Purification of rat Schwann cells from cultures of peripheral nerve: an immunoselective method using surfaces coated with anti-immunoglobulin antibodies

Combined effects of rat Schwann cells and 17β-estradiol in a spinal cord injury model

Spinal cord injury (SCI) is a devastating traumatic event which burdens the affected individuals and the health system. Schwann cell (SC) transplantation is a promising repair strategy after SCI. However, a large number of SCs do not survive following transplantation. Previous studies demonstrated that 17β-estradiol (E2) protects different cell types and reduces tissue damage in SCI experimental animal model. In the current study, we evaluated the protective potential of E2 on SCs in vitro and investigated whether the combination of hormonal and SC therapeutic strategy has a better effect on the outcome after SCI. Primary SC cultures were incubated with E2 for 72 h. In a subsequent experiment, thoracic contusion SCI was induced in male rats followed by sustained administration of E2 or vehicle. Eight days after SCI, DiI-labeled SCs were transplanted into the injury epicenter in vehicle and E2-treated animals. The combinatory regimen decreased neurological and behavioral deficits and protected neurons and oligodendrocytes in comparison to vehicle rats. Moreover, E2 and SC significantly decreased the number of Iba-1+ (microglia) and GFAP⁺ cells (astrocyte) in the SCI group. In addition, we found a significant reduction of mitochondrial fission-markers (Fis1) and an increase of fusion-markers (Mfn1 and Mfn2) in the injured spinal cord after E2 and SC treatment. These data demonstrated that E2 protects SCs against hypoxia-induced SCI and improves the survival of transplanted SCs.

Detailed Protocols for the Isolation, Culture, Enrichment and Immunostaining of Primary Human Schwann Cells

This chapter emphasizes detailed protocols for the effective establishment of highly enriched human Schwann cell cultures and their characterization via immunostaining. The Schwann cells are isolated from immediately dissociated fascicle tissue and expanded prior to purification. Two purification methods are described that use either fluorescence-activated cell sorting for the Schwann cell marker TNR16 (p75^NTR) or a less-manipulative two-step enrichment exploiting the differential adhesion properties of Schwann cells and fibroblasts, which is especially useful for low Schwann cell numbers. In addition, a method to determine Schwann cell purity via stained cytospin slides is introduced. Together with an immunofluorescence staining procedure for the combined analysis of extra- and intracellular markers, this chapter provides a solid basis to study human primary Schwann cells.

Isolation and Purification of Schwann Cells from Spinal Nerves of Neonatal Rat

Primary cultured Schwann cells (SCs) are widely used in the investigation of the biology of SC and are important seed cells for neural tissue engineering. Here, we describe a novel protocol for harvesting primary cultured SCs from neonatal Sprague-Dawley (SD) rats. In the present protocol, dissociated SCs are isolated from the spinal nerves of neonatal rats and purified by the treatment of cytosine arabinoside (AraC).

Dispase rapidly and effectively purifies Schwann cells from newborn mice and adult rats

In the present study, Schwann cells were isolated from the sciatic nerve of neonatal mice and purified using dispase and collagenase. Results showed that after the first round of purification with dispase, most of the Schwann cells appeared round in shape and floated in culture solution after 15 minutes. In addition, cell yield and cell purity were higher when compared to the collagenase group. After the second round of purification, the final cell yield for the dispase group was higher than that for the collagenase group, but no significant difference was found in cell purity. Moreover, similar results in cell quantity and purity were observed in adult Sprague-Dawley rats. These findings indicate that purification with dispase can result in the rapid isolation of Schwann cells with a high yield and purity.

An efficient system for selection and culture of Schwann cells from adult rat peripheral nerves

Schwann cells (SCs), the supporting cells of the peripheral nerves, are indispensable for regenerating the peripheral and central nervous system. Copious preparation of these cells in a well-defined manner is to be a privileged position. SCs cultivation is overwhelmed by contaminating fibroblasts which are often outgrowing as the predominant cell type in an in vitro culture. This study introduces a technically simple and efficient procedure for SCs isolation and enrichment based on implementing recombinant and defined supplements. Collected adult rat sciatic nerves were cultured for 10 days as in vitro predegeneration. After dissociation and plating, the medium changed to knockout serum replacement supplemented DMDM/F12 medium containing various growth factors. The whole procedure took 3 weeks and SCs purity was then evaluated through implementing specific cytoplasmic and membranous markers. The viability of enriched SCs were evaluated by MTT assay. Within 10 days, over 99 % homogenous SCs were achieved and confirmed through immunofluorescence staining and flow-cytometry for P75(NTR) and S100 markers, respectively. MTT data revealed that the viability and metabolic activities of purified SCs were increased in expansion medium. This study provides a technically easy and efficient method with the benefits of not utilizing bovine serum or other animal products for SCs isolation and enrichment.

