Myelin repair: the role of stem and precursor cells in multiple sclerosis

Fingolimod after a first unilateral episode of acute optic neuritis (MOVING) - preliminary results from a randomized, rater-blind, active-controlled, phase 2 trial

Background

Neuroprotection and promotion of remyelination represent important therapeutic gaps in multiple sclerosis (MS). Acute optic neuritis (ON) is a frequent MS manifestation. Based on the presence and properties of sphingosine-1-phosphate receptors (S1PR) on astrocytes and oligodendrocytes, we hypothesized that remyelination can be enhanced by treatment with fingolimod, a S1PR modulator currently licensed for relapsing-remitting MS.

Methods

MOVING was an investigator-driven, rater-blind, randomized clinical trial. Patients with acute unilateral ON, occurring as a clinically isolated syndrome or MS relapse, were randomized to 6 months of treatment with 0.5 mg oral fingolimod or subcutaneous IFN-β 1b 250 μg every other day. The change in multifocal visual evoked potential (mfVEP) latency of the qualifying eye was examined as the primary (month 6 vs. baseline) and secondary (months 3, 6 and 12 vs. baseline) outcome. In addition, full field visual evoked potentials, visual acuity, optical coherence tomography as well as clinical relapses and measures of disability, cerebral MRI, and self-reported visual quality of life were obtained for follow-up. The study was halted due to insufficient recruitment (n = 15), and available results are reported.

Results

Per protocol analysis of the primary endpoint revealed a significantly larger reduction of mfVEP latency at 6 months compared to baseline with fingolimod treatment (n = 5; median decrease, 15.7 ms) than with IFN-β 1b treatment (n = 4; median increase, 8.15 ms) (p <  0.001 for interaction). Statistical significance was maintained in the secondary endpoint analysis. Descriptive results are reported for other endpoints.

Conclusion

Preliminary results of the MOVING trial argue in support of a beneficial effect of fingolimod on optic nerve remyelination when compared to IFN-β treatment. Interpretation is limited by the small number of complete observations, an unexpected deterioration of the control group and a difference in baseline mfVEP latencies. The findings need to be confirmed in larger studies.

Trial registration

The trial was registered as EUDRA-CT 2011–004787-30 on October 26, 2012 and as NCT01647880 on July 24, 2012.

The role of MRI in the evaluation of secondary progressive multiple sclerosis

Magnetic resonance imaging already has an established role in the diagnosis of multiple sclerosis, but it also has the potential to provide prognostic information, and to monitor [corrected] disease progression in clinical trials and practice. Magnetic resonance imaging measures are increasingly being used as the primary outcome in early phase clinical trials of immunomodulatory therapies (for example brain white matter lesion counts or volumes, and gadolinium contrast enhancing lesions) and putatively neuroprotective agents (for example measures of whole brain atrophy), and trials of agents that promote remyelination are also likely to follow suit. In this review we consider the use of magnetic resonance imaging measures as predictors and markers of disease progression in multiple sclerosis, and explore possible future directions in this rapidly developing field.

Mesenchymal stem cells for the treatment of neurodegenerative and psychiatric disorders

Mesenchymal stem cells (MSCs) are multipotent progenitor cells that have the capacity to differentiate into all lineages of mesodermal origin, e.g., cartilage, bone, and adipocytes. MSCs have been identified at different stages of development, including adulthood, and in different tissues, such as bone marrow, adipose tissue and umbilical cord. Recent studies have shown that MSCs have the ability to migrate to injured sites. In this regard, an important characteristic of MSCs is their immunomodulatory and anti-inflammatory effects. For instance, there is evidence that MSCs can regulate the immune system by inhibiting proliferation of T and B cells. Clinical interest in the use of MSCs has increased considerably over the past few years, especially because of the ideal characteristics of these cells for regenerative medicine. Therapies with MSCs have shown promising results neurodegenerative diseases, in addition to regulating inflammation, they can promote other beneficial effects, such as neuronal growth, decrease free radicals, and reduce apoptosis. Notwithstanding, despite the vast amount of research into MSCs in neurodegenerative diseases, the mechanism of action of MSCs are still not completely clarified, hindering the development of effective treatments. Conversely, studies in models of psychiatric disorders are scarce, despite the promising results of MSCs therapies in this field as well.

