Enrichment of Schwann cell cultures from neonatal rat sciatic nerve by differential adhesion

Nerve growth factor-basic fibroblast growth factor poly-lactide co-glycolid sustained-release microspheres and the small gap sleeve bridging technique to repair peripheral nerve injury

We previously prepared nerve growth factor poly-lactide co-glycolid sustained-release microspheres to treat rat sciatic nerve injury using the small gap sleeve technique. Multiple growth factors play a synergistic role in promoting the repair of peripheral nerve injury; as a result, in this study, we added basic fibroblast growth factors to the microspheres to further promote nerve regeneration. First, in an in vitro biomimetic microenvironment, we developed and used a drug screening biomimetic microfluidic chip to screen the optimal combination of nerve growth factor/basic fibroblast growth factor to promote the regeneration of Schwann cells. We found that 22.56 ng/mL nerve growth factor combined with 4.29 ng/mL basic fibroblast growth factor exhibited optimal effects on the proliferation of primary rat Schwann cells. The successfully prepared nerve growth factor-basic fibroblast growth factor-poly-lactide-co-glycolid sustained-release microspheres were used to treat rat sciatic nerve transection injury using the small gap sleeve bridge technique. Compared with epithelium sutures and small gap sleeve bridging alone, the small gap sleeve bridging technique combined with drug-free sustained-release microspheres has a stronger effect on rat sciatic nerve transfection injury repair at the structural and functional level.

Isolation of Female Germline Stem Cells from Mouse and Human Ovaries by Differential Adhesion

Spermatogonial stem cell (SSC) counterparts known as female germline stem cells (fGSCs) were found in the mammalian ovary in 2004. Although the existence of fGSCs in the mammalian postnatal ovary is still under controversy, fGSC discovery encourages investigators to better understand the various aspects of these cells. However, their existence is not accepted by all scientists in the field because isolation of fGSCs by fluorescent activated cell sorting (FACS) has not been reproducible. In this study, we used differential adhesion to isolate and enrich fGSCs from mouse and human ovaries and subsequently cultured them in vitro. fGSCs were able to proliferate in vitro and expressed germ cell-specific markers Vasa, Dazl, Blimp1, Fragilis, Stella, and Oct4, at the protein level. Moreover, mouse and human fGSCs were, respectively, cultured for more than four months and one month in culture. Both mouse and human fGSCs maintained the expression of germ cell-specific markers over these times. In vitro cultured fGSCs spontaneously produced oocyte-like cells (OLCs) which expressed oocyte-relevant markers. Our results demonstrated that differential adhesion allows reproducible isolation of fGSCs that are able to proliferate in vitro over time. This source of fGSCs can serve as a suitable material for studying mechanisms underlying female germ cell development and function.

Curcumin and Ethanol Effects in Trembler-J Schwann Cell Culture

Charcot-Marie-Tooth (CMT) syndrome is the most common progressive human motor and sensory peripheral neuropathy. CMT type 1E is a demyelinating neuropathy affecting Schwann cells due to peripheral-myelin-protein-22 (PMP22) mutations, modelized by Trembler-J mice. Curcumin, a natural polyphenol compound obtained from turmeric (Curcuma longa), exhibits dose- and time-varying antitumor, antioxidant and neuroprotective properties, however, the neurotherapeutic actions of curcumin remain elusive. Here, we propose curcumin as a possible natural treatment capable of enhancing cellular detoxification mechanisms, resulting in an improvement of the neurodegenerative Trembler-J phenotype. Using a refined method for obtaining enriched Schwann cell cultures, we evaluated the neurotherapeutic action of low dose curcumin treatment on the PMP22 expression, and on the chaperones and autophagy/mammalian target of rapamycin (mTOR) pathways in Trembler-J and wild-type genotypes. In wild-type Schwann cells, the action of curcumin resulted in strong stimulation of the chaperone and macroautophagy pathway, whereas the modulation of ribophagy showed a mild effect. However, despite the promising neuroprotective effects for the treatment of neurological diseases, we demonstrate that the action of curcumin in Trembler-J Schwann cells could be impaired due to the irreversible impact of ethanol used as a common curcumin vehicle necessary for administration. These results contribute to expanding our still limited understanding of PMP22 biology in neurobiology and expose the intrinsic lability of the neurodegenerative Trembler-J genotype. Furthermore, they unravel interesting physiological mechanisms of cellular resilience relevant to the pharmacological treatment of the neurodegenerative Tremble J phenotype with curcumin and ethanol. We conclude that the analysis of the effects of the vehicle itself is an essential and inescapable step to comprehensibly assess the effects and full potential of curcumin treatment for therapeutic purposes.

