaneously affect the self-renewal and differentiation of neural stem cells.Howeve r,the tissue repair process instigated by endogenous neural stem cells is incapable of restoring central nervous system injuries without external intervention.Recently,resident/peripheral immune cells have been demonstrated to exert significant effects on neural stem cells.Thus,the resto ration of traumatic injuries in the central nervous system by the immune intervention in neural stem cells represents a potential therapeutic method.In this review,we discuss the roles and possible mechanisms of immune cells on the selfrenewal and differentiation of neural stem cells along with the prognosis of central nervous system injuries based on immune intervention.Finally,we discuss remaining research challenges that need to be considered in the future.Further elucidation of these challenges will fa cilitate the successful application of neural stem cells in central nervous system injuries.

Low-temperature 3D-printed collagen/chitosan scaffolds loaded with exosomes derived from neural stem cells pretreated with insulin growth factor-1 enhance neural regeneration after traumatic brain injury

There are various clinical treatments for traumatic brain injury,including surgery,drug therapy,and rehabilitation therapy;howeve r,the therapeutic effects are limited.Scaffolds combined with exosomes represent a promising but challenging method for improving the repair of traumatic brain injury.In this study,we determined the ability of a novel 3D-printed collagen/chitosan scaffold loaded with exosomes derived from neural stem cells pretreated with insulin-like growth factor-1(3D-CC-INEXOS) to improve traumatic brain injury repair and functional recove ry after traumatic brain injury in rats.Composite scaffolds comprising collagen,chitosan,and exosomes derived from neural stem cells pretreated with insulin-like growth fa ctor-1(INEXOS) continuously released exosomes for 2weeks.Transplantation of 3D-CC-INExos scaffolds significantly improved motor and cognitive functions in a rat traumatic brain injury model,as assessed by the Morris water maze test and modified neurological seve rity scores.In addition,immunofluorescence staining and transmission electron microscopy showed that3D-CC-INExos implantation significantly improved the recove ry of damaged nerve tissue in the injured area.In conclusion,this study suggests that transplanted3D-CC-INExos scaffolds might provide a potential strategy for the treatment of traumatic brain injury and lay a solid foundation for clinical translation.

Neuroprotective effects of neural stem cells pretreated with neuregulin1β on PC12 cells exposed to oxygen-glucose deprivation/reoxygenation

Studies on ischemia/reperfusion(I/R)injury suggest that exogenous neural stem cells(NSCs)are ideal candidates for stem cell therapy reperfusion injury.However,NSCs are difficult to obtain owing to ethical limitations.In addition,the survival,differentiation,and proliferation rates of transplanted exogenous NSCs are low,which limit their clinical application.Our previous study showed that neuregulin1β(NRG1β)alleviated cerebral I/R injury in rats.In this study,we aimed to induce human umbilical cord mesenchymal stem cells into NSCs and investigate the improvement effect and mechanism of NSCs pretreated with 10 nM NRG1βon PC12 cells injured by oxygen-glucose deprivation/reoxygenation(OGD/R).Our results found that 5 and 10 nM NRG1βpromoted the generation and proliferation of NSCs.Co-culture of NSCs and PC12 cells under condition of OGD/R showed that pretreatment of NSCs with NRG1βimproved the level of reactive oxygen species,malondialdehyde,glutathione,superoxide dismutase,nicotinamide adenine dinucleotide phosphate,and nuclear factor erythroid 2-related factor 2(Nrf2)and mitochondrial damage in injured PC12 cells;these indexes are related to ferroptosis.Research has reported that p53 and solute carrier family 7 member 11(SLC7A11)play vital roles in ferroptosis caused by cerebral I/R injury.Our data show that the expression of p53 was increased and the level of glutathione peroxidase 4(GPX4)was decreased after RNA interference-mediated knockdown of SLC7A11 in PC12 cells,but this change was alleviated after co-culturing NSCs with damaged PC12 cells.These findings suggest that NSCs pretreated with NRG1βexhibited neuroprotective effects on PC12 cells subjected to OGD/R through influencing the level of ferroptosis regulated by p53/SLC7A11/GPX4 pathway.

