Purification of viable ciliated cuboidal ependymal cells from rat brain

A Novel Monoclonal Antibody Against Neuroepithelial and Ependymal Cells and Characteristics of Its Positive Cells in Neurospheres

There are still few useful cell membrane surface antigens suitable for identification and isolation of neural stem cells (NSCs). We generated a novel monoclonal antibody (mAb), designated as mAb against immature neural cell antigens (INCA mAb), which reacted with the areas around a lateral ventricle of a fetal cerebrum. INCA mAb specifically reacted with neuroepithelial cells in fetal cerebrums and ependymal cells in adult cerebrums. The recognition molecules were O-linked 40 and 42 kDa glycoproteins on the cell membrane surface (gp40 INCA and gp42 INCA). Based on expression pattern analysis of the recognition molecules in developing cerebrums, it was concluded that gp42 INCA was a stage-specific antigen expressed on undifferentiated neuroepithelial cells, while gp40 INCA was a cell lineage-specific antigen expressed at the stages of differentiation from neuroepithelial cells to ependymal cells. A flow cytometric analysis showed that fetal and young adult neurospheres were divided into INCA mAb(-) CD133 polyclonal antibody (pAb)(-), INCA mAb(+) CD133 pAb(-), and INCA mAb(+) CD133 pAb(+) cell populations based on the reactivity against INCA mAb and CD133 pAb. The proportion of cells having the neurosphere formation capability in the INCA mAb(+) CD133 pAb(+) cell population was significantly larger than that of undivided neurospheres. Neurospheres formed by clonal expansion of INCA mAb(+) CD133 pAb(+) cells gave rise to neurons and glial cells. INCA mAb will be a useful immunological probe in the study of NSCs.

A simple method to obtain pure cultures of multiciliated ependymal cells from adult rodents

Ependymal cells form an epithelium lining the ventricular cavities of the vertebrate brain. Numerous methods to obtain primary culture ependymal cells have been developed. Most of them use foetal or neonatal rat brain and the few that utilize adult brain hardly achieve purity. Here, we describe a simple and novel method to obtain a pure non-adherent ependymal cell culture from explants of the striatal and septal walls of the lateral ventricles. The combination of a low incubation temperature followed by a gentle enzymatic digestion allows the detachment of most of the ependymal cells from the ventricular wall in a period of 6 h. Along with ependymal cells, a low percentage (less than 6 %) of non-ependymal cells also detaches. However, they do not survive under two restrictive culture conditions: (1) a simple medium (alpha-MEM with glucose) without any supplement; and (2) a low density of 1 cell/µl. This purification method strategy does not require cell labelling with antibodies and cell sorting, which makes it a simpler and cheaper procedure than other methods previously described. After a period of 48 h, only ependymal cells survive such conditions, revealing the remarkable survival capacity of ependymal cells. Ependymal cells can be maintained in culture for up to 7-10 days, with the best survival rates obtained in Neurobasal supplemented with B27 among the tested media. After 7 days in culture, ependymal cells lose most of the cilia and therefore the mobility, while acquiring radial glial cell markers (GFAP, BLBP, GLAST). This interesting fact might indicate a reprogramming of the cell identity.

Glycogen metabolism in rat ependymal primary cultures: regulation by serotonin

Ependymal primary cultures are a model for studying ependymal energy metabolism. Intracellular glycogen is built up in the cultures dependent on culture age and the presence of glucose and glutamate. This energy store is mobilized upon glucose withdrawal, stimulation with isoproterenol, forskolin or serotonin and after uncoupling of oxidative phosphorylation from ATP production. Serotonin regulates ependymal glycogen metabolism predominantly via 5-HT receptor (5-HTR) 7, which elicits an increase in the level of ependymal cyclic AMP. Although the most abundant mRNAs for serotonin receptors are those of 5-HTR 2B and 5-HTR 3A, ependymal cells in primary culture do not respond to serotonin with an increase in their concentration of cytosolic calcium ions. The mRNAs of 5-HTRs 1A, 6, 1B, 5B, 7, 1/2C and 5A are also detectable in order of decreasing abundance. The mRNAs for 5-HTRs 1D, 1F, 3B and 4 are absent from the cultured cells. The ability of serotonin to mobilize ependymal glycogen depends on the culture age and the time allowed for glycogen buildup. During glycogen buildup time, glutamate is consumed by the cells. An increased ability of 5-HT to mobilize ependymal glycogen stores is noticed after the depletion of glutamate from the glycogen buildup medium. In ependymal primary cultures, cilia are colocalized with glycogen phosphorylase isozyme BB, while the MM isoform is not expressed. It is known from the literature that an increase in the concentration of cytosolic cAMP in ependymal cells leads to a decrease in ciliary beat frequency. Therefore, the present data point towards a function for ependymal glycogen other than supplying energy for the movement of cilia.

