Disseminated sparganosis in a cynomolgus macaque (Macaca fascicularis).

An adult male cynomolgus macaque (Macaca fascicularis) from Mauritius arrived at our facility in France after a 1-year period of quarantine in Spain. Clinical examination soon after arrival revealed the presence of numerous firm cutaneous and subcutaneous nodules (0.1-0.5 cm diameter) in the scrotal and inguinal areas, and persistent mild eosinophilia. On necropsy examination additional similar nodules were found in the peritoneum and abdominal wall, omentum and mesentery. Microscopical examination revealed disseminated eosinophilic granulomas containing tapeworm larvae identified as Spirometra erinaceieuropaei by direct sequencing of the cox1 gene.

Absence of an intrathecal immune reaction to a helper-dependent adenoviral vector delivered into the cerebrospinal fluid of non-human primates.

Inflammation and immune reaction, or pre-existing immunity towards commonly used viral vectors for gene therapy severely impair long-term gene expression in the central nervous system (CNS), impeding the possibility to repeat the therapeutic intervention. Here, we show that injection of a helper-dependent adenoviral (HD-Ad) vector by lumbar puncture into the cerebrospinal fluid (CSF) of non-human primates allows long-term (three months) infection of neuroepithelial cells, also in monkeys bearing a pre-existing anti-adenoviral immunity. Intrathecal injection of the HD-Ad vector was not associated with any sign of systemic or local toxicity, nor by signs of a CNS-specific immune reaction towards the HD-Ad vector. Injection of HD-Ad vectors into the CSF circulation may thus represent a valuable approach for CNS gene therapy allowing for long-term expression and re-administration.

[Promoting myelin repair in disorders such as multiple sclerosis and some types of leukodystrophy: current studies]. / Approche expérimentale des stratégies réparatrices des maladies demyélinisantes du système nerveux central.

Several ways of promoting myelin repair in myelin disorders such as multiple sclerosis and certain types of leukodystrophies are currently being investigated. Numerous studies suggest that it is possible to repair the central nervous system (CNS) by cell transplantation or by enhancing endogenous remyelination. Investigations in animal models indicate that cell therapy results in robust anatomical and functional recovery of acute myelin lesions. These models are also used to explore and validate the role of candidate molecules to stimulate endogenous remyelination by activating the myelin competent population or providing neuroprotection. However, in view of the heterogeneity of the lesion environment in MS, it seems more likely that cell therapy alone will not be able to contribute efficiently to the repair of the lesion. Further developments should indicate whether combining multiple approaches will be more powerful to achieve global myelin repair in the CNS than applying these strategies alone.

Migration and multipotentiality of PSA-NCAM+ neural precursors transplanted in the developing brain.

By optimizing the previously described strategy for obtention of spheres enriched in PSA-NCAM+ precursors, we prepared PSA-NCAM-immunoselected cell populations from cerebral hemispheres of neonatal MBP-LacZ transgenic mice. These cells expressed Nestin, exhibited clonal expansion potential and formed spheres, which were initially enriched in PSA-NCAM+ cells but became enriched in GD3+ oligodendrocyte progenitors after 1 week in B104 contionned medium. One month after their periventricular transplantation into the brain of wild-type and/or shiverer newborn mice, cells from PSA-NCAM+ spheres exhibited a higher rostral migration potential than cells from GD3+ spheres, and clearly contributed to myelination in the olfactory bulb. In shiverer hosts, both sphere populations generated oligodendrocytes with similar myelination potential. In addition PSA-NCAM+ sphere cells generated GFAP+ astrocytes and NeuN+ neurons, depending on their site of insertion. These results evidence the high plasticity of newborn PSA-NCAM+ neural precursors and suggest that they are promising tools for cell therapy of CNS diseases, including myelin disorders.

Do central nervous system axons remyelinate?

In multiple sclerosis (MS), one of the most frequent demyelinating diseases in man, remyelination of demyelinating lesions exists but is often incomplete. Also reported in experimental models of demyelination, this phenomenom confirms the regenerating potential of the demyelinated central nervous system (CNS) and, in particular, the existence of an endogenous mechanism of oligodendrocyte renewal. Failure in efficient remyelination could result from exhaustion of the pool of remyelinating cells, loss of axons and absence of a permissive environment for remyelination. Identifying the nature and the origin of the cells capable of generating new oligodendrocytes for remyelination could contribute to strategies to activate these cells, and thereby enhance their potential for myelin repair. Within the adult CNS, several cell types are capable of generating new oligodendrocytes following myelin damage: post-mitotic oligodendrocytes frequently found at the lesion site, oligodendrocyte progenitors whose existence has been confirmed both in vitro and in vivo, and multipotent cells localized in the germinative areas of the brain and the spinal cord. Although restricted to particular sites of the CNS, these multipotent cells, which maintain the capacity to self-renew and to migrate throughout adulthood, could constitute a powerful source of remyelinating cells. The study of the mechanisms of proliferation, migration and differentiation of these cells in response to demyelination should allow the definition of new strategies to promote endogenous remyelination and develop therapeutic approaches for demyelinating diseases such as MS. This goal is an appealing alternative to the transplantation of myelin-forming cells and should efficiently complement strategies aimed at reducing neuronal loss and inflammation.

