Lentiviral vectors for gene delivery to normal and demyelinated white matter

Lentiviral vectors are increasingly used for gene delivery to neurons and in experimental models of neurodegeneration. Their use in gene delivery to white matter and their potential value in preventing or repairing CNS demyelination has received less attention. Here we show using a VSV-G-pseudotyped HIV-derived vector expressing the marker gene LacZ that lentiviral vectors transduce the major macroglial cell types present in normal white matter (astrocytes, oligodendrocytes, and oligodendrocyte progenitors). Injection of lentiviral vectors causes an inflammatory response at the injection site characterized by OX42(+) and ED1(+) macrophages, but only a few CD8(+) and no CD4(+) lymphocytes, and mild demyelination. Injection of lentiviral vectors into areas of toxin-induced demyelination resulted in significant numbers of cells expressing the marker gene and was a more effective means of gene delivery than was a LacZ-expressing murine retroviral vector.

Olfactory ensheathing cells: historical perspective and therapeutic potential

Olfactory ensheathing cells (OECs) are the glial cells that ensheath the axons of the first cranial nerve. They are attracting increasing attention from neuroscientists as potential therapeutic agents for use in the repair of spinal cord injury and as a source of myelinating glia for use in remyelinating axons in demyelinating diseases such as multiple sclerosis. This review mainly addresses the cell biological aspects of OECs pertinent to addressing two questions. Namely, where do OECs fit into the groupings of central nervous system (CNS)/peripheral nervous system (PNS) glial cells and should OECs be viewed as a clinically relevant alternative to Schwann cells in the treatment of spinal cord injury? The evidence indicates that OECs are indeed a clinically relevant alternative to Schwann cells. However, much more work needs to be done before we can even come close to answering the first question as to the lineage and functional relationship of OECs to the other types of CNS and PNS glial cells.

Remyelination by transplanted olfactory ensheathing cells

The olfactory ensheathing cells (OECs) of the peripheral olfactory system associate with the axons of the first cranial nerve. These axons are not myelinated by OECs because of their very small diameter. However, when OECs are transplanted into areas where they encounter larger-diameter axons, such as in a model of primary demyelination, these cells assume a myelinating phenotype. Myelinating OECs very closely resemble myelinating Schwann cells by all criteria currently examined, including morphology, ultrastructure, biochemistry, and transcriptional regulation. Indeed, it is currently impossible to reliably distinguish myelinating OECs and myelinating Schwann cells that have been transplanted into experimental models of CNS demyelination. This article describes recent studies on the myelinating properties of transplanted OECs, focusing on their intrinsic myelinating potential and how this can be augmented by the presence of meningeal cells. The relative merits of OECs compared with Schwann cells when transplanted into astrocyte-containing lesions in the CNS are discussed together with their potential role in transplanted-mediated repair of demyelinating disease such as multiple sclerosis.

Olfactory ensheathing glia transplantation: a therapy to promote repair in the mammalian central nervous system

A therapy to treat injuries to the central nervous system (CNS) is, to date, a major clinical challenge. The devastating functional consequences they cause in human patients have encouraged many scientists to search, in animal models, for a repair strategy that could, in the future, be applied to humans. However, although several experimental approaches have obtained some degree of success, very few have been translated into clinical trials. Traumatic and demyelinating lesions of the spinal cord have attracted several groups with the same aim: to find a way to promote axonal regeneration, remyelination, and functional recovery, by using a simple, safe, effective, and viable procedure. During the past decade, olfactory ensheathing glia (OEG) transplantation has emerged as a very promising experimental therapy to promote repair of spinal cords, after different types of injuries. Transplants of these cells promoted axonal regeneration and functional recovery after partial and complete spinal cord lesions. Moreover, olfactory ensheathing glia were able to form myelin sheaths around demyelinated axons. In this article, we review these recent advances and discuss to what extent olfactory ensheathing glia transplantation might have a future as a therapy for different spinal cord affections in humans.

CD154 blockade results in transient reduction in Theiler's murine encephalomyelitis virus-induced demyelinating disease

Transient CD154 blockade at the onset of Theiler's murine encephalomyelitis virus-induced demyelinating disease ameliorated disease progression for 80 days, reduced immune cell infiltration, and transiently increased viral loads in the central nervous system. Peripheral antiviral and autoimmune T-cell responses were normal, and disease severity returned to control levels by day 120.

[What are the realistic hopes for remyelinization in the central nervous system?]