Parallel changes in structural and functional measures of optic nerve myelination after optic neuritis

Introduction

Visual evoked potential (VEP) latency prolongation and optic nerve lesion length after acute optic neuritis (ON) corresponds to the degree of demyelination, while subsequent recovery of latency may represent optic nerve remyelination. We aimed to investigate the relationship between multifocal VEP (mfVEP) latency and optic nerve lesion length after acute ON.

Methods

Thirty acute ON patients were studied at 1,3,6 and 12 months using mfVEP and at 1 and 12 months with optic nerve MRI. LogMAR and low contrast visual acuity were documented. By one month, the mfVEP amplitude had recovered sufficiently for latency to be measured in 23 (76.7%) patients with seven patients having no recordable mfVEP in more than 66% of segments in at least one test. Only data from these 23 patients was analysed further.

Results

Both latency and lesion length showed significant recovery during the follow-up period. Lesion length and mfVEP latency were highly correlated at 1 (r = 0.94, p = <0.0001) and 12 months (r = 0.75, p < 0.001). Both measures demonstrated a similar trend of recovery. Speed of latency recovery was faster in the early follow-up period while lesion length shortening remained relatively constant. At 1 month, latency delay was worse by 1.76ms for additional 1mm of lesion length while at 12 months, 1mm of lesion length accounted for 1.94ms of latency delay.

Conclusion

A strong association between two putative measures of demyelination in early and chronic ON was found. Parallel recovery of both measures could reflect optic nerve remyelination.

Biological characteristics of a new human glioma cell line transformed into A2B5(+) stem cells

Objective

The new glioma cell line SHG-139 was established and its phenotype, tumorigenicity, pathological characteristics, derived stem cells SHG139S were studied.

Methods

Immunohistochemistry was used to assess expressions in the patient and mouse tumor tissues, SHG-139 and SHG-139S. Primary SHG-139 culture was performed, cell proliferation, cell cycle and genetic characteristics were assessed. MiRNA (Micro RNA) and LncRNA (Long non-coding RNA) microarray was performed.

Results

We found that the glioma tissue was positive for A2B5 (Glial precursors ganglioside), GFAP (Glial fibrillary acidic protein), S-100 (Acid calcium bingding protein), VEGF (Vascular endothelial growth factor), VEGFR (Vascular endothelial growth factor receptor) and negative for Ki-67 (Nuclcar- associated antigen). SHG-139 proliferated significantly within 24h; its total number of chromosomes was 68; ratios of SHG-139 and SHG-139S cells in G1 phase were highest. SHG-139 cells were positive for A2B5, GalC (Galactocerebrosides), GFAP, S-100 and Vimentin, while SHG-139S cells were positive for A2B5, Nestin, and NG2 (Neuron-glia antigen2), and negative for Vimentin and IDHR132H (Isocitrate dehydrogenase); cells rarely stained for CD133 (Cluster of differentiation133). SHG-139 intracranial xenografts expressed GFAP, but no overt oligodendroglioma was observed. In SHG-139S xenografts, GFAP and S-100 were expressed, while CD133 was not detected; a few A2B5⁺ cells were found at tumor edges, and typical oligodendroglioma were obtained. In addition, SHG-139S xenograft tumors were more aggressive than those of SHG-139. Anti-mouse CD31 (Cluster of differentiation31) staining revealed murine vessels at the border between xenograft tumor and normal brain tissue; Anti-human CD34 (Cluster of differentiation34) staining was negative. Biochip technology of SHG139S showed several miRNA and lncRNA were differently expressed in SHG139 and SHG139S.

Conclusions

SHG-139 was an astroglioma cell line which yielded stem cells SHG-139S. SHG-139S cells constituted an A2B5⁺/CD133⁻ GSC subgroup.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0343-z) contains supplementary material, which is available to authorized users.

Mobilization of progenitors in the subventricular zone to undergo oligodendrogenesis in the Theiler's virus model of multiple sclerosis: implications for remyelination at lesions sites

Remyelination involves the generation of new myelin sheaths around axons, as occurs spontaneously in many multiple sclerosis (MS) lesions and other demyelinating diseases. When considering repairing a diseased brain, the adult mouse subventricular zone (SVZ) is of particular interest since the stem cells in this area can migrate and differentiate into the three major cell types in the central nervous system (CNS). In Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD), we assessed the relative contribution of the SVZ to the remyelination in the corpus callosum at preclinical stages in this MS model. CNPase, MBP and Luxol Fast Blue staining revealed prominent demyelination 35days post-infection (dpi), concomitant with a strong staining in GFAP(+) type B astrocytes in the SVZ and the increased proliferation in this area. The migration of oligodendrocyte progenitors from the SVZ contributed to the remyelination observed at 60 dpi, evident through the number of APC(+)/BrdU(+) mature oligodendrocytes in the corpus callosum of infected animals. These data suggest that the inflammation induced by the Theiler's virus not only provokes strong preclinical demyelination but also, it is correlated with oligodendrocyte generation in the adult SVZ, cells that along with resident progenitor cells contribute to the prompt remyelination observed in the corpus callosum.

