Embryonic stem cell-derived L1 overexpressing neural aggregates enhance recovery in Parkinsonian mice

Extracellular vesicles from UTX-knockout endothelial cells boost neural stem cell differentiation in spinal cord injury

BACKGROUND

Vascular endothelial cells are pivotal in the pathophysiological progression following spinal cord injury (SCI). The UTX (Ubiquitously Transcribed Tetratripeptide Repeat on Chromosome X) serves as a significant regulator of endothelial cell phenotype. The manipulation of endogenous neural stem cells (NSCs) offers a compelling strategy for the amelioration of SCI.

METHODS

Two mouse models were used to investigate SCI: NSCs lineage-traced mice and mice with conditional UTX knockout (UTX KO) in endothelial cells. To study the effects of UTX KO on neural differentiation, we harvested extracellular vesicles (EVs) from both UTX KO spinal cord microvascular endothelial cells (SCMECs) and negative control SCMECs. These EVs were then employed to modulate the differentiation trajectory of endogenous NSCs in the SCI model.

RESULTS

In our NSCs lineage-traced mice model of SCI, a marked decrease in neurogenesis was observed post-injury. Notably, NSCs in UTX KO SCMECs mice showed enhanced neuronal differentiation compared to controls. RNA sequencing and western blot analyses revealed an upregulation of L1 cell adhesion molecule (L1CAM), a gene associated with neurogenesis, in UTX KO SCMECs and their secreted EVs. This aligns with the observed promotion of neurogenesis in UTX KO conditions. In vivo administration of L1CAM-rich EVs from UTX KO SCMECs (KO EVs) to the mice significantly enhanced neural differentiation. Similarly, in vitro exposure of NSCs to KO EVs resulted in increased activation of the Akt signaling pathway, further promoting neural differentiation. Conversely, inhibiting Akt phosphorylation or knocking down L1CAM negated the beneficial effects of KO EVs on NSC neuronal differentiation.

CONCLUSIONS

In conclusion, our findings substantiate that EVs derived from UTX KO SCMECs can act as facilitators of neural differentiation following SCI. This study not only elucidates a novel mechanism but also opens new horizons for therapeutic interventions in the treatment of SCI. Video Abstract.

Genetically engineered neural stem cells (NSCs) therapy for neurological diseases; state-of-the-art

Neural stem cells (NSCs) are multipotent stem cells with remarkable self-renewal potential and also unique competencies to differentiate into neurons, astrocytes, and oligodendrocytes (ODCs) and improve the cellular microenvironment. In addition, NSCs secret diversity of mediators, including neurotrophic factors (e.g., BDNF, NGF, GDNF, CNTF, and NT-3), pro-angiogenic mediators (e.g., FGF-2 and VEGF), and anti-inflammatory biomolecules. Thereby, NSCs transplantation has become a reasonable and effective treatment for various neurodegenerative disorders by their capacity to induce neurogenesis and vasculogenesis and dampen neuroinflammation and oxidative stress. Nonetheless, various drawbacks such as lower migration and survival and less differential capacity to a particular cell lineage concerning the disease pathogenesis hinder their application. Thus, genetic engineering of NSCs before transplantation is recently regarded as an innovative strategy to bypass these hurdles. Indeed, genetically modified NSCs could bring about more favored therapeutic influences post-transplantation in vivo, making them an excellent option for neurological disease therapy. This review for the first time offers a comprehensive review of the therapeutic capability of genetically modified NSCs rather than naïve NSCs in neurological disease beyond brain tumors and sheds light on the recent progress and prospect in this context.

Extracellular Matrix Biomimetic Hydrogels, Encapsulated with Stromal Cell-Derived Factor 1, Improve the Composition of Foetal Tissue Grafts in a Rodent Model of Parkinson's Disease

Clinical studies have provided evidence for dopamine (DA) cell replacement therapy in Parkinson’s Disease. However, grafts derived from foetal tissue or pluripotent stem cells (PSCs) remain heterogeneous, with a high proportion of non-dopaminergic cells, and display subthreshold reinnervation of target tissues, thereby highlighting the need to identify new strategies to improve graft outcomes. In recent work, Stromal Cell-Derived Factor-1 (SDF1), secreted from meninges, has been shown to exert many roles during ventral midbrain DA development and DA-directed differentiation of PSCs. Related, co-implantation of meningeal cells has been shown to improve neural graft outcomes, however, no direct evidence for the role of SDF1 in neural grafting has been shown. Due to the rapid degradation of SDF1 protein, here, we utilised a hydrogel to entrap the protein and sustain its delivery at the transplant site to assess the impact on DA progenitor differentiation, survival and plasticity. Hydrogels were fabricated from self-assembling peptides (SAP), presenting an epitope for laminin, the brain’s main extracellular matrix protein, thereby providing cell adhesive support for the grafts and additional laminin–integrin signalling to influence cell fate. We show that SDF1 functionalised SAP hydrogels resulted in larger grafts, containing more DA neurons, increased A9 DA specification (the subpopulation of DA neurons responsible for motor function) and enhanced innervation. These findings demonstrate the capacity for functionalised, tissue-specific hydrogels to improve the composition of grafts targeted for neural repair.

The Importance of Studying Human Brain

Due to its numerous distinctive functions and unique pathology, the human brain, or rather forebrain has been difficult to study in common animal models. Although many basic molecular and cellular events are conserved across species, human brain connectivity, pertinent especially to the cerebral cortex circuitry, is unique and demands extensive research. Despite a great advancement in functional imaging methods accomplished over the last two decades, many basic features of healthy and diseased human forebrain remain elusive. Here we address difficulties in anatomical studies of developing and adult human brain and indicate the new directions and challenges to be addressed in the future. We pay special attention to possibilities of translating animal brain research to human cases. We consider that, although animal experiments play a vital role in understanding fundamental molecular and cellular mechanisms behind brain function, understanding of higher brain functions (language, intelligence, memory) has to be based on understanding uniqueness of human circuitries. Furthermore, brain is the site of many human-specific diseases, such as multiple sclerosis, schizophrenia, and Alzheimer’s disease, for which only partial animal models exist. To study human brain, thus, remains irreplaceable in the quest for new therapeutic tools, as well as in understanding the essence of our being.

Mitochondrial Metabolism as Target of the Neuroprotective Role of Erythropoietin in Parkinson's Disease

Existing therapies for Parkinson's disease (PD) are only symptomatic. As erythropoietin (EPO) is emerging for its benefits in neurodegenerative diseases, here, we test the protective effect driven by EPO in in vitro (SH-SY5Y cells challenged by MPP⁺) and in vivo (C57BL/6J mice administered with MPTP) PD models. EPO restores cell viability in both protective and restorative layouts, enhancing the dopaminergic recovery. Specifically, EPO rescues the PD-induced damage to mitochondria, as shown by transmission electron microscopy, Mitotracker assay and PINK1 expression. Moreover, EPO promotes a rescue of mitochondrial respiration while markedly enhancing the glycolytic rate, as shown by the augmented extracellular acidification rate, contributing to elevated ATP levels in MPP⁺-challenged cells. In PD mice, EPO intrastriatal infusion markedly improves the outcome of behavioral tests. This is associated with the rescue of dopaminergic markers and decreased neuroinflammation. This study demonstrates cellular and functional recovery following EPO treatment, likely mediated by the 37 Kda isoform of the EPO-receptor. We report for the first time, that EPO-neuroprotection is exerted through restoring ATP levels by accelerating the glycolytic rate. In conclusion, the redox imbalance and neuroinflammation associated with PD may be successfully treated by EPO.