Up to now, there is no therapy in order to stimulate a remyelination in the adult central nervous system. So, the study the ontogenesis of oligodendrocytes at the cellular and molecular level could provide cues in order to design such a treatment that will be efficient to remyelinate patients after a multiple sclerosis relapse. In our work, we demonstrated that both neurotransmitters acting trough ionotropic receptors, expressed by oligodendrocytes precursors and some members of the neuregulin growth factors family, could modulate the proliferation and the differentiation of oligodendrocytes progenitors. Furthermore, we demonstrated that the graft of neural stem cells in experimental demyelinated lesion in adult animals is responsible for an efficient remyelination.

Immunotherapy for IgM anti-Myelin-Associated Glycoprotein paraprotein-associated peripheral neuropathies

BACKGROUND

Serum monoclonal anti-Myelin Associated Glycoprotein antibodies may be pathogenic in some patients with IgM paraprotein and demyelinating neuropathy. Immunotherapies aimed at reducing the level of these antibodies might be expected to be of benefit in the treatment of the neuropathy. Many potential therapies have been described in small trials, uncontrolled studies and case reports.

OBJECTIVES

To examine the efficacy of any form of immunotherapy in reducing disability and impairment resulting from IgM anti-Myelin Associated Glycoprotein paraprotein-associated demyelinating peripheral neuropathy.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group register (August 2002) and MEDLINE (January 1966 - August 2002) and EMBASE (January 1980 - August 2002) for controlled trials, checked the bibliographies to identify other controlled trials and contacted authors and other experts in the field.

SELECTION CRITERIA

Types of studies: randomised or quasi-randomised controlled trials.

TYPES OF PARTICIPANTS

patients of any age with anti-Myelin Associated Glycoprotein antibody associated demyelinating peripheral neuropathy with monoclonal gammopathy of undetermined significance of any severity. Types of interventions: any type of immunotherapy. Types of outcome measures: Primary: improvement in the Neuropathy Disability Score or Modified Rankin Scale six months after randomisation Secondary: Neuropathy Disability Score and/or the Modified Rankin Score 12 months after randomisation. Ten metre walk time, subjective clinical scores and electrophysiological parameters at six and 12 months after randomisation. IgM paraprotein levels and anti-Myelin Associated Glycoprotein antibody titres six months after randomisation. Adverse effects of treatments.

DATA COLLECTION AND ANALYSIS

We identified six randomised controlled trials of which five were included after discussion between the authors. One author extracted the data and the other checked them. No missing data could be obtained from authors.

MAIN RESULTS

The five eligible trials used four of the many available immunotherapy treatments. Only two had comparable interventions and outcomes but these were only short-term studies. There were no significant benefits of the treatments used in the predefined outcomes. However intravenous immunoglobulin showed benefits in terms of improved Modified Rankin Scale at two weeks and 10 metre walk time at four weeks. Serious adverse effects of intravenous immunoglobulin are known to occur from observational studies but none were encountered in these trials.

REVIEWER'S CONCLUSIONS

There is inadequate reliable evidence from trials of immunotherapies in anti-Myelin Associated Glycoprotein paraproteinaemic neuropathy to recommend any particular immunotherapy treatment. Intravenous immunoglobulin is relatively safe and may produce some short-term benefit. Large well designed randomised trials are required to assess the efficacy of promising new therapies.

Acute demyelinating optic neuritis

Acute demyelinating optic neuritis associated with multiple sclerosis (MS) is the most common cause of inflammation of the optic nerve. The Optic Neuritis Treatment Trial (ONTT) has provided important clinical data on the use of corticosteroids, and demonstrated that patients with characteristic inflammatory lesions within the brain on magnetic resonance imaging had a greater chance of developing clinically definite MS (CDMS). The current approach to patients with optic neuritis has been modified by the results of the Controlled High-Risk Subjects Avonex Multiple Sclerosis Prevention Study (CHAMPS). Patients with an initial clinical episode of demyelination (optic neuritis, incomplete transverse myelitis, or brain-stem/cerebellar syndrome) and at least two characteristic demyelinating lesions within the brain were randomized to receive interferon beta-1a or placebo after initial treatment with intravenous corticosteroids. At the 3-year point patients treated with interferon beta-1a showed a 50% less risk of CDMS. The results of this study have set the standard for patients with a first bout of demyelinating optic neuritis.

