Migration Of Neural Stem/progenitor Cells Research Articles

Substrate-bound and soluble domains of tenascin-C regulate differentiation, proliferation and migration of neural stem and progenitor cells.

The lack of regenerative capacity of the central nervous system is one of the major challenges nowadays. The knowledge of guidance cues that trigger differentiation, proliferation, and migration of neural stem and progenitor cells is one key element in regenerative medicine. The extracellular matrix protein tenascin-C (Tnc) is a promising candidate to regulate cell fate due to its expression in the developing central nervous system and in the adult neural stem cell niches. Of special interest are the alternatively spliced fibronectin type III (FnIII) domains of Tnc whose combinatorial diversity could theoretically generate up to 64 isoforms in the mouse. A total of 27 isoforms have already been discovered in the developing brain, among others the domain combinations A1D, CD, and A124BCD. In the present study, these domains as well as the combination of the constitutively expressed FnIII domains 7 and 8 (78) were expressed in Chinese hamster ovary cells as pseudo-antibodies fused to the Fc-fragment of a human immunoglobulin G antibody. The fusion proteins were presented to primary mouse neural stem/progenitor cells (NSPCs) grown as neurospheres, either as coated culture substrates or as soluble additives in vitro. The influence of the domains on the differentiation, proliferation and migration of NSPCs was analyzed. We observed that the domain combination A124BCD promoted the differentiation of neurons and oligodendrocytes, whereas the domain A1D supported astrocyte differentiation. The constitutively expressed domain 78 had a proliferation and migration stimulating impact. Moreover, most effects were seen only in one of the presentation modes but not in both, suggesting different effects of the Tnc domains in two- and three-dimensional cultures. This knowledge about the different effect of the Tnc domains might be used to create artificial three-dimensional environments for cell transplantation. Hydrogels spiked with Tnc-domains might represent a promising tool in regenerative medicine.

The Role and Mechanism of Transglutaminase 2 in Regulating Hippocampal Neurogenesis after Traumatic Brain Injury.

Traumatic brain injury usually results in neuronal loss and cognitive deficits. Promoting endogenous neurogenesis has been considered as a viable treatment option to improve functional recovery after TBI. However, neural stem/progenitor cells (NSPCs) in neurogenic regions are often unable to migrate and differentiate into mature neurons at the injury site. Transglutaminase 2 (TGM2) has been identified as a crucial component of neurogenic niche, and significantly dysregulated after TBI. Therefore, we speculate that TGM2 may play an important role in neurogenesis after TBI, and strategies targeting TGM2 to promote endogenous neural regeneration may be applied in TBI therapy. Using a tamoxifen-induced Tgm2 conditional knockout mouse line and a mouse model of stab wound injury, we investigated the role and mechanism of TGM2 in regulating hippocampal neurogenesis after TBI. We found that Tgm2 was highly expressed in adult NSPCs and up-regulated after TBI. Conditional deletion of Tgm2 resulted in the impaired proliferation and differentiation of NSPCs, while Tgm2 overexpression enhanced the abilities of self-renewal, proliferation, differentiation, and migration of NSPCs after TBI. Importantly, injection of lentivirus overexpressing TGM2 significantly promoted hippocampal neurogenesis after TBI. Therefore, TGM2 is a key regulator of hippocampal neurogenesis and a pivotal therapeutic target for intervention following TBI.

Adhesive, Stretchable, and Spatiotemporal Delivery Fibrous Hydrogels Harness Endogenous Neural Stem/Progenitor Cells for Spinal Cord Injury Repair.