The L1 cell adhesion molecule affects protein kinase D1 activity in the cerebral cortex in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) is characterized by deposition of β-amyloid protein (Aβ), neurofibrillary tangles and cognitive deficits resulting from neuronal cell death. In search for the molecular underpinnings of the disease, we were interested in the relationship between Aβ, L1 cell adhesion molecule and protein kinase D1 (PKD1), which are not only implicated in neural development and functional maintenance in the adult, but are also neuroprotective under pathological conditions. Based on our observations that L1 and phosphorylated, i.e. activated, protein kinase PKD1 (pPKD1) co-localize in cultured neurons, we investigated the functional relationship between L1 and pPKD1 in the frontal lobe of an AD human cortical tissue microarray, and found increased and positively correlating levels of both molecules when compared to a non-affected human brain. Also in the APP_SWE mouse model of AD, L1 and pPKD1 levels were increased in the frontal lobe. To investigate whether L1 influences PKD1-based functions in AD, cultured cortical neurons were stressed with either H₂O₂ or oligomeric Aβ_1-42, in the presence or absence of recombinant L1 extracellular domain, and PKD1 phosphorylation was measured. As indicated by the cell viability assay, L1 maintained neuronal survival under oxidative stress and under application of oligomeric Aβ_1-42, when PKD1 activity was inhibited, suggesting that L1 ameliorates some aspects of Aβ_1-42 pathology in parallel with reducing PKD1 function.

A mimetic peptide of α2,6-sialyllactose promotes neuritogenesis

Oxidative stress contributes to the pathogenesis of neurodegenerative diseases. With the aim to find reagents that reduce oxidative stress, a phage display library was screened for peptides mimicking α2,6-sialyllactose (6'-SL), which is known to beneficially influence neural functions. Using Sambucus nigra lectin, which specifically binds to 6'-SL, we screened a phage display library and found a peptide comprising identical sequences of 12 amino acids. Mimetic peptide, reverse peptide and scrambled peptide were tested for inhibition of 6'-SL binding to the lectin. Indeed, lectin binding to 6'-SL was inhibited by the most frequently identified mimetic peptide, but not by the reverse or scrambled peptides, showing that this peptide mimics 6'-SL. Functionally, mimetic peptide, but not the reverse or scrambled peptides, increased viability and expression of neural cell adhesion molecule L1 in SK-N-SH human neuroblastoma cells, and promoted survival and neurite outgrowth of cultured mouse cerebellar granule neurons challenged by H₂O₂-induced oxidative stress. The combined results indicate that the 6'-SL mimetic peptide promotes neuronal survival and neuritogenesis, thus raising hopes for the treatment of neurodegenerative diseases. This study was approved by the Medical Ethics Committee of Shantou University Medical College, China (approval No. SUMC 2014-004) on February 20, 2014.

Counteracting neuroinflammation in experimental Parkinson's disease favors recovery of function: effects of Er-NPCs administration

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disease, presenting with midbrain dopaminergic neurons degeneration. A number of studies suggest that microglial activation may have a role in PD. It has emerged that inflammation-derived oxidative stress and cytokine-dependent toxicity may contribute to nigrostriatal pathway degeneration and exacerbate the progression of the disease in patients with idiopathic PD. Cell therapies have long been considered a feasible regenerative approach to compensate for the loss of specific cell populations such as the one that occurs in PD. We recently demonstrated that erythropoietin-releasing neural precursors cells (Er-NPCs) administered to MPTP-intoxicated animals survive after transplantation in the recipient's damaged brain, differentiate, and rescue degenerating striatal dopaminergic neurons. Here, we aimed to investigate the potential anti-inflammatory actions of Er-NPCs infused in an MPTP experimental model of PD.

METHODS

The degeneration of dopaminergic neurons was caused by MPTP administration in C57BL/6 male mice. 2.5 × 105 GFP-labeled Er-NPCs were administered by stereotaxic injection unilaterally in the left striatum. Functional recovery was assessed by two independent behavioral tests. Neuroinflammation was investigated measuring the mRNAs levels of pro-inflammatory and anti-inflammatory cytokines, and immunohistochemistry studies were performed to evaluate markers of inflammation and the potential rescue of tyrosine hydroxylase (TH) projections in the striatum of recipient mice.

RESULTS

Er-NPC administration promoted a rapid anti-inflammatory effect that was already evident 24 h after transplant with a decrease of pro-inflammatory and increase of anti-inflammatory cytokines mRNA expression levels. This effect was maintained until the end of the observational period, 2 weeks post-transplant. Here, we show that Er-NPCs transplant reduces macrophage infiltration, directly counteracting the M1-like pro-inflammatory response of murine-activated microglia, which corresponds to the decrease of CD68 and CD86 markers, and induces M2-like pro-regeneration traits, as indicated by the increase of CD206 and IL-10 expression. Moreover, we also show that this activity is mediated by Er-NPCs-derived erythropoietin (EPO) since the co-injection of cells with anti-EPO antibodies neutralizes the anti-inflammatory effect of the Er-NPCs treatment.

CONCLUSION

This study shows the anti-inflammatory actions exerted by Er-NPCs, and we suggest that these cells may represent good candidates for cellular therapy to counteract neuroinflammation in neurodegenerative disorders.

Confocal Synaptology: Synaptic Rearrangements in Neurodegenerative Disorders and upon Nervous System Injury

The nervous system is a notable exception to the rule that the cell is the structural and functional unit of tissue systems and organs. The functional unit of the nervous system is the synapse, the contact between two nerve cells. As such, synapses are the foci of investigations of nervous system organization and function, as well as a potential readout for the progression of various disorders of the nervous system. In the past decade the development of antibodies specific to presynaptic terminals has enabled us to assess, at the optical, laser scanning microscopy level, these subcellular structures, and has provided a simple method for the quantification of various synapses. Indeed, excitatory (glutamatergic) and inhibitory synapses can be visualized using antibodies against the respective vesicular transporters, and choline-acetyl transferase (ChAT) immunoreactivity identifies cholinergic synapses throughout the central nervous system. Here we review the results of several studies in which these methods were used to estimate synaptic numbers as the structural equivalent of functional outcome measures in spinal cord and femoral nerve injuries, as well as in genetic mouse models of neurodegeneration, including Alzheimer's disease (AD). The results implicate disease- and brain region-specific changes in specific types of synapses, which correlate well with the degree of functional deficit caused by the disease process. Additionally, results are reproducible between various studies and experimental paradigms, supporting the reliability of the method. To conclude, this quantitative approach enables fast and reliable estimation of the degree of the progression of neurodegenerative changes and can be used as a parameter of recovery in experimental models.