Heterogeneity of pathogenesis in multiple sclerosis: implications for promotion of remyelination

Enhancing myelin repair remains an important therapeutic goal in primary demyelinating diseases of the central nervous system (CNS) such as multiple sclerosis (MS). The emerging heterogeneity of pathology within MS lesions, and differential oligodendrocyte survival in particular, suggests that therapeutic strategies may need to be tailored to an individual patient's requirements. A number of therapeutic strategies have been proposed to enhance myelin repair in the CNS: cell transplantation, growth factor therapy, and antibody therapy, but each proposed therapy has different implications with respect to pathogenetic mechanisms of demyelination. Of these, antibody therapy is the most amenable to immediate application in patients-but a combination of therapeutic approaches may be required in practice.

Treatment of steroid-unresponsive tumefactive demyelinating disease with plasma exchange

The authors describe a patient with an isolated, gadolinium-enhancing, biopsy-proven focus of tumefactive demyelination. There was marked clinical improvement with plasma exchange after failure of high-dose i.v. corticosteroids. The post-treatment clinical course correlated with decreasing enhancement and lesion size on MRI. This patient's rapid clinical and MRI response suggests that plasma exchange may be beneficial in this disorder, and could perhaps serve as a diagnostic tool to avoid the need for brain biopsy.

A patient with delayed posthypoxic demyelination: a case report of hyperbaric oxygen treatment

A 62-year-old man who developed akinetic mutism with delayed white matter demyelination after hypoxia was treated with hyperbaric oxygen (HBO). HBO in the subacute period markedly improved the patient's activity in daily life, cognitive function and organization on EEG. 1H-MRS showed a recovery of aerobic metabolism of the neurons. However, dementia and cerebral atrophy slowly progressed despite HBO treatment. Thus, HBO had a beneficial effect on the activity of depressed neurons but did not improve the prognosis.

Cryopreserved cells isolated from the adult canine olfactory bulb are capable of extensive remyelination following transplantation into the adult rat CNS

Naturally occurring spinal cord injury in dogs provides a potentially powerful intermediate model for testing the efficacy of therapeutic strategies developed in experimental rodent models before phase 1 trials in human patients. A particularly promising strategy involves transplantation of olfactory ensheathing cells (OECs) that both promote axon regeneration and generate new myelin sheaths. As a first step in developing OEC transplantation in the canine intermediate model we describe the isolation, purification, and characterization of OECs from adult dog olfactory bulb. We also show that the canine OEC behaves in a manner similar to its rodent counterpart following transplantation into demyelinating lesions in rat spinal cord and that these properties are retained following cryopreservation.

Diabetic demyelinating polyneuropathy responsive to intravenous immunoglobulin therapy

BACKGROUND

There is growing evidence that idiopathic chronic inflammatory demyelinating polyneuropathy (CIDP) and polyneuropathy in patients with diabetes mellitus (DM) that meets the electrophysiological criteria for CIDP (DM-CIDP) have many similarities.

OBJECTIVE

To evaluate whether DM-CIDP responds to intravenous immunoglobulin (IVIG) therapy.

PATIENTS AND METHODS

Twenty-six patients (mean [SD] age, 64 [8.9] years; age range, 40-80 years) with type 2 DM (n = 25), who met the electrophysiological criteria for CIDP, were given IVIG therapy (400 mg/kg body weight per day for 5 days) in a prospective open-label pilot study. All patients had quantitative evaluation using the Neuropathy Impairment Score at baseline and at the end of 4 weeks from the initiation of IVIG therapy.

RESULTS

The mean Neuropathy Impairment Score improved significantly from baseline (mean [SD], 61.5 [26.0] points) to the end of the fourth week (33 [29.6] points; P<.00l). This clinically significant improvement occurred in 21 (80.8%) of the 26 patients. Conduction block occurred in 11 (42.3%) of the 26 patients; improvement in the Neuropathy Impairment Score was more frequent in patients who had a conduction block (11 of 11 patients) than in those who did not (10/15 [66.7%]; P =.03). Adverse reactions to IVIG included reversible renal dysfunction in 3 patients, flulike symptoms in 5, headache in 5, and chest pain and shortness of breath in 1.

CONCLUSION

Although IVIG therapy seemed to improve DM-CIDP in this uncontrolled trial, a controlled trial is required for confirmation of our findings.

