Publications by authors named "Luca Peruzzotti-Jametti"

39 Publications

Metabolic Control of Smoldering Neuroinflammation.

Front Immunol 2021 23;12:705920. Epub 2021 Jun 23.

Department of Clinical Neurosciences and National Institute for Health Research (NIHR) Biomedical Research Centre, University of Cambridge, Cambridge, United Kingdom.

Compelling evidence exists that patients with chronic neurological conditions, which includes progressive multiple sclerosis, display pathological changes in neural metabolism and mitochondrial function. However, it is unknown if a similar degree of metabolic dysfunction occurs also in non-neural cells in the central nervous system. Specifically, it remains to be clarified (i) the full extent of metabolic changes in tissue-resident microglia and infiltrating macrophages after prolonged neuroinflammation (e.g., at the level of chronic active lesions), and (ii) whether these alterations underlie a unique pathogenic phenotype that is amenable for therapeutic targeting. Herein, we discuss how cell metabolism and mitochondrial function govern the function of chronic active microglia and macrophages brain infiltrates and identify new metabolic targets for therapeutic approaches aimed at reducing smoldering neuroinflammation.
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http://dx.doi.org/10.3389/fimmu.2021.705920DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8262770PMC
June 2021

Neural stem cells traffic functional mitochondria via extracellular vesicles.

PLoS Biol 2021 Apr 7;19(4):e3001166. Epub 2021 Apr 7.

Department of Clinical Neurosciences and NIHR Biomedical Research Centre, University of Cambridge, United Kingdom.

Neural stem cell (NSC) transplantation induces recovery in animal models of central nervous system (CNS) diseases. Although the replacement of lost endogenous cells was originally proposed as the primary healing mechanism of NSC grafts, it is now clear that transplanted NSCs operate via multiple mechanisms, including the horizontal exchange of therapeutic cargoes to host cells via extracellular vesicles (EVs). EVs are membrane particles trafficking nucleic acids, proteins, metabolites and metabolic enzymes, lipids, and entire organelles. However, the function and the contribution of these cargoes to the broad therapeutic effects of NSCs are yet to be fully understood. Mitochondrial dysfunction is an established feature of several inflammatory and degenerative CNS disorders, most of which are potentially treatable with exogenous stem cell therapeutics. Herein, we investigated the hypothesis that NSCs release and traffic functional mitochondria via EVs to restore mitochondrial function in target cells. Untargeted proteomics revealed a significant enrichment of mitochondrial proteins spontaneously released by NSCs in EVs. Morphological and functional analyses confirmed the presence of ultrastructurally intact mitochondria within EVs with conserved membrane potential and respiration. We found that the transfer of these mitochondria from EVs to mtDNA-deficient L929 Rho0 cells rescued mitochondrial function and increased Rho0 cell survival. Furthermore, the incorporation of mitochondria from EVs into inflammatory mononuclear phagocytes restored normal mitochondrial dynamics and cellular metabolism and reduced the expression of pro-inflammatory markers in target cells. When transplanted in an animal model of multiple sclerosis, exogenous NSCs actively transferred mitochondria to mononuclear phagocytes and induced a significant amelioration of clinical deficits. Our data provide the first evidence that NSCs deliver functional mitochondria to target cells via EVs, paving the way for the development of novel (a)cellular approaches aimed at restoring mitochondrial dysfunction not only in multiple sclerosis, but also in degenerative neurological diseases.
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http://dx.doi.org/10.1371/journal.pbio.3001166DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8055036PMC
April 2021

Succinate Receptor 1: An Emerging Regulator of Myeloid Cell Function in Inflammation.

Trends Immunol 2021 01 2;42(1):45-58. Epub 2020 Dec 2.

Department of Clinical Neurosciences and NIHR Biomedical Research Centre, University of Cambridge, Cambridge, UK. Electronic address:

The rapidly evolving area of immunometabolism has shed new light on the fundamental properties of products and intermediates of cellular metabolism (metabolites), highlighting their key signaling roles in cell-to-cell communication. Recent evidence identifies the succinate-succinate receptor 1 (SUCNR1) axis as an essential regulator of tissue homeostasis. Succinate signaling via SUCNR1 guides divergent responses in immune cells, which are tissue and context dependent. Herein, we explore the main cellular pathways regulated by the succinate-SUCNR1 axis and focus on the biology of SUCNR1 and its roles influencing the function of myeloid cells. Hence, we identify new therapeutic targets and putative therapeutic approaches aimed at resolving detrimental myeloid cell responses in tissues, including those occurring in the persistently inflamed central nervous system (CNS).
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http://dx.doi.org/10.1016/j.it.2020.11.004DOI Listing
January 2021

Harnessing the Neural Stem Cell Secretome for Regenerative Neuroimmunology.

Front Cell Neurosci 2020 5;14:590960. Epub 2020 Nov 5.

Department of Clinical Neurosciences and NIHR Biomedical Research Centre, University of Cambridge, Cambridge, United Kingdom.

Increasing evidence foresees the of neural stem cells (NSCs) to confer superimposable beneficial properties as exogenous NSC transplants in experimental treatments of traumas and diseases of the central nervous system (CNS). Naturally produced biologics include membrane-free signaling molecules and extracellular membrane vesicles (EVs) capable of regulating broad functional responses. The development of high-throughput screening pipelines for the identification and validation of NSC targets is still in early development. Encouraging results from pre-clinical animal models of disease have highlighted -based (acellular) therapeutics as providing significant improvements in biochemical and behavioral measurements. Most of these responses are being hypothesized to be the result of modulating and promoting the restoration of key inflammatory and regenerative programs in the CNS. Here, we will review the most recent findings regarding the identification of NSC-secreted factors capable of modulating the immune response to promote the regeneration of the CNS in animal models of CNS trauma and inflammatory disease and discuss the increased interest to refine the pro-regenerative features of the NSC into a clinically available therapy in the emerging field of Regenerative Neuroimmunology.
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http://dx.doi.org/10.3389/fncel.2020.590960DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7674923PMC
November 2020

Systematic approach to selecting licensed drugs for repurposing in the treatment of progressive multiple sclerosis.