Glia maturation factor deficiency suppresses 1-methyl-4-phenylpyridinium-induced oxidative stress in astrocytes

Inflammation is closely intertwined with pathogenesis of Parkinson's disease (PD). Increasing evidence suggests that inhibition of glia-mediated inflammation might represent a promising therapeutic target for PD. Glia maturation factor (GMF), an inflammatory protein, predominantly localized in astrocytes is previously isolated, sequenced and cloned in our laboratory. In the present investigation, we demonstrate that GMF-deficiency in astrocytes upregulates the antioxidant status and limit the extent of lipid peroxidation and production of reactive oxygen species (ROS) along with diminished nuclear factor-κB-mediated inflammatory responses in 1-methyl-4-phenylpyridinium (MPP(+))-induced toxicity. Primary astrocytes obtained from wild-type (Wt) and GMF-deficient (GMF-KO) mice were treated with 5, 10, and 20 μM MPP(+) for 24, 48, and 72 h in vitro. Our results show decreased release of ROS and increased level of glutathione in astrocytes obtained from GMF-KO mice when compared to astrocytes derived from Wt mice following MPP(+) treatment. Additionally, we found decreased activity of NF-κB, and reduced levels of proinflammatory tumor necrosis factor- α, interleukin-1β (IL-1β), IL-17, IL-33, and chemokine (C-C motif) ligand 2 (CCL2) in GMF-KO astrocytes when compared to Wt astrocytes. Our overall results suggest that GMF-KO astrocytes are significantly resistant to MPP(+) toxicity when compared to Wt astrocytes.

Novel method to obtain highly enriched cultures of adult rat Schwann cells

Schwann cells (SCs) can be used to repair both the peripheral and central nervous systems. Therefore, establishment of a procedure to obtain activated, highly proliferative SCs, in an appropriate time for clinical applications, is a prerequisite. Purification is complicated by contamination with fibroblasts which often become the predominant cell type in an in vitro SC culture. This study describes a novel and efficient method to enrich SCs by utilizing the differential detachment properties of the two cell types. In culture, cells were treated with two different media and the chelator, EGTA, which detached SCs faster than fibroblasts and allowed for easy isolation of SCs. Within seven days, high yields of SCs with a purity of greater than 99% were achieved. This was confirmed by immunostaining characterization and flow-cytometric analyses using an antibody against the p75 low affinity nerve growth factor receptor (p75LNGFR). The entire procedure was completed in approximately 21 days. This method has the advantage of being technically easier, faster, and more efficient than other previously described methods. An SC culture that was about 99% homogenous was achieved.

Pharmacological and local toxicity studies of a liposomal formulation for the novel local anaesthetic ropivacaine

This study reports an investigation of the pharmacological activity, cytotoxicity and local effects of a liposomal formulation of the novel local anaesthetic ropivacaine (RVC) compared with its plain solution. RVC was encapsulated into large unilamellar vesicles (LUVs) composed of egg phosphatidylcholine, cholesterol and α-tocopherol (4:3:0.07, mole%). Particle size, partition coefficient determination and in-vitro release studies were used to characterize the encapsulation process. Cytotoxicity was evaluated by the tetrazolium reduction test using sciatic nerve Schwann cells in culture. Local anaesthetic activity was assessed by mouse sciatic and rat infraorbital nerve blockades. Histological analysis was performed to verify the myotoxic effects evoked by RVC formulations. Plain (RVCPLAIN) and liposomal RVC (RVCLUV) samples were tested at 0.125%, 0.25% and 0.5% concentrations. Vesicle size distribution showed liposomal populations of 370 and 130 nm (85 and 15%, respectively), without changes after RVC encapsulation. The partition coefficient value was 132 ± 26 and in-vitro release assays revealed a decrease in RVC release rate (1.5 fold, P < 0.001) from liposomes. RVCLUV presented reduced cytotoxicity (P < 0.001) when compared with RVCPLAIN. Treatment with RVCLUV increased the duration (P < 0.001) and intensity of the analgesic effects either on sciatic nerve blockade (1.4–1.6 fold) and infraorbital nerve blockade tests (1.5 fold), in relation to RVCPLAIN. Regarding histological analysis, no morphological tissue changes were detected in the area of injection and sparse inflammatory cells were observed in only one of the animals treated with RVCPLAIN or RVCluv at 0.5%. Despite the differences between these preclinical studies and clinical conditions, we suggest RVCLUV as a potential new formulation, since RVC is a new and safe local anaesthetic agent.