Recovery from experimental parkinsonism by intrastriatal application of erythropoietin or EPO-releasing neural precursors

An extensive literature has shown a powerful neuroprotective action of Erythropoietin (EPO) both in vivo and in vitro. This study shows that EPO, whether ectopically administered or released by neural precursors, does reverse MPTP-induced parkinsonism in mice. Unilateral stereotaxic injection of 2.5 × 10⁵ erythropoietin-releasing neural precursor cells (Er-NPCs) rescued degenerating striatal dopaminergic neurons and promoted behavioral recovery as shown by three independent behavioral tests. These effects were replicated through direct intrastriatal administration of recombinant human EPO. At the end of the observational period, most of the transplanted Er-NPCs were vital and migrated via the striatum to reach Substantia Nigra. The restorative effects appear to be mediated by EPO since co-injection of anti-EPO or anti-EPOR antibodies antagonized the positive outcomes. Furthermore, this report supports the neuroprotective action of EPO, which may also be achieved via administration of EPO-releasing cells such as Er-NPCs.

L1.2, the zebrafish paralog of L1.1 and ortholog of the mammalian cell adhesion molecule L1 contributes to spinal cord regeneration in adult zebrafish

PURPOSE

The aim of the study was to investigate the functional role of L1.2, the zebrafish paralog of L1.1 and ortholog of mammalian L1CAM in adult zebrafish spinal cord regeneration after injury. L1CAM and L1.1 have shown beneficial features in ameliorating nervous system dysfunctions in different experimental paradigms. It thus deemed important to characterize the L1.2 member of the L1CAM family, the functions of which are unknown.

METHODS

Spinal cord transection of adult zebrafish, application of anti-sense morpholino to reduce L1.2 expression, qPCR, immunohistology, immunoblotting, in situ hybridization, retrograde tracing, anterograde tracing.

RESULTS

Similar to L1.1, L1.2 expression in adult zebrafish is upregulated after spinal cord transection. By co-localization of in situ hybridization and immunohistology, L1.2 is expressed in neurons and, in contrast to L1.1, it is also expressed in GFAP-immunoreactive glia. Reducing L1.2 protein levels leads to impaired locomotor recovery and reduction of regrowth of severed descending axons from a brain stem nucleus which is composed of neurons innately capable of axonal regrowth.

CONCLUSIONS

Our findings support the speculation that paralogs of duplicated genes can exert similar functions and may thus represent an advantage over other species that do not carry duplicated genes.

Grafted Neural Precursors Integrate Into Mouse Striatum, Differentiate and Promote Recovery of Function Through Release of Erythropoietin in MPTP-Treated Mice

Erythropoietin-releasing neural precursor cells (Er-NPCs) are a subclass of subventricular zone-derived neural progenitors, capable of surviving for 6 hr after death of donor. They present higher neural differentiation. Here, Er-NPCs were studied in animal model of Parkinson's disease. Dopaminergic degeneration was caused by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine intraperitoneal administration in C57BL/6 mice. The loss of function was evaluated by specific behavioral tests. Er-NPCs (2.5 × 10⁵) expressing the green fluorescent protein were administered by stereotaxic injection unilaterally in the left striatum. At the end of observational research period (2 weeks), most of the transplanted Er-NPCs were located in the striatum, while several had migrated ventrally and caudally from the injection site, up to ipsilateral and contralateral substantia nigra. Most of transplanted cells had differentiated into dopaminergic, cholinergic, or GABAergic neurons. Er-NPCs administration also promoted a rapid functional improvement that was already evident at the third day after cells administration. This was accompanied by enhanced survival of nigral neurons. These effects were likely promoted by Er-NPCs-released erythropoietin (EPO), since the injection of Er-NPCs in association with anti-EPO or anti-EPOR antibodies had completely neutralized the recovery of function. In addition, intrastriatal administration of recombinant EPO mimics the effects of Er-NPCs. We suggest that Er-NPCs, and cells with similar properties, may represent good candidates for cellular therapy in neurodegenerative disorders of this kind.

A systematic review on the role of environmental toxicants in stem cells aging

Stem cells are an important target for environmental toxicants. As they are the main source for replenishing of organs in the body, any changes in their normal function could affect the regenerative potential of organs, leading to the appearance of age-related disease and acceleration of the aging process. Environmental toxicants could exert their adverse effect on stem cell function via multiple cellular and molecular mechanisms, resulting in changes in the stem cell differentiation fate and cell transformation, and reduced self-renewal capacity, as well as induction of stress-induced cellular senescence. The present review focuses on the effect of environmental toxicants on stem cell function associated with the aging process. We categorized environmental toxicants according to their preferred molecular mechanism of action on stem cells, including changes in genomic, epigenomic, and proteomic levels and enhancing oxidative stress. Pesticides, tobacco smoke, radiation and heavy metals are well-studied toxicants that cause stem cell dysfunction via induction of oxidative stress. Transgenerational epigenetic changes are the most important effects of a variety of toxicants on germ cells and embryos that are heritable and could affect health in the next several generations. A better understanding of the underlying mechanisms of toxicant-induced stem cell aging will help us to develop therapeutic intervention strategies against environmental aging. Meanwhile, more efforts are required to find the direct in vivo relationship between adverse effect of environmental toxicants and stem cell aging, leading to organismal aging.

L1 modulates PKD1 phosphorylation in cerebellar granule neurons

The neural cell adhesion molecule L1 (L1CAM) is crucial for the development of the nervous system, with an essential role in regulating multiple cellular activities. Protein kinase D1 (PKD1) serves as a key kinase given its diverse array of functions within the cell. Here, we investigated various aspects of the functional relationship between L1 and phosphorylated PKD1 (pPKD1) in cerebellar granule neurons. To study the relationship between L1 and PKD1 phosphorylation, human cerebellar tissue microarrays were subject to immunofluorescence staining. We observed a positive correlation between L1 protein levels and PKD1 phosphorylation. In addition, L1 also co-localized with pPKD1. To analyze the regulatory role of L1 on PKD1 phosphorylation, primary mouse cerebellar granule neurons were treated with various concentrations of rL1 for 48 h. Using Western blot, we revealed that L1 significantly increased PKD1 phosphorylation compared with vehicle control, with the maximal effect observed at 5 nM. ERK1/2 phosphorylation was significantly increased by 2.5 nM and 10nM L1, with no apparent change in SRC phosphorylation. However, SRC expression was markedly reduced by 10nM rL1. AKT1 expression and phosphorylation levels were significantly increased by rL1, with the maximal effect observed at 2.5 and 5 nM, respectively. Our combined data revealed a positive relationship between L1 and pPKD1 in both cultured cerebellar neurons and human cerebellar tissue, suggesting that L1 functions in the modulation of PKD1 phosphorylation.