J Neurol Neurosurg Psychiatry 2021 Mar 12;92(3):295-302. Epub 2020 Nov 12.

Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.

Objective: To establish a rigorous, expert-led, evidence-based approach to the evaluation of licensed drugs for repurposing and testing in clinical trials of people with progressive multiple sclerosis (MS).

Methods: We long-listed licensed drugs with evidence of human safety, blood-brain barrier penetrance and demonstrable efficacy in at least one animal model, or mechanistic target, agreed by a panel of experts and people with MS to be relevant to the pathogenesis of progression. We systematically reviewed the preclinical and clinical literature for each compound, condensed this into a database of summary documents and short-listed drugs by scoring each one of them. Drugs were evaluated for immediate use in a clinical trial, and our selection was scrutinised by a final independent expert review.

Results: From a short list of 55 treatments, we recommended four treatments for immediate testing in progressive MS: R-α-lipoic acid, metformin, the combination treatment of R-α-lipoic acid and metformin, and niacin. We also prioritised clemastine, lamotrigine, oxcarbazepine, nimodipine and flunarizine.

Conclusions: We report a standardised approach for the identification of candidate drugs for repurposing in the treatment of progressive MS.
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http://dx.doi.org/10.1136/jnnp-2020-324286DOI Listing
March 2021

Transplantation of induced neural stem cells (iNSCs) into chronically demyelinated corpus callosum ameliorates motor deficits.

Acta Neuropathol Commun 2020 06 9;8(1):84. Epub 2020 Jun 9.

Department of Anatomy, Physiology and Genetics, F. Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd, Bethesda, MD, 20814, USA.

Multiple Sclerosis (MS) causes neurologic disability due to inflammation, demyelination, and neurodegeneration. Immunosuppressive treatments can modify the disease course but do not effectively promote remyelination or prevent long term neurodegeneration. As a novel approach to mitigate chronic stage pathology, we tested transplantation of mouse induced neural stem cells (iNSCs) into the chronically demyelinated corpus callosum (CC) in adult mice. Male C57BL/6 mice fed 0.3% cuprizone for 12 weeks exhibited CC atrophy with chronic demyelination, astrogliosis, and microglial activation. Syngeneic iNSCs were transplanted into the CC after ending cuprizone and perfused for neuropathology 2 weeks later. Magnetic resonance imaging (MRI) sequences for magnetization transfer ratio (MTR), diffusion-weighted imaging (T2), and diffusion tensor imaging (DTI) quantified CC pathology in live mice before and after iNSC transplantation. Each MRI technique detected progressive CC pathology. Mice that received iNSCs had normalized DTI radial diffusivity, and reduced astrogliosis post-imaging. A motor skill task that engages the CC is Miss-step wheel running, which demonstrated functional deficits from cuprizone demyelination. Transplantation of iNSCs resulted in marked recovery of running velocity. Neuropathology after wheel running showed that iNSC grafts significantly increased host oligodendrocytes and proliferating oligodendrocyte progenitors, while modulating axon damage. Transplanted iNSCs differentiated along astrocyte and oligodendrocyte lineages, without myelinating, and many remained neural stem cells. Our findings demonstrate the applicability of neuroimaging and functional assessments for pre-clinical interventional trials during chronic demyelination and detect improved function from iNSC transplantation. Directly reprogramming fibroblasts into iNSCs facilitates the future translation towards exogenous autologous cell therapies.
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http://dx.doi.org/10.1186/s40478-020-00960-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7285785PMC
June 2020

Promises and Limitations of Neural Stem Cell Therapies for Progressive Multiple Sclerosis.

Trends Mol Med 2020 10 21;26(10):898-912. Epub 2020 May 21.

Department of Clinical Neurosciences and National Institute for Health Research (NIHR) Biomedical Research Centre, University of Cambridge, Cambridge, UK.

Multiple disease-modifying medications with regulatory approval to treat multiple sclerosis (MS) are unable to prevent inflammatory tissue damage in the central nervous system (CNS), and none directly promote repair. Thus, there is an unmet clinical need for therapies that can arrest and reverse the persistent accumulation of disabilities associated with progressive forms of MS (P-MS). Preclinical research has revealed an unexpected ability of neural stem cell (NSC) therapies to provide neurotrophic support and inhibit detrimental host immune responses in vivo following transplantation into the chronically inflamed CNS. We discuss NSC transplantation as a promising therapy for P-MS, elaborate on the necessities of clinical trial validation and formalized usage guidelines, and caution about unscrupulous 'clinics' marketing unproven therapies to patients.
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http://dx.doi.org/10.1016/j.molmed.2020.04.005DOI Listing
October 2020

The neural stem cell secretome and its role in brain repair.

Brain Res 2020 02 19;1729:146615. Epub 2019 Dec 19.

Department of Clinical Neurosciences and NIHR Biomedical Research Centre, University of Cambridge, Hills Road, CB2 0HA Cambridge, UK.

