Expression of glial antigens C1 and M1 in the peripheral nervous system during development and regeneration

Primary culture of glial cells from mouse sympathetic cervical ganglion: a valuable tool for studying glial cell biology

Central nervous system glial cells as astrocytes and microglia have been investigated in vitro and many intracellular pathways have been clarified upon various stimuli. Peripheral glial cells, however, are not as deeply investigated in vitro despite its importance role in inflammatory and neurodegenerative diseases. Based on our previous experience of culturing neuronal cells, our objective was to standardize and morphologically characterize a primary culture of mouse superior cervical ganglion glial cells in order to obtain a useful tool to study peripheral glial cell biology. Superior cervical ganglia from neonatal C57BL6 mice were enzymatically and mechanically dissociated and cells were plated on diluted Matrigel coated wells in a final concentration of 10,000cells/well. Five to 8 days post plating, glial cell cultures were fixed for morphological and immunocytochemical characterization. Glial cells showed a flat and irregular shape, two or three long cytoplasm processes, and round, oval or long shaped nuclei, with regular outline. Cell proliferation and mitosis were detected both qualitative and quantitatively. Glial cells were able to maintain their phenotype in our culture model including immunoreactivity against glial cell marker GFAP. This is the first description of immunocytochemical characterization of mouse sympathetic cervical ganglion glial cells in primary culture. This work discusses the uses and limitations of our model as a tool to study many aspects of peripheral glial cell biology.

Nestin expression in glial and neuronal progenitors of the developing human spinal ganglia

Expression of the neural crest marker nestin was studied in glial and neuronal progenitors of developing human spinal ganglia using immunohistochemistry in 10 conceptuses, 5-10 weeks old. Quantification was performed by counting the ratio of positive cells in the total cell number, expressed as mean + or - SD and by the Mann-Whitney test. Strong expression of nestin in the 5th-6th developmental week (56%) decreased to 49% in the foetal period. During the same period, number of PGP9.5-positive cells increased from 38% to 42%. At earliest stages, the number of cells expressing GFAP was two folds higher (21%) than S100 (11%). During further development, their number nearly levelled (23% and 28%, respectively), and finally reached level of 25% for GFAP and 40% for S100. While expression of nestin was constantly higher in the dorsal parts of spinal ganglia, number of PGP9.5-, GFAP- and S100-positive cells was higher in their ventral parts, thus indicating ventral to dorsal direction of spinal ganglia differentiation. Co-localization of nestin and GFAP or nestin and S100 was observed during the whole investigate period, while PGP9.5 did not co-localize with nestin. Some ganglion cells simultaneously co-expressing GFAP and S100 might be satellite cells and immature Schwann cells. We suggest that some nestin-positive cells might be capable to differentiate into neurons during the earliest stages of development. Gangliogenesis seems to be important process during the whole ganglion development. Continuous presence of neural crest cells during development might be important in regenerative processes following damage of the spinal ganglia.

A decline in glial cell-line-derived neurotrophic factor expression is associated with impaired regeneration after long-term Schwann cell denervation

In the peripheral nervous system, regeneration of motor and sensory axons into chronically denervated distal nerve segments is impaired compared to regeneration into acutely denervated nerves. In order to find possible causes for this phenomenon we examined the changes in the expression pattern of the glial cell-line-derived neurotrophic factor (GDNF) family of growth factors and their receptors in chronically denervated rat sciatic nerves as a function of time with or without regeneration. Among the GDNF family of growth factors, only GDNF mRNA expression was rapidly upregulated in Schwann cells as early as 48 h after denervation. This upregulation peaked at 1 week and then declined to minimal levels by 6 months of denervation. The changes in the protein expression paralleled the changes in the expression of the GDNF mRNA. The mRNAs for receptors GFRalpha-1 and GFRalpha-2 were upregulated only after maximal GDNF upregulation and remained elevated as late as 6 months. There were no significant changes in the expression of GFRalpha-3 or the tyrosine kinase coreceptor, RET. When we examined the expression of GDNF in a delayed regeneration paradigm, there was no upregulation in the distal chronically denervated tibial nerve even when the freshly axotomized peroneal branch of the sciatic nerve was sutured to the distal tibial nerve. This study suggests that one of the reasons for impaired regeneration into chronically denervated peripheral nerves may be the inability of Schwann cells to maintain important trophic support for both motor and sensory neurons.

Organization of radial glia and related cells in the developing murine CNS. An analysis based upon a new monoclonal antibody marker

A monoclonal antibody, RC1, has been generated which provides a selective and sensitive immunohistochemical marker of radial glial cells and related cell forms during development of the mouse CNS. Beginning on embryonic day E10, immunocytochemistry performed on cryostat sections stains throughout the CNS a subpopulation of cells in the ventricular zone with radial processes that terminate with endfeet at the pial surface. These processes become fasciculated and attain maximal densities by E12-14 in the spinal cord and lower brainstem and by E14-16 in the midbrain, cerebellum and forebrain. Fasciculation is especially prominent for a subclass of these cells at the midline of the brainstem and spinal cord. As nuclear and cortical structures develop, the trajectories of the radial fiber fascicles undergo systematic and region-specific distortions in their initially simple linear configuration, in the process maintaining a consistent spatial registration of germinal ventricular zones with distal sites of assembly of post-migratory neurons. In the late fetal period, radial glial progressively disappear and scattered immature astrocytes bearing multiple fine processes appear in most regions of the CNS. In the spinal cord, a transitional unipolar radial form is identified in the emerging ventral and lateral funiculi between E13 and E17. In the cerebellum, precursors to the unipolar Bergmann glial cell are identified by E15, and in the retina, precursors of the bipolar Müller cell are identified by E16. Postnatally, RC1-stained radial glia become sparse, and after one week, immunoreactive cells include only ependymal cells, hypothalamic tanycytes, Bergmann glia, Müller cells, a unipolar radial form in the dentate gyrus, and a subpopulation of white matter astrocytes. These results suggest that radial cells of astroglial lineage comprise a diverse set of cell classes which subserve multiple functions in the developing and adult brain.

Glial cells in the pineal gland of mice and rats. A combined immunofluorescence and electron-microscopic study

Antigenic markers characteristic of astrocytes and their differentiative states (i.e., glial fibrillary acidic protein (GFAP), vimentin, and M1 and C1 antigens) were investigated in the pineal gland of mouse and rat using double immunolabeling techniques. In both species the so-called interstitial cells as characterized by TEM were shown to be astrocytes, since they expressed vimentin, but neither fibronectin (a marker for fibroblasts and endothelial cells) nor the neuron-specific L1 antigen or tetanus toxin receptors. Subpopulations of vimentin-positive pineal astrocytes were also GFAP- and C1- antigen-positive. M1- antigen-positive cells were not detected. It is concluded that a considerable proportion of interstitial cells in the pineal gland of rat and mouse are immature astrocytes which, in contrast to other parts of the central nervous system, persist into adulthood.