Neural stem cells for Parkinson’s disease management:Challenges,nanobased support,and prospects

Parkinson’s disease(PD),characterized by loss of nigrostriatal dopaminergic neurons,is one of the most predominant neurodegenerative diseases affecting the elderly population worldwide.The concept of stem cell therapy in managing neurodegenerative diseases has evolved over the years and has recently rapidly progressed.Neural stem cells(NSCs)have a few key features,including selfrenewal,proliferation,and multipotency,which make them a promising agent targeting neurodegeneration.It is generally agreed that challenges for NSC-based therapy are present at every stage of the transplantation process,including preoperative cell preparation and quality control,perioperative procedures,and postoperative graft preservation,adherence,and overall therapy success.In this review,we provided a comprehensive,careful,and critical discussion of experimental and clinical data alongside the pros and cons of NSC-based therapy in PD.Given the state-of-the-art accomplishments of stem cell therapy,gene therapy,and nanotechnology,we shed light on the perspective of complementing the advantages of each process by developing nano-stem cell therapy,which is currently a research hotspot.Although various obstacles and challenges remain,nano-stem cell therapy holds promise to cure PD,however,continuous improvement and development from the stage of laboratory experiments to the clinical application are necessary.

Culture and identification of neonatal rat brain-derived neural stem cells

BACKGROUND Timing of passaging,passage number,passaging approaches and methods for cell identification are critical factors influencing the quality of neural stem cells(NSCs)culture.How to effectively culture and identify NSCs is a continuous interest in NSCs study while these factors are comprehensively considered.AIM To establish a simplified and efficient method for culture and identification of neonatal rat brain-derived NSCs.METHODS First,curved tip operating scissors were used to dissect brain tissues from new born rats(2 to 3 d)and the brain tissues were cut into approximately 1 mm^(3)sections.Filter the single cell suspension through a nylon mesh(200-mesh)and culture the sections in suspensions.Passaging was conducted with TrypLTM Express combined with mechanical tapping and pipetting techniques.Second,identify the 5th generation of passaged NSCs as well as the revived NSCs from cryopreservation.BrdU incorporation method was used to detect self-renew and proliferation capabilities of cells.Different NSCs specific antibodies(anti-nestin,NF200,NSE and GFAP antibodies)were used to identify NSCs specific surface markers and muti-differentiation capabilities by immunofluorescence staining.RESULTS Brain derived cells from newborn rats(2 to 3 d)proliferate and aggregate into spherical-shaped clusters with sustained continuous and stable passaging.When BrdU was incorporated into the 5th generation of passaged cells,positive BrdU cells and nestin cells were observed by immunofluorescence staining.After induction of dissociation using 5%fetal bovine serum,positive NF200,NSE and GFAP cells were observed by immunofluorescence staining.CONCLUSION This is a simplified and efficient method for neonatal rat brain-derived neural stem cell culture and identification.

Targeting β-secretase with RNAi in neural stem cells for Alzheimer's disease therapy

There are several major pathological changes in Alzheimer＇s disease, including apoptosis of cho- linergic neurons, overactivity or overexpression of 13-site amyloid precursor protein cleaving enzyme 1 （BACE1） and inflammation. In this study, we synthesized a 19-nt oligonucleotide targeting BACE1, the key enzyme in amyloid beta protein （AI3） production, and introduced it into the pSilenCircle vector to construct a short hairpin （shRNA） expression plasmid against the BACE1 gene. We transfected this vector into C17.2 neural stem cells and primary neural stem cells, resulting in downregulation of the BACE1 gene, which in turn induced a considerable reduction in reducing AI3 protein production. We anticipate that this technique combining cell transplantation and gene ther- apy will open up novel therapeutic avenues for Alzheimer＇s disease, particularly because it can be used to simultaneously target several pathogenetic changes in the disease.