Regulation by insulin and insulin-like growth factor of 2-deoxyglucose uptake in primary ependymal cell cultures

Ependymal cells have been reported to express the facilitative glucose carriers GLUT1, GLUT2, and GLUT4, as well as glucokinase. They are therefore speculated to be part of the cerebral glucose sensing system and may also respond to insulin with alterations in their glucose uptake rate. A cell culture model was employed to study the functional status of ependymal insulin-regulated glucose uptake in vitro. Insulin increased the uptake of the model substrate 2-deoxyglucose (2-DG) dependent on the insulin concentration. This was due to a near doubling of the maximal 2-DG uptake rate. Insulin-like growth factor (IGF-1) was at least 10 times more potent than insulin in stimulating the rate of ependymal 2-DG uptake, suggesting that IGF-1, rather than insulin, is the physiological agonist regulating glucose transport in ependymal cells. The predominant glucose transporter in ependymal cell cultures was found to be GLUT1, which is apparently regulated by IGF-1 in ependymal cells.

Atrial natriuretic peptides elevate cyclic GMP levels in primary cultures of rat ependymal cells

The aim of this study was to examine the effect of atrial natriuretic peptides on primary cultures of ependymal cells, as measured by changes in intracellular levels of cyclic GMP. Incubation of ependymal cells with rat atrial natriuretic peptide-(1-28) (rANP) elicited a 30-fold increase in ependymal cGMP content within 1 min and more than a 100-fold increase within 10 min to a plateau value of approximately 30 pmol/mg protein. The C-type natriuretic peptide (CNP) elicited a similar increase in cGMP levels; however the maximal effect was observed within 1 min and the levels subsequently dropped by 90% to a low plateau within 10 min. A comparison of the concentration-response curves for rANP, human ANP-(1-28) (hANP) and CNP showed that rANP, hANP and CNP had similar effects, with regards to elevation of cGMP levels at high concentrations, but with differing EC50 values. These results demonstrate the presence of a heterogenous population of functional ANP receptors i n cultured ependymalcells suggesting that ANP may regulate specific ependymal cell activity.

Scanning electron microscopy of central nervous system cerebrospinal-fluid-contacting surfaces: a bibliography (1963-1995)

This bibliography is compiled to assist in locating papers related to the application of scanning electron microscopy (SEM) to cerebrospinal-fluid-contacting surfaces in vertebrates. The use of SEM by neuroscientists has continued apace since the publication of the first bibliography in 1980. SEM studies now include more than 50 species of vertebrates and range from cyclostomes to humans; they encompass development from embryo to senescence and concern both normal and pathologic morphology. Although remarkable strides have been made toward a greater understanding of many aspects of the structure and function of cerebrospinal-fluid-contacting surfaces, many significant problems await the judicious application of scanning electron microscopy.

Ependymal and choroidal cells in culture: characterization and functional differentiation

During the past 10 years, our teams developed long-term primary cultures of ependymal cells derived from ventricular walls of telencephalon and hypothalamus or choroidal cells (modified ependymal cells) derived from plexuses dissected out of fetal or newborn mouse or rat brains. Cultures were established in serum-supplemented or chemically defined media after seeding on serum-, fibronectin-, or collagen-laminin-coated plastic dishes or semipermeable inserts. To identify and characterize cell types growing in our cultures, we used morphological features provided by phase contrast, scanning, and transmission electron microscopy. We used antibodies against intermediate filament proteins (vimentin, glial fibrillary acidic protein, cytokeratin, desmin, neurofilament proteins), actin, myosin, ciliary rootlets, laminin, and fibronectin in single or double immunostaining, and monoclonal antibodies against epitopes of ependymal or endothelial cells, to recognize ventricular wall cell types with immunological criteria. Ciliated or nonciliated ependymal cells in telencephalic cultures, tanycytes and ciliated and nonciliated ependymal cells in hypothalamic cultures always exceeded 75% of the cultured cells under the conditions used. These cells were characterized by their cell shape and epithelial organization, by their apical differentiations observed by scanning and transmission electron microscopy, and by specific markers (e.g., glial fibrillary acidic protein, ciliary rootlet proteins, DARPP 32) detected by immunofluorescence. All these cultured ependymal cell types remarkably resembled in vivo ependymocytes in terms of molecular markers and ultrastructural features. Choroidal cells were also maintained for several weeks in culture, and abundantly expressed markers were detected in both choroidal tissue and culture (Na+-K+-dependent ATPase, DARPP 32, G proteins, ANP receptors). In this review, the culture models we developed (defined in terms of biological material, media, substrates, duration, and subculturing) are also compared with those developed by other investigators during the last 10 years. Focusing on morphological and functional approaches, we have shown that these culture models were suitable to investigate and provide new insights on (1) the gap junctional communication of ependymal, choroidal, and astroglial cells in long-term primary cultures by freeze-fracture or dye transfer of Lucifer Yellow CH after intracellular microinjection; (2) some ionic channels; (3) the hormone receptors to tri-iodothyronine or atrial natriuretic peptides; (4) the regulatory effect of tri-iodothyronine on glutamine synthetase expression; (5) the endocytosis and transcytosis of proteins; and (6) the morphogenetic effects of galactosyl-ceramide. We also discuss new insights provided by recent results reported on in vitro ependymal and choroidal expressions of neuropeptide-processing enzymes and neurosecretory proteins or choroidal expression of transferrin regulated through serotoninergic activation.