A novel method for isolating Schwann cells using the extracellular domain of Necl1

Myelinating cocultures of Schwann cells and dorsal root ganglion neurons are a powerful experimental system for probing the molecular mechanisms of axon-Schwann cell interaction. The isolation of a pure population of myelination-competent Schwann cells is a prerequisite for this experimental system. We describe here a protocol for a FACS-based isolation of Schwann cells utilizing a specific affinity reagent (Necl1-Fc) and the use of these isolated cells in myelinating cocultures. An advantage of the myelinating coculture system is that Schwann cells and the neurons can be genetically manipulated before they are cocultured. We further show that our method allows the isolation of virally transduced Schwann cells in a single purification step. This protocol for the FACS-based isolation of myelination-competent Schwann cells by Necl1-Fc and the use of these cells in myelinating cocultures should significantly facilitate future studies aimed at delineation of the molecular mechanisms of axon-Schwann cell interactions and myelination.

Expression of basal lamina components by Schwann cells cultured on poly(lactic acid) (PLLA) and poly(caprolactone) (PCL) membranes

The present in vitro study investigated the expression of basal lamina components by Schwann cells (SCs) cultivated on PCL and PLLA membranes prepared by solvent evaporation. Cultures of SCs were obtained from sciatic nerves from neonatal Sprague Dawley rats and seeded on 24 well culture plates containing the polymer membranes. The purity of the cultures was evaluated with a Schwann cell marker antibody (anti-S-100). After one week, the cultures were fixed and processed for immunocytochemistry by using antibodies against type IV collagen, laminin I and II. Positive labeling against the studied molecules was observed, indicating that such biomaterials positively stimulate Schwann cell adhesion and proliferation. Overall, the present results provide evidence that membrane-derived biodegradable polymers, particularly those derived from PLLA, are able to provide adequate substrate and stimulate SCs to produce ECM molecules, what may have in turn positive effects in vivo, influencing the peripheral nerve regeneration process.

Glia maturation factor modulates beta-amyloid-induced glial activation, inflammatory cytokine/chemokine production and neuronal damage

Glia maturation factor (GMF), discovered and characterized in our laboratory, is a highly conserved protein primarily localized in mammalian central nervous system. Previously we demonstrated that GMF is required in the induced production of proinflammatory cytokines and chemokines in brain cells. We now report that ventricular infusion of human amyloid beta peptide1-42 (Abeta1-42) in mouse brain caused glial activation and large increases in the levels of GMF as well as induction of inflammatory cytokine/chemokine known for launching the neuro inflammatory cascade in Alzheimer's disease (AD). To test the hypothesis that GMF is involved in the pathogenesis of AD, we infused Abeta1-42 in the brain of GMF-deficient (GMF-KO) mice, recently prepared in our laboratory. GMF-deficient mice showed reduced glial activation and significantly suppressed proinflammatory cytokine/chemokine production following Abeta infusion compared to wild type (Wt) mice. The decrease in glial activation in the GMF-KO mice is also associated with significant reduction in Abeta induced loss of pre-synaptic marker, synaptophysin, and post-synaptic density protein-95 (PSD 95). We also examined the potential relationship between GMF or lack of it with learning and memory using the T-maze, Y-maze, and water maze, hippocampal-dependent spatial memory tasks. Our results show that memory retention was improved in GMF-KO mice compared to Wt controls following Abeta infusion. Diminution of these Abeta1-42 effects in primary cultures of GMF-KO astrocyte and microglia were reversed by reconstituted expression of GMF. Taken together, our results indicate a novel mediatory role of GMF in the neuro-inflammatory pathway of Abeta and its pro-inflammatory functions.

Isolation of skin-derived precursors (SKPs) and differentiation and enrichment of their Schwann cell progeny

This protocol describes methods of isolating skin-derived precursors (SKPs) from rodent and human skin, and for generating and enriching Schwann cells from rodent SKPs. SKPs are isolated as a population of non-adherent cells from the dermis that proliferate and self-renew as floating spheres in response to fibroblast growth factor 2 (FGF2) and epidermal growth factor (EGF). Their differentiation into Schwann cells and subsequent enrichment of these differentiated progeny involves culturing SKPs as adherent cells in the absence of FGF2 and EGF, but in the presence of neuregulins, and then mechanically isolating the Schwann cell colonies using cloning cylinders. Methods for expanding and characterizing these Schwann cells are provided. Generation of primary SKPs takes approximately 2 weeks, while differentiation of Schwann cells requires an additional 4-6 weeks.