Oscillating field stimulation promotes neurogenesis of neural stem cells through miR-124/Tal1 axis to repair spinal cord injury in rats

Spinal cord injury often leads to severe motor and sensory deficits,and prognosis using the currently available therapies remains poor.Therefore,we aimed to explore a novel therapeutic approach for improving the prognosis of spinal cord injury.In this study,we implanted oscillating field stimulation devices and transplanted neural stem cells into the thoracic region(T9–T10)of rats with a spinal cord contusion.Basso-Beattie-Bresnahan scoring revealed that oscillating field stimulation combined with neural stem cells transplantation promoted motor function recovery following spinal cord injury.In addition,we investigated the regulation of oscillating field stimulation on the miR-124/Tal1 axis in neural stem cells.Transfection of lentivirus was performed to investigate the role of Tal1 in neurogenesis of neural stem cells induced by oscillating field stimulation.Quantitative reverse transcription-polymerase chain reaction,immunofluorescence and western blotting showed that oscillating field stimulation promoted neurogenesis of neural stem cells in vitro and in vivo.Hematoxylin and eosin staining showed that oscillating field stimulation combined with neural stem cells transplantation alleviated cavities formation after spinal cord injury.Taking the results together,we concluded that oscillating field stimulation decreased miR-124 expression and increased Tal1 content,thereby promoting the neurogenesis of neural stem cells.The combination of oscillating field stimulation and neural stem cells transplantation improved neurogenesis,and thereby promoted structural and functional recovery after spinal cord injury.

Adult neural stem cells in the mammalian central nervous system

Neural stem cells （NSCs） are present not only during the embryonic development but also in the adult brain of all mammalian species, including humans. Stem cell niche architecture in vivo enables adult NSCs to continuously generate functional neurons in specific brain regions throughout life. The adult neurogenesis process is subject to dynamic regulation by various physiological, pathological and pharmacological stimuli. Multipotent adult NSCs also appear to be intrinsically plastic, amenable to genetic programing during normal differentiation, and to epigenetic reprograming during de-differentiation into pluripotency. Increasing evidence suggests that adult NSCs significantly contribute to specialized neural functions under physiological and pathological conditions. Fully understanding the biology of adult NSCs will provide crucial insights into both the etiology and potential therapeutic interventions of major brain disorders. Here, we review recent progress on adult NSCs of the mammalian central nervous system, including topics on their identity, niche, function, plasticity, and emerging roles in cancer and regenerative medicine.

Roles of neural stem cells in the repair of peripheral nerve injury

Currently, researchers are using neural stem cell transplantation to promote regeneration after peripheral nerve injury, as neural stem cells play an important role in peripheral nerve injury repair. This article reviews recent research progress of the role of neural stem cells in the repair of peripheral nerve injury. Neural stem cells can not only differentiate into neurons, astrocytes and oligodendrocytes, but can also differentiate into Schwann-like cells, which promote neurite outgrowth around the injury. Transplanted neural stem cells can differentiate into motor neurons that innervate muscles and promote the recovery of neurological function. To promote the repair of peripheral nerve injury, neural stem cells secrete various neurotrophic factors, including brain-derived neurotrophic factor, fibroblast growth factor, nerve growth factor, insulin-like growth factor and hepatocyte growth factor. In addition, neural stem cells also promote regeneration of the axonal myelin sheath, angiogenesis, and immune regulation. It can be concluded that neural stem cells promote the repair of peripheral nerve injury through a variety of ways.

Human neural stem cells promote proliferation of endogenous neural stem cells and enhance angiogenesis in ischemic rat brain

Transplantation of human neural stem cells into the dentate gyrus or ventricle of rodents has been reportedly to enhance neurogenesis. In this study, we examined endogenous stem cell proliferation and angiogenesis in the ischemic rat brain after the transplantation of human neural stem cells. Focal cerebral ischemia in the rat brain was induced by middle cerebral artery occlusion. Human neural stem cells were transplanted into the subventricular zone. The behavioral performance of human neural stem cells-treated ischemic rats was significantly improved and cerebral infarct volumes were reduced compared to those in untreated animals. Numerous transplanted human neural stem cells were alive and preferentially localized to the ipsilateral ischemic hemisphere. Furthermore, 5-bromo-2′-deoxyuridine-labeled endogenous neural stem cells were observed in the subventricular zone and hippocampus, where they differentiated into cells immunoreactive for the neural markers doublecortin, neuronal nuclear antigen Neu N, and astrocyte marker glial fibrillary acidic protein in human neural stem cells-treated rats, but not in the untreated ischemic animals. The number of 5-bromo-2′-deoxyuridine-positive ？ anti-von Willebrand factor-positive proliferating endothelial cells was higher in the ischemic boundary zone of human neural stem cells-treated rats than in controls. Finally, transplantation of human neural stem cells in the brains of rats with focal cerebral ischemia promoted the proliferation of endogenous neural stem cells and their differentiation into mature neural-like cells, and enhanced angiogenesis. This study provides valuable insights into the effect of human neural stem cell transplantation on focal cerebral ischemia, which can be applied to the development of an effective therapy for stroke.