Schwann cell transplantation exerts neuroprotective roles in rat model of spinal cord injury by combating inflammasome activation and improving motor recovery and remyelination

Inflammasome activation in the traumatic central nervous system (CNS) injuries is responsible for propagation of an inflammatory circuit and neuronal cell death resulting in sensory/motor deficiencies. NLRP1 and NLRP3 are known as activators of inflammasome complex in the spinal cord injury (SCI). In this study, cell therapy using Schwann cells (SCs) was applied for targeting NLRP inflammasome complexes outcomes in the motor recovery. These cells were chosen due to their regenerative roles for CNS injuries. SCs were isolated from sciatic nerves and transplanted to the contusive SCI-induced Wistar rats. NLRP1 and NLRP3 inflammasome complexes and their related pro-inflammatory cytokines were assayed in both mRNA and protein levels. Neuronal cell survival (Nissl staining), motor recovery and myelination (Luxol fast blue/LFB) were also evaluated. The groups were laminectomy, SCI, vehicle and treatment. The treatment group received Schwann cells, and the vehicle group received solvent for the cells. SCI caused increased expressions for both NLRP1 and NLRP3 inflammasome complexes along with their related pro-inflammatory cytokines, all of which were abrogated after administration of SCs (except for IL-18 protein showing no change to the cell therapy). Motor deficits in the hind limb, neuronal cell death and demyelination were also found in the SCI group, which were counteracted in the treatment group. From our findings we conclude promising role for cell therapy with SCs for targeting axonal demyelination and degeneration possibly through attenuation of the activity for inflammasome complexes and related inflammatory circuit.

Effect of exosomes from adipose-derived stem cells on the apoptosis of Schwann cells in peripheral nerve injury

Aims

Recovery after peripheral nerve injury (PNI) is often difficult, and there is no optimal treatment. Schwann cells (SCs) are important for peripheral nerve regeneration, so SC‐targeting treatments have gained importance. Adipose‐derived stem cells (ADSCs) and their exosomes can promote peripheral nerve repair, but their interactions with SCs are unclear.

Methods

Purified SCs from sciatic nerve injury sites were harvested, and apoptosis and proliferation of SCs at post‐PNI 24 hours were analyzed. The effects of coculture with ADSCs and different concentrations of ADSC‐derived exosomes (ADSC‐Exo) were studied through in vitro experiments by flow cytometry, CCK8 assay, immunofluorescence staining, and histological analysis. The expression of the apoptosis‐related genes Bcl‐2 and Bax was also analyzed by qRT‐PCR.

Results

ADSC‐Exo reduced the apoptosis of SCs after PNI by upregulating the anti‐apoptotic Bcl‐2 mRNA expression and downregulating the pro‐apoptotic Bax mRNA expression. Further, it also improved the proliferation rate of SCs. This effect was confirmed by the morphological and histological findings in PNI model rats.

Conclusion

Our results present a novel exosome‐mediated mechanism for ADSC‐SC cross talk that reduces the apoptosis and promotes the proliferation of SCs and may have therapeutic potential in the future.

Isolation, primary culture, and morphological characterization of gland epithelium from forest musk deer (Moschus berezovskii)

Research of epithelial cells in musk gland is lacking. There are no good characterized epithelial cell lines that can provide complementary in vitro models for in vivo research. We successfully cultivated epithelial cells of musk gland for the first time. The protocol described here produces epithelial cell lines from the mature secreting musk gland. Based on morphological observation, epithelial cells of musk gland were isolated and cultured in vitro. After the third passage, the musk gland-derived cells were filled with many lipid droplets and proliferated well. We used gas chromatography and mass spectrometry to explore the chemical composition of lipid droplets in the musk gland-derived cells. The main components of secreted lipid droplet were alkanes, esters, amines, alcohols, ketones, organic acids, and aldehydes. Muscone, which is the main active compound of musk, was not found. This is a new attempt in the field of animal musk to obtain naturally secreted animal musk in vitro by cloning specialized cells. In conclusion, this study provides a reference at the cellular level to further analyze the biology and physiology of the musk gland epithelium and secretion mechanism of musk deer.

Establishment and characterization of GCSR1, a multi-drug resistant signet ring cell gastric cancer cell line

Signet ring cell gastric cancer (SRCGC) has very poor prognosis worldwide, and studying its molecular characteristics is urgent for improving the outcome. However, few well-characterized SRCGC cell lines are available for research. Therefore, we established a novel cell line GCSR1, from a Chinese male SRCGC patient. Cell morphology of GCSR1 in culture, maintained in vitro for over 90 passages, is similar to the cells from the patient. GCSR1 cells proliferated in vitro with a doubling time of 67.65 h. Karyotyping showed they were aneuploid. Missense mutation occurred in codon 193 of P53 and deletion occurred in exons 1 and 3 of P16. Results of CCK8 assay revealed that GCSR1 was more resistant to 5-fluorouracil (5-FU) and mitomycin (MMC) than other gastric cancer cell lines. Stem cell marker assay by flow cytometry showed that GCSR1 had high proportion of CD44+ and/or CD133+ cells. It formed colonies easily in soft agar and generated xenograft tumors in nude mice. In conclusion, GCSR1 is a well-established, well-characterized multi-drug resistant cell line with abundant cancer stem cells.