A novel role of glia maturation factor: induction of granulocyte-macrophage colony-stimulating factor and pro-inflammatory cytokines

The glia maturation factor (GMF), which was discovered in our laboratory, is a highly conserved protein predominantly localized in astrocytes. GMF is an intracellular regulator of stress-related signal transduction. We now report that the overexpression of GMF in astrocytes leads to the destruction of primary oligodendrocytes by interactions between highly purified cultures of astrocytes, microglia, and oligodendrocytes. We infected astrocytes with a replication-defective adenovirus carrying the GMF cDNA. The overexpression of GMF caused the activation of p38 MAP kinase and transcription factor NF-kappaB, as well as the induction of granulocyte-macrophage colony-stimulating factor (GM-CSF) mRNA and protein in astrocytes. Small interfering RNA-mediated GMF knockdown completely blocked the GMF-dependent activation of p38 mitogen-activated protein kinase (MAPK), NF-kappaB, and enhanced expression of GM-CSF by astrocytes. Inhibition of p38 MAPK or NF-kappaB by specific inhibitors prevented GM-CSF production. The cell-free conditioned medium from overexpressing GMF astrocytes contained 320 +/- 33 pg/mL of GM-CSF, which was responsible for enhanced production and secretion of TNF-alpha, IL-1beta, IL-6, and IP-10 by microglia. Presence of these inflammatory cytokines in the conditioned medium from microglia efficiently destroyed oligodendrocytes in culture. These results suggest that GMF-induced production of GM-CSF in astrocytes is depending on p38 MAPK and NF-kappaB activation. The GM-CSF-dependent expression and secretion of inflammatory cytokine/chemokine, TNF-alpha, IL-1beta, IL-6, and IP-10, is cytotoxic to oligodendrocytes, the myelin-forming cells in the central nervous system, and as well as neurons. Our results suggest a novel pathway of GMF-initiated cytotoxicity of brain cells, and implicate its involvement in inflammatory diseases such as multiple sclerosis.

Olfactory ensheathing cells express smooth muscle α-actin in vitro and in vivo

One strategy for spinal cord repair after injury that has moved quickly from the research laboratory to the clinic is the implantation of olfactory ensheathing cells (OECs). These unique glial cells of the olfactory system have been associated with axonal remyelination and regeneration after grafting into spinalized animals. Despite these promising observations, there remains a lack of direct empirical evidence of the exact fate of OECs after intraspinal implantation, in large part because of a surprising paucity of defined biomarkers that unequivocally distinguish these cells from phenotypically similar Schwann cells. Here we provide direct neurochemical proof that OECs, both in vitro and in vivo, express smooth muscle alpha-actin. That OECs synthesize this contractile protein (and a variety of actin-binding proteins including caldesmon) provides compelling evidence that these cells are, in fact, quite different from Schwann cells. The identification of several smooth muscle-related proteins in OECs points to a new appreciation of the structural and functional features of this population of olfactory glia. These biomarkers can now be used to elucidate the fate of OECs after intraspinal implantation, in particular assessing whether smooth muscle alpha-actin-expressing OECs are capable of facilitating axon remyelination and regeneration.

Neural crest stem cells undergo multilineage differentiation in developing peripheral nerves to generate endoneurial fibroblasts in addition to Schwann cells

Neural crest stem cells (NCSCs) persist in peripheral nerves throughout late gestation but their function is unknown. Current models of nerve development only consider the generation of Schwann cells from neural crest, but the presence of NCSCs raises the possibility of multilineage differentiation. We performed Cre-recombinase fate mapping to determine which nerve cells are neural crest derived. Endoneurial fibroblasts, in addition to myelinating and non-myelinating Schwann cells, were neural crest derived, whereas perineurial cells, pericytes and endothelial cells were not. This identified endoneurial fibroblasts as a novel neural crest derivative, and demonstrated that trunk neural crest does give rise to fibroblasts in vivo, consistent with previous studies of trunk NCSCs in culture. The multilineage differentiation of NCSCs into glial and non-glial derivatives in the developing nerve appears to be regulated by neuregulin, notch ligands, and bone morphogenic proteins, as these factors are expressed in the developing nerve, and cause nerve NCSCs to generate Schwann cells and fibroblasts, but not neurons, in culture. Nerve development is thus more complex than was previously thought, involving NCSC self-renewal, lineage commitment and multilineage differentiation.

Purification of Schwann cells by selection of p75 low affinity nerve growth factor receptor expressing cells from adult peripheral nerve

The intrinsic capacity of Schwann cells to promote regeneration after limited peripheral nerve lesions has been successfully transferred to extensive peripheral nerve injuries and central nervous system lesions by autologous transplantation strategies. However, both the intrinsic ability of axotomized neurons to regenerate and the permissiveness of the parenchyma surrounding the acute injury site diminish over time. Therefore, the autologous transplantation mode requires a fast and effective method to isolate Schwann cells from peripheral nerve biopsies. Here, we report a method to purify p75 low affinity nerve growth factor receptor (p75LNGFr) expressing Schwann cells from peripheral nerve biopsies in adult rats using magnetic-activated cell separation (MACS). After 1 week of nerve degeneration in culture, nerve fragments were dissociated resulting in mixed cultures containing Schwann cells and fibroblasts. After incubation with specific anti-p75LNGFr antibodies and secondary magnetic bead conjugated antibodies followed by one cycle of MACS, 95% pure Schwann cell cultures were generated as confirmed by flow-cytometry and immunocytochemistry. In contrast to established methods, MACS separation of p75LNGFr expressing cells allows the reliable purification of Schwann cells within 9 days after biopsy employing direct selection of Schwann cells rather than fibroblast depletion assays. Therefore, this method represents an effective and fast means to generate autologous Schwann cells for clinical transplantation strategies aiming for axon repair and remyelination.