Evaluation of poly(3,4-ethylenedioxythiophene)/carbon nanotube neural electrode coatings for stimulation in the dorsal root ganglion

OBJECTIVE

The dorsal root ganglion is an attractive target for implanting neural electrode arrays that restore sensory function or provide therapy via stimulation. However, penetrating microelectrodes designed for these applications are small and deliver low currents. For long-term performance of microstimulation devices, novel coating materials are needed in part to decrease impedance values at the electrode-tissue interface and to increase charge storage capacity.

APPROACH

Conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and multi-wall carbon nanotubes (CNTs) were coated on the electrode surface and doped with the anti-inflammatory drug, dexamethasone. Electrode characteristics and the tissue reaction around neural electrodes as a result of stimulation, coating and drug release were characterized. Hematoxylin and eosin staining along with antibodies recognizing Iba1 (microglia/macrophages), NF200 (neuronal axons), NeuN (neurons), vimentin (fibroblasts), caspase-3 (cell death) and L1 (neural cell adhesion molecule) were used. Quantitative image analyses were performed using MATLAB.

MAIN RESULTS

Our results indicate that coated microelectrodes have lower in vitro and in vivo impedance values. Significantly less neuronal death/damage was observed with coated electrodes as compared to non-coated controls. The inflammatory response with the PEDOT/CNT-coated electrodes was also reduced.

SIGNIFICANCE

This study is the first to report on the utility of these coatings in stimulation applications. Our results indicate PEDOT/CNT coatings may be valuable additions to implantable electrodes used as therapeutic modalities.

Analysis of human embryonic stem cells with regulatable expression of the cell adhesion molecule l1 in regeneration after spinal cord injury

Cell replacement therapy is one potential avenue for central nervous system (CNS) repair. However, transplanted stem cells may not contribute to long-term recovery of the damaged CNS unless they are engineered for functional advantage. To fine tune regenerative capabilities, we developed a human neural cell line expressing L1, a regeneration-conducive adhesion molecule, under the control of a doxycycline regulatable Tet-off promoter. Controlled expression of L1 is desired because overexpression after regenerative events may lead to adverse consequences. The regulated system was tested in several cell lines, where doxycycline completely eliminated green fluorescent protein or L1 expression by 3-5 days in vitro. Increased colony formation as well as decreased proliferation were observed in H9NSCs without doxycycline (hL1-on). To test the role of L1 in vivo after acute compression spinal cord injury of immunosuppressed mice, quantum dot labeled hL1-on or hL1-off cells were injected at three sites: lesion; proximal; and caudal. Mice transplanted with hL1-on cells showed a better Basso Mouse Scale score, when compared to those with hL1-off cells. As compared to the hL1-off versus hL1-on cell transplanted mice 6 weeks post-transplantation, expression levels of L1, migration of transplanted cells, and immunoreactivity for tyrosine hydroxylase were higher, whereas expression of chondroitin sulfate proteoglycans was lower. Results indicate that L1 expression is regulatable in human stem cells by doxycycline in a nonviral engineering approach. Regulatable expression in a prospective nonleaky Tet-off system could hold promise for therapy, based on the multifunctional roles of L1, including neuronal migration and survival, neuritogenesis, myelination, and synaptic plasticity.

The effects of harvesting media on biological characteristics and repair potential of neural stem cells after traumatic brain injury

Various solutions are utilized widely for the isolation, harvesting, sorting, testing and transplantation of neural stem cells (NSCs), whereas the effects of harvesting media on the biological characteristics and repair potential of NSCs remain unclear. To examine some of these effects, NSCs were isolated from cortex of E14.5 mice and exposed to the conventional harvesting media [0.9% saline (Saline), phosphate-buffered saline (PBS) or artificial cerebrospinal fluid (ACSF)] or the proliferation culture medium (PCM) for different durations at 4°C. Treated NSCs were grafted by in situ injection into the lesion sites of traumatic brain injury (TBI) mice. In vitro, harvesting media-exposed NSCs displayed time-dependent reduction of viability and proliferation. S phase entry decreased in harvesting media-exposed cells, which was associated with upregulation of p53 protein and downregulation of cyclin E1 protein. Moreover, harvesting media exposure induced the necrosis and apoptosis of NSCs. The levels of Fas-L, cleaved caspase 3 and 8 were increased, which suggests that the death receptor signaling pathway is involved in the apoptosis of NSCs. In addition, exposure to Saline did not facilitate the neuronal differentiation of NSCs, suggesting that Saline exposure may be disadvantageous for neurogenesis. In vivo, NSC-mediated functional recovery in harvesting media-exposed NSC groups was notably attenuated in comparison with the PCM-exposed NSC group. In conclusion, harvesting media exposure modulates the biological characteristics and repair potential of NSCs after TBI. Our results suggest that insight of the effects of harvesting media exposure on NSCs is critical for developing strategies to assure the successful long-term engraftment of NSCs.

Molecular targeting of TRF2 suppresses the growth and tumorigenesis of glioblastoma stem cells

Glioblastoma is the most prevalent primary brain tumor and is essentially universally fatal within 2 years of diagnosis. Glioblastomas contain cellular hierarchies with self-renewing glioblastoma stem cells (GSCs) that are often resistant to chemotherapy and radiation therapy. GSCs express high amounts of repressor element 1 silencing transcription factor (REST), which may contribute to their resistance to standard therapies. Telomere repeat-binding factor 2 (TRF2) stablizes telomeres and REST to maintain self-renewal of neural stem cells and tumor cells. Here we show viral vector-mediated delivery of shRNAs targeting TRF2 mRNA depletes TRF2 and REST from GSCs isolated from patient specimens. As a result, GSC proliferation is reduced and the level of proteins normally expressed by postmitotic neurons (L1CAM and β3-tubulin) is increased, suggesting that loss of TRF2 engages a cell differentiation program in the GSCs. Depletion of TRF2 also sensitizes GSCs to temozolomide, a DNA-alkylating agent currently used to treat glioblastoma. Targeting TRF2 significantly increased the survival of mice bearing GSC xenografts. These findings reveal a role for TRF2 in the maintenance of REST-associated proliferation and chemotherapy resistance of GSCs, suggesting that TRF2 is a potential therapeutic target for glioblastoma.