Cerebrospinal fluid derived from progressive multiple sclerosis patients promotes neuronal and oligodendroglial differentiation of human neural precursor cells in vitro

In the adult CNS, tissue-specific germinal niches, such as the subventricular zone of the lateral ventricles and the subgranular zone of the dentate gyrus of the hippocampus, contain multipotent neural precursor cells (NPCs) with the capacity to self-renew and differentiate into functional brain cells (i.e. neurons, astrocytes or oligodendrocytes). Due to their intrinsic plasticity, NPCs can be considered an essential part of the cellular mechanism(s) by which the CNS tries to repair itself after an injury. In inflammatory CNS disorders, such as multiple sclerosis (MS), neurogenesis and gliogenesis occur as part of an 'intrinsic' self-repair process. However, full and long-lasting repair in progressive MS is not achieved. Recent data suggest that endogenous NPCs, while trying to repair the damaged CNS in MS, may become the target of the disease itself. It is possible that factors produced during MS, like CNS-infiltrating blood-borne inflammatory mononuclear cells, reactive CNS-resident cells, and humoral mediators, can alter the physiological properties of NPCs, ultimately impairing their ability to promote neural regeneration. Here, we investigate the effect of cerebrospinal fluid (CSF) derived from primary progressive (PPMS) and secondary progressive (SPMS) MS patients (CSF-MS) on the survival, proliferation, and differentiation of commercially available human embryonic-derived NPCs named ENStem-A. We found that PPMS derived CSF markedly reduced the proliferation of ENStem-A and increased their differentiation toward neuronal and oligodendroglial cells, compared to control CSF. Similar but less striking results were seen when ENstem-A were treated with SPMS derived CSF. Our findings suggest that in both SPMS and PPMS the CNS milieu, as determined by extrapolation from CSF findings, may stimulate the endogenous pool of NPCs to differentiate into neurons and oligodendrocytes.

Multiple sclerosis, relapses, and the mechanism of action of adrenocorticotropic hormone

Relapses in multiple sclerosis (MS) are disruptive and frequently disabling for patients, and their treatment is often a challenge to clinicians. Despite progress in the understanding of the pathophysiology of MS and development of new treatments for long-term management of MS, options for treating relapses have not changed substantially over the past few decades. Corticosteroids, a component of the hypothalamic-pituitary-adrenal axis that modulate immune responses and reduce inflammation, are currently the mainstay of relapse treatment. Adrenocorticotropic hormone (ACTH) gel is another treatment option. Although it has long been assumed that the efficacy of ACTH in treating relapses depends on the peptide’s ability to increase endogenous corticosteroid production, evidence from research on the melanocortin system suggests that steroidogenesis may only partly account for ACTH influences. Indeed, the melanocortin peptides [ACTH and α-, β-, γ-melanocyte-stimulating hormones (MSH)] and their receptors (Melanocortin receptors, MCRs) exert multiple actions, including modulation of inflammatory and immune mediator production. MCRs are widely distributed within the central nervous system and in peripheral tissues including immune cells (e.g., macrophages). This suggests that the mechanism of action of ACTH includes not only steroid-mediated indirect effects, but also direct anti-inflammatory and immune-modulating actions via the melanocortin system. An increased understanding of the role of the melanocortin system, particularly ACTH, in the immune and inflammatory processes underlying relapses may help to improve relapse management.