Interleukin-6 expression and regulation in rat enteric glial cells

As yet, little is known about the function of the glia of the enteric nervous system (ENS), particularly in an immune-stimulated environment. This prompted us to study the potential of cultured enteroglial cells for cytokine synthesis and secretion. Jejunal myenteric plexus preparations from adult rats were enzymatically dissociated, and enteroglial cells were purified by complement-mediated cytolysis and grown in tissue culture. Cultured cells were stimulated with recombinant rat interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha, and IL-6 mRNA expression and secretion were assessed using RT-PCR and a bioassay, respectively. Stimulation with TNF-alpha did not affect IL-6 mRNA expression, whereas IL-1beta stimulated IL-6 mRNA and protein synthesis in a time- and concentration-dependent fashion. In contrast, IL-6 significantly and dose-dependently suppressed IL-6 mRNA expression. In summary, we have presented evidence that enteric glial cells are a potential source of IL-6 in the myenteric plexus and that cytokine production by enteric glial cells can be regulated by cytokines. These findings strongly support the contention that enteric glial cells act as immunomodulatory cells in the enteric nervous system.

Isolation of enteric glia and establishment of transformed enteroglial cell lines from the myenteric plexus of adult rat

Although enteroglial cells (EGCs) may play a key role in the inflammatory response of the enteric nervous system, little is known about their immunophysiological properties. To facilitate further characterization of enteric glia, we have developed a novel method to isolate and purify EGCs from the myenteric plexus. Myenteric plexus preparations were enzymatically dissociated and EGCs purified by complement-mediated cytolysis of contaminating cells and transformed by retroviral gene transfer. Primary and transformed cells were characterized immunohistochemically and by dot-blot analysis. Functionally, c-fos mRNA expression was assessed in primary and transformed enteroglial cells. All cells displayed robust glial fibrillary acidic protein, S-100 and vimentin immunoreactivities, but no Thy-1.1, desmin, smooth muscle alpha-actin or C3 complement receptor immunoreactivity. This confirmed their enteroglial lineage and excluded contamination with other cell types. Both primary and transformed EGCs displayed little constitutive c-fos mRNA expression. This, however, could be upregulated by various stimuli, including proinflammatory cytokines. In summary, we present a novel method to purify EGCs from rat myenteric plexus for tissue culture and to establish transformed EGC lines that retain their glial nature and functional properties. Such cell lines are now available for physiological studies of the functional properties of enteric glia in vitro.

Cold jet: a method to obtain pure Schwann cell cultures without the need for cytotoxic, apoptosis-inducing drug treatment

This paper presents a new and gentle method to separate Schwann cells from fibroblasts obtained from foetal rat dorsal root ganglia (DRG). The method exploits the different growth and adhesion characteristics of fibroblasts and Schwann cells under different experimental conditions such that antiproliferative (cytotoxic) drugs or time-consuming centrifugation is not needed. Standard procedures were used to obtain mixed cultures of Schwann cells, fibroblasts and neurons. After about 5 days further purification of the cells was achieved by exploiting the different responses of Schwann cells and fibroblasts to a temperature shock. Cooling the cells with cold phosphate-buffered saline (PBS), followed by pipetting cold medium directly on top of the cells ('cold jet'), resulted in specific detachment of Schwann cells and neurons, whereas fibroblasts remained securely attached. Schwann cells attached to the surface of new, uncoated culture dishes whereas neurons did not. Two cycles of the cold jet procedure resulted in nearly pure (98-100%) cultures of Schwann cells. Besides being gentle, this method is easy and fast, and because cytotoxic drugs are not used, it does not affect cell survival negatively.

Separation of round spermatids from the rat using an immunoselection panning technique

A method was devised for the isolation of round spermatids from the rat using a positive immunoselection technique (panning). A testis suspension was prepared from adult rats by enzymatic digestion of seminiferous tubules with collagenase. Specific mouse monoclonal antibody (97.25) was indirectly attached to Petri dishes and used in a panning protocol to purify spermatids from the testis cell suspension. The quantity and purity of cells isolated were determined by cell counts and histochemical (periodic acid-Schiff stain) or by immunostaining with acrosome-specific antibodies. A mean yield of 1.38 +/- 0.15 x 10(7) cells per dish was obtained with a purity of more than 90%. The viability of the cells was confirmed by epifluorescent microscopy with propidium iodide/carboxyfluorescein acetate probes. Northern blot analysis of RNA extracted directly from the dish indicated good integrity of a spermatid-specific transcript of glyceraldehyde-3-phosphate dehydrogenase (GAPDH).

Neuron-Schwann cell signals are conserved across species: purification and characterization of embryonic chicken Schwann cells

A monoclonal antibody, 1E8, which recognizes the peripheral myelin protein, P0, specific for chicken Schwann cells and their precursors (Bhattacharyya et al., Neuron 7:831-844, 1991), was used to immunoselect Schwann cells from embryonic day 14 (E14) chicken sciatic nerve. When cultured, these immunoselected cells displayed properties characteristic of perinatal rodent Schwann cells, including S100-immunoreactivity and O4 antigen-immunoreactivity. In addition, the purified chicken Schwann cells divided slowly when cultured alone, but when co-cultured with chicken or rat sensory neurons, they bound to axons and proliferated. Proliferation was also stimulated by the addition of bovine brain membrane extracts or chicken brain membranes. The 1E8 monoclonal antibody was also used to test the effect of axonal contact on P0 expression. Chicken Schwann cells purified using the 1E8 monoclonal antibody gradually lost P0 when cultured alone. These cells remained 1E8-negative even after prolonged co-culture with embryonic rat dorsal root ganglion neurons or chicken sensory ganglia. These results demonstrate that chicken Schwann cells behave like rodent Schwann cells in their expression of specific antigens, interactions with axons, and regulation of P0 expression. In addition, chicken Schwann cells respond to neuronal signals from the rat and cow, illustrating the cross-species conservation of these signals.

Isolation and characterization of neonatal Schwann cells from cryopreserved rat sciatic nerves

Much of our knowledge about the development and maintenance of the peripheral nervous system has been learned through studying the interaction of neurons, or their isolated membranes, with Schwann cells (SC), in tissue culture. Numerous approaches have been employed to obtain an adequate quantity of SC, but all have been limited by either the uncertainty of obtaining a sufficient amount of starting material, the time and expertise required to isolate the SC, or by the limited number of SC that can be generated. We have developed a procedure to isolate SC from cryopreserved sciatic nerves. This procedure allows for sciatic nerves to be pooled until adequate numbers of nerves are obtained, yet still produces cells that retain the functional abilities of SC isolated from fresh nerves. Sciatic nerves were isolated from 2 day old rat pups, placed in either DME media and used fresh or placed in a freezing solution containing DME media (25%), DMSO (25%), fetal calf serum (50%), frozen at -70 degrees C and stored in liquid nitrogen. The frozen nerves were rapidly thawed to 37 degrees C and single cells were prepared from both fresh and frozen nerves using enzymatic and mechanical disruption as previously described (Brockes et al., Brain Res 165: 105-118, 1979). Comparable cell yields were obtained for SC isolated from both frozen and fresh nerves. Immunohistochemical staining of both fresh and frozen SC produced similar staining patterns with antibodies to GFAP, laminin, CNPase, S100, MBP, and P0 protein. Addition of axolemmal enriched membrane fractions to both the frozen and fresh SC gave a similar dose response curve of 3H-thymidine incorporation, with SC from frozen sciatic nerves responding even better than fresh sciatic nerves at higher doses (50 micrograms and 100 micrograms of protein/ml). As demonstrated by the cell yield, immunohistochemical staining and responses to axolemmal mitogens, this procedure produces SC from frozen sciatic nerves with similar characteristics to those isolated from fresh nerves. This procedure will allow the production and utilization of a large number of SC, which will be critical in further studies on the development and maintenance of the peripheral nervous system.

Age-related changes in attachment and proliferation of mouse Schwann cells in vitro

Schwann cells can be cultured readily from the peripheral nerves of the neonatal animal but not from the adult. To correlate the physiological properties of Schwann cells relevant to such a difference, we examined age-related changes in attachment and proliferation of mouse Schwann cells in vitro. The capacity of Schwann cells to attach to polylysine-coated coverslips at 1 day in vitro declined rapidly between 3 and 30 days of age, followed by a more gradual decrease with age. Attachment of Schwann cells from younger mice (but not older mice) was enhanced by precoating coverslips with laminin or to a lesser degree with fibronectin, suggesting an age-dependent decrease in receptors for these substrates. Indeed, the staining for fibronectin receptor could be demonstrated in vivo, and was more intense and diffuse in neonatal sciatic nerves. In vitro, although staining of Schwann cells and fibroblasts was clear, there was no age-related difference for the intensity or distribution of the staining. Proliferation, as assessed by thymidine incorporation at 1 day in vitro, was high when Schwann cells were isolated from younger mice but declined as a function of the age of mice from which cells were prepared. Removal of axonal and myelin debris from cultures 3 h after plating resulted in a reduction of thymidine uptake by Schwann cells from 30-day-old mice, but much less from 10-day-old mice. Schwann cell growth was faster in the cells from younger mice than older ones, thus leading to early confluency and cell-contact inhibition in the former. In addition, evidence is presented that in medium supplemented with fetal bovine serum, thymidine uptake by Schwann cells from mice at 3-30 days of age was three times higher than that by Schwann cells from age-matched rats. These results indicate that the methodology usually used for purification of rat Schwann cells involving antimitotics is not suitable for highly proliferating mouse Schwann cells.

Antiproliferative function of glia maturation factor beta

Recombinant human glia maturation factor beta (GMF-beta) reversibly inhibits the proliferation of neoplastic cells in culture by arresting the cells in the G0/G1 phase. This phenomenon is not target-cell specific, as neural and nonneural cells are equally inhibited. When tested simultaneously, GMF-beta suppresses the mitogenic effect of acidic fibroblasts growth factor (aFGF), but the two are synergistic in promoting the morphologic differentiation of cultured astrocytes. GMF-beta also counteracts the growth-stimulating effect of pituitary extract and cholera toxin on Schwann cells. The results underscore the regulatory role of GMF-beta and its intricate interaction with the mitogenic growth factors.

Rat sciatic nerve Schwann cell microcultures: responses to mitogens and production of trophic and neurite-promoting factors

During embryonic development and in response to injury, the growing axons of peripheral neurons may influence the migration and proliferation of Schwann cells which, in return, may present neurons with a critical supply of factors required for neuronal survival, growth and differentiation. The identification and characterization of agents influencing the proliferation of Schwann cells as well as Schwann cell production of factors affecting neurons is greatly facilitated by the use of in vitro techniques. We describe here a simplified method of obtaining large numbers of purified neonatal rat sciatic nerve Schwann cells for use in generating large numbers of replicate microcultures. We then illustrate the use of these microcultures to examine Schwann cell: i) morphology and survival; ii) proliferation; and iii) production of neuronotrophic and neurite-promoting activities. We report that rat Schwann cells in microculture proliferate in response to serum, laminin and fibronectin, cholera toxin, and chick embryo parasympathetic ciliary neurons. Also, extracts of Schwann cell microcultures contain independently regulated activities which support the survival and neurite outgrowth of peripheral ganglionic neurons.

A simple method for the Schwann cell preparation from newborn rat sciatic nerves

We have developed a simple and relatively rapid method for obtaining a sufficient number of Schwann cells with a favorable purification ratio from newborn rat sciatic nerves. Perineurium-free nerves were torn into small fascicles of approximately 150-200 microns in diameter and explanted twice on type I collagen gel every 2 days of the culture period in order to reduce the number of contaminant fibroblasts. The last explanted tissues were fed with Dulbecco's modified Eagle medium supplemented with 10% fetal bovine serum and 100 micrograms/ml bovine pituitary extract for 10 days. More than 10 X 10(4) Schwann cells (greater than 95% purity) were obtained from newborn rat sciatic nerves.

Detection of a nerve growth factor receptor on fetal human Schwann cells in culture: absence of the receptor on fetal human astrocytes

Cultures of human Schwann cells and astrocytes were established from fetal nerves and brains respectively. The human Schwann cells in culture expressed a nerve growth factor (NGF) receptor as determined by indirect immunofluorescence, autoradiography, and immunoprecipitation. In contrast, the human astrocytes in culture did not have an NGF receptor. Cultures of rat Schwann cells and astrocytes were also established for comparison, with similar results. The rat Schwann cells had an NGF receptor whereas the astrocytes did not. The functional significance of this NGF receptor on Schwann cells, as well as the lack of the receptor on astrocytes, is discussed.

Immunological, morphological, and electrophysiological variation among retinal ganglion cells purified by panning

Two different monoclonal antibodies to the Thy-1 antigen, T11D7 and 2G12, were used to purify and characterize retinal ganglion cells from postnatal rat retina. Although Thy-1 has been reported to be a specific marker for ganglion cells in retina, retinal cell suspensions contained several other types of Thy-1-positive cells as well. Nevertheless, a simple two-step "panning" procedure allowed isolation of ganglion cells to nearly 100% purity. We found that postnatal ganglion cells differed in antigenic, morphological, and intrinsic electrophysiological characteristics, and that these properties were correlated with one another. Minor variations of this panning protocol should allow rapid, high yield purification to homogeneity of many other neuronal and glial cell types.

Endogenous immunoreactive glia maturation factor-like molecule in cultured rat Schwann cells

Using the monoclonal antibody G2-09 raised against bovine glia maturation factor (GMF), we demonstrated that cultured rat Schwann cells and Schwannoma cells, but not their conditioned media, possessed endogenous GMF-like immunoreactivity. The presence of immunoreactive GMF correlated well with GMF bioactivity. The GMF-like factor in Schwann cells was characterized by immunodotting, immunofluorescence, immunoadsorption and immunoblotting. Immunofluorescence confirmed the intracellular location of GMF. Immunoadsorption completely eliminated the GMF-like bioactivity from the cell extracts. Immunoblotting identified a protein band with a molecular weight of 14,000. Thus, the evidence strongly supports the argument that the GMF-like factor in rat Schwann cells is identical with GMF from the bovine brain. The GMF-like molecule in Schwannoma cells showed properties similar to those in Schwann cells, but for unknown reasons was not detectable by immunofluorescence. The presence of GMF in cultured rat Schwann cells suggests that the factor may play a role in the peripheral nervous system.

Schwann cell-conditioned medium supports neurite outgrowth and survival of spinal cord neurons in culture

The effect of Schwann cell-conditioned medium (SCM) on the development in vitro of spinal cord neurons was studied. Spinal cord neurons from 18-day-old rat embryos were cultured in serum-free conditioned medium obtained from confluent rat Schwann cells. In cultures fed SCM, the cells developed typical neuronal morphology and were identified by indirect immunofluorescence using a monoclonal antibody to neurofilament protein. SCM stimulated neurite outgrowth and supported survival of spinal cord neurons. Preliminary characterization suggests that the neurotrophic factor in SCM appears to be a protein with a molecular weight greater than 8000 daltons.

Endogenous immunoreactive glia maturation factor-like molecule in astrocytes and glioma cells

Using the monoclonal antibody G2-09 raised against bovine glia maturation factor (GMF), we conducted a survey of GMF-like immunoreactivity in various cell types. Of all the normal and neoplastic cells tested, only extracts from astroblasts, gliomas, Schwann cells and schwannomas, but not their conditioned media, possessed endogenous GMF-like immunoreactivity. The presence of immunoreactive GMF correlated well with GMF bioactivity. Using the same monoclonal antibody, the GMF-like factor in astroblasts and C6 glioma cells was characterized by immunofluorescence, immunoadsorption and immunoblotting. Immunofluorescence confirmed the intracellular location of GMF. Immunoadsorption completely eliminated the GMF-like bioactivity from the cell extracts. Immunoblotting identified a protein band having a mol. wt. of 14,000 Da. Thus, the evidence strongly supports the argument that the GMF-like factor in astroblasts and C6 cells is identical with GMF from the bovine brain. In order to explain the fact that astroblasts and C6 cells are both the source and targets of GMF, we propose the hypothesis that GMF functions as an injury signal, being released from the injured glia and serving as a stimulant for gliosis in the neighboring intact glia.

Rat astrocytes and Schwann cells in culture synthesize nerve growth factor-like neurite-promoting factors

Neurite-promoting activity in feeding medium conditioned by rat astrocytes and Schwann cells in culture was examined. The conditioned medium (CM) from both types of glial cultures stimulated extensive neurite outgrowth from embryonic chick dorsal root ganglia (DRG) as well as pheochromocytoma (PC12) cells. Both the DRG and PC12 cells also produce neurite outgrowth in the presence of nerve growth factor (NGF). With the DRG, the neurite growth rates observed with the glial cell CM were identical to growth rates seen with NGF. Although anti-NGF antibody did not inhibit the neurite outgrowth produced by either of the glial CM, a nerve growth factor radioreceptor assay did detect an NGF-like molecule in both CM. Since the extensive neurite outgrowth stimulated by the glial CM was not mimicked by pure laminin alone, we conclude that the glial neurite promoting factors are distinct from laminin.

Glia maturation factor promotes proliferation and morphologic expression of rat Schwann cells

Glia maturation factor (GMF) is an acidic protein with a molecular weight of about 20,000 daltons, found in the adult brain of many species. Previously GMF was observed to stimulate the proliferation and subsequent maturation of rat astroblasts in culture. We investigated the effects of GMF on Schwann cells. Schwann cells were dissociated from rat sciatic nerve and purified by means of antimitotic agents and by selective immunoadsorption of contaminating fibroblasts. Cultured Schwann cells after 3 passages assumed a flat polygonal shape. Exposure of the cells to GMF converted the cells to the elongated, spindle morphology typical of Schwann cells. GMF also stimulated a 7-fold increase in DNA synthesis when compared with control cultures grown in F10 medium containing 5% fetal calf serum. The mitogenic activity of GMF was still detectable at 5 ng protein/ml medium. The maximal effect on DNA synthesis occurred 72 h after the initial exposure to GMF. Although the cells were positive for the Schwann cell marker Ran-1, GMF failed to induce the production of myelin-associated glycolipids (galactocerebroside) and proteins (Po) nor did it induce the astrocytic marker glial fibrillary acidic protein (GFAP). The effects of GMF on Schwann cells extend its biological role beyond the central nervous system.