Uridine 5'-triphosphate promotes in vitro Schwannoma cell migration through matrix metalloproteinase-2 activation

In response to peripheral nerve injury, Schwann cells adopt a migratory phenotype and modify the extracellular matrix to make it permissive for cell migration and axonal re-growth. Uridine 5′-triphosphate (UTP) and other nucleotides are released during nerve injury and activate purinergic receptors expressed on the Schwann cell surface, but little is known about the involvement of purine signalling in wound healing. We studied the effect of UTP on Schwannoma cell migration and wound closure and the intracellular signaling pathways involved. We found that UTP treatment induced Schwannoma cell migration through activation of P2Y₂ receptors and through the increase of extracellular matrix metalloproteinase-2 (MMP-2) activation and expression. Knockdown P2Y₂ receptor or MMP-2 expression greatly reduced wound closure and MMP-2 activation induced by UTP. MMP-2 activation evoked by injury or UTP was also mediated by phosphorylation of all 3 major mitogen-activated protein kinases (MAPKs): JNK, ERK1/2, and p38. Inhibition of these MAPK pathways decreased both MMP-2 activation and cell migration. Interestingly, MAPK phosphorylation evoked by UTP exhibited a biphasic pattern, with an early transient phosphorylation 5 min after treatment, and a late and sustained phosphorylation that appeared at 6 h and lasted up to 24 h. Inhibition of MMP-2 activity selectively blocked the late, but not the transient, phase of MAPK activation. These results suggest that MMP-2 activation and late MAPK phosphorylation are part of a positive feedback mechanism to maintain the migratory phenotype for wound healing. In conclusion, our findings show that treatment with UTP stimulates in vitro Schwannoma cell migration and wound repair through a MMP-2-dependent mechanism via P2Y₂ receptors and MAPK pathway activation.

GDNF-treated acellular nerve graft promotes motoneuron axon regeneration after implantation into cervical root avulsed spinal cord

It is well known that glial cell line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor for motoneurons. We have previously shown that it greatly enhanced motoneuron survival and axon regeneration after implantation of peripheral nerve graft following spinal root avulsion.

AIMS

In the current study, we explore whether injection of GDNF promotes axon regeneration in decellularized nerve induced by repeated freeze-thaw cycles.

METHODS

We injected saline or GDNF into the decellularized nerve after root avulsion in adult Sprague-Dawley rats and assessed motoneuron axon regeneration and Schwann cell migration by retrograde labelling and immunohistochemistry.

RESULTS

We found that no axons were present in saline-treated acellular nerve whereas Schwann cells migrated into GDNF-treated acellular nerve grafts. We also found that Schwann cells migrated into the nerve grafts as early as 4 days after implantation, coinciding with the first appearance of regenerating axons in the grafts. Application of GDNF outside the graft did not induce Schwann cell infiltration nor axon regeneration into the graft. Application of pleiotrophin, a trophic factor which promotes axon regeneration but not Schwann cell migration, did not promote axon infiltration into acellular nerve graft.

CONCLUSIONS

We conclude that GDNF induced Schwann cell migration and axon regeneration into the acellular nerve graft. Our findings can be of potential clinical value to develop acellular nerve grafting for use in spinal root avulsion injuries.

N-cadherin expression is regulated by UTP in schwannoma cells

Schwann cells (SCs) are peripheral myelinating glial cells that express the neuronal Ca(2+)-dependent cell adhesion molecule, neural cadherin (N-cadherin). N-cadherin is involved in glia-glia and axon-glia interactions and participates in many key events, which range from the control of axonal growth and guidance to synapse formation and plasticity. Extracellular UTP activates P2Y purinergic receptors and exerts short- and long-term effects on several tissues to promote wound healing. Nevertheless, the contribution of P2Y receptors in peripheral nervous system functions is not completely understood. The current study demonstrated that UTP induced a dose- and time-dependent increase in N-cadherin expression in SCs. Furthermore, N-cadherin expression was blocked by the P2 purinoceptor antagonist suramin. The increased N-cadherin expression induced by UTP was mediated by phosphorylation of mitogen-activated protein kinases (MAPKs), such as Jun N-terminal kinase, extracellular-regulated kinase and p38 kinase. Moreover, the Rho kinase inhibitor Y27632, the phospholipase C inhibitor U73122 and the protein kinase C inhibitor calphostin C attenuated the UTP-induced activation of MAPKs significantly. Extracellular UTP also modulated increased in the expression of the early transcription factors c-Fos and c-Jun. We also demonstrated that the region of the N-cadherin promoter between nucleotide positions -3698 and -2620, which contained one activator protein-1-binding site, was necessary for UTP-induced gene expression. These results suggest a novel role for P2Y purinergic receptors in the regulation of N-cadherin expression in SCs.

Iron and holotransferrin induce cAMP-dependent differentiation of Schwann cells

The differentiation of myelin-forming Schwann cells (SC) is completed with the appearance of myelin proteins MBP and P(0) and a concomitant downregulation of markers GFAP and p75NTR, which are expressed by immature and adult non-myelin-forming SC. We have previously demonstrated that holotransferrin (hTf) can prevent SC dedifferentiation in culture (Salis et al., 2002), while apotransferrin (aTf) cannot. As a consequence, we used pure cultured SC and submitted them to serum deprivation in order to promote dedifferentiation and evaluate the prodifferentiating ability of ferric ammonium citrate (FAC) through the expression of MBP, P(0), p75NTR and c-myc. The levels of cAMP, CREB and p-CREB were also measured. Results show that Fe(3+), either in its free form or as hTf, can prevent the dedifferentiation promoted by serum withdrawal. Both FAC and hTf were proven to promote differentiation, probably through the increase in cAMP levels and CREB phosphorylation, as well as levels of reactive oxygen species. This effect was inhibited by deferroxamine (Dfx, an iron chelator), H9 (a cAMP-PKA antagonist) and N-acetylcysteine (NAC, a powerful antioxidant).