Experimental and therapeutic opportunities for stem cells in multiple sclerosis

Multiple Sclerosis (MS) is an inflammatory demyelinating neurodegenerative disorder of the brain and spinal cord that causes significant disability in young adults. Although the precise aetiopathogenesis of MS remains unresolved, its pathological hallmarks include inflammation, demyelination, axonal injury (acute and chronic), astrogliosis and variable remyelination. Despite major recent advances in therapeutics for the early stage of the disease there are currently no disease modifying treatments for the progressive stage of disease, whose pathological substrate is axonal degeneration. This represents the great and unmet clinical need in MS. Against this background, human stem cells offer promise both to improve understanding of disease mechanism(s) through in-vitro modeling as well as potentially direct use to supplement and promote remyelination, an endogenous reparative process where entire myelin sheaths are restored to demyelinated axons. Conceptually, stem cells can act directly to myelinate axons or indirectly through different mechanisms to promote endogenous repair; importantly these two mechanisms of action are not mutually exclusive. We propose that discovery of novel methods to invoke or enhance remyelination in MS may be the most effective therapeutic strategy to limit axonal damage and instigate restoration of structure and function in this debilitating condition. Human stem cell derived neurons and glia, including patient specific cells derived through reprogramming, provide an unprecedented experimental system to model MS “in a dish” as well as enable high-throughput drug discovery. Finally, we speculate upon the potential role for stem cell based therapies in MS.

Periventricular leukomalacia long-term prognosis may be improved by treatment with UDP-glucose, GDNF, and memantine in neonatal rats

The therapeutic effects of UDP-glucose (UDPG), an endogenous agonist of GPR17 that may promote the self-repair of white matter, glial cell line-derived neurotrophic factor (GDNF), a neurotrophic factor correlated with the growth and survival of nerve cells, and memantine, an antagonist of NMDA receptors, were evaluated for functional improvement of neonatal rats with experimental periventricular leukomalacia (PVL). Five day-old neonatal rat pups were subjected to an ischemia-induced model of PVL. The pups were then randomly divided into sham, PVL, PVL plus UDPG, PVL plus GDNF, and PVL plus memantine groups. All pups were weighed and the age at first eye opening recorded. Pathological changes and myelin sheath formation in the white matter were assessed under both light and electron microscopy on day 7 and 21 after induction of PVL. Values of escape latency (EL) and swimming distance (SD) in Morris water maze test, and the modified inclined plane scores in Rivlin inclined plane test were recorded for rats on day 26. Pups in the PVL group were found to be significantly lower in weight (p<0.05), delayed in age at first eye opening (p<0.01), and impaired in their inclined plane (p<0.01) and Morris water maze (p<0.01) performance compared with those in the sham, UDPG, GDNF and memantine groups. Histopathological grading of the white matter classified all pups in the PVL group with significantly more severe injury (p<0.01), and the number and thickness of their myelin sheaths were significantly less (p<0.01), compared to the UDPG, GDNF, memantine, or sham groups. These results indicate that treatment with UDPG, GDNF, and memantine may significantly improve long-term prognosis in neonatal rats with cerebral white matter injury, characteristic of PVL.

Emerging oral immunomodulating agents - focus on teriflunomide for the treatment of multiple sclerosis

Treatment for multiple sclerosis (MS), a chronic disease of the central nervous system, has historically relied exclusively on the use of injectable therapies. As the disease requires lifelong therapy, the development of oral therapies that are safe and effective would provide a more convenient dosage form that may improve patient compliance. One oral medication (fingolimod) was recently approved for treatment of MS. Teriflunomide, an immunomodulator, is one of four oral therapies currently undergoing Phase III trials. Teriflunomide exerts its clinical effects via selective inhibition of de novo pyrimidine synthesis, primarily targeting proliferating T and B lymphocytes in the periphery. Teriflunomide was effective as monotherapy in reducing magnetic resonance imaging lesions and annual relapse rates in Phase II and Phase III trials. When teriflunomide was added to interferon or glatiramer acetate therapy in Phase II trials, teriflunomide reduced magnetic resonance imaging lesions significantly more than either interferon or glatiramer acetate alone. Treatment-emergent adverse events occurred at similar rates among all groups in teriflunomide studies, with a trend towards a higher treatment emergent adverse events rate in the higher dosage group of teriflunomide (14 mg daily). Treatment discontinuations in teriflunomide trials were relatively low, suggesting that teriflunomide monotherapy is well tolerated. This article reviews the mode of action of teriflunomide, its pharmacokinetic, clinical efficacy, and safety profiles.

Quantitative and phenotypic analysis of bone marrow-derived cells in the intact and inflamed central nervous system

Bone marrow has been proposed as a possible source of cells capable of replacing injured neural cells in diseases such as Multiple Sclerosis (MS). Previous studies have reported conflicting results regarding the transformation of bone marrow cells into neural cells in vivo. This study is a detailed analysis of the fate of bone marrow derived cells (BMDC) in the CNS of C57Bl/6 mice with and without experimental autoimmune encephalomyelitis using flow cytometry to identify GFP-labeled BMDC that lacked the pan-hematopoietic marker, CD45 and co-expressed neural markers polysialic acid-neural cell adhesion molecule or A2B5. A small number of BMDC displaying neural markers and lacking CD45 expression was identified within both the non-inflamed and inflamed CNS. However, the majority of BMDC exhibited a hematopoietic phenotype.