Aligned fibrous hydrogels capable of recruiting endogenous neural stem/progenitor cells (NSPCs) show great promise in spinal cord injury (SCI) repair. However, the hydrogels suffer from severe issues in close contact with the transected nerve stumps and harnessing the NSPC fate in the lesion microenvironment. Herein, we report aligned collagen-fibrin (Col-FB) fibrous hydrogels with stretchable property, adhesive behavior, and stromal cell-derived factor-1α (SDF1α)/paclitaxel (PTX) spatiotemporal delivery capability. The resultant Col-FB fibrous hydrogels exhibited 1.98 times longer elongation at break (230%), 2.55 times lower Young's modulus (17.93 ± 1.16 KPa), and 2.21 times greater adhesive strength (3.45 ± 0.48 KPa) than collagen (Col) fibrous hydrogels. The soft aligned fibrous hydrogels simulate the oriented microstructure and soft tissue feature of a natural spinal cord and provide elasticity and adhesivity to ensure a persistent close contact with host stumps. The repair of complete transection SCI in rats demonstrates that "middle-to-bilateral" SDF1α gradient release induced endogenous NSPC migration to the lesion site in 10 days, and SDF1α/PTX sequential release promoted neuronal differentiation of the recruited NSPCs over 8 weeks, leading to hind limb locomotion recovery. The presented strategy was proved to be efficient for harnessing endogenous NSPCs, which facilitate SCI repair significantly.

Parkinson's disease, aging and adult neurogenesis: Wnt/β-catenin signalling as the key to unlock the mystery of endogenous brain repair.

A common hallmark of age‐dependent neurodegenerative diseases is an impairment of adult neurogenesis. Wingless‐type mouse mammary tumor virus integration site (Wnt)/β‐catenin (WβC) signalling is a vital pathway for dopaminergic (DAergic) neurogenesis and an essential signalling system during embryonic development and aging, the most critical risk factor for Parkinson's disease (PD). To date, there is no known cause or cure for PD. Here we focus on the potential to reawaken the impaired neurogenic niches to rejuvenate and repair the aged PD brain. Specifically, we highlight WβC‐signalling in the plasticity of the subventricular zone (SVZ), the largest germinal region in the mature brain innervated by nigrostriatal DAergic terminals, and the mesencephalic aqueduct‐periventricular region (Aq‐PVR) Wnt‐sensitive niche, which is in proximity to the SNpc and harbors neural stem progenitor cells (NSCs) with DAergic potential. The hallmark of the WβC pathway is the cytosolic accumulation of β‐catenin, which enters the nucleus and associates with T cell factor/lymphoid enhancer binding factor (TCF/LEF) transcription factors, leading to the transcription of Wnt target genes. Here, we underscore the dynamic interplay between DAergic innervation and astroglial‐derived factors regulating WβC‐dependent transcription of key genes orchestrating NSC proliferation, survival, migration and differentiation. Aging, inflammation and oxidative stress synergize with neurotoxin exposure in “turning off” the WβC neurogenic switch via down‐regulation of the nuclear factor erythroid‐2‐related factor 2/Wnt‐regulated signalosome, a key player in the maintenance of antioxidant self‐defense mechanisms and NSC homeostasis. Harnessing WβC‐signalling in the aged PD brain can thus restore neurogenesis, rejuvenate the microenvironment, and promote neurorescue and regeneration.

Chondroitin sulfate proteoglycan represses neural stem/progenitor cells migration via PTPσ/α-actinin4 signaling pathway.