Combination therapies in the CNS: engineering the environment

The inhibitory extracellular environment that develops in response to traumatic brain injury and spinal cord injury hinders axon growth thereby limiting restoration of function. Several strategies have been developed to engineer a more permissive central nervous system (CNS) environment to promote regeneration and functional recovery. The multi-faced inhibitory nature of the CNS lesion suggests that therapies used in combination may be more effective. In this mini-review we summarize the most recent attempts to engineer the CNS extracellular environment after injury using combinatorial strategies. The advantages and limits of various combination therapies utilizing neurotrophin delivery, cell transplantation, and biomaterial scaffolds are discussed. Treatments that reduce the inhibition by chondroitin sulfate proteoglycans, myelin-associated inhibitors, and other barriers to axon regeneration are also reviewed. Based on the current state of the field, future directions are suggested for research on combination therapies in the CNS.

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.

Intraspinal cord graft of autologous activated Schwann cells efficiently promotes axonal regeneration and functional recovery after rat's spinal cord injury

Basic research in spinal cord injury (SCI) has made great strides in recent years, and some new insights and strategies have been applied in promoting effective axonal regrowth and sprouting. However, a relatively safe and efficient transplantation technique remains undetermined. This study, therefore, was aimed to address a question of how to graft Schwann cells to achieve the best possible therapeutic effects. To clarify the issue, the rats were subjected to spinal cord injury at T10. Autologous activated Schwann cells (AASCs) were obtained by prior ligation of saphenous nerve and subsequently isolated and purified in vitro and then grafted into spinal cord-injured rats via three different routes (group I: intravenous, group II: intrathecal and group III: intraspinal cord). Neurologic function was serially evaluated by Basso, Beattie, Bresnahan locomotor rating scale and footprint analysis. We also evaluated the migration of the transplanted cells at 2 weeks after transplantation. Using biotinylated dextran amine (BDA) anterograde tracing, we demonstrated that more regenerative axons of corticospinal tract (CST) surrounding the injured cavity in group III than those in the other two groups, and we also confirmed it further by quantitative analysis. The microenvironment surrounding the injured spinal cord has been improved to the greatest extent in group III, as determined by immunohistological staining. Relatively complete myelin sheaths and more neurofilaments in axons were found in groups II and III than those in group I under electron microscopy. The results showed that intraspinal cord injection of AASCs promoted recovery of hindlimb locomotor function of injured rats more efficiently than the other grafting routes. In addition, intact myelin sheaths and sufficient neurofilaments in axons were not adequate for full functional recovery after SCI, suggesting that reestablishment of normal synaptic connection is indispensable. The findings in this study strongly suggest that transplantation of AASCs directly into the spinal cord may be one of the promising candidates for potential scaffold for injured spinal cord, and such strategy of transplantation of AASCs could be hopeful to treat patients with SCI.

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.

Presence of alpha-globin mRNA and migration of bone marrow cells after sciatic nerve injury suggests their participation in the degeneration/regeneration process

We have previously reported that in the distal stump of ligated sciatic nerves, there is a change in the distribution of myelin basic protein (MBP) and P0 protein immunoreactivities. These results agreed with the studies of myelin isolated from the distal stump of animals submitted to ligation of the sciatic nerve, showing a gradual increase in a 14 kDa band with an electrophoretic mobility similar to that of an MBP isoform, among other changes. This band, which was resolved into two bands of 14 and 15 kDa using a 16% gel, was found to contain a mixture of MBP fragments and peptides with great homology with alpha- and beta-globins. In agreement with these results, we have demonstrated that the mRNA of alpha-globin is present in the proximal and distal stumps of the ligated nerve. It is also detected at very low levels in Schwann cells isolated from normal nerves. These results could be due to the presence of alpha- and/or beta-globin arising from immature cells of the erythroid series. Also, they could be present in macrophages, which spontaneously migrate to the injured nerve to promote the degradation of myelin proteins. Cells isolated from normal adult rat bone marrow which were injected intraortically were found to migrate to the injured area. These cells could contribute to the remyelination of the damaged area participating in the removal of myelin debris, through their transdifferentiation into Schwann cells or through their fusion with preexisting Schwann cells in the distal stump of the injured sciatic nerve.

Tissue-engineered peripheral nerve grafting by differentiated bone marrow stromal cells

Bone marrow stromal cells are multipotential stem cells that contribute to the differentiation of tissues such as bone, cartilage, fat and muscle. In the experiment, we found that bone marrow stromal cells can be induced to differentiate into cells expressing characteristic markers of Schwann cells, such as S-100 and glial fibrillary acidic protein, promoting peripheral nerve regeneration. Tissue-engineered bioartificial nerve grafting of rats by differentiated bone marrow stromal cells was applied for bridging a 10 mm-long sciatic nerve defect. Twenty-eight inbred strains of female F344 rats weighing 160 approximately 200 g were randomly divided into four nerve grafting groups, with seven rats in each group. Differentiated bone marrow stromal cell-laden group: poly(lactic-co-glycolic) acid tubes with an intrinsic framework were seeded with syngeneic bone marrow stromal cells which were induced for 5 days; Schwann cell-laden group: poly(lactic-co-glycolic) acid tubes with an intrinsic framework were seeded with syngeneic Schwann cells; acellular group: poly(lactic-co-glycolic) acid tubes were only filled with an intrinsic framework; autografts group. Three months later, a series of examinations was performed, including electrophysiological methods, walking track analysis, immunohistological staining of nerves, immunostaining of S-100 and neurofilament, and axon counts. The outcome indicated that bone marrow stromal cells are able to differentiate into Schwann-like cells and Schwann-like cells could promote nerve regeneration. Bone marrow stromal cells may be potentially optional seed cells for peripheral nerve tissue engineering because of abilities of promoting axonal regeneration.