Multiple sclerosis

Multiple sclerosis (MS) is a chronic, complex neurological disease with a variable clinical course in which several pathophysiological mechanisms such as axonal/ neuronal damage, demyelination, inflammation, gliosis, remyelination and repair, oxidative injury and excitotoxicity, alteration of the immune system as well as biochemical disturbances and disruption of blood-brain barrier are involved.(1,2) Exacerbations of MS symptoms reflect inflammatory episodes, while the neurodegenerative aspects of gliosis and axonal loss result in the progression of disability. The precise aetiology of MS is not yet known, although epidemiological data indicate that it arises from a complex interactions between genetic susceptibility and environmental factors.(3) In this chapter the brain structures and processes involved in immunopathogenesis of MS are presented. Additionally, clinical phenotypes and biomarkers of MS are showed.

NG2 expression in glioblastoma identifies an actively proliferating population with an aggressive molecular signature

Glioblastoma multiforme (GBM) is the most common type of primary brain tumor and a highly malignant and heterogeneous cancer. Current conventional therapies fail to eradicate or curb GBM cell growth. Hence, exploring the cellular and molecular basis of GBM cell growth is vital to develop novel therapeutic approaches. Neuroglia (NG)-2 is a transmembrane proteoglycan expressed by NG2+ progenitors and is strongly linked to cell proliferation in the normal brain. By using NG2 as a biomarker we identify a GBM cell population (GBM NG2+ cells) with robust proliferative, clonogenic, and tumorigenic capacity. We show that a significant proportion (mean 83%) of cells proliferating in the tumor mass express NG2 and that over 50% of GBM NG2+ cells are proliferating. Compared with the GBM NG2- cells from the same tumor, the GBM of NG2+ cells overexpress genes associated with aggressive tumorigenicity, including overexpression of Mitosis and Cell Cycling Module genes (e.g., MELK, CDC, MCM, E2F), which have been previously shown to correlate with poor survival in GBM. We also show that the coexpression pattern of NG2 with other glial progenitor markers in GBM does not recapitulate that described in the normal brain. The expression of NG2 by such an aggressive and actively cycling GBM population combined with its location on the cell surface identifies this cell population as a potential therapeutic target in a subset of patients with GBM.

Prevalence of celiac disease in multiple sclerosis

BACKGROUND

Celiac disease (CD) is a common systemic disease related to a permanent intolerance to gluten and is often associated with different autoimmune and neurological diseases. Its mean prevalence in the general population is 1-2% worldwide. Our aim was to study the prevalence of celiac disease in a prospective series of Multiple Sclerosis (MS) patients and their first-degree relatives.

METHODS

We analyzed the prevalence of serological, histological and genetic CD markers in a series of 72 MS patients and in their 126 first-degree relatives, compared to 123 healthy controls.

RESULTS

Tissue IgA-anti-transglutaminase-2 antibodies were positive in 7 MS patients (10%), compared to 3 healthy controls (2.4%) (p < 0.05). OR: 5.33 (CI-95%: 1.074-26.425). No differences were found in HLA-DQ2 markers between MS patients (29%) and controls (26%) (NS).We detected mild or moderate villous atrophy (Marsh III type) in duodenal biopsies, in 8 MS patients (11.1%). We also found a high proportion of CD among first-degree relatives: 23/126 (32%). Several associated diseases were detected, mainly dermatitis 41 (57%) and iron deficiency anemia in 28 (39%) MS patients. We also found in them, an increased frequency of circulating auto-antibodies such as anti-TPO in 19 (26%), ANA in 11 (15%) and AMA in 2 (3%).

CONCLUSIONS

We have found an increased prevalence of CD in 8 of the 72 MS patients (11.1%) and also in their first-degree relatives (23/126 [32%]). Therefore, increased efforts aimed at the early detection and dietary treatment of CD, among antibody-positive MS patients, are advisable.