Compelling evidence from experimental animal disease models and early-phase clinical trials identifies the transplantation of neural progenitor/stem cells (NSCs) as a viable path towards the development of clinically applicable exogenous stem cell therapies. Building from current advances in the field of NSC biology and following the positive outcomes of NSC transplantation studies, the contemporary view is that transplanted NSCs act as local 'factories' capable of producing and secreting a wide array of immune and neurotrophic factors. This has launched a 'stem cell race' to identify the mechanisms behind stem-cell mediated repair in what has been labeled the paracrine hypothesis. This hypothesis proposes that NSC grafts act as a natural source of potent biologics capable of modulating and promoting the restoration of several key functions in the central nervous system (CNS) tissue following acute or chronic tissue damage. Investigators have been inspired to examine novel ways to harness and utilize the pro-regenerative properties of NSC therapies as an alternative approach to a more classical (small molecule based) treatment of CNS diseases. In this review, we will discuss the most recent findings of human NSC (hNSCs) transplants in experimental animal models of CNS diseases that identify of hNSC-secreted factors, including those trafficked within extracellular membrane vesicles (EVs), and the outcomes of recent clinical trials utilizing hNSC therapeutics in CNS diseases.
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http://dx.doi.org/10.1016/j.brainres.2019.146615DOI Listing
February 2020

SUMOylation promotes survival and integration of neural stem cell grafts in ischemic stroke.

EBioMedicine 2019 Apr 21;42:214-224. Epub 2019 Mar 21.

Department of Clinical Neurosciences, University of Cambridge, UK; NIHR Biomedical Research Centre, University of Cambridge, UK. Electronic address:

Background: Neural stem cell (NSC)-based therapies hold great promise for treating diseases of the central nervous system (CNS). However, several fundamental problems still need to be overcome to fully exploit the clinical potential of NSC therapeutics. Chief among them is the limited survival of NSC grafts within hostile microenvironments.

Methods: Herein, we sought to engineer NSCs in an effort to increase graft survival within ischemic brain lesions via upregulation of global SUMOylation, a post-translational modification critically involved in mediating tolerance to ischemia/reperfusion.

Findings: NSCs overexpressing the SUMO E2-conjugase Ubc9 displayed resistance to oxygen-glucose-deprivation/restoration of oxygen/glucose (OGD/ROG) and enhanced neuronal differentiation in vitro, as well as increased survival and neuronal differentiation when transplanted in mice with transient middle cerebral artery occlusion in vivo.

Interpretation: Our work highlights a critical role for SUMOylation in NSC biology and identifies a biological pathway that can be targeted to increase the effectiveness of exogenous stem cell medicines in ischemic stroke. FUND: Intramural Research Program of the NINDS/NIH, the Italian Multiple Sclerosis Foundation (FISM), the Bascule Charitable Trust, NIH-IRTA-OxCam and Wellcome Trust Research Training Fellowships.
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http://dx.doi.org/10.1016/j.ebiom.2019.03.035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6491415PMC
April 2019

Foxg1 Antagonizes Neocortical Stem Cell Progression to Astrogenesis.

Cereb Cortex 2019 12;29(12):4903-4918

Laboratory of Cerebral Cortex Development, Neuroscience Area, SISSA, Trieste, Italy.

Neocortical astrogenesis follows neuronogenesis and precedes oligogenesis. Among key factors dictating its temporal articulation, there are progression rates of pallial stem cells (SCs) towards astroglial lineages as well as activation rates of astrocyte differentiation programs in response to extrinsic gliogenic cues. In this study, we showed that high Foxg1 SC expression antagonizes astrocyte generation, while stimulating SC self-renewal and committing SCs to neuronogenesis. We found that mechanisms underlying this activity are mainly cell autonomous and highly pleiotropic. They include a concerted downregulation of 4 key effectors channeling neural SCs to astroglial fates, as well as defective activation of core molecular machineries implementing astroglial differentiation programs. Next, we found that SC Foxg1 levels specifically decline during the neuronogenic-to-gliogenic transition, pointing to a pivotal Foxg1 role in temporal modulation of astrogenesis. Finally, we showed that Foxg1 inhibits astrogenesis from human neocortical precursors, suggesting that this is an evolutionarily ancient trait.
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http://dx.doi.org/10.1093/cercor/bhz031DOI Listing
December 2019

Targeting Mitochondrial Metabolism in Neuroinflammation: Towards a Therapy for Progressive Multiple Sclerosis.

Trends Mol Med 2018 10 9;24(10):838-855. Epub 2018 Aug 9.

Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK; NIHR Biomedical Research Centre, University of Cambridge, Cambridge, UK. Electronic address:

The lack of effective treatment options for chronic neurological conditions, such as multiple sclerosis (MS), highlights the need to re-evaluate disease pathophysiology in the process of identifying novel therapeutic targets. The persistent activation of mononuclear phagocytes (MPs) is one of the major drivers of neurodegeneration and it sustains central nervous system (CNS) damage. Mitochondrial metabolism influences the activity of MPs, and the metabolites that they produce have key signalling roles in inflammation. However, how changes in immune cell metabolism sustain a chronic state of neuroinflammation is not fully understood. Novel molecular and cellular therapies for chronic neuroinflammation should be developed to target mitochondrial metabolism in innate immune cells to prevent secondary neurological damage and the accumulation of irreversible disability in patients.
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http://dx.doi.org/10.1016/j.molmed.2018.07.007DOI Listing
October 2018

Neural Stem Cell Grafts Promote Astroglia-Driven Neurorestoration in the Aged Parkinsonian Brain via Wnt/β-Catenin Signaling.

Stem Cells 2018 08 16;36(8):1179-1197. Epub 2018 Apr 16.

Oasi Research Institute-IRCCS, Troina, Italy.