Rapid method for culturing embryonic neuron-glial cell cocultures

A streamlined, simple technique for primary cell culture from E17 rat tissue is presented. In an attempt to standardize culturing methods for all neuronal cell types in the embryo, we evaluated a commercial medium without serum and used similar times for trypsinization and tested different surfaces for plating. In 1 day, using one method and a single medium, it is possible to produce robust E17 cultures of dorsal root ganglia (DRG), cerebellum, and enteric plexi. Allowing the endogenous glial cells to repopulate the cultures saves time compared with existing techniques, in which glial cells are added to cultures first treated with antimitotic agents. It also ensures that all the cells present in vivo will be present in the culture. Myelination commences after approximately 2 weeks in culture for dissociated DRG and 3-4 weeks in cerebellar cultures. In enteric cultures, glial wrapping of the enteric neurons is seen after 3 weeks (2 weeks in ascorbic acid), suggesting that basal lamina production is important even for glial ensheathment in the enteric nervous system. No overgrowth of fibroblasts or other nonneuronal cells was noted in any cultures, and myelination of the peripheral nervous system and central nervous system cultures was very robust.

HoloTransferrin but not ApoTransferrin prevents Schwann cell de-differentiation in culture

Schwann cells (SCs) in culture, without the presence of axons, become de-differentiated, reaching a condition similar to that of their precursor cells. The cytoplasmic accumulation of transferrin (Tf) in the myelinated peripheral nerve has been reported and data in the literature support a role for apoTf in myelination in the CNS. In the present report, we used SC cultures to evaluate the capacity of apoTf and holoTf to prevent cell de-differentiation promoted by fetal calf serum deprivation. SCs incubated in a serum-free medium showed a decrease in the expression of myelin basic protein (MBP) and P(0), markers of mature myelin-forming SCs, together with an increase in the levels of p75NTR and glial fibrillary acidic protein, markers of immature SCs. Treatment with holoTf prevented the decrease in expression of MBP and P(0) and the increase in p75NTR. ApoTf was unable to prevent these changes except when iron was added to the cultures. These results suggest a role for holoTf in the regulation of myelin formation by SCs.

Apoptosis in Schwann cell cultures is closely interrelated with the activity of the ubiquitin-proteasome proteolytic pathway

Although the participation of the ubiquitin-dependent pathway and of the proteasome in apoptosis has been proposed, its role in this process is not yet clearly defined. In previous studies, we have shown that in the central nervous system of the rat, programmed cell death and the ubiquitin-dependent proteolytic pathway are closely related to each other and that different types of neurons and of glial cells, shown different types of correlation between the two phenomena. In this work, we have used lactacystin, a highly specific inhibitor of the proteasome, to explore in Schwann cell cultures the relationship between the activity of the Ub-dependent pathway and apoptosis. Apoptosis was explored analyzing changes in nuclear morphology, using the Annexin V assay and by flow cytometry. Activity of caspase-3 was also measured. Changes in the levels of ubiquitin-protein conjugates and of the ubiquitin activating enzymes, E1, as well as expression of proteins that instruct the cells to apoptosis (p53, NFkappaB-IkappaB, Bcl2), or that participate in the control and regulation of the cell cycle, were also examined. Our results indicate that the decrease in the activity of the proteasome induced by lactacystin in Schwann cells, induces apoptotic cell death through changes in the concentration of certain key proteins that are involved in the apoptosis-signaling pathways.

The neuronal adhesion protein TAG-1 is expressed by Schwann cells and oligodendrocytes and is localized to the juxtaparanodal region of myelinated fibers

The neural cell adhesion molecule TAG-1, which is a glycosylphosphatidylinositol-linked member of the Ig superfamily, is expressed by various neuronal populations in the developing CNS and PNS. We demonstrate here that Schwann cells and oligodendrocytes also express TAG-1. In the PNS, TAG-1 is detected in ensheathing Schwann cells early postnatally and is maintained throughout adulthood. In mature myelinated fibers of the CNS and PNS, TAG-1 is localized to the juxtaparanodal region. The CNS of the UDP-galactose ceramide galactosyl transferase(-/-) (CGT(-/-)) mouse mutants, which do not synthesize the abundant galactolipids of myelin, display severely disrupted axoglial interactions at the paranodal region. In contrast, axoglial interactions in the PNS of these mutants are less affected. Interestingly, TAG-1 localization is completely undetected in myelinated fibers of the CNS. In the PNS of these mutants, TAG-1 abnormally localizes in the paranodal region. These data raise the intriguing possibility that TAG-1 localization in the juxtaparanodal area mediates, or at least requires, the axoglial contact normally displayed in this region. The abnormal localization of TAG-1 in the CGT mutants might contribute to the disrupted axoglial interactions observed in these animals.