Neurosteroid progesterone is up-regulated in the brain of jimpy and shiverer mice.

Concentrations of neurosteroids have been measured in the brains of postnatal myelin mutants jimpy (jp) and shiverer (shi) mice and of their normal controls. Progesterone (PROG) concentrations were increased more than threefold in the brains of mutant mice. Marked astroglial reaction occurs in the brains of jp mice and to a much smaller extent in shi ones. Whereas the mitochondrial benzodiazepine/diazepam binding inhibitor (DBI) receptor (MBR) was below the immunohistochemical detection limit in normal mice (except in the choroid plexus and ependyma cells), it was significantly expressed in many reactive astrocytes of jp and shi mice brains. DBI-like peptides, investigated either by immunohistochemistry or by radioimmunoassay, were expressed to similar extents in mutant and control mice. Reversed-phase HPLC indicated that DBI-like peptides were almost exclusively of the triakontatetraneuropeptide size. It was concluded that the increased expression of MBR (involved in the intramitochondrial delivery of cholesterol to P450scc) likely accounts for the large PROG content in mutant mice brain. The role of PROG in myelin repair is discussed.

Mouse oligospheres: from pre-progenitors to functional oligodendrocytes.

To study the biology and repair capacities of mouse oligodendroglial cells, we established cultures of cells purified from neonatal wild-type and 9.6-kb MBP-LacZ transgenic newborn mice cerebral hemispheres as free-floating aggregates in the continuous presence of neuroblastoma conditioned medium (N1-B104). In vitro analysis indicated that the initial cell preparations were enriched in oligodendrocyte pre-progenitors that expressed PSA-NCAM and GAP-43 but not GD3, O4, NF68 or glial fibrillary acidic protein (GFAP) markers. These pre-progenitors required increased concentrations of insulin and progesterone to allow their survival in vitro. With time in culture, spheres composed of oligodendrocyte pre-progenitors became oligospheres enriched in oligodendrocyte progenitors expressing GAP-43 and GD3. As well as conserving bipotentiality in vitro, these spheres were able to form myelin in vivo after transplantation into the neonatal shiverer mouse brain. Thus, the oligosphere strategy is a powerful method for generating large populations of mouse oligodendrocyte pre-progenitors and progenitors. The ability to generate oligospheres from transgenic mice will be instrumental in the further dissection of the molecular and cellular mechanisms of myelination and remyelination of the central nervous system.

Progenitor cells of the adult mouse subventricular zone proliferate, migrate and differentiate into oligodendrocytes after demyelination.

Identifying a source of cells with the capacity to generate oligodendrocytes in the adult CNS would help in the development of strategies to promote remyelination. In the present study, we examined the ability of the precursor cells of the adult mouse subventricular zone (SVZ) to differentiate into remyelinating oligodendrocytes. After lysolecithin-induced demyelination of the corpus callosum, progenitors of the rostral SVZ (SVZa) and the rostral migratory pathway (RMS), expressing the embryonic polysialylated form of the neural cell adhesion molecule (PSA-NCAM), increased progressively with a maximal expansion occurring after 2 weeks. This observation correlated with an increase in the proliferation activity of the neural progenitors located in the SVZa and RMS. Moreover, polysialic acid (PSA)-NCAM-immunoreactive cells arizing from the SVZa were detected in the lesioned corpus callosum and within the lesion. Tracing of the constitutively cycling cells of the adult SVZ and RMS with 3H-thymidine labelling showed their migration toward the lesion and their differentiation into oligodendrocytes and astrocytes but not neurons. These data indicate that, in addition to the resident population of quiescent oligodendrocyte progenitors of the adult CNS, neural precursors from the adult SVZ constitute a source of oligodendrocytes for myelin repair.

In vitro and in vivo behaviour of NDF-expanded monkey Schwann cells.

Schwann cells, the myelin-forming cells of the peripheral nervous system may play a major role in the regeneration and remyelination not only of the peripheral but also of the central nervous system. The discovery of the mitogenicity of human recombinant forms of neuregulins (glial growth factors) on primate Schwann cells allows us to envisage a considerable expansion of these cells in culture with a view to autologous transplantation in the central nervous system. To assay this possibility, we used human recombinant neu-differentiation factor beta (NDFbeta) to expand monkey Schwann cells derived from perinatal and adult nerve biopsies. We report that NDFbeta containing the epidermal growth factor (EGF)-like domain (residues 177-228) is a potent mitogen for monkey Schwann cells but is more effective on perinatal than adult Schwann cells. Moreover, continuous treatment with NDFbeta, does not seem to prevent Schwann cells differentiation into myelin-forming cells after their transplantation into the demyelinated mouse spinal cord. These observations, in addition to the close similarities of in vitro behaviour which exist between human and monkey Schwann cells, indicate that monkey Schwann cells could be an ideal tool to study the potential and limits of autologous transplantation in a non-human primate model of central nervous system demyelination.