During aging-one the most potent risk factors for Parkinson's disease (PD)-both astrocytes and microglia undergo functional changes that ultimately hamper homoeostasis, defense, and repair of substantia nigra pars compacta (SNpc) midbrain dopaminergic (mDA) neurons. We tested the possibility of rejuvenating the host microenvironment and boosting SNpc DA neuronal plasticity via the unilateral transplantation of syngeneic neural stem/progenitor cells (NSCs) in the SNpc of aged mice with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced experimental PD. Transplanted NSCs within the aged SNpc engrafted and migrated in large proportions to the tegmental aqueduct mDA niche, with 30% acquiring an astroglial phenotype. Both graft-derived exogenous (ex-Astro) and endogenous astrocytes (en-Astro) expressed Wnt1. Both ex-Astro and en-Astro were key triggers of Wnt/β-catenin signaling in SNpc-mDA neurons and microglia, which was associated with mDA neurorescue and immunomodulation. At the aqueduct-ventral tegmental area level, NSC grafts recapitulated a genetic Wnt1-dependent mDA developmental program, inciting the acquisition of a mature Nurr1 TH neuronal phenotype. Wnt/β-catenin signaling antagonism abolished mDA neurorestoration and immune modulatory effects of NSC grafts. Our work implicates an unprecedented therapeutic potential for somatic NSC grafts in the restoration of mDA neuronal function in the aged Parkinsonian brain. Stem Cells 2018;36:1179-1197.
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http://dx.doi.org/10.1002/stem.2827DOI Listing
August 2018

RNA Nanotherapeutics for the Amelioration of Astroglial Reactivity.

Mol Ther Nucleic Acids 2018 Mar 24;10:103-121. Epub 2017 Nov 24.

Department of Clinical Neurosciences, Division of Stem Cell Neurobiology, Wellcome Trust-Medical Research Council Stem Cell Institute and NIHR Biomedical Research Centre, University of Cambridge, Cambridge, UK. Electronic address:

In response to injuries to the CNS, astrocytes enter a reactive state known as astrogliosis, which is believed to be deleterious in some contexts. Activated astrocytes overexpress intermediate filaments including glial fibrillary acidic protein (GFAP) and vimentin (Vim), resulting in entangled cells that inhibit neurite growth and functional recovery. Reactive astrocytes also secrete inflammatory molecules such as Lipocalin 2 (Lcn2), which perpetuate reactivity and adversely affect other cells of the CNS. Herein, we report proof-of-concept use of the packaging RNA (pRNA)-derived three-way junction (3WJ) motif as a platform for the delivery of siRNAs to downregulate such reactivity-associated genes. In vitro, siRNA-3WJs induced a significant knockdown of Gfap, Vim, and Lcn2 in a model of astroglial activation, with a concomitant reduction in protein expression. Knockdown of Lcn2 also led to reduced protein secretion from reactive astroglial cells, significantly impeding the perpetuation of inflammation in otherwise quiescent astrocytes. Intralesional injection of anti-Lcn2-3WJs in mice with contusion spinal cord injury led to knockdown of Lcn2 at mRNA and protein levels in vivo. Our results provide evidence for siRNA-3WJs as a promising platform for ameliorating astroglial reactivity, with significant potential for further functionalization and adaptation for therapeutic applications in the CNS.
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http://dx.doi.org/10.1016/j.omtn.2017.11.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5738063PMC
March 2018

Macrophage-Derived Extracellular Succinate Licenses Neural Stem Cells to Suppress Chronic Neuroinflammation.

Cell Stem Cell 2018 03 22;22(3):355-368.e13. Epub 2018 Feb 22.

Department of Clinical Neurosciences and NIHR Biomedical Research Centre, University of Cambridge, Cambridge, UK. Electronic address:

Neural stem cell (NSC) transplantation can influence immune responses and suppress inflammation in the CNS. Metabolites, such as succinate, modulate the phenotype and function of immune cells, but whether and how NSCs are also activated by such immunometabolites to control immunoreactivity and inflammatory responses is unclear. Here, we show that transplanted somatic and directly induced NSCs ameliorate chronic CNS inflammation by reducing succinate levels in the cerebrospinal fluid, thereby decreasing mononuclear phagocyte (MP) infiltration and secondary CNS damage. Inflammatory MPs release succinate, which activates succinate receptor 1 (SUCNR1)/GPR91 on NSCs, leading them to secrete prostaglandin E2 and scavenge extracellular succinate with consequential anti-inflammatory effects. Thus, our work reveals an unexpected role for the succinate-SUCNR1 axis in somatic and directly induced NSCs, which controls the response of stem cells to inflammatory metabolic signals released by type 1 MPs in the chronically inflamed brain.
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http://dx.doi.org/10.1016/j.stem.2018.01.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5842147PMC
March 2018

Evaluation of RGD functionalization in hybrid hydrogels as 3D neural stem cell culture systems.

Biomater Sci 2018 Feb;6(3):501-510

Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, via Mancinelli 7, 20131 Milan, Italy.

The use of neural stem cells (NSCs) in cell therapy has become a powerful tool used for the treatment of central nervous system diseases, including traumatic brain and spinal cord injuries. However, a significant drawback is related to the limited viability after transplantation in situ. The design of three-dimensional (3D) scaffolds that are capable of resembling the architecture and physico-chemical features of an extracellular environment could be a suitable approach to improve cell survival and preserve their cellular active phase over time. In this study, we investigated NSC adhesion and proliferation in hydrogel systems. In particular, we evaluated the effect of RGD binding domains on cell fate within the polymeric scaffold. The introduction of a tripeptide via hydrogel chemical functionalization improved the percentage of proliferating cells until 8 days after seeding when compared to the unmodified scaffold. The beneficial effects of this 3D culture system was further evident when compared to a NSC monolayer (2D) culture, resulting in an approximately 40% increase in cells in the active phases at 4 and 8 days, and maintained a difference of 25% until 21 days after seeding.
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http://dx.doi.org/10.1039/c7bm01056gDOI Listing
February 2018

Topotecan is a potent inhibitor of SUMOylation in glioblastoma multiforme and alters both cellular replication and metabolic programming.