Function-triggering antibodies to the adhesion molecule L1 enhance recovery after injury of the adult mouse femoral nerve

L1 is among the few adhesion molecules that favors repair after trauma in the adult central nervous system of vertebrates by promoting neuritogenesis and neuronal survival, among other beneficial features. In the peripheral nervous system, L1 is up-regulated in Schwann cells and regrowing axons after nerve damage, but the functional consequences of this expression remain unclear. Our previous study of L1-deficient mice in a femoral nerve injury model showed an unexpected improved functional recovery, attenuated motoneuronal cell death, and enhanced Schwann cell proliferation, being attributed to the persistent synthesis of neurotrophic factors. On the other hand, transgenic mice over-expressing L1 in neurons led to improved remyelination, but not improved functional recovery. The present study was undertaken to investigate whether the monoclonal L1 antibody 557 that triggers beneficial L1 functions in vitro would trigger these also in femoral nerve repair. We analyzed femoral nerve regeneration in C57BL/6J mice that received this antibody in a hydrogel filled conduit connecting the cut and sutured nerve before its bifurcation, leading to short-term release of antibody by diffusion. Video-based quantitative analysis of motor functions showed improved recovery when compared to mice treated with conduits containing PBS in the hydrogel scaffold, as a vehicle control. This improved recovery was associated with attenuated motoneuron loss, remyelination and improved precision of preferential motor reinnervation. We suggest that function-triggering L1 antibodies applied to the lesion site at the time of injury over a limited time period will not only be beneficial in peripheral, but also central nervous system regeneration.

Gold nanoparticles functionalized with a fragment of the neural cell adhesion molecule L1 stimulate L1-mediated functions

The neural cell adhesion molecule L1 is involved in nervous system development and promotes regeneration in animal models of acute and chronic injury of the adult nervous system. To translate these conducive functions into therapeutic approaches, a 22-mer peptide that encompasses a minimal and functional L1 sequence of the third fibronectin type III domain of murine L1 was identified and conjugated to gold nanoparticles (AuNPs) to obtain constructs that interact homophilically with the extracellular domain of L1 and trigger the cognate beneficial L1-mediated functions. Covalent conjugation was achieved by reacting mixtures of two cysteine-terminated forms of this L1 peptide and thiolated poly(ethylene) glycol (PEG) ligands (~2.1 kDa) with citrate stabilized AuNPs of two different sizes (~14 and 40 nm in diameter). By varying the ratio of the L1 peptide-PEG mixtures, an optimized layer composition was achieved that resulted in the expected homophilic interaction of the AuNPs. These AuNPs were stable as tested over a time period of 30 days in artificial cerebrospinal fluid and interacted with the extracellular domain of L1 on neurons and Schwann cells, as could be shown by using cells from wild-type and L1-deficient mice. In vitro, the L1-derivatized particles promoted neurite outgrowth and survival of neurons from the central and peripheral nervous system and stimulated Schwann cell process formation and proliferation. These observations raise the hope that, in combination with other therapeutic approaches, L1 peptide-functionalized AuNPs may become a useful tool to ameliorate the deficits resulting from acute and chronic injuries of the mammalian nervous system.

Engraftment of mouse embryonic stem cells differentiated by default leads to neuroprotection, behaviour revival and astrogliosis in parkinsonian rats

We report here protection against rotenone-induced behavioural dysfunction, striatal dopamine depletion and nigral neuronal loss, following intra-striatal transplantation of neurons differentiated from murine embryonic stem cells (mES). mES maintained in serum free medium exhibited increase in neuronal, and decrease in stem cell markers by 7th and 10th days as revealed by RT-PCR and immunoblot analyses. Tyrosine hydroxylase, NURR1, PITX3, LMX1b and c-RET mRNA showed a significant higher expression in differentiated cells than in mES. Dopamine level was increased by 3-fold on 10th day as compared to 7 days differentiated cells. Severity of rotenone-induced striatal dopamine loss was attenuated, and amphetamine-induced unilateral rotations were significantly reduced in animals transplanted with 7 days differentiated cells, but not in animals that received undifferentiated ES transplant. However, the ratio of contralateral to ipsilateral swings in elevated body swing test was significantly reduced in both the transplanted groups, as compared to control. Striatal grafts exhibited the presence of tyrosine hydroxylase positive cells, and the percentage of dopaminergic neurons in the substantia nigra was also found to be higher in the ipsilateral side of 7 days and mES grafted animals. Increased expression of CD11b and IBA-1, suggested a significant contribution of these microglia-derived factors in controlling the limited survival of the grafted cells. Astrocytosis in the grafted striatum, and significant increase in the levels of glial cell line derived neurotrophic factor may have contributed to the recovery observed in the hemiparkinsonian rats following transplantation.

Transgenic overexpression of the cell adhesion molecule L1 in neurons facilitates recovery after mouse spinal cord injury

It has been shown that the X-chromosome-linked neural cell adhesion molecule L1 plays a beneficial role in regeneration after spinal cord injury (SCI) in young adult rodents when applied in various molecular and cellular forms. In an attempt to further characterize the multiple functions of L1 after severe SCI we analyzed locomotor functions and measured axonal regrowth/sprouting and sparing, glial scarring, and synaptic remodeling at 6 weeks after severe spinal cord compression injury at the T7-9 levels of L1-deficient mice (L1-/y) and their wild-type (L1+/y) littermates, as well as mice that overexpress L1 under the control of the neuron-specific Thy-1 promoter (L1tg) and their wild-type littermates (L1+/+). No differences were found in the locomotor scale score and single frame motion analysis between L1-/y and L1+/y mice during 6 weeks after SCI, most likely due to the very low expression of L1 in the adult spinal cord of wild-type mice. L1tg mice, however, showed better locomotor recovery than their L1+/+ littermates, being associated with enhanced numbers of catecholaminergic axons in the lumbar spinal cord, but not of cholinergic, GABAergic or glutamatergic terminals around motoneuron cell bodies in the lumbar spinal cord. Additionally, no difference between L1tg and L1+/+ mice was detectable in dieback of corticospinal tract axons. Neuronal L1 overexpression did not influence the size of the glial fibrillary acidic protein-immunoreactive astrocytic scar 6 weeks after injury. We conclude that neuronal overexpression of L1 improves functional recovery from SCI by increasing catecholaminergic axonal regrowth/sprouting and/or sparing of severed axons without affecting the glial scar size.

A network view on Parkinson's disease

Network-based systems biology tools including Pathway Studio 9.0 were used to identify Parkinson's disease (PD) critical molecular players, drug targets, and underlying biological processes. Utilizing several microarray gene expression datasets, biomolecular networks such as direct interaction, shortest path, and microRNA regulatory networks were constructed and analyzed for the disease conditions. Network topology analysis of node connectivity and centrality revealed in combination with the guilt-by-association rule 17 novel genes of PD-potential interest. Seven new microRNAs (miR-132, miR-133a1, miR-181-1, miR-182, miR-218-1, miR-29a, and miR-330) related to Parkinson's disease were identified, along with more microRNA targeted genes of interest like RIMS3, SEMA6D and SYNJ1. David and IPA enrichment analysis of KEGG and canonical pathways provided valuable mechanistic information emphasizing among others the role of chemokine signaling, adherence junction, and regulation of actin cytoskeleton pathways. Several routes for possible disease initiation and neuro protection mechanisms triggered via the extra-cellular ligands such as CX3CL1, SEMA6D and IL12B were thus uncovered, and a dual regulatory system of integrated transcription factors and microRNAs mechanisms was detected.