Towards improved animal models of neonatal white matter injury associated with cerebral palsy

Newborn neurological injuries are the leading cause of intellectual and motor disabilities that are associated with cerebral palsy. Cerebral white matter injury is a common feature in hypoxic-ischemic encephalopathy (HIE), which affects full-term infants, and in periventricular leukomalacia (PVL), which affects preterm infants. This article discusses recent efforts to model neonatal white matter injury using mammalian systems. We emphasize that a comprehensive understanding of oligodendrocyte development and physiology is crucial for obtaining new insights into the pathobiology of HIE and PVL as well as for the generation of more sophisticated and faithful animal models.

Defective adult oligodendrocyte and Schwann cell development, pigment pattern, and craniofacial morphology in puma mutant zebrafish having an alpha tubulin mutation

The processes of myelination remain incompletely understood but are of profound biomedical importance owing to the several dysmyelinating and demyelinating disorders known in humans. Here, we analyze the zebrafish puma mutant, isolated originally for pigment pattern defects limited to the adult stage. We show that puma mutants also have late-arising defects in Schwann cells of the peripheral nervous system, locomotor abnormalities, and sex-biased defects in adult craniofacial morphology. Using methods of positional cloning, we identify a critical genetic interval harboring two alpha tubulin loci, and we identify a chemically induced missense mutation in one of these, tubulin alpha 8-like 3a (tuba8l3a). We demonstrate tuba8l3a expression in the central nervous system (CNS), leading us to search for defects in the development of oligodendrocytes, the myelinating cells of the CNS. We find gross reductions in CNS myelin and oligodendrocyte numbers in adult puma mutants, and these deficits are apparent already during the larval-to-adult transformation. By contrast, analyses of embryos and early larvae reveal a normal complement of oligodendrocytes that nevertheless fail to localize normal amounts of myelin basic protein (mbp) mRNA in cellular processes, and fail to organize these processes as in the wild-type. This study identifies the puma mutant as a valuable model for studying microtubule-dependent events of myelination, as well as strategies for remyelination in the adult.

Remyelination of optic nerve lesions: spatial and temporal factors

Optic neuritis provides an in vivo model to study demyelination. The effects of myelin loss and recovery can be measured by the latency of the multifocal visual evoked potentials. We investigated whether the extent of initial inflammatory demyelination in optic neuritis correlates with the remyelinating capacity of the optic nerve. Forty subjects with acute unilateral optic neuritis and good visual recovery underwent multifocal visual evoked potentials testing at 1, 3, 6 and 12 months. Average latency changes were analyzed. Extensive latency delay at baseline significantly improved over time with rate of recovery slowed down after 6 months. Magnitude of latency recovery was independent of initial latency delay. Latency recovery ranged from 7 to 17 ms across the whole patient cohort (average = 11.3 (3.1) ms) despite the fact that in a number of cases the baseline latency delay was more than 35—40 ms. Optic nerve lesions tend to remyelinate at a particular rate irrespective of the size of the initial demyelinated zone with smaller lesions accomplishing recovery more completely. The extent of the initial inflammatory demyelination is probably the single most important factor determining completeness of remyelination. The time period favorable to remyelination is likely to be within the first 6 months after the attack.

Pregnancy modulates precursor cell proliferation in a murine model of focal demyelination

In mice, pregnancy has been shown to have a beneficial effect on the endogenous repair of focal lysolecithin-induced CNS demyelinative lesions, enhancing the genesis of new oligodendrocytes and the degree of remyelination. To identify local cells undergoing mitosis in response to such lesions, we examined the time course of phospho-histone H3 (PH3) and myelin basic protein (MBP) expression by immunohistochemistry. After lysolecithin injection into the corpus callosum of virgin female mice, the number of dividing cells peaked about 48 h after injection and declined gradually to baseline by day 7; in pregnant mice, this initial peak was unchanged, but a new delayed peak on day 4 was induced. Colocalization data using PH3 and NG2 proteoglycan, or bromodeoxyuridine (BrdU) and oligodendrocyte transcription factor 1 (Olig1), suggested that about 75% of the proliferating cells on day 2, and about 40% of the cells on day 4, were likely of oligodendrocyte lineage; these differential percentages were of the same magnitude in both virgin and pregnant animals. Notably, the heightened proliferative response to focal lysolecithin injection during pregnancy was specific to gestational stage (early, but not late) and to lesion location (in the corpus callosum of the periventricular forebrain, but not in the caudal cerebellar peduncle of the hindbrain).