Neural stem/progenitor cells (NSPCs) are a promising candidate for the cell-replacement therapy after central nervous system (CNS) injury. However, the short of sufficient NSPCs migration and integration into the lesions is an essential challenge for cell-based therapy after CNS injury due to the disturbance of local environmental homeostasis. Chondroitin sulfate proteoglycan (CSPG) is obviously accumulated at the lesions and destroyed local homeostasis after CNS injury. The previous study has demonstrated that the CSPG is a dominating ingredient inhibiting axonal regrowth of newly born neurons after CNS injury. NSPCs, a strain of special neural subtypes, hold the capacity of leading processes formation to regulate NSPCs migration, which has the same mechanism as axonal regrowth. Hence, it is worth investigating the effect of CSPG on NSPCs migration and its underlying mechanism. Here, different concentration of CSPG was used to evaluate its effect on NSPCs migration. The results showed that the CSPG suppressed NSPCs migration in a dose-dependent manner from 10 to 80 µg/mL with phase-contrast microscopy after 24 hours. Meanwhile, transwell assays were performed to certify the above results. Our data indicated that the 40 µg/mL CSPG obviously suppressed NSPCs migration via decreasing filopodia formation using immunofluorescence staining. Furthermore, data indicated that the 40 µg/mL CSPG upregulated protein tyrosine phosphatase receptor σ (PTPσ) expression and decreased α-actinin4 (ACTN4) expression through immunofluorescence, reverse transcription polymerase chain reaction, and Western blot assays. While the inhibitory effect was attenuated using PTPσ-specific small interfering RNA. In addition, data demonstrated that the 40 µg/mL CSPG facilitated NSPCs differentiation into glial fibrillary acidic protein-positive cells and inhibited NSPCs directing into MAP2- and MBP-positive cells. Collectively, these data demonstrated that the CSPG suppressed NSPCs migration through PTPσ/ACTN4 signaling pathway. Meanwhile, CSPG facilitated NSPCs differentiation into astrocytes and inhibited NSPCs directing into neurons and oligodendrocytes.

Amyloid-β1-42 dynamically regulates the migration of neural stem/progenitor cells via MAPK-ERK pathway

Neural stem/progenitor cell (NSPC) based therapy represents an attractive treatment for Alzheimer's disease (AD), the most common neurodegenerative disorder with no effective treatment to date. This can be achieved by stimulating endogenous NSPCs and/or administrating exogenously produced NSPCs. Successful repair requires the migration of NSPCs to the loci where neuronal loss occurs, differentiation and integration into neural networks. However, the progressive loss of neurons in the brain of AD patients suggests that the repair by endogenous NSPCs in the setting of AD may be defective. The production and deposition of amyloid-β1-42 (Aβ1-42) peptides is thought to be a central event in the pathogenesis of AD. Here we report that Aβ1-42 peptides inhibit the migration of in vitro cultured NSPCs by disturbing the ERK-MAPK signal pathway. We found that the migratory capacity of NSPCs was compromised upon treatment with oligomeric Aβ1-42; the inhibitory effect occurred in a dose-dependent manner. Our previous studies have shown that Aβ1-42 triggers the expression of GRK2 by unknown mechanism. Herein we found that the Aβ1-42 evoked upregulation of GRK2 expression was attenuated upon treatment with the ERK inhibitor SCH772984 at 2.5 μM, but not with inhibitors for p38 or JNK. We detected a dose-dependent increase in levels of phosphorylated ERK1/2 after incubation of cells with oligomeric Aβ1-42 peptides for 3 days. We observed that an increase in the phosphorylation of p38 and JNK coincided with reduced phosphorylation of ERK1/2 upon treatment with Aβ1-42 for 6 and/or 9 days. We hypothesize that the divergence of the activation of the MAPK family of pathways may contribute to the inhibition of NSPCs migration after the long-term incubation with Aβ1-42. Pretreatment with 1 μM MEK inhibitor U0126 reversed the effects of Aβ1-42 on GRK2 expression of and NSPC migration. Together, our results suggest that Aβ1-42 oligomers compromise the migratory capacity of NSPCs through the MEK-ERK pathway.

Fibrin functionalization with synthetic adhesive ligands interacting with α6β1 integrin receptor enhance neurite outgrowth of embryonic stem cell-derived neural stem/progenitors.

Impact statement: The transplantation of NSPCs derived from pluripotent stem cells holds much promise for the treatment of central nervous system disorders. Moreover, the combinatorial use of biodegradable hydrogels with NSPCs was shown to contribute to the establishment of a more permissive environment for survival and integration of transplanted cells. In this study, fibrin hydrogels functionalized with a synthetic peptide engaging integrin α6β1 (HYD1) were shown to promote neurite extension of ES-NSPCs, which is fundamental for the formation of functional neuronal relay circuits after NSPC transplantation. Notably, HYD1-functionalized fibrin per se led to enhanced axonal growth ex vivo and to an improvement in locomotor function after implantation in a rat model of spinal cord injury. Conjugation of α6β1 integrin-binding motifs may therefore be of interest to confer bioactivity to NSPC hydrogel vehicles.