Adhesion molecule L1 binds to amyloid beta and reduces Alzheimer's disease pathology in mice

Alzheimer's disease (AD) is a devastating neurodegenerative disorder and the most common cause of elderly dementia. In an effort to contribute to the potential of molecular approaches to reduce degenerative processes we have tested the possibility that the neural adhesion molecule L1 ameliorates some characteristic cellular and molecular parameters associated with the disease in a mouse model of AD. Three-month-old mice overexpressing mutated forms of amyloid precursor protein and presenilin-1 under the control of a neuron-specific promoter received an injection of adeno-associated virus encoding the neuronal isoform of full-length L1 (AAV-L1) or, as negative control, green fluorescent protein (AAV-GFP) into the hippocampus and occipital cortex. Four months after virus injection, the mice were analyzed for histological and biochemical parameters of AD. AAV-L1 injection decreased the Aβ plaque load, levels of Aβ42, Aβ42/40 ratio and astrogliosis compared with AAV-GFP controls. AAV-L1 injected mice also had increased densities of inhibitory synaptic terminals on pyramidal cells in the hippocampus when compared with AAV-GFP controls. Numbers of microglial cells/macrophages were similar in both groups, but numbers of microglial cells/macrophages per plaque were increased in AAV-L1 injected mice. To probe for a molecular mechanism that may underlie these effects, we analyzed whether L1 would directly and specifically interact with Aβ. In a label-free binding assay, concentration dependent binding of the extracellular domain of L1, but not of the close homolog of L1 to Aβ40 and Aβ42 was seen, with the fibronectin type III homologous repeats 1-3 of L1 mediating this effect. Aggregation of Aβ42 in vitro was reduced in the presence of the extracellular domain of L1. The combined observations indicate that L1, when overexpressed in neurons and glia, reduces several histopathological hallmarks of AD in mice, possibly by reduction of Aβ aggregation. L1 thus appears to be a candidate molecule to ameliorate the pathology of AD, when applied in therapeutically viable treatment schemes.

Heterozygosity for the mutated X-chromosome-linked L1 cell adhesion molecule gene leads to increased numbers of neurons and enhanced metabolism in the forebrain of female carrier mice

Mutations in the X-chromosomal L1CAM gene lead to severe neurological deficits. In this study, we analyzed brains of female mice heterozygous for L1 (L1+/-) to gain insights into the brain structure of human females carrying one mutated L1 allele. From postnatal day 7 onward into adulthood, L1+/- female mice show an increased density of neurons in the neocortex and basal ganglia in comparison to wild-type (L1+/+) mice, correlating with enhanced metabolic parameters as measured in vivo. The densities of astrocytes and parvalbumin immunoreactive interneurons were not altered. No significant differences between L1+/- and L1+/+ mice were seen for cell proliferation in the cortex during embryonic days 11.5-15.5. Neuronal differentiation as estimated by analysis of doublecortin-immunoreactive cortical cells of embryonic brains was similar in L1+/- and L1+/+ mice. Interestingly, at postnatal days 3 and 5, apoptosis was reduced in L1+/- compared to L1+/+ mice. We suggest that reduced apoptosis leads to increased neuronal density in adult L1+/- mice. In conclusion, L1+/- mice display an unexpected phenotype that is not an intermediate between L1+/+ mice and mice deficient in L1 (L1-/y), but a novel phenotype which is challenging to understand regarding its underlying molecular and cellular mechanisms.

In vitro generation of three-dimensional substrate-adherent embryonic stem cell-derived neural aggregates for application in animal models of neurological disorders

In vitro-differentiated embryonic stem (ES) cells comprise a useful source for cell replacement therapy, but the efficiency and safety of a translational approach are highly dependent on optimized protocols for directed differentiation of ES cells into the desired cell types in vitro. Furthermore, the transplantation of three-dimensional ES cell-derived structures instead of a single-cell suspension may improve graft survival and function by providing a beneficial microenvironment for implanted cells. To this end, we have developed a new method to efficiently differentiate mouse ES cells into neural aggregates that consist predominantly (>90%) of postmitotic neurons, neural progenitor cells, and radial glia-like cells. When transplanted into the excitotoxically lesioned striatum of adult mice, these substrate-adherent embryonic stem cell-derived neural aggregates (SENAs) showed significant advantages over transplanted single-cell suspensions of ES cell-derived neural cells, including improved survival of GABAergic neurons, increased cell migration, and significantly decreased risk of teratoma formation. Furthermore, SENAs mediated functional improvement after transplantation into animal models of Parkinson's disease and spinal cord injury. This unit describes in detail how SENAs are efficiently derived from mouse ES cells in vitro and how SENAs are isolated for transplantation. Furthermore, methods are presented for successful implantation of SENAs into animal models of Huntington's disease, Parkinson's disease, and spinal cord injury to study the effects of stem cell-derived neural aggregates in a disease context in vivo.

Transplantation of neural stem cells co-transfected with Nurr1 and Brn4 for treatment of Parkinsonian rats

Neural stem cells (NSCs) tranplantation has great potential for the treatment of neurodegenerative disease such as Parkinson's disease (PD). However, the usage of NSCs is limited because the differentiation of NSCs into specific dopaminergic neurons has proven difficult. We have recently demonstrated that transgenic expression of Nurr1 could induce the differentiation of NSCs into tyrosine hydroxylase (TH) immunoreactive dopaminergic neurons, and forced co-expression of Nurr1 with Brn4 caused a dramatic increase in morphological and phenotypical maturity of these neurons. In this study, we investigated the effect of transplanted NSCs in PD model rats. The results showed that overexpression of Nurr1 promoted NSCs to differentiate into dopaminergic neurons in vivo, increased the level of dopamine (DA) neurotransmitter in the striatum, resulting in behavioral improvement of PD rats. Importantly, co-expression of Nurr1 and Brn4 in NSCs significantly increased the maturity and viability of dopaminergic neurons, further raised the DA amount in the striatum and reversed the behavioral deficit of the PD rats. Our findings provide a new potential and strategy for the use of NSCs in cell replacement therapy for PD.

In vivo effects of L1 coating on inflammation and neuronal health at the electrode-tissue interface in rat spinal cord and dorsal root ganglion

The spinal cord (SC) and dorsal root ganglion (DRG) are target implantation regions for neural prosthetics, but the tissue-electrode interface in these regions is not well-studied. To improve understanding of these locations, the tissue reactions around implanted electrodes were characterized. L1, an adhesion molecule shown to maintain neuronal density and reduce gliosis in brain tissue, was then evaluated in SC and DRG implants. Following L1 immobilization onto neural electrodes, the bioactivities of the coatings were verified in vitro using neuron, astrocyte and microglia cultures. Non-modified and L1-coated electrodes were implanted into adult rats for 1 or 4 weeks. Hematoxylin and eosin staining along with cell-type specific antibodies were used to characterize the tissue response. In the SC and DRG, cells aggregated at the electrode-tissue interface. Microglia staining was more intense around the implant site and decreased with distance from the interface. Neurofilament staining in both locations decreased or was absent around the implant, compared with surrounding tissue. With L1, neurofilament staining was significantly increased while neuronal cell death decreased. These results indicate that L1-modified electrodes may result in an improved chronic neural interface and will be evaluated in recording and stimulation studies.