Induction of Functional Recovery by Co-transplantation of Neural Stem Cells and Schwann Cells in a Rat Spinal Cord Contusion Injury Model

Objective To study the transplantation efficacy of neural stem cells （NSCs） and Schwann cells （SC） in a rat model of spinal cord contusion injury. Methods Multipotent neural stem cells （NSCs） and Schwann cells were harvested from the spinal cords of embryonic rats at 16 days post coitus and sciatic nerves of newborn rats, respectively. The differential characteristics of NSCs in vitro induced by either serum-based culture or co-culture with SC were analyzed by immunofluorescence. NSCs and SCs were co-transplanted into adult rats having undergone spinal cord contusion at T9 level. The animals were weekly monitored using the Basso-Beattie-Bresnahan locomotor rating system to evaluate functional recovery from contusion-induced spinal cord injury. Migration and differentiation of transplanted NSCs were studied in tissue sections using immunohistochemical staining. Results Embryonic spinal cord-derived NSCs differentiated into a large number of oligodendrocytes in serum-based culture upon the withdrawal of mitogens. In cocultures with SCs, NSCs differentiated into neuron more readily. Rats with spinal cord contusion injury which had undergone transplantation of NSCs and SCs into the intraspinal cavity demonstrated a moderate improvement in motor functions. Conclusions SC may contribute to neuronal differentiation of NSCs in vitro and in vivo. Transplantation of NSCs and SCs into the affected area may be a feasible approach to promoting motor recovery in patients after spinal cord injury.

Are newborn rat-derived neural stem cells more sensitive to lead neurotoxicity?

Lead ion （Pb2＋） has been proven to be a neurotoxin due to its neurotoxicity on mammalian nervous system, especially for the developing brains of juveniles. However, many reported studies involved the negative effects of Pb2＋ on adult neural cells of humans or other mammals, only few of which have examined the effects of Pb2＋ on neural stem cells. The purpose of this study was to reveal the biological effects of Pb2＋from lead acetate [Pb （0H30OO）2] on viability, proliferation and differentiation of neural stem cells derived from the hippocampus of newborn rats aged 7 days and adult rats aged 90 days, respectively. This study was carried out in three parts. In the first part, 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide assay （MTT viability assay） was used to detect the effects of Pb2＋ on the cell viability of passage 2 hippocampal neural stem cells after 48-hour exposure to 0-200 pM Pb2＋. In the second part, 10 pM bromodeoxyuridine was added into the culture medium of passage 2 hippocampal neural stem cells after 48-hour exposure to 0- 200 pM Pb2＋, followed by immunocytochemical staining with anti-bromodeoxyuridine to demonstrate the effects of Pb2＋ on cell proliferation. In the last part, passage 2 hippocampal neural stem cells were allowed to grow in the differentiation medium with 0-200 pM Pb2＋. Immunocytochemical staining with anti-microtubule-associated protein 2 （a neuron marker）, anti-glial fibrillary acidic protein （an astrocyte marker）, and anti-RIP （an oligodendrocyte marker） was performed to detect the differentiation commitment of affected neural stem cells after 6 days. The data showed that Pb2~ inhibited not only the viability and proliferation of rat hippocampal neural stem cells, but also their neuronal and oligodendrocyte differentiation in vitro. Moreover, increased activity of astrocyte differentiation of hippocampal neural stem cells from both newborn and adult rats was observed after exposure to high concentration of lead ion in vitro. These findings suggest that hippocampal neural stem cells of newborn rats were more sensitive than those from adult rats to Pb2＋cytotoxicity.