MicroRNAs as Big Regulators of Neural Stem/Progenitor Cell Proliferation, Differentiation and Migration: A Potential Treatment for Stroke.

Neural stem/progenitor cells (NSPCs)-based treatment is a potential therapeutic approach for stroke. MicroRNAs (miRNAs) have been recently verified as promoters or suppressors in the regulation of NSPCs. However, the underlying mechanisms regulating cell biological behaviors of NSPCs remain largely unknown. we retrieved papers focusing on potential roles and mechanisms of miRNAs in the regulation of NSPCs, and paid a special attention to clinical therapeutic potentials of miRNAs in stroke patients. This narrative review provides a comprehensive and critical landscape of this issue. We summarize the most recent studies on the roles and mechanisms of miRNAs in regulating the proliferation, differentiation and migration of NSPCs and fully discuss the potential clinical implications of miRNAs interacting with NSPCs in stroke patients. Promising but full of hurdles, miRNAs have been confirmed to play a critical role in regulating NSPCs. Clinical potentials of miRNAs are huge in treating stroke patients receiving NSPCs-based therapy, which can be used as biomarkers for the diagnosis and prognosis, and as targets for controlling the proliferation, differentiation and migration of NSPCs.

TFEB activation restores migration ability to Tsc1-deficient adult neural stem/progenitor cells.

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder caused by mutations in either of two genes, TSC1 or TSC2, resulting in the constitutive activation of the mammalian target of rapamycin complex 1 (mTORC1). mTOR inhibitors are now considered the treatment of choice for TSC disease. A major pathological feature of TSC is the development of subependymal giant cell astrocytomas (SEGAs) in the brain. Nowadays, it is thought that SEGAs could be a consequence of aberrant aggregation and migration of neural stem/progenitor cells (NSPCs). Therefore, reactivation of cell migration of NSPCs might be the crucial step for the treatment of patients. In order to identify potential in vitro targets activating migration, we generated Tsc1-deficient NSPCs. These cells summarize most of the biochemical and morphological characteristics of TSC neural cells, such as the mTORC1 activation, the formation of abnormally enlarged astrocytes-like cells, the reduction of autophagy flux and the impairment of cell migration. Moreover, nuclear translocation, namely activation of the transcription factor EB (TFEB) was markedly impaired. Herein, we show that compounds such as everolimus, ionomycin and curcumin, which directly or indirectly stimulate TFEB nuclear translocation, restore Tsc1-deficient NSPC migration. Our data suggest that reduction of TFEB activation, caused by mTORC1 hyperactivation, contributes to the migration deficit characterizing Tsc1-deficient NSPCs. The present work highlights TFEB as a druggable protein target for SEGAs therapy, which can be additionally or alternatively exploited for the mTORC1-directed inhibitory approach.

Poly-L-ornithine enhances migration of neural stem/progenitor cells via promoting α-Actinin 4 binding to actin filaments.

The recruitment of neural stem/progenitor cells (NSPCs) for brain restoration after injury is a promising regenerative therapeutic strategy. This strategy involves enhancing proliferation, migration and neuronal differentation of NSPCs. To date, the lack of biomaterials, which facilitate these processes to enhance neural regeneration, is an obstacle for the cell replacement therapies. Our previous study has shown that NSPCs grown on poly-L-ornithine (PO) could proliferate more vigorously and differentiate into more neurons than that on Poly-L-Lysine (PLL) and Fibronectin (FN). Here, we demonstrate that PO could promote migration of NSPCs in vitro, and the underlying mechanism is PO activates α-Actinins 4 (ACTN4), which is firstly certified to be expessed in NSPCs, to promote filopodia formation and therefore enhances NSPCs migration. Taken together, PO might serve as a better candidate for transplanted biomaterials in the regenerative therapeutic strategy, compared with PLL and FN.