Promotion of spinal cord regeneration by neural stem cell-secreted trimerized cell adhesion molecule L1

The L1 cell adhesion molecule promotes neurite outgrowth and neuronal survival in homophilic and heterophilic interactions and enhances neurite outgrowth and neuronal survival homophilically, i.e. by self binding. We investigated whether exploitation of homophilic and possibly also heterophilic mechanisms of neural stem cells overexpressing the full-length transmembrane L1 and a secreted trimer engineered to express its extracellular domain would be more beneficial for functional recovery of the compression injured spinal cord of adult mice than stem cells overexpressing only full-length L1 or the parental, non-engineered cells. Here we report that stem cells expressing trimeric and full-length L1 are indeed more efficient in promoting locomotor recovery when compared to stem cells overexpressing only full-length L1 or the parental stem cells. The trimer expressing stem cells were also more efficient in reducing glial scar volume and expression of chondroitin sulfates and the chondroitin sulfate proteoglycan NG2. They were also more efficient in enhancing regrowth/sprouting and/or preservation of serotonergic axons, and remyelination and/or myelin sparing. Moreover, degeneration/dying back of corticospinal cord axons was prevented more by the trimer expressing stem cells. These results encourage the view that stem cells engineered to drive the beneficial functions of L1 via homophilic and heterophilic interactions are functionally optimized and may thus be of therapeutic value.

Current challenges for the advancement of neural stem cell biology and transplantation research

Transplantation of neural stem cells (NSC) is hoped to become a promising primary or secondary therapy for the treatment of various neurodegenerative disorders of the central nervous system (CNS), as demonstrated by multiple pre-clinical animal studies in which functional recovery has already been demonstrated. However, for NSC therapy to be successful, the first challenge will be to define a transplantable cell population. In the first part of this review, we will briefly discuss the main features of ex vivo culture and characterisation of NSC. Next, NSC grafting itself may not only result in the regeneration of lost tissue, but more importantly has the potential to improve functional outcome through many bystander mechanisms. In the second part of this review, we will briefly discuss several pre-clinical studies that contributed to a better understanding of the therapeutic potential of NSC grafts in vivo. However, while many pre-clinical animal studies mainly report on the clinical benefit of NSC grafting, little is known about the actual in vivo fate of grafted NSC. Therefore, the third part of this review will focus on non-invasive imaging techniques for monitoring cellular grafts in the brain under in vivo conditions. Finally, as NSC transplantation research has evolved during the past decade, it has become clear that the host micro-environment itself, either in healthy or injured condition, is an important player in defining success of NSC grafting. The final part of this review will focus on the host environmental influence on survival, migration and differentiation of grafted NSC.

Uric acid promotes neuronal differentiation of human placenta-derived mesenchymal stem cells in a time- and concentration-dependent manner

Uric acid is an important, naturally occurring serum antioxidant. The present study investigates the use of uric acid for promoting proliferation and neuronal differentiation of mesenchymal stem cells derived from human placenta tissue. Human placenta-derived mesenchymal stem cells were pre-induced in the presence of either 0, 0.2, 0.4 or 0.8 mM uric acid in combination with 1 mM β-mercaptoethanol for 24 hours, followed by exposure to identical uric acid concentrations and 5 mM β-mercaptoethanol for 6 and 10 hours. Cells developed a neuronal-like morphology, with formation of interconnected process extensions, typical of neural cells. Immunocytochemistry and immunofluorescence staining showed neuron specific enolase positive cells were present in each group except the control group. A greater number of neuron specific enolase positive cells were observed in 0.8 mM uric acid in combination with 5 mM β-mercaptoethanol at 10 hours. After 24 hours of induction, Nissl bodies were detected in the cytoplasm of all differentiated cell groups except the control group and Nissl body numbers were greatest in human placenta-derived mesenchymal stem cells grown in the presence of 0.8 mM uric acid and 5 mM β-mercaptoethanol. These results suggest uric acid accelerates differentiation of human placenta-derived mesenchymal stem cells into neuronal-like cells in a time- and concentration-dependent manner.

Docosahexaenoic Acid Promotes Dopaminergic Differentiation in Induced Pluripotent Stem Cells and Inhibits Teratoma Formation in Rats with Parkinson-Like Pathology

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the degeneration of dopaminergic (DA) neurons in the midbrain. Induced pluripotent stem (iPS) cells have shown potential for differentiation and may become a resource of functional neurons for the treatment of PD. However, teratoma formation is a major concern for transplantation-based therapies. This study examined whether functional neurons could be efficiently generated from iPS cells using a five-step induction procedure combined with docosahexaenoic acid (DHA) treatment. We demonstrated that DHA, a ligand for the RXR/Nurr1 heterodimer, significantly activated expression of the Nurr1 gene and the Nurr1-related pathway in iPS cells. DHA treatment facilitated iPS differentiation into tyrosine hydroxylase (TH)-positive neurons in vitro and in vivo and functionally increased dopamine release in transplanted grafts in PD-like animals. Furthermore, DHA dramatically upregulated the endogenous expression levels of neuroprotective genes ( Bcl-2, Bcl-xl, brain-derived neurotrophic factor, and glial cell-derived neurotrophic factor) and protected against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced apoptosis in iPS-derived neuronal precursor cells. DHA-treated iPS cells significantly improved the behavior of 6-hydroxydopamine (6-OHDA)-treated PD-like rats compared to control or eicosapentaenoic acid-treated group. Importantly, the in vivo experiment suggests that DHA induces the differentiation of functional dopaminergic precursors and improves the abnormal behavior of 6-OHDA-treated PD-like rats by 4 months after transplantation. Furthermore, we found that DHA treatment in iPS cell-grafted rats significantly downregulated the mRNA expression of embryonic stem cell-specific genes (Oct-4 and c-Myc) in the graft and effectively blocked teratoma formation. Importantly, 3 Tesla-magnetic resonance imaging and ex vivo green fluorescence protein imaging revealed that no teratomas were present in transplanted grafts of DHA-treated iPS-derived DA neurons 4 months after implantation. Therefore, our data suggest that DHA plays a crucial role in iPS differentiation into functional DA neurons and that this approach could provide a novel therapeutic approach for PD treatment.