Sci Rep 2017 08 7;7(1):7425. Epub 2017 Aug 7.

Stroke Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.

Protein SUMOylation is a dynamic post-translational modification shown to be involved in a diverse set of physiologic processes throughout the cell. SUMOylation has also been shown to play a role in the pathobiology of myriad cancers, one of which is glioblastoma multiforme (GBM). As such, the clinical significance and therapeutic utility offered via the selective control of global SUMOylation is readily apparent. There are, however, relatively few known/effective inhibitors of global SUMO-conjugation. Herein we describe the identification of topotecan as a novel inhibitor of global SUMOylation. We also provide evidence that inhibition of SUMOylation by topotecan is associated with reduced levels of CDK6 and HIF-1α, as well as pronounced changes in cell cycle progression and cellular metabolism, thereby highlighting its putative role as an adjuvant therapy in defined GBM patient populations.
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http://dx.doi.org/10.1038/s41598-017-07631-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5547153PMC
August 2017

Extracellular vesicles are independent metabolic units with asparaginase activity.

Nat Chem Biol 2017 Sep 3;13(9):951-955. Epub 2017 Jul 3.

Wellcome Trust-Medical Research Council Stem Cell Institute, Department of Clinical Neurosciences-Division of Stem Cell Neurobiology, and NIHR Biomedical Research Centre, University of Cambridge, Cambridge, UK.

Extracellular vesicles (EVs) are membrane particles involved in the exchange of a broad range of bioactive molecules between cells and the microenvironment. Although it has been shown that cells can traffic metabolic enzymes via EVs, much remains to be elucidated with regard to their intrinsic metabolic activity. Accordingly, herein we assessed the ability of neural stem/progenitor cell (NSC)-derived EVs to consume and produce metabolites. Our metabolomics and functional analyses both revealed that EVs harbor L-asparaginase activity, catalyzed by the enzyme asparaginase-like protein 1 (Asrgl1). Critically, we show that Asrgl1 activity is selective for asparagine and is devoid of glutaminase activity. We found that mouse and human NSC EVs traffic Asrgl1. Our results demonstrate, for the first time, that NSC EVs function as independent metabolic units that are able to modify the concentrations of critical nutrients, with the potential to affect the physiology of their microenvironment.
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http://dx.doi.org/10.1038/nchembio.2422DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5563455PMC
September 2017

Neural stem cell transplantation in ischemic stroke: A role for preconditioning and cellular engineering.

J Cereb Blood Flow Metab 2017 Jul 17;37(7):2314-2319. Epub 2017 Mar 17.

2 Stroke Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health (NINDS/NIH), Bethesda, MD, USA.

Ischemic stroke continues to be a leading cause of morbidity and mortality throughout the world. To protect and/or repair the ischemic brain, a multitiered approach may be centered on neural stem cell (NSC) transplantation. Transplanted NSCs exert beneficial effects not only via structural replacement, but also via immunomodulatory and/or neurotrophic actions. Unfortunately, the clinical translation of such promising therapies remains elusive, in part due to their limited persistence/survivability within the hostile ischemic microenvironment. Herein, we discuss current approaches for the development of NSCs more amenable to survival within the ischemic brain as a tool for future cellular therapies in stroke.
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http://dx.doi.org/10.1177/0271678X17700432DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5531358PMC
July 2017

Treatment Challenges of a Primary Vertebral Artery Aneurysm Causing Recurrent Ischemic Strokes.

Case Rep Neurol Med 2017 10;2017:2571630. Epub 2017 Jan 10.

Stroke Unit, Department of Neurology and Neurophysiology, San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy.

. Extracranial vertebral artery aneurysms are a rare cause of embolic stroke; surgical and endovascular therapy options are debated and long-term complication may occur. . A 53-year-old man affected by neurofibromatosis type 1 (NF1) came to our attention for recurrent vertebrobasilar embolic strokes, caused by a primary giant, partially thrombosed, fusiform aneurysm of the left extracranial vertebral artery. The aneurysm was treated by endovascular approach through deposition of Guglielmi Detachable Coils in the proximal segment of the left vertebral artery. Six years later the patient presented stroke recurrence. Cerebral angiography and Color Doppler Ultrasound well characterized the unique hemodynamic condition developed over the years responsible for the new embolic event: the aneurysm had been revascularized from its distal portion by reverse blood flow coming from the patent vertebrobasilar axis. A biphasic Doppler signal in the left vertebral artery revealed a peculiar behavior of the blood flow, alternately directed to the aneurysm and backwards to the basilar artery. Surgical ligation of the distal left vertebral artery and excision of the aneurysm were thus performed. . This is the first described case of NF1-associated extracranial vertebral artery aneurysm presenting with recurrent embolic stroke. Complete exclusion of the aneurysm from the blood circulation is advisable to achieve full resolution of the embolic source.
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http://dx.doi.org/10.1155/2017/2571630DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5259648PMC
January 2017

Modulation of host immune responses following non-hematopoietic stem cell transplantation: Translational implications in progressive multiple sclerosis.

J Neuroimmunol 2019 06 15;331:11-27. Epub 2016 Dec 15.

Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, Wellcome Trust-MRC Stem Cell Institute, NIHR Biomedical Research Centre, University of Cambridge, Cambridge, UK. Electronic address:

There exists an urgent need for effective treatments for those patients suffering from chronic/progressive multiple sclerosis (MS). Accordingly, it has become readily apparent that different classes of stem cell-based therapies must be explored at both the basic science and clinical levels. Herein, we provide an overview of the basic mechanisms underlying the pre-clinical benefits of exogenously delivered non-hematopoietic stem cells (nHSCs) in animal models of MS. Further, we highlight a number of early clinical trials in which nHSCs have been used to treat MS. Finally, we identify a series of challenges that must be met and ultimately overcome if such promising therapeutics are to be advanced from the bench to the bedside.
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http://dx.doi.org/10.1016/j.jneuroim.2016.12.005DOI Listing
June 2019

Interleukin-4 induced 1 (IL4I1) promotes central nervous system remyelination.