Fibrin hydrogels functionalized with alpha6beta1 ligands for transplantation of neural stem/progenitor cells

Event Abstract Back to Event Fibrin hydrogels functionalized with alpha6beta1 ligands for transplantation of neural stem/progenitor cells Joana N. Silva1, 2, Ana R. Bento1, 2, 3, Tiago L. Laundos1, 2, Ana P. Pêgo1, 2, 3, 4 and Isabel Amaral1, 2, 3 1 INEB - Instituto de Engenharia Biomédica, University of Porto, NanoBiomaterials for Targeted Therapies (nBTT) group, Biomaterials for Neuroscience Research Team, Portugal 2 I3S - Instituto de Investigação e Inovação em Saúde, University of Porto, Portugal 3 Faculdade de Engenharia da Universidade do Porto, Portugal 4 Instituto de Ciências Biomédicas Abel Salazar, Portugal Introduction: Transplantation of neural stem/progenitor cells (NSPCs) has emerged as a promising therapy to overcome the limited capacity of the central nervous system to repair. Still, despite their functional benefits, NSPCs directly injected into the lesion site of chronic injuries show low survival and integration of grafted cells. To overcome these limitations, NSPCs are being combined with biodegradable hydrogels which, besides allowing a homogenous distribution of transplanted cells, constitute a more permissive environment for NSPC anchorage, migration, and differentiation. In this study we aimed at developing a fibrin (Fb)-based hydrogel for transplantation of embryonic stem (ES)-derived NSPCs. To enhance Fb specificity towards NSPCs and promote NSPC migration in vivo, Fb was functionalized with ligands for selective binding to α6β1 integrin receptors, an integrin highly expressed by NSCs and involved in NSC migration [1]. Six peptides with reported affinity to α6β1 integrin (P3, HYD1, T1, AG10, N4 and A5G81) were investigated. Methods: NSPCs were derived from a mouse ES cell line (46C) expressing GFP under the promoter of the neural-specific Sox1 gene. NSPCs were seeded on peptide-adsorbed surfaces and cell adhesion (in the presence/absence of mAbs against α6β1 integrin subunits), attachment strength, migration and differentiation along the neuronal lineage were quantitatively assessed. Bi-domain peptides with the selected α6β1 ligands at the C-terminus and the factor XIIIa substrate domain at the N-terminus were bound to Fb gels at different concentrations by the action of factor XIIIa [2]. Peptide binding efficiency was determined using 125I-labeled peptides while structural changes in Fb network were followed by confocal microscopy using FITC-labelled fibrinogen.To assess the effect of immobilized ligands on NSPC migration, neurospheres (NSPC aggregates) were seeded on functionalized Fb gels and radial outgrowth (outgrowth area and maximal outgrowth distance) determined after 72 h of cell culture using automatic image analysis. Unmodified Fb and Fb containing laminin (LN) 111/LN 511 were used as controls. To assess the effect of immobilized ligands on neurite extension, rat E18 DRGs were cultured in functionalized gels and neurite outgrowth quantified after 48h of cell culture. Results & discussion: Among the tested peptides HYD1, T1, and A5G81 were selected for immobilization in Fb due to their higher efficiency in promoting NSPC adhesion mediated through α6β1 integrin. Following incorporation in Fb, soluble LN was not able to promote radial outgrowth from neurospheres, regardless of the LN isoform used. Functionalization of Fb with A5G81, neither. Still, immobilization of HYD1 and T1 in Fb led to significantly higher outgrowth area (2.4-fold and 2.2-fold increase) as well as maximal outgrowth distance, for bi-domain peptide concentrations of 20 µM and 40 µM, respectively. Blocking against α6β1 integrin subunits significantly inhibited cell outgrowth on Fb gels functionalized with HYD1/T1, indicating that HYD1/T1 ability to promote NSC migration on Fb is partially mediated through α6β1 integrin. Finally, HYD1- and T1-functionalized Fb gels led to a 2-fold and 1.9-fold increase in neurite extension from rat E18 DRGs for bi-domain peptide concentrations of 20 µM and 40 µM, respectively. Presently, the in vivo biological performance of HYD1/T1-functionalized Fb is being assessed. The authors would like to acknowledge Prof. Domingos Henrique (Instituto de Medicina Molecular, Lisbon) for providing the ES 46C cell line.; This work was supported by FCT / MEC through National Funds (PTDC/SAU-BMA/118869/2010), and co-financed by the FEDER through COMPETE (FCOMP-01-0124-FEDER-021125), Programa Operacional Regional do Norte (ON.2) under the QREN (NORTE-07-0162-FEDER-00018/000067), and via the PT2020 Partnership Agreement under the 4293 Unit I&D.