Distribution and morphology of transgenic mouse oligodendroglial-lineage cells following transplantation into normal and myelin-deficient rat CNS

Glial cells from neonatal MbetaP5 transgenic mice, which express bacterial beta-galactosidase (lacZ) under control of the myelin basic protein (MBP) promoter (Gow et al, 1992), were transplanted into the spinal cord or cerebral hemisphere of immunosuppressed normal and myelin-deficient (md) rats in order to assess the ability of the donor cells to survive, migrate, and differentiate within normal compared with myelin-deficient central nervous system (CNS). LacZ+ cells were detected as early as 6-7 days after transplantation into the low thoracic cord and by 10 days had spread rostrally to the brainstem and caudally to the sacral spinal cord. Initially, compact lacZ+ cells, lacking processes, were found associated with small blood vessels and with the glia limitans. Cells of this type persisted throughout the experiment. Later, lacZ+ cells with processes were seen along fiber tracts in the dorsal columns and, after intracerebral injection, subjacent to ventricular ependyma, as well as scattered in cerebral white and gray parenchyma. The extent of spread was comparable in md and normal rats, but in the md group, the success rate was higher, and more cells differentiated into process-bearing oligodendrocytes. Acceptance of xenografts in immunosuppressed recipients equaled that of allografts. The overall spread of grafted cells exceeded that of injected charcoal, indicating active migration. In contrast to earlier studies that identified oligodendrocytes based on morphology alone, this study has allowed us to identify and track oligodendrocytes based on myelin gene expression. We show some oligodendrocytes whose morphology is consistent with classical morphological descriptions, some that resemble astrocytes, and a class of compact perivascular oligodendrocyte-lineage cells that we suggest are migratory.

Cellular sources and targets of IFN-gamma-mediated protection against viral demyelination and neurological deficits

IFN-gamma is an anti-viral and immunomodulatory cytokine critical for resistance to multiple pathogens. Using mice with targeted disruption of the gene for IFN-gamma, we previously demonstrated that this cytokine is critical for resistance to viral persistence and demyelination in the Theiler's virus model of multiple sclerosis. During viral infections, IFN-gamma is produced by natural killer (NK) cells, CD4(+) and CD8(+) T cells; however, the proportions of lymphocyte subsets responding to virus infection influences the contributions to IFN-gamma-mediated protection. To determine the lymphocyte subsets that produce IFN-gamma to maintain resistance, we used adoptive transfer strategies to generate mice with lymphocyte-specific deficiencies in IFN-gamma-production. We demonstrate that IFN-gamma production by both CD4(+) and CD8(+) T cell subsets is critical for resistance to Theiler's murine encephalomyelitis virus (TMEV)-induced demyelination and neurological disease, and that CD4(+) T cells make a greater contribution to IFN-gamma-mediated protection. To determine the cellular targets of IFN-gamma-mediated responses, we used adoptive transfer studies and bone marrow chimerism to generate mice in which either hematopoietic or somatic cells lacked the ability to express IFN-gamma receptor. We demonstrate that IFN-gamma receptor must be present on central nervous system glia, but not bone marrow-derived lymphocytes, in order to maintain resistance to TMEV-induced demyelination.

A quantitative morphometric analysis of rat spinal cord remyelination following transplantation of allogenic Schwann cells

Quantitative morphometric techniques were used to assess the extent and pattern of remyelination produced by transplanting allogenic Schwann cells into demyelinated lesions in adult rat spinal cords. The effects of donor age, prior culturing of donor cells, prior lesioning of donor nerves, and host immunosuppression were evaluated by transplanting suspensions of 30,000 acutely dissociated or cultured Schwann cells from neonatal, young adult, or aged adult rat sciatic nerves into X-irradiation and ethidium bromide-induced demyelinated dorsal column lesions, with or without co-transplantation of neonatal optic nerve astrocytes. Three weeks after transplantation, spinal cords were processed for histological analysis. Under all Schwann cell transplant protocols, large areas containing many Schwann cell-like myelinated axon profiles could be readily observed throughout most of the lesion length. Within these "myelin-rich" regions, the vast majority of detectable axons showed a peripheral-like pattern of myelination. However, interaxonal spacing also increased, resulting in densities of myelinated axons that were more similar to peripheral nerve than intact dorsal columns. Freshly isolated Schwann cells remyelinated more axonal length than cultured Schwann cells, and cells from younger donors remyelinated slightly more axon length than cells from older donors, but all Schwann cell transplant protocols remyelinated tens of thousands of millimeters of axon length and remyelinated axons at similar densities. These results indicate that Schwann cells prepared under a variety of conditions are capable of eliciting remyelination, but that the density of remyelinated axons is much lower than the myelinated axon density in intact spinal cords.

Apheresis in treatment of the inflammatory demyelinating peripheral neuropathies

The inflammatory demyelinating peripheral neuropathies are recognizable treatable entities within the broad field of diseases of the peripheral nervous system. Most peripheral nerve diseases are still of undetermined causation and have no direct disease-modifying treatment. This paper reviews the diagnostic features of the inflammatory neuropathies, presumed mechanisms of pathogenesis, and the role of apheresis, along with other immunomodulating therapies, in the management of these diseases.

Focal cooling improves neuronal conduction in peroneal neuropathy at the fibular neck

Heat can induce conduction block (CB) in demyelinated neurons; whether cooling can reverse CB and increase strength is uncertain. In six patients with electrophysiologic evidence of peroneal neuropathy at the fibular neck with definite motor CB, standard motor nerve conduction studies were performed at 32 degrees C and then after the fibular neck region was cooled with an ice pack to 8 degrees -12 degrees C. In all patients, cooling increased the amplitude and area of the compound motor action potential obtained with popliteal fossa stimulation, decreasing the relative amplitude drop across the fibular neck from a mean of 78% to 55%. A concomitant increase in foot dorsiflexor strength was clearly observed in three of the six patients. Both the electrophysiologic and clinical changes readily reversed upon rewarming. These data support the belief that, in compressive neuropathies, cooling relieves conduction block in selected motor neurons, improving strength.

Progressive demyelinating neuropathy after initiation of continuous ambulatory peritoneal dialysis--report of two cases

We report on two patients who developed rapidly progressive demyelinating neuropathy within 6 to 10 weeks after the initiation of continuous ambulatory peritoneal dialysis. The neuropathy in one patient resolved after kidney transplantation while that of the other patient improved with immunosuppressive therapy. The close temporal relationship between the initiation of peritoneal dialysis and the onset of neuropathy suggests that these two events may be causally related.

IVIG-pools: regulatory gifts--transiting from harmony toward harmonious immunoglobulins: why? and why not?

Based on 'initial conditions' which depend on each donors' exposure to a unique environment, a pooled intravenous immunoglobulin (IVIG) product transfers its immunoglobulin molecule repertoire, unchanged, to the altered host. The relay function of the cell-bound receptors, especially that of the inhibitory Fc(gamma)RIIB, may then allow sufficient amplification to make regulatory activity possible. To the clinician, IVIG may be considered a tool to promote reversal of the dysregulation causing autoimmune disease. Generically, IVIG may be seen as a promoter allowing a progression from harm by an inflammatory/fibrotic reaction, then down-regulating toward restitutio ad integrum. By modifying natural processes, IVIG may play minor roles in promoting defense against spontaneous bleeding and, perhaps, stimulating remyelination. The wide spectrum of IVIG specificities, by reflecting evolutionary epitope selection, may not further destabilize cell/molecule disarray in the affected host. Benefit to the patient by IVIG treatment cannot be predicted nor can potentially severe or even fatal accidents entirely be excluded. Important aspects of IVIG treatment still await clarification including dosage, timing and the isotype form. In the foreseeable future it does not seem that biotechnological advances will match the physiologic harmony of IVIG, leaving antibody characteristics aside.

Recent studies on the roles of antiglycosphingolipids in the pathogenesis of neurological disorders

Evidence is mounting to suggest a causal role of humoral immunity arising from antiglycosphingolipid (GSL) antibodies in a variety of neurological disorders. These disorders include the demyelinating and axonal forms of Guillain-Barre syndrome, multifocal motor neuropathy, chronic inflammatory demyelinating polyradiculoneuropathy, and IgM paraproteinemia. Many claims have been made regarding other neurological disorders, which should be carefully scrutinized for their validity, based on several criteria proposed in this review. These criteria include 1) characterization of the causative antigens and immunoglobulins, 2) correlation of the pathological lesions and clinical manifestation of the antigens, 3) establishment of animal models using pure GSLs as the antigens, 4) immunopathogenic mechanisms of the neurodenerative process, 5) mechanisms for the malfunctioning of blood-nerve barrier and the ensuing leakage of circulating antibodies into peripheral nerve parenchyma, and 6) the roles of anti-GSL antibodies that may cause humorally mediated nerve dysfunction and injury as well as interference with ion channel function at the node of Ranvier, where carbohydrate epitopes are located. Finally, the origin of the anti-GSL antibodies is discussed in light of the recent circumstantial evidence pointing to a molecular mimicry mechanism with infectious agents. With a better understanding of the immunopathogenic mechanisms, it will then be possible to devise rational and effective diagnostic and therapeutic strategies for the treatment of these neurological disorders.