The ependyma: a protective barrier between brain and cerebrospinal fluid

This review summarizes the current scientific literature concerning the ependymal lining of the cerebral ventricles of the brain with an emphasis on selective barrier function and protective roles for the common ependymal cell. Topics covered include the development, morphology, protein and enzyme expression including reactive changes, and pathology. Some cells lining the neural tube are committed at an early stage to becoming ependymal cells. They serve a secretory function and perhaps act as a cellular/axonal guidance system, particularly during fetal development. In the mature mammalian brain ependymal cells possess the structural and enzymatic characteristics necessary for scavenging and detoxifying a wide variety of substances in the CSF, thus forming a metabolic barrier at the brain-CSF interface.

Immunohistochemical demonstration of glycogen phosphorylase in rat brain slices

Paraffin-embedded sections from paraformaldehyde-fixed rat brain were stained immunocytochemically for glycogen phosphorylase brain isozyme BB, using a monoclonal mouse antibody and the biotin-strept-avidin method, with either horseradish peroxidase or beta-galactosidase as marker enzymes. Two cell types showed strong glycogen phosphorylase-immunoreactivity: Astrocytes and ependymal cells. Most intensive staining was observed in the cerebellar cortex, the neocortex and the hippocampus. Astrocytes in the cerebellar white matter stained positively. The choroid plexus cells stained poorly or not at all. Neurons throughout the brain were negative, as well as oligodendrocytes and bundles of myelinated nerve fibers. These data are consistent with the immunocytochemical localization of glycogen phosphorylase in astroglia-rich primary cultures derived from rat brain.

Characterization of ependymal cells in hypothalamic and choroidal primary cultures

Long-term primary cultures derived from fetal mouse or rat hypothalamus and choroid plexus were obtained in serum-supplemented and chemically defined media. In order to identify and characterize cell types growing in our cultures, we used morphological features provided by phase-contrast, scanning and transmission electron microscopy. Immunological criteria were recognized, using antibodies against intermediate filament proteins (vimentin, gliofibrillar acid protein, cytokeratin, desmin, neurofilament proteins), actin, myosin, ciliary rootlets, laminin and fibronectin in single or double immunostaining, and monoclonal antibodies known to detect epitopes of ependymal or endothelial cells. Minor cell types such as astrocytes, fibroblasts and endothelial cells were distinguished. Ependymal cells, which exceeded 75% of the cultured cells, were identified by their cell shape and epithelial organization revealed by phase-contrast and transmission electron microscopy, by their apical differentiation evidenced by scanning and transmission electron microscopy, and by certain molecular markers (e.g. gliofibrillar acid or ciliary rootlet proteins) detected by immunofluorescence. Four ependymal cell types were recognized: choroidal ependymocytes, ciliated and unciliated ependymal cells, and tanycytes. All these cultured ependymal cell types showed a remarkable resemblance to in vivo ependymocytes, in terms of marker expression and ultrastructural features.