Caspase inhibition impaired the neural stem/progenitor cell response after cortical ischemia in mice.

Cortical ischemia induces proliferation of neural stem/progenitor cells (NSPCs) in the subventricular zone (SVZ) and provokes migration of these cells toward the injured area. Despite sustained migration of NSPCs for an extended period of time after injury, they do not appear to survive. Here, we hypothesized that the anti-apoptotic broad-spectrum caspase inhibitor Q-VD-OPh would increase NSPC survival in the injured cortex. However, contrary to our expectations, caspase inhibition did not promote NSPC survival and cortical neurogenesis. On the contrary, it abolished ischemia-induced proliferation and decreased the number of migrating neuroblasts in the injured cortex. Moreover, caspase inhibition decreased the levels of the chemoattractant chemokine CCL2 (MCP-1) and the pro-inflammatory cytokine IL-1β. We hence for the first time show that caspase inhibition abrogates the response of NSPCs to an ischemic injury, presumably by inhibiting the production of pro-inflammatory factors. Thus, caution is warranted if anti-apoptotic strategies are applied for neuroprotection.

532 nm Low-Power Laser Irradiation Facilitates the Migration of GABAergic Neural Stem/Progenitor Cells in Mouse Neocortex.

Background and ObjectiveAccumulating evidence has shown that low-power laser irradiation (LLI) affects cell proliferation and survival, but little is known about LLI effects on neural stem/progenitor cells (NSPCs). Here we investigate whether transcranial 532 nm LLI affects NSPCs in adult murine neocortex and in neurospheres from embryonic mice.Study Design/Materials and MethodsWe applied 532 nm LLI (Nd:YVO4, CW, 60 mW) on neocortical surface via cranium in adult mice and on cultured cells from embryonic mouse brains in vitro to investigate the proliferation and migration of NSPCs and Akt expression using immunohistochemical assays and Western blotting techniques.ResultsIn vivo experiments demonstrated that 532 nm LLI significantly facilitated the migration of GABAergic NSPCs that were induced to proliferate in layer 1 by mild ischemia. In vitro experiments using GABAergic NSPCs derived from embryonic day 14 ganglionic eminence demonstrated that 532 nm LLI for 60 min promoted the migration of GAD67-immunopositive NSPCs with a significant increase of Akt expression. Meanwhile, the LLI induced proliferation, but not migration, of NSPCs that give rise to excitatory neurons.ConclusionIt is concluded that 532 nm LLI promoted the migration of GABAergic NSPCs into deeper layers of the neocortex in vivo by elevating Akt expression.