Prospects of repair in multiple sclerosis

In multiple sclerosis, physiological repair mechanisms can help the nervous system to recover from tissue injury. Enhancing such repair mechanisms is an important, and increasingly realistic, therapeutic goal in multiple sclerosis. With respect to remyelination, several promising therapeutic avenues are currently being explored, including stem cell transplantation, LINGO-1, prolactin and glatiramer acetate. Glatiramer acetate is believed to act by the induction of specific populations of anti-inflammatory Th2 cells or Type 2 monocytes which infiltrate sites of injury in the nervous system where they release anti-inflammatory cytokines leading to bystander suppression of inflammation. In addition, these cells can release neurotrophic factors such as BDNF and IGF-1 which have been shown to stimulate the differentiation of oligodendrocyte precursor cells and thus enhance remyelination. In addition, neurotrophic factors released in response to glatiramer acetate may stimulate the differentiation of neuronal progenitor cells into mature neurones that can replace neurones lost through the disease process. This repair capacity of glatiramer acetate may contribute to the long-term well-being of patients with multiple sclerosis treated with glatiramer acetate.

Disease-responsive neural precursor cells are present in multiple sclerosis lesions

AIMS

Spontaneous tissue repair occurs in multiple sclerosis (MS), but the origin of remyelinating cells remains obscure. Here we explore the hypothesis that endogenous neural precursors are involved in MS disease processes.

MATERIALS & METHODS

We studied postmortem brain and spinal cord samples from MS patients using immunocytochemical techniques.

RESULTS

We show that cells co-positive for nestin and musashi-1 are not merely present in lesions, but found in markedly increased numbers (up to fivefold). Small numbers of nestin-positive cells show direct evidence of proliferation, co-staining for Ki67; some also coexpress glial fibrillary acidic protein or oligodendrocyte progenitor markers (NG-2 or PDGF-alpha receptor), or the early neuronal marker doublecortin, consistent with transition from neural precursors.

CONCLUSIONS

These findings suggest that endogenous neural precursors react to disease processes in MS.

Paving the axonal highway: from stem cells to myelin repair

Multiple sclerosis (MS), a demyelinating disorder of the central nervous system (CNS), remains among the most prominent and devastating diseases in contemporary neurology. Despite remarkable advances in anti-inflammatory therapies, the inefficiency or failure of myelin-forming oligodendrocytes to remyelinate axons and preserve axonal integrity remains a major impediment for the repair of MS lesions. To this end, the enhancement of remyelination through endogenous and exogenous repair mechanisms and the prevention of axonal degeneration are critical objectives for myelin repair therapies. Thus, recent advances in uncovering myelinating cell sources and the intrinsic and extrinsic factors that govern neural progenitor differentiation and myelination may pave a way to novel strategies for myelin regeneration. The scope of this review is to discuss the potential sources of stem/progenitor cells for CNS remyelination and the molecular mechanisms underlying oligodendrocyte myelination.

Effects of direct transplantation of multipotent mesenchymal stromal/stem cells into the demyelinated spinal cord

The adult bone marrow contains a population of multipotent mesenchymal stromal cells (MSCs), defined by plastic adherence, expression of stromal cell surface markers, and differentiation into mesenchymal lineages. There has been much interest in the possible therapeutic use of MSCs in the treatment of demyelinating diseases of the central nervous system. One therapeutic possibility is that these cells may be able to remyelinate when directly injected into the demyelinated spinal cord. Here we examine the effects of direct transplantation of green fluorescent protein (GFP)-labeled MSCs into a model of focal spinal cord demyelination induced by ethidium bromide. We demonstrate that direct intralesional injection of undifferentiated MSCs does not lead to remyelination. Furthermore, we report that transplanted MSCs migrate into areas of normal tissue, deposit collagen, and are associated with axonal damage. These findings support the need for further experimental evaluation of the safety and efficacy of direct parenchymal injection of MSCs into demyelinated lesions and highlight an important issue regarding potential clinical consequences of culture heterogeneity of MSCs between centers.

Multiple sclerosis

Multiple sclerosis is primarily an inflammatory disorder of the brain and spinal cord in which focal lymphocytic infiltration leads to damage of myelin and axons. Initially, inflammation is transient and remyelination occurs but is not durable. Hence, the early course of disease is characterised by episodes of neurological dysfunction that usually recover. However, over time the pathological changes become dominated by widespread microglial activation associated with extensive and chronic neurodegeneration, the clinical correlate of which is progressive accumulation of disability. Paraclinical investigations show abnormalities that indicate the distribution of inflammatory lesions and axonal loss (MRI); interference of conduction in previously myelinated pathways (evoked electrophysiological potentials); and intrathecal synthesis of oligoclonal antibody (examination by lumbar puncture of the cerebrospinal fluid). Multiple sclerosis is triggered by environmental factors in individuals with complex genetic-risk profiles. Licensed disease modifying agents reduce the frequency of new episodes but do not reverse fixed deficits and have questionable effects on the long-term accumulation of disability and disease progression. We anticipate that future studies in multiple sclerosis will provide a new taxonomy on the basis of mechanisms rather than clinical empiricism, and so inform strategies for improved treatment at all stages of the disease.