A Schwann cell-seeded intrinsic framework and its satisfactory biocompatibility for a bioartificial nerve graft

To optimize the internal environment of a collagen nerve tube, we designed a Schwann cell-seeded intrinsic framework and its biocompatibility was investigated. We fixed 6-0 polyglactin woven filaments (Vicryl) or polydioxanone monofilaments (PDS) on a silicone ring in a net fashion. It was coated with matrigel and then incubated with cultured newborn or adult Schwann cells. Furthermore, we implanted 1.5-cm-long filament-filled collagen tubes in a rat model. Using a live/dead fluorescent assay and electron microscopy, we found that adherent Schwann cells onto filaments remained viable and oriented longitudinally along filaments. The preliminary in vivo study indicated that a mild inflammatory reaction was present around the tube wall. However, nerve regeneration occurred around and between filaments. We concluded that the arrangement of Schwann cell columns onto filaments was achieved, mimicking Bünger bands. It was shown that the biomaterials did not impede nerve regeneration.

Columns of Schwann cells extruded into the CNS induce in-growth of astrocytes to form organized new glial pathways

Our previous work showed that stereotaxic microextrusion of columns of purified peripheral nerve-derived Schwann cells into the thalamus of syngeneic adult rats induces host axons to grow into the column and form a new fiber tract. Here we describe the time course of cellular events that lead to the formation of this new tract. At 2 h postoperation, numerous OX42-positive microglia accumulated at the graft-host interface, after which donor columns became progressively and heavily infiltrated by microglia/macrophages that took on an elongated morphology in parallel with the highly orientated processes of the donor Schwann cells. The penetration of host astrocytic processes into the Schwann cell columns was substantially slower in onset, being first detected at 4 days postoperation. This event was contemporaneous with the in-growth of host thalamic axons. Between 7 and 14 days postoperation, GFAP-positive astrocytes became fully incorporated into the transplants, where they too adopted an elongated form, orientated in parallel with the longitudinal axis of the graft. Thus, the columns became a mosaic of elongated and highly orientated donor Schwann cells intimately mingled with host microglia, astrocytes, and numerous, largely unbranched 200-kDa neurofilament-positive axons from the adjacent thalamus. Electron microscopy demonstrated that the processes of donor Schwann cells and host astrocytes within the column formed tightly packed bundles that were surrounded by a partial or complete basal lamina. Control columns, formed by extruding freeze-thaw-killed Schwann cells or purified peripheral nerve fibroblasts induced a reactive injury response by the adjacent host microglia and astrocytes, but neither host astrocytes nor neurofilament-positive axons were incorporated into the columns. A better understanding of the mechanisms that regulate the interactions between donor and host glia should facilitate improved integration of such grafts and enhance their potential for inducing tissue repair.

TNF-alpha and TGF-beta act synergistically to kill Schwann cells

Interactions between cytokines and Schwann cells (SC) are important in development, repair, and disorders of the peripheral nervous system (PNS). Tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta) are two prominent cytokines which may be involved in these processes and their gene products are upregulated in some experimental neuropathies. This study focuses on the in vitro effects of these cytokines, both singly and in combination, on cultured SC. Expression of both Type I and Type II TNF-alpha receptors was demonstrated on the SC surface by immunocytochemistry. Treatment of SC with a combination of TNF-alpha plus TGF-beta causes significant detachment and cell death while treatment with each cytokine alone is not significantly cytotoxic. When compared with control cultures, SC treated with the combination of cytokines exhibit an increase in the number of cells with condensed nuclei and evidence of DNA fragmentation, characteristics consistent with cells undergoing programmed cell death. Thus, TNF-alpha plus TGF-beta induce SC loss of adhesion which is predominantly due to cell death. Apoptotic mechanisms are likely to contribute to some extent to this cell death. These findings provide in vitro evidence to support the hypothesis that cytokines can directly damage SC in PNS disorders.

Toxic effects of hexane derivatives on cultured rat Schwann cells

The cytotoxic effects of the following five hexane-related compounds were examined on Schwann cell DNA synthesis: 2,5-hexanedione (2,5-HD), 2-hexanol (2-OH), 2-hexanone (MnBK), 2,5-dimethylfuran (DF) and gamma-valerolactone (VL). Schwann cells were isolated from the sciatic nerves of neonatal Sprague-Dawley rats and cultured. [(3)H]-thymidine incorporation into Schwann cell nuclei was measured by scintillation spectrometry and autoradiography when hexane derivatives were added to the culture medium. All of the hexane-related compounds suppressed [(3)H]-thymidine incorporation in a concentration-dependent manner. DF was the most cytotoxic for the inhibition of Schwann cell DNA synthesis among the compounds. The finding suggests that DF-mediated cytotoxicity should be taken into account as a possible additional mechanism of hexane intoxication, especially in the impairment of mitotic cells.

Mitogen induced proliferation of isolated adult mouse Schwann cells

The proliferation of neonatal Schwann cells (SCs) in response to mitogenic agents has been well analyzed in vitro, but a limited range of mitogens have been defined. We investigated whether three identified neonatal SC mitogens [glial growth factor (GGF), platelet-derived growth factor BB (PDGF-BB), and basic fibroblast growth factor (bFGF)] are required to stimulate mitosis of adult SCs. Adult SCs were isolated from mouse sciatic nerves by mechanical and chemical dissociation, following three experimental steps: 1) culturing the dissociated cells for 24 hr in 10% FCS-F12 medium, 2) culturing these cells in serum-free medium for the next 48 hr, and 3) purifying adult SCs by differential adhesion. We describe a new method for preparation of SCs from peripheral nerves of adult mouse that provides 99.5% pure SCs populations at cell yields of greater than 3 x 10(3) cells/mg of starting nerve wet weight within 5 culture days. Although mitosis of SCs in culture in response to mitogens requires the presence of serum, the complex nature of serum renders difficult a complete analysis of mitogens required for SCs DNA synthesis, so we examined the proliferating response of adult SCs to GGF, PDGF-BB, and bFGF in serum-free medium. GGF alone had mitogenicity for adult SCs in a dose-dependent manner, and synergistic activation coupling with forskolin was not observed. Neither PDGF-BB nor bFGF was mitogenic for adult SCs when used alone or with forskolin.(ABSTRACT TRUNCATED AT 250 WORDS)