Promoted Growth of Brain Tumor by the Transplantation of Neural Stem/Progenitor Cells Facilitated by CXCL12

The targeted migration of neural stem/progenitor cells (NSPCs) is a prerequisite for the use of stem cell therapy in the treatment of pathologies. This migration is regulated mainly by C-X-C motif chemokine 12 (CXCL12). Therefore, promotion of the migratory responses of grafted cells by upregulating CXCL12 signaling has been proposed as a strategy for improving the efficacy of such cell therapies. However, the effects of this strategy on brain tumors have not yet been examined in vivo. The aim of the present study was thus to elucidate the effects of grafted rat green fluorescent protein (GFP)–labeled NSPCs (GFP-NSPCs) with CXCL12 enhancement on a model of spontaneous rat brain tumor induced by N-ethyl-N-nitrosourea. T2-weighted magnetic resonance imaging was applied to determine the changes in tumor volume and morphology over time. Postmortem histology was performed to confirm the tumor pathology, expression levels of CXCL12 and C-X-C chemokine receptor type 4, and the fate of GFP-NSPCs. The results showed that the tumor volume and hypointense areas of T2-weighted images were both significantly increased in animals treated with combined NSPC transplantation and CXCL12 induction, but not in control animals or in those with tumors that received only one of the treatments. GFP-NSPCs appear to migrate toward tumors with CXCL12 enhancement and differentiate uniquely into a neuronal lineage. These findings suggest that CXCL12 is an effective chemoattractant that facilitates exogenous NSPC migration toward brain tumors and that CXCL12 and NSPC can act synergistically to promote tumor progression with severe hemorrhage.

Chemotactic Responses of Neural Stem Cells to SDF-1α Correlate Closely with Their Differentiation Status

Chemotaxis of neural stem/progenitor cells (NSCs) is regulated by a variety of factors, and much effort has been devoted to the delineation of factors that are involved in NSC migration. However, the relationship between NSC chemotactic migration and differentiation remains uncharacterized. In the present study, by comparing the transfilter migration rate, single-cell migration speed, and directional efficiency of NSCs in stromal cell-derived factor-1 alpha (SDF-1α)-induced Boyden chamber and Dunn chamber chemotaxis assays, we demonstrate that NSCs in varying differentiation stages possess different migratory capacity. Furthermore, F-actin microfilament reorganization upon stimulation varies greatly among separate differentiation states. We show that signaling pathways involved in NSC migration, such as PI3K/Akt and mitogen-activated protein kinase (MAPK) (ERK1/2, JNK, and p38 MAPK) pathways, are differentially activated by SDF-1α among each NSC differentiation stages, and the extent to which these pathways participate in cell chemotaxis exhibits a differentiation stage-dependent manner. Taken together, these results suggest that the differentiation of NSCs influences their chemotactic responses to SDF-1α, providing new insight into the optimization of the therapeutic efficacy of NSCs for neural regeneration and nerve repair after injury.

Monitoring ferumoxide-labelled neural progenitor cells and lesion evolution by magnetic resonance imaging in a model of cell transplantation in cerebral ischaemia.

Efficacy of neural stem/progenitor cell (NPC) therapies after cerebral ischaemia could be better evaluated by monitoring in vivo migration and distribution of cells post-engraftment in parallel with analysis of lesion volume and functional recovery. Magnetic resonance imaging (MRI) is ideally placed to achieve this, but still poses several challenges. We show that combining the ferumoxide MRI contrast agent Endorem with protamine sulphate (FePro) improves iron oxide uptake in cells compared to Endorem alone and is non-toxic. Hence FePro complex is a better contrast agent than Endorem for monitoring NPCs. FePro complex-labelled NPCs proliferated and differentiated normally in vitro, and upon grafting into the brain 48 hours post-ischaemia they were detected in vivo by MRI. Imaging over four weeks showed the development of a confounding endogenous hypointense contrast evolution at later timepoints within the lesioned tissue. This was at least partly due to accumulation within the lesion of macrophages and endogenous iron. Neither significant NPC migration, assessed by MRI and histologically, nor a reduction in the ischaemic lesion volume was observed in NPC-grafted brains. Crucially, while MRI provides reliable information on engrafted cell location early after an ischaemic insult, pathophysiological changes to ischaemic lesions can interfere with cellular imaging at later timepoints.