Brain 2016 12;139(Pt 12):3052-3054

Department of Clinical Neurosciences, Division of Stem Cell Neurobiology, Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK.

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http://dx.doi.org/10.1093/brain/aww266DOI Listing
December 2016

Astrocyte power fuels neurons during stroke.

Swiss Med Wkly 2016 10;146:w14374. Epub 2016 Nov 10.

MRC Cancer Unit, University of Cambridge, UK.

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http://dx.doi.org/10.4414/smw.2016.14374DOI Listing
September 2017

Neural Stem Cell Transplantation Induces Stroke Recovery by Upregulating Glutamate Transporter GLT-1 in Astrocytes.

J Neurosci 2016 10;36(41):10529-10544

Neuroimmunology Unit, Institute of Experimental Neurology and

Ischemic stroke is the leading cause of disability, but effective therapies are currently widely lacking. Recovery from stroke is very much dependent on the possibility to develop treatments able to both halt the neurodegenerative process as well as to foster adaptive tissue plasticity. Here we show that ischemic mice treated with neural precursor cell (NPC) transplantation had on neurophysiological analysis, early after treatment, reduced presynaptic release of glutamate within the ipsilesional corticospinal tract (CST), and an enhanced NMDA-mediated excitatory transmission in the contralesional CST. Concurrently, NPC-treated mice displayed a reduced CST degeneration, increased axonal rewiring, and augmented dendritic arborization, resulting in long-term functional amelioration persisting up to 60 d after ischemia. The enhanced functional and structural plasticity relied on the capacity of transplanted NPCs to localize in the peri-ischemic and ischemic area, to promote the upregulation of the glial glutamate transporter 1 (GLT-1) on astrocytes and to reduce peri-ischemic extracellular glutamate. The upregulation of GLT-1 induced by transplanted NPCs was found to rely on the secretion of VEGF by NPCs. Blocking VEGF during the first week after stroke reduced GLT-1 upregulation as well as long-term behavioral recovery in NPC-treated mice. Our results show that NPC transplantation, by modulating the excitatory-inhibitory balance and stroke microenvironment, is a promising therapy to ameliorate disability, to promote tissue recovery and plasticity processes after stroke.

Significance Statement: Tissue damage and loss of function occurring after stroke can be constrained by fostering plasticity processes of the brain. Over the past years, stem cell transplantation for repair of the CNS has received increasing interest, although underlying mechanism remain elusive. We here show that neural stem/precursor cell transplantation after ischemic stroke is able to foster axonal rewiring and dendritic plasticity and to induce long-term functional recovery. The observed therapeutic effect of neural precursor cells seems to underlie their capacity to upregulate the glial glutamate transporter on astrocytes through the vascular endothelial growth factor inducing favorable changes in the electrical and molecular stroke microenvironment. Cell-based approaches able to influence plasticity seem particularly suited to favor poststroke recovery.
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http://dx.doi.org/10.1523/JNEUROSCI.1643-16.2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5059427PMC
October 2016

Metabolic determinants of the immune modulatory function of neural stem cells.

J Neuroinflammation 2016 09 2;13(1):232. Epub 2016 Sep 2.

Department of Clinical Neurosciences, Wellcome Trust-Medical Research Council Stem Cell Institute and National Institute for Health Research Biomedical Research Centre, University of Cambridge, Hills Road, CB2 0HA, Cambridge, UK.

Background: Neural stem cells (NSCs) display tissue trophic and immune modulatory therapeutic activities after transplantation in central nervous system disorders. The intercellular interplay between stem cells and target immune cells is increased in NSCs exposed to inflammatory cues. Here, we hypothesize that inflammatory cytokine signalling leads to metabolic reprogramming of NSCs regulating some of their immune modulatory effects.

Methods: NSC lines were prepared from the subventricular zone (SVZ) of 7-12-week-old mice. Whole secretome-based screening and analysis of intracellular small metabolites was performed in NSCs exposed to cocktails of either Th1-like (IFN-γ, 500 U/ml; TNF-α, 200 U/ml; IL-1β, 100 U/ml) or Th2-like (IL-4, IL-5 and IL-13; 10 ng/ml) inflammatory cytokines for 16 h in vitro. Isotopologues distribution of arginine and downstream metabolites was assessed by liquid chromatography/mass spectrometry in NSCs incubated with U-(13)C6 L-arginine in the presence or absence of Th1 or Th2 cocktails (Th1 NSCs or Th2 NSCs). The expression of arginase I and II was investigated in vitro in Th1 NSCs and Th2 NSCs and in vivo in the SVZ of mice with experimental autoimmune encephalomyelitis, as prototypical model of Th1 cell-driven brain inflammatory disease. The effects of the inflammatory cytokine signalling were studied in NSC-lymph node cells (LNC) co-cultures by flow cytometry-based analysis of cell proliferation following pan-arginase inhibition with N(ω)-hydroxy-nor-arginine (nor-NOHA).

Results: Cytokine-primed NSCs showed significantly higher anti-proliferative effect in co-cultures vs. control NSCs. Metabolomic analysis of intracellular metabolites revealed alteration of arginine metabolism and increased extracellular arginase I activity in cytokine-primed NSCs. Arginase inhibition by nor-NOHA partly rescued the anti-proliferative effects of cytokine-primed NSCs.