Stem cell technology for neurodegenerative diseases

Over the past 20 years, stem cell technologies have become an increasingly attractive option to investigate and treat neurodegenerative diseases. In the current review, we discuss the process of extending basic stem cell research into translational therapies for patients suffering from neurodegenerative diseases. We begin with a discussion of the burden of these diseases on society, emphasizing the need for increased attention toward advancing stem cell therapies. We then explain the various types of stem cells utilized in neurodegenerative disease research, and outline important issues to consider in the transition of stem cell therapy from bench to bedside. Finally, we detail the current progress regarding the applications of stem cell therapies to specific neurodegenerative diseases, focusing on Parkinson disease, Huntington disease, Alzheimer disease, amyotrophic lateral sclerosis, and spinal muscular atrophy. With a greater understanding of the capacity of stem cell technologies, there is growing public hope that stem cell therapies will continue to progress into realistic and efficacious treatments for neurodegenerative diseases.

The Injured and Regenerating Nervous System

Understanding restricted functional recovery and designing efficient treatments to alleviate dysfunction after injury of the nervous system remain major challenges in neuroscience and medicine. Numerous molecules of potential significance in neural repair have been identified in vitro, but only few of these have proved to be of major importance in vivo up to now. Among the molecules involved in regeneration are several members of the immunoglobulin superfamily, most notably the neural cell adhesion molecules L1, its close homologue CHL1, and NCAM and, in particular, its polysialic acid glycan moiety. Sufficient evidence is now available to justify the statement that these molecules are major players not only in nervous system development but also in the adult during neural repair and synaptic plasticity. Importantly, insights into the functions of these molecules in promoting or inhibiting functional recovery have allowed the design and assessment of therapeutic approaches in animal models of central nervous system injury that could prove to be applicable in clinical settings.

Transplanted L1 expressing radial glia and astrocytes enhance recovery after spinal cord injury

A major obstacle for the transplantation of neural stem cells (NSCs) into the lesioned spinal cord is their predominant astrocytic differentiation after transplantation. We took advantage of this predominant astrocytic differentiation of NSCs and expressed the paradigmatic beneficial neural cell adhesion molecule L1 in radial glial cells and reactive and nonreactive astrocytes as novel cellular vehicles to express L1 under the control of the promoter for the human glial fibrillary acidic protein (GFAP-L1 NSCs). Behavioral analysis and electrophysiological H-reflex recordings revealed that mice transplanted with GFAP-L1 NSCs showed enhanced locomotor recovery in comparison to mice injected with wild type (WT) NSCs or control mice injected with phosphate-buffered saline (PBS). This functional recovery was further accelerated in mice transplanted with L1-expressing radial glial cells that had been immunoisolated from GFAP-L1 NSCs (GFAP-L1-i cells). Morphological analysis revealed that mice grafted with GFAP-L1 NSCs exhibited increased neuronal differentiation and migration of transplanted cells, as well as increased soma size and cholinergic synaptic coverage of host motoneurons and increased numbers of endogenous catecholaminergic nerve fibers caudal to the lesion site. These findings show that L1-expressing astrocytes and radial glial cells isolated from GFAP-L1 NSC cultures represent a novel strategy for improving functional recovery after spinal cord injury, encouraging the use of the human GFAP promoter to target beneficial transgene expression in transplanted stem cells.

Restoring neuronal function after stroke by cell replacement: anatomic and functional considerations

BACKGROUND AND PURPOSE

A major challenge to effective treatment after stroke is the restoration of neuronal function. In recent years, cell-based therapies for stroke have been explored in experimental animal models, and the results have suggested behavioral improvements. However, the anatomic targets of a cell-based stroke therapy and the relationship of cell grafts to post stroke reorganization are poorly understood, which results in difficulties defining strategies for neuronal substitution. Given that stroke causes a variety of secondary changes at locations beyond the infarct lesion, overcoming these difficulties is even more important.

SUMMARY OF REVIEW

We describe which brain structures and cell types are candidates for substitution and how new neuronal functionality could be implemented in a damaged brain by capitalizing on current concepts of post stroke plasticity.

Recent progress in cell therapy for basal ganglia disorders with emphasis on menstrual blood transplantation in stroke

Cerebrovascular diseases are the third leading cause of death and the primary cause of long-term disability in the United States. The only approved therapy for stroke is tPA, strongly limited by the short therapeutic window and hemorrhagic complications, therefore excluding most patients from its benefits. Parkinson's and Huntington's disease are the other two most studied basal ganglia diseases and, as stroke, have very limited treatment options. Inflammation is a key feature in central nervous system disorders and it plays a dual role, either improving injury in early phases or impairing neural survival at later stages. Stem cells can be opportunely used to modulate inflammation, abrogate cell death and, therefore, preserve neural function. We here discuss the role of stem cells as restorative treatments for basal ganglia disorders, including Parkinson's disease, Huntington's disease and stroke, with special emphasis to the recently investigated menstrual blood stem cells. We highlight the availability, proliferative capacity, pluripotentiality and angiogenic features of these cells and explore their present and future experimental and clinical applications.

Embryonic stem cell-derived L1 overexpressing neural aggregates enhance recovery after spinal cord injury in mice

An obstacle to early stem cell transplantation into the acutely injured spinal cord is poor survival of transplanted cells. Transplantation of embryonic stem cells as substrate adherent embryonic stem cell-derived neural aggregates (SENAs) consisting mainly of neurons and radial glial cells has been shown to enhance survival of grafted cells in the injured mouse brain. In the attempt to promote the beneficial function of these SENAs, murine embryonic stem cells constitutively overexpressing the neural cell adhesion molecule L1 which favors axonal growth and survival of grafted and imperiled cells in the inhibitory environment of the adult mammalian central nervous system were differentiated into SENAs and transplanted into the spinal cord three days after compression lesion. Mice transplanted with L1 overexpressing SENAs showed improved locomotor function when compared to mice injected with wild-type SENAs. L1 overexpressing SENAs showed an increased number of surviving cells, enhanced neuronal differentiation and reduced glial differentiation after transplantation when compared to SENAs not engineered to overexpress L1. Furthermore, L1 overexpressing SENAs rescued imperiled host motoneurons and parvalbumin-positive interneurons and increased numbers of catecholaminergic nerve fibers distal to the lesion. In addition to encouraging the use of embryonic stem cells for early therapy after spinal cord injury L1 overexpression in the microenvironment of the lesioned spinal cord is a novel finding in its functions that would make it more attractive for pre-clinical studies in spinal cord regeneration and most likely other diseases of the nervous system.

Stem Cells for the Treatment of Neurodegenerative Diseases

Neurodegenerative diseases are characterized by neurodegenerative changes or apoptosis of neurons involved in networks, leading to permanent paralysis and loss of sensation below the site of the injury. Cell replacement therapy has provided the basis for the development of potentially powerful new therapeutic strategies for a broad spectrum of human neurological diseases. In recent years, neurons and glial cells have successfully been generated from stem cells, and extensive efforts by investigators to develop stem cell-based brain transplantation therapies have been carried out. We review here notable previously published experimental and preclinical studies involving stem cell-based cell for neurodegenerative diseases and discuss the future prospects for stem cell therapy of neurological disorders in the clinical setting. Steady and solid progress in stem cell research in both basic and preclinical settings should support the hope for development of stem cell-based cell therapies for neurological diseases.