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.

Monitoring ferumoxide-labelled neural progenitor cells and lesion evolution by magnetic resonance imaging in a model of cell transplantation in cerebral ischaemia

Efficacy of neural stem/progenitor cell (NPC) therapies after cerebral ischaemia could be better evaluated by monitoring in vivo migration and distribution of cells post-engraftment in parallel with analysis of lesion volume and functional recovery. Magnetic resonance imaging (MRI) is ideally placed to achieve this, but still poses several challenges. We show that combining the ferumoxide MRI contrast agent Endorem with protamine sulphate (FePro) improves iron oxide uptake in cells compared to Endorem alone and is non-toxic. Hence FePro complex is a better contrast agent than Endorem for monitoring NPCs. FePro complex-labelled NPCs proliferated and differentiated normally in vitro, and upon grafting into the brain 48 hours post-ischaemia they were detected in vivo by MRI. Imaging over four weeks showed the development of a confounding endogenous hypointense contrast evolution at later timepoints within the lesioned tissue. This was at least partly due to accumulation within the lesion of macrophages and endogenous iron. Neither significant NPC migration, assessed by MRI and histologically, nor a reduction in the ischaemic lesion volume was observed in NPC-grafted brains. Crucially, while MRI provides reliable information on engrafted cell location early after an ischaemic insult, pathophysiological changes to ischaemic lesions can interfere with cellular imaging at later timepoints.

ZY-1, A Novel Nicotinic Analog, Promotes Proliferation and Migration of Adult Hippocampal Neural Stem/Progenitor Cells

Neural stem/progenitor cells (NSPCs) of the subgranular zone have been implicated in cognitive processes, which represent a potentially important source of regenerative medicine for the treatment of neurodegenerative diseases such as Alzheimer's disease (AD). In our previous studies, ZY-1, a novel nicotinic analog, improved cognitive function in transgenic mice model of AD. However, the effect of ZY-1 on the NSPCs remains unclear. Here, we show that ZY-1 significantly increased proliferation and migration of NSPCs, but failed to affect NSPCs differentiation in vitro. Furthermore, during the proliferative period, ZY-1 enhanced intracellular reactive oxygen species (ROS) levels. Meanwhile, ZY-1 also inhibited the levels of Aβ42-induced ROS. Our data indicate that ZY-1 regulates adult hippocampal neurogenesis in vitro, at least partly due to modulating intracellular ROS levels. These results, taken together with those of our previous studies, suggest that ZY-1 might have a potential therapeutic effect for the treatment of AD.

Inhibition of neuronal nitric oxide synthase activity promotes migration of human‐induced pluripotent stem cell‐derived neural stem cells toward cancer cells

The breakthrough in derivation of human-induced pluripotent stem cells (hiPSCs) provides an approach that may help overcome ethical and allergenic challenges posed in numerous medical applications involving human cells, including neural stem/progenitor cells (NSCs). Considering the great potential of NSCs in targeted cancer gene therapy, we investigated in this study the tumor tropism of hiPSC-derived NSCs and attempted to enhance the tropism by manipulation of biological activities of proteins that are involved in regulating the migration of NSCs toward cancer cells. We first demonstrated that hiPSC-NSCs displayed tropism for both glioblastoma cells and breast cancer cells in vitro and in vivo. We then compared gene expression profiles between migratory and non-migratory hiPSC-NSCs toward these cancer cells and observed that the gene encoding neuronal nitric oxide synthase (nNOS) was down-regulated in migratory hiPSC-NSCs. Using nNOS inhibitors and nNOS siRNAs, we demonstrated that this protein is a relevant regulator in controlling migration of hiPSC-NSCs toward cancer cells, and that inhibition of its activity or down-regulation of its expression can sensitize poorly migratory NSCs and be used to improve their tumor tropism. These findings suggest a novel application of nNOS inhibitors in neural stem cell-mediated cancer therapy.