Equiscala: versão brasileira e estudo de confiabilidade e validade da Equiscale

Este estudo consistiu na tradução para o português e na verificação da confiabilidade e validade do teste original de equilíbrio Equiscale. A versão brasileira foi testada em 11 indivíduos com esclerose múltipla selecionados aleatoriamente, que foram inicialmente avaliados pela Escala de Equilíbrio de Berg (EEB), Medida de Independência Funcional e pela Escala do Estado de Deficiência Expandida (EDSS). Foram feitas duas avaliações usando a Equiscala (teste-reteste) por três fisioterapeutas, para verificar a confiabilidade interexaminador. A confiabilidade teste-reteste e interexaminador foi verificada pelo coeficiente de correlação intra-classe (CCI); e a relação entre a Equiscala e as demais escalas, pelo coeficiente de correlação de Spearman. Foi demonstrada adequada confiabilidade teste-reteste (CCI=0,882; 0,906) e interexaminador(CCI=0,947; 0,933; 0,962). Também foi encontrada boa correlação da Equiscala com a Escala de Equilíbrio de Berg (rs=0,8940; p=0,0002) e a EDSS (rs=-0,7139; p=0,0136). Os resultados indicam que a Equiscala apresenta adequada confiabilidade e validade, podendo ser aplicada na avaliação do equilíbrio em pacientes com esclerose múltipla.

From fish to man: understanding endogenous remyelination in central nervous system demyelinating diseases

In the central nervous system (CNS) of man, evolutionary pressure has preserved some capability for remyelination while axonal regeneration is very limited. In contrast, two efficient programmes of regeneration exist in the adult fish CNS, neurite regrowth and remyelination. The rapidity of CNS remyelination is critical since it not only restores fast conduction of nerve impulses but also maintains axon integrity. If myelin repair fails, axons degenerate, leading to increased disability. In the human CNS demyelinating disease multiple sclerosis (MS), remyelination often takes place in the midst of inflammation. Here, we discuss recent studies that address the innate repair capabilities of the axon-glia unit from fish to man. We propose that expansion of this research field will help find ways to maintain or enhance spontaneous remyelination in man.

Neurodegeneration and cell replacement

The past decade has witnessed ground-breaking advances in human stem cell biology with scientists validating adult neurogenesis and establishing methods to isolate and propagate stem cell populations suitable for transplantation. These advances have forged promising strategies against human neurodegenerative diseases. For example, growth factor administration could stimulate intrinsic repair from endogenous neural stem cells, and cultured stem cells engineered into biopumps could be transplanted to deliver neuroprotective or restorative agents. Stem cells could also be transplanted to generate new neural elements that augment and potentially replace degenerating central nervous system (CNS) circuitry. Early efforts in neural tissue transplantation have shown that these strategies can improve functional outcome, but the ultimate success of clinical stem cell-based strategies will depend on detailed understanding of stem cell biology in the degenerating brain and detailed evaluation of their functional efficacy and safety in preclinical animal models.

Human stem cells for CNS repair

Although most peripheral tissues have at least a limited ability for self-repair, the central nervous system (CNS) has long been known to be relatively resistant to regeneration. Small numbers of stem cells have been found in the adult brain but do not appear to be able to affect any significant recovery following disease or insult. In the last few decades, the idea of being able to repair the brain by introducing new cells to repair damaged areas has become an accepted potential treatment for neurodegenerative diseases. This review focuses on the suitability of various human stem cell sources for such treatments of both slowly progressing conditions, such as Parkinson's disease, Huntington's disease and multiple sclerosis, and acute insult, such as stroke and spinal cord injury. Despite stem cell transplantation having now moved a step closer to the clinic with the first trials of autologous mesenchymal stem cells, the effects shown are moderate and are not yet at the stage of development that can fulfil the hopes that have been placed on stem cells as a means to replace degenerating cells in the CNS. Success will depend on careful investigation in experimental models to enable us to understand not just the practicalities of stem cell use, but also the underlying biological principles.