Conclusions: Our work underlines the use of metabolic profiling as hypothesis-generating tools that helps unravelling how stem cell-mediated mechanisms of tissue restoration become affected by local inflammatory responses. Among different therapeutic candidates, we identify arginase signalling as novel metabolic determinant of the NSC-to-immune system communication.
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http://dx.doi.org/10.1186/s12974-016-0667-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5009670PMC
September 2016

A novel quantitative high-throughput screen identifies drugs that both activate SUMO conjugation via the inhibition of microRNAs 182 and 183 and facilitate neuroprotection in a model of oxygen and glucose deprivation.

J Cereb Blood Flow Metab 2016 Feb 23;36(2):426-41. Epub 2015 Oct 23.

Stroke Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health (NINDS/NIH), Bethesda, MD, USA

The conjugation/de-conjugation of Small Ubiquitin-like Modifier (SUMO) has been shown to be associated with a diverse set of physiologic/pathologic conditions. The clinical significance and ostensible therapeutic utility offered via the selective control of the global SUMOylation process has become readily apparent in ischemic pathophysiology. Herein, we describe the development of a novel quantitative high-throughput screening (qHTS) system designed to identify small molecules capable of increasing SUMOylation via the regulation/inhibition of members of the microRNA (miRNA)-182 family. This assay employs a SHSY5Y human neuroblastoma cell line stably transfected with a dual firefly-Renilla luciferase reporter system for identification of specific inhibitors of either miR-182 or miR-183. In this study, we have identified small molecules capable of inducing increased global conjugation of SUMO in both SHSY5Y cells and rat E18-derived primary cortical neurons. The protective effects of a number of the identified compounds were confirmed via an in vitro ischemic model (oxygen/glucose deprivation). Of note, this assay can be easily repurposed to allow high-throughput analyses of the potential drugability of other relevant miRNA(s) in ischemic pathobiology.
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http://dx.doi.org/10.1177/0271678X15609939DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4759677PMC
February 2016

Functional Magnetic Resonance Imaging of Rats with Experimental Autoimmune Encephalomyelitis Reveals Brain Cortex Remodeling.

J Neurosci 2015 Jul;35(27):10088-100

Computer Science, University of Verona, I-37134 Verona, Italy, National Interuniversity Consortium of Materials Science and Technology, I-50121 Florence, Italy,

Unlabelled: Cortical reorganization occurring in multiple sclerosis (MS) patients is thought to play a key role in limiting the effect of structural tissue damage. Conversely, its exhaustion may contribute to the irreversible disability that accumulates with disease progression. Several aspects of MS-related cortical reorganization, including the overall functional effect and likely modulation by therapies, still remain to be elucidated. The aim of this work was to assess the extent of functional cortical reorganization and its brain structural/pathological correlates in Dark Agouti rats with experimental autoimmune encephalomyelitis (EAE), a widely accepted preclinical model of chronic MS. Morphological and functional MRI (fMRI) were performed before disease induction and during the relapsing and chronic phases of EAE. During somatosensory stimulation of the right forepaw, fMRI demonstrated that cortical reorganization occurs in both relapsing and chronic phases of EAE with increased activated volume and decreased laterality index versus baseline values. Voxel-based morphometry demonstrated gray matter (GM) atrophy in the cerebral cortex, and both GM and white matter atrophy were assessed by ex vivo pathology of the sensorimotor cortex and corpus callosum. Neuroinflammation persisted in the relapsing and chronic phases, with dendritic spine density in the layer IV sensory neurons inversely correlating with the number of cluster of differentiation 45-positive inflammatory lesions. Our work provides an innovative experimental platform that may be pivotal for the comprehension of key mechanisms responsible for the accumulation of irreversible brain damage and for the development of innovative therapies to reduce disability in EAE/MS.

Significance Statement: Since the early 2000s, functional MRI (fMRI) has demonstrated profound modifications in the recruitment of cortical areas during motor, cognitive, and sensory tasks in multiple sclerosis (MS) patients. Experimental autoimmune encephalomyelitis (EAE) represents a reliable model of the chronic-progressive variant of MS. fMRI studies in EAE have not been performed extensively up to now. This paper reports fMRI studies in a rat model of MS with somatosensory stimulation of the forepaw. We demonstrated modifications in the recruitment of cortical areas consistent with data from MS patients. To the best of our knowledge, this is the first report of cortical remodeling in a preclinical in vivo model of MS.
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http://dx.doi.org/10.1523/JNEUROSCI.0540-15.2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4495237PMC
July 2015

The role of immune cells, glia and neurons in white and gray matter pathology in multiple sclerosis.

Prog Neurobiol 2015 Apr 21;127-128:1-22. Epub 2015 Mar 21.

Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, Wellcome Trust-MRC Stem Cell Institute and NIHR Biomedical Research Centre, University of Cambridge, CB2 0PY, UK.

Multiple sclerosis is one of the most common causes of chronic neurological disability beginning in early to middle adult life. Multiple sclerosis is idiopathic in nature, yet increasing correlative evidence supports a strong association between one's genetic predisposition, the environment and the immune system. Symptoms of multiple sclerosis have primarily been shown to result from a disruption in the integrity of myelinated tracts within the white matter of the central nervous system. However, recent research has also highlighted the hitherto underappreciated involvement of gray matter in multiple sclerosis disease pathophysiology, which may be especially relevant when considering the accumulation of irreversible damage and progressive disability. This review aims at providing a comprehensive overview of the interplay between inflammation, glial/neuronal damage and regeneration throughout the course of multiple sclerosis via the analysis of both white and gray matter lesional pathology. Further, we describe the common pathological mechanisms underlying both relapsing and progressive forms of multiple sclerosis, and analyze how current (as well as future) treatments may interact and/or interfere with its pathology. Understanding the putative mechanisms that drive disease pathogenesis will be key in helping to develop effective therapeutic strategies to prevent, mitigate, and treat the diverse morbidities associated with multiple sclerosis.
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http://dx.doi.org/10.1016/j.pneurobio.2015.02.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4578232PMC
April 2015

Defining minor symptoms in acute ischemic stroke.