Partial purification of a novel mitogen for oligodendroglia

A protein with a MWapp of 50-70 kDa isolated from the salt extract of crude membranes from neonatal rat brain increases the numbers of oligodendroglia in mixed glial cultures prepared from neonatal rat cerebral white matter. After partial purification by ion exchange and gel exclusion chromatography, and elution from an SDS-polyacrylamide gel, this protein ("oligodendroglial trophic factor," OTF) elicited half-maximal oligodendroglial recruitment at a concentration of 5 ng/mL. OTF is a mitogen for oligodendroglia, and to a lesser extent, for oligodendroglial progenitor (O2A) cells, but does not stimulate proliferation of astroglia, Schwann cells, or endoneurial fibroblasts. OTF, unlike platelet-derived growth factor (PDGF), is not an oligodendroglial survival factor. Antibodies against PDGF and basic fibroblast growth factor (bFGF) do not interfere with the accumulation of oligodendroglia induced by OTF. When OTF is given simultaneously with either PDGF or bFGF, there is an additive increase in the numbers of cells of the oligodendroglial lineage.

Morphology and migration of cultured Schwann cells transplanted into the fimbria and hippocampus in adult rats

Schwann cells cultured from neonatal rat peripheral nerve were injected into the fimbria and hippocampus of syngeneic adult rats by a microtransplantation technique which causes minimal disturbance to the host brain structure at the site of implantation, and thus allows the grafted cells to come into immediate contact with intact host tissue. Numerous Schwann cells could be identified for up to 6 weeks (and with decreasing frequency for up to 3 months) by intense immunoreactivity for low affinity nerve growth factor receptor. The transplanted cells adopted a distinctive elongated form, with a central, ovoid nucleus flanked by processes which were up to 300 microns long, and which ranged from swollen segments with a diameter as large as 12 microns down to thread-like fibres of 1 micron or less. This morphology is different from that of any of the host cells. The transplanted Schwann cells migrated freely into the host tissue along blood vessels and according to the position of the grafts, they either entered the hippocampal neuropil, or migrated (for distances of up to 2 mm) along the longitudinal axis of the fimbria, where they were interspersed in parallel with the interfascicular glial rows and axons. The host astrocytes did not appear to impede the migration of the donor Schwann cells. Although the host astrocytic processes became hypertrophic, with increased glial fibrillary acidic protein and vimentin expression, the predominant longitudinal orientation of the astrocytic tract processes was maintained. The transplanted Schwann cells did not form peripheral myelin (as detected by P0 immunoreactivity), and it is not clear whether they survive beyond the period at which we detect them.

Schwann cells transplanted into the CNS

A small volume of purified Schwann cells, cultured from early postnatal rat sciatic nerve, was injected into the hippocampus or fimbria of syngeneic adult hosts. The procedure caused minimal structural disturbance at the transplantation site, with close graft-host contact and maximal opportunity for integration. The donor Schwann cells were identified by a combination of light and electron microscopic features (which include characteristic deep and complex infoldings of a well marked nuclear envelope), antigenic profile (especially low affinity nerve growth factor receptor immunoreactivity), uptake of fluorescent latex microspheres and autoradiography of [3H]thymidine-labelled dividing cells. The donor Schwann cells adopted a distinctive elongated form, with a central, ovoid nucleus flanked by processes which were up to 300 microns long, and which ranged from swollen segments with a diameter as large as 12 microns down to thread-like fibres of 1 microns or less with growth cone-like expansions. Transplanted cells migrated from the graft, particularly along blood vessels and could permeate all cytoarchitectonic regions of the adjacent host hippocampal neuropil. Donor Schwann cells also migrated along the longitudinal axis of the fimbria, where they were interspersed in parallel with the interfascicular glial rows and axons. The grafted cells induced a transient but marked host astrocytic hypertrophy, which did not appear to impede the migration of the donor Schwann cells. The transplanted Schwann cells did not form peripheral myelin (as detected by P0 immunoreactivity), and it is not clear whether they survive beyond the period at which we detect them.

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 of activated adult Schwann cells and a spontaneously immortal Schwann cell clone

Successful mammalian peripheral nerve regeneration is dependent on activated Schwann cells. Schwann cells facilitate neuronal regrowth through the production of tropic cell membrane molecules, neurotrophins, and extracellular matrix components. To better understand Schwann cell function in the regenerating nerve, we have designed a method of isolating proliferating adult Schwann cells from the injured rat sciatic nerve. Relying on the mitotic signal that is present after a crush injury, we can obtain sufficient numbers of dividing Schwann cells within one week of initial culture. A spontaneously immortal Schwann cell clone (iSC) was observed in and isolated from one of these primary cultures. These cells were transformed at a time of maximal Schwann cell activation in response to injury. Both the primary Schwann cells and the iSC have been characterized as Schwann cells by morphology, immunohistochemistry and gene expression.