Autoimmunity following viral infection: demonstration of monoclonal antibodies against normal tissue following infection of mice with reovirus and demonstration of shared antigenicity between virus and lymphocytes

Splenic lymphocytes from adult C57BL/6 mice infected with purified reovirus type 1 or 3 particles were fused with NS1 myeloma cells. Approximately 300 clones were obtained from each fusion (type 1 or type 3) and the supernatants from these clones were screened by radioimmunoassay for their ability to bind virus, T lymphocytes, brain, liver, lung tissues and isolated oligodendrocytes and ependymal cells. Approximately 10% of clones (33 and 26 clones, respectively) were positive for each fusion. For reovirus type 1:21% of positive clones bound only virus, 64% bound one of the normal tissues but not virus, and 15% bound both virus and one or more of the normal tissues. For reovirus type 3: 19% of positive clones bound only virus, 73% bound normal tissue only, and 8% bound both virus and normal tissue. Only 3 positive clones were obtained from uninfected control animals. These experiments demonstrate that (a) during the course of an immune response to a virus, autoantibodies are generated which react with a large variety of normal tissues and that (b) there are shared antigenic structures between viral determinants and normal tissue that can be identified by monoclonal antibodies. Although these results suggest two mechanisms by which an autoimmune response may develop following viral infection, the biological significance of these autoreactive monoclonal antibodies remains to be elucidated.

Generation of a monoclonal antibody (Epenl) which binds selectively to murine ependymal cells

In order to define surface antigens unique to ependymal cells, spleen cells from C57/B16 mice immunized with a suspension of 70-80% purified isolated ependymal cells from syngeneic animals were fused with NS-1 myeloma cells. Five hybridomas were found which secrete monoclonal antibodies that recognize ependymal cells both by indirect immunofluorescence and radioimmunoassay. One of them, Epenl, appears to be a relatively specific surface marker of murine and rat ependymal cells, whereas the 4 others also recognize neurons, astrocytes, and/or oligodendrocytes. Absorption of Epenl with murine cerebral cortex did not affect its binding, whereas absorption with ependymal cells abolished it. Labeling of in vivo sections with Epenl demonstrates prominent binding to ependymal cells lining ventricular cavities. Epenl does not bind to neurons or astrocytes in culture, and binds only minimally to isolated oligodendrocytes. It does, however, recognize an antigenic determinant present in lung tissue.

Neuroimmunology. II: Antigenic specificity of the nervous system

Antigenic specificity of the nervous system refers to a property conveyed by unique cell surface structures that are present on different classes of nervous system tissue. These structures are of major importance for the study of nervous system structure and function, and can play a central role in determining patterns of nervous system injury. Thus, the major classes of nervous system cells are identified by structures that are unique to them: neurons by the presence of tetanus toxin receptors on their surface and oligodendrocytes by the presence of surface galactocerebroside, for example. With the advent of hybridoma technology, a large number of monoclonal antibodies are being identified which have increased by several orders of magnitude the ability to define subclasses of nervous system tissue according to unique antigens. In addition, surface antigens of nervous system tissue may determine the specificity of nervous system injury by (1) functioning as receptors for viruses or (2) being the targets of autoimmune responses. Patterns of viral injury to the nervous system are often extraordinarily selective (e.g., poliovirus tropism for motor neurons), and nervous system viral tropism is due is some instances to the interaction of a virus with a unique surface antigen on neural cells. The specificity of injury in autoimmune disease (such as that against the acetylcholine receptor in myasthenia gravis) likewise must be explained by an immune response against unique antigenic determinants on the tissue being damaged. Some antigens are known to be shared between nervous system and other tissues or between nervous system and infectious agents such as bacteria or viruses. The presence of shared antigenic structures between the nervous system and infectious agents creates the possibility that an immune response generated against a virus may concurrently damage normal nervous system tissue.

Viral receptors on isolated murine and human ependymal cells

Viruses that infect ependyma cause ependymitis in humans and hydrocephalus in experimental animals. We report that reovirus type 1 (which induces hydrocephalus in mice) binds to the surface of isolated human and murine ciliated ependymal cells. With the use of recombinant viral clones, the binding property was mapped to the type 1 viral hemagglutinin, which also determines in vivo the affinity of reovirus type 1 for ependyma. Mumps virus, measles virus, parainfluenza type 3, and herpes simplex virus type 1 bind to murine ependyma cells, whereas reovirus type 3, herpes simplex virus type 2, and poliovirus type 2 do not.

Identification of a hemagglutinin-specific idiotype associated with reovirus recognition shared by lymphoid and neural cells

A xenogeneic antiserum raised to antireovirus immunoglobulin was used to define an idiotypic determinant present on antibodies to reovirus type 3 hemagglutinin. The same idiotype was identified on nonimmune lymphoid cells and on neuronal cells that specifically bind the hemagglutinin of type 3 reovirus. This idiotypic determinant, called Id3, is shared by (a) a monoclonal antibody to the neutralization site of hemagglutinin from type 3 reovirus; (b) BALB/c serum antibodies to the hemagglutinin of reovirus type 3; (c) R1.1, a murine thymoma cell line that binds reovirus type 3; (d) primary cultures of murine neuronal cells. The presence of an idiotype shared by antihemagglutinin antibodies and by structures on nonlymphoid cells suggests a general relationship between disparate receptors that recognize a common determinant. Furthermore, this suggests a novel approach for the study of viral receptor interactions and for analysis of mechanisms of autoimmune responses.

Interaction of viruses with cell surface receptors

This chapter discusses the interaction of viruses with cell surface receptors. The rigorous characterizations of receptor–ligand interactions have been derived from binding studies of radiolabeled ligands in neuropharmacology and endocrinology. The definition of viral recognition sites as receptors involves three major criteria that are derived from models of ligand–receptor interactions: saturability, specificity, and competition. A variety of approaches have been used to study the interaction of viral particles with cell surface receptors or reception sites. A rigorous study of viral–receptor interactions requires the use of more than one technique as different approaches provide complementary information about viral binding. The chapter discusses membrane components that interact with viruses. The identification of the subviral components that are responsible for the binding of viruses to cell surfaces has preceded the structural understanding of the cellular receptors themselves. The chapter summarizes current data concerning the viral attachment protein (VAP) of selected viruses.

Survey of virally mediated permeability changes

1. Sendai virus causes permeability changes when added to freshly isolated brain cells (cerebellum or ependymal cells) or to a culture of forebrain cells. 2. Sendai virus causes permeability changes when added to organ cultures of ferret lung or nasal turbinate. Influenza virus causes no permeability changes under these conditions. 3. Rabies virus and vesicular-stomatitis virus, in contrast with Sendai virus, do not cause permeability changes in BHK cells or Lettrée cells. 4. Serum from patients suffering from viral hepatitis does not cause permeability changes in human leucocytes; addition to Sendai virus causes permeability changes. 5. It is concluded that permeability changes accompanying viral entry occur only with certain types of paramyxovirus, but that there is little restriction on cell type. 6. MDBK cells infected with Sendai virus show permeability changes during viral release, similar to those that occur during viral entry. Because these changes do not appear to be restricted to paramyxoviruses, they may have considerable clinical significance.

Development, reactivity and GFA immunofluorescence of astroglia-containing monolayer cultures from rat cerebrum

This report describes detailed protocols for the dissociation, seeding and growth in vitro of monolayer cultures derived from neonatal rat cerebrum. Primary cultures derived by using different seeding densities and in vitro ages were examined qualitatively and quantitatively for morphological composition in terms of two major cell classes (flat cells and process-bearing cells) and for the presence within these classes of glial fibrillary acidic protein (GFA) as detected by immunofluorescence histochemistry. Also examined was the reaction of the cells to serum withdrawal plus the administration of dibutyryl cyclic AMP in terms of the conversion of flat cells into process-bearing cells. Conditions are defined for the generation of in vitro cell populations, more than 90% of which are GFA-containing flat cells which can all be experimentally converted into cells with processes. These well-defined culture preparations will serve as useful models for future studies of astroglial behaviour.

Spontaneous and osmotically-stimulated activity in slices of rat hypothalamus

Single unit activity was recorded from 400-500 mu m thick slices of rat hypothalamus, using either NaCl- or horseradish peroxidase-filled glass micropipettes. Spontaneous activity was present in the following hypothalamic loci: anterior hypothalamic-preoptic area, nucleus circularis, nucleus of the diagonal band of Broca, paraventricular accessory nucleus, paraventricular nucleus (all portions), periventricular regions of the anterior hypothalamus, and the suprachiasmatic nucleus. The supraoptic nucleus was the only major cell group studied to exhibit no spontaneous activity. Cells of the paraventricular and circularis nuclei were spontaneously active, displayed firing rates and patterns of activity similar to those recorded in vivo for magnocellular elements of the hypothalamus, and in some cases responded to increases in the osmolality of the bathing medium with altered firing rates and/or patterns of activity. Many cells in these preparations were characterized by phasic, bursting patterns of activity. Slow, irregular and regular, continuous activity was also frequently observed, as is typical in vivo. Median firing rates were in the range of 4-6 spikes/sec, somewhat faster than the rates usually reported for anesthetized in vivo preparations. These rates are more similar to those observed in unanesthetized monkeys or rats with diencephalic islands. Extracellular HRP marking provided a high degree of localization for many of the recorded cells. These results indicate that the hypothalamic slice preparation is useful for studies in which it is desirable to eliminate extrahypothalamic connections and in which it is necessary to exercise a fine degree of control over the extracellular environment of the cells.