Cerebrovasc Dis 2015 14;39(3-4):209-15. Epub 2015 Mar 14.

San Raffaele Scientific Institute-Institute of Experimental Neurology, Stroke Unit-Department of Neurology and Neurophysiology, Milan, Italy.

Background: Thrombolysis is often withheld from acute ischemic stroke patients presenting with mild symptoms; however, up to 40% of these patients end up with a poor outcome when left untreated. Since there is lack of consensus on the definition of minor symptoms, we aimed at addressing this issue by looking for features that would better predict functional outcomes at 3 months.

Methods: Among all acute ischemic stroke patients admitted to our Stroke Unit (n = 1,229), we selected a cohort of patients who arrived within 24 hours from symptoms onset, with baseline NIHSS ≤6, not treated with thrombolysis (n = 304). Epidemiological data, comorbidities, radiological features and clinical presentation (NIHSS items) were collected to identify predictors of outcome. Our cohort was tested against minor stroke definitions selected from the literature and a newly proposed one.

Results: Three months after stroke onset, 97 patients (31.9%) had mRS ≥ 2. Independent predictors of poor outcome were age (OR 0.97 [95% CI 0.95-9.99]) and baseline NIHSS score (OR 0.79 [95% CI 0.67-0.94]), while cardioembolic aetiology was negatively associated (OR 3.29 [95% CI 1.51-7.14]). Items of NIHSS associated with poor outcome were impairment of right motor arm (OR 0.49 [95% CI 0.27-0.91]) or the involvement of any of the motor items (OR 0.69 [95% CI 0.48-0.99]). The definition of minor stroke as NIHSS ≤3 and the new proposed definition had the highest sensitivity and accuracy and were independent predictors of outcome.

Conclusions: Our study confirmed that in spite of a low NIHSS score, one third of patients had poor outcome. As already described, age and NIHSS score remained independent predictors of poor outcome even in mild stroke. Also, motor impairment appeared a major determinant of poor outcome. The new proposed definition of minor stroke featured the NIHSS score and the NIHSS items that better predicted functional outcome. Awareness that even minor stroke can yield to poor outcome should sensitize patients to arrive early to the ED and neurologists to administer rt-PA.
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http://dx.doi.org/10.1159/000375151DOI Listing
February 2016

Neural precursor cells in the ischemic brain - integration, cellular crosstalk, and consequences for stroke recovery.

Front Cell Neurosci 2014 16;8:291. Epub 2014 Sep 16.

John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, NIHR Biomedical Research Centre, and Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge Cambridge, UK.

After an ischemic stroke, neural precursor cells (NPCs) proliferate within major germinal niches of the brain. Endogenous NPCs subsequently migrate toward the ischemic lesion where they promote tissue remodeling and neural repair. Unfortunately, this restorative process is generally insufficient and thus unable to support a full recovery of lost neurological functions. Supported by solid experimental and preclinical data, the transplantation of exogenous NPCs has emerged as a potential tool for stroke treatment. Transplanted NPCs are thought to act mainly via trophic and immune modulatory effects, thereby complementing the restorative responses initially executed by the endogenous NPC population. Recent studies have attempted to elucidate how the therapeutic properties of transplanted NPCs vary depending on the route of transplantation. Systemic NPC delivery leads to potent immune modulatory actions, which prevent secondary neuronal degeneration, reduces glial scar formation, diminishes oxidative stress and stabilizes blood-brain barrier integrity. On the contrary, local stem cell delivery allows for the accumulation of large numbers of transplanted NPCs in the brain, thus achieving high levels of locally available tissue trophic factors, which may better induce a strong endogenous NPC proliferative response. Herein we describe the diverse capabilities of exogenous (systemically vs. locally transplanted) NPCs in enhancing the endogenous neurogenic response after stroke, and how the route of transplantation may affect migration, survival, bystander effects and integration of the cellular graft. It is the authors' claim that understanding these aspects will be of pivotal importance in discerning how transplanted NPCs exert their therapeutic effects in stroke.
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http://dx.doi.org/10.3389/fncel.2014.00291DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4165213PMC
October 2014

The role of the immune system in central nervous system plasticity after acute injury.

Neuroscience 2014 Dec 29;283:210-221. Epub 2014 Apr 29.

John van Geest Centre for Brain Repair, Dept of Clinical Neurosciences.

Acute brain injuries cause rapid cell death that activates bidirectional crosstalk between the injured brain and the immune system. In the acute phase, the damaged CNS activates resident and circulating immune cells via the local and systemic release of soluble mediators. This early immune activation is necessary to confine the injured tissue and foster the clearance of cellular debris, thus bringing the inflammatory reaction to a close. In the chronic phase, a sustained immune activation has been described in many CNS disorders, and the degree of this prolonged response has variable effects on spontaneous brain regenerative processes. The challenge for treating acute CNS damage is to understand how to optimally engage and modify these immune responses, thus providing new strategies that will compensate for tissue lost to injury. Herein we have reviewed the available information regarding the role and function of the innate and adaptive immune responses in influencing CNS plasticity during the acute and chronic phases of after injury. We have examined how CNS damage evolves along the activation of main cellular and molecular pathways that are associated with intrinsic repair, neuronal functional plasticity and facilitation of tissue reorganization.
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http://dx.doi.org/10.1016/j.neuroscience.2014.04.036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4167877PMC
December 2014
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