Expression of genes encoding receptors for IgG (FcRIII) and for C3b/C4b (Crry) in rat sciatic nerve during development and Wallerian degeneration

Northern blots were used to examine the expression of genes encoding receptors for IgG (FcRIII) and for C3b/C4b (Crry) in rat sciatic nerve during development and Wallerian degeneration. Steady state levels of FcRIII (1.4 kb) and Crry (1.9 and 2.1 kb) mRNAs were higher in adult rat nerves than in 6 day and 21 day postnatal rat nerves, indicating that the expression of these receptors is developmentally regulated. The FcRIII and Crry cDNA probes also hybridized with total RNA from 3 day old rat Schwann cells and from adult rat peritoneal macrophages. The size of the FcRIII mRNA expressed by cultured Schwann cells (1.6 kb) differed from that expressed by peritoneal macrophages (1.4 kb); the two may be splice variants of one transcript or products of related genes. Peritoneal macrophages contained approximately 100 times higher FcRIII mRNA levels than Schwann cells. In contrast, steady state levels of both 1.9 and 2.1 kb Crry mRNAs were similar in cultured Schwann cells and macrophages. Nerve transection induced a generalized increase in the level of sciatic FcRIII mRNA (1.4 kb) 3 days post-surgery, whereas the level of Crry mRNA was increased only in the nerve segment immediately to the cut. The increase of FcRIII mRNA that occurred in Wallerian degeneration was most likely due to infiltration of macrophages, as FcRIII mRNA-positive macrophages were demonstrated in the degenerating nerves by in situ hybridization. FcRIII mRNA-positive macrophages were not found in normal nerve. The functions of FcRIII and Crry in peripheral nerves are uncertain, but they may be of significance in phagocytosis, antibody-dependent cellular cytotoxicity, and in local immune regulation.

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.

Expression of the neu proto-oncogene by Schwann cells during peripheral nerve development and Wallerian degeneration

The neu gene, which encodes a putative tyrosine kinase growth factor receptor termed p185neu, was originally identified as a dominant transforming gene in neurogliomas and schwannomas induced by transplacental treatment of rat embryos with ethylnitrosourea. The present studies were undertaken to determine the expression pattern of the neu gene in peripheral nerve. Northern blot analysis of total RNA isolated from rat sciatic nerves demonstrated prominent neu mRNA expression on postnatal days 1 and 7, with substantially lower expression up to adulthood. Immunohistochemical studies confirmed expression of p185neu by Schwann cells (SC) in developing sciatic nerve and minimal p185neu immunoreactivity in adult nerves. However, neu mRNA and p185neu protein progressively increased following sciatic nerve transection in adult animals. In addition, neu mRNA and p185neu were found in neonatal rat sciatic nerve SC and several SC-derived cell lines. In resting SC, neu mRNA was expressed at a low level, but was greatly increased by treatment with forskolin and glial growth factor. These studies demonstrate that the neu gene and its protein product, p185neu, are expressed by SC both in vivo and in vitro and suggest that p185neu plays a role in the regulation of SC proliferation or differentiation.

Platelet-derived growth factor and regulation of Schwann cell proliferation in vivo

To examine the role of platelet-derived growth factor (PDGF) in the in vivo regulation of Schwann cell proliferation, steady-state levels of mRNAs encoding PDGF A and B chains, and PDGF alpha and beta receptors were measured in immature and adult rat sciatic nerves and in cultured rat Schwann cells. PDGF B chain and PDGF beta receptor mRNAs are present in immature rat sciatic nerves and to a lesser extent in adult rat nerves. Short-term cultures of neonatal rat Schwann cells express PDGF beta receptor mRNA, but not PDGF B chain mRNA, and are stimulated to synthesize DNA by addition of PDGF BB to the medium. These data indicate that PDGF BB is a developmentally regulated paracrine growth factor for rat Schwann cells. Very long-term cultures of rat Schwann cells, which have lost normal dependence on exogenous growth factors, express PDGF B chain mRNA as well as mRNAs encoding the PDGF alpha and beta receptors, suggesting that, under these circumstances, PDGF BB also act as an autocrine growth factor. PDGF A chain mRNA is present in both immature and adult rat sciatic nerves and is expressed by primary and secondary cultures of rat Schwann cells as well. However, because the abundance of PDGF alpha receptor mRNA is very low in rat Schwann cells, PDGF AA is not likely to be a significant autocrine growth factor for rat Schwann cells.

Structure and expression of proteolipid protein in the peripheral nervous system

Proteolipid protein (PLP), the major myelin protein in the central nervous system (CNS), is also made by Schwann cells (SC) in the peripheral nervous system (PNS) but is not incorporated into the SC myelin sheath. We analyzed several PLP cDNA clones isolated from a rat sciatic nerve cDNA library and found that their coding sequences were identical to PLP cDNAs previously isolated from the CNS. In addition, we have discovered an unusual form of PLP message, present in both brain and sciatic nerve RNA, that is likely formed by alternative splicing within the 3' untranslated region of the primary PLP transcript. The absence of PLP from the SC myelin sheath thus cannot be explained by an alteration in its amino acid sequence. Steady-state levels of PLP mRNA in SC cultures treated with the cAMP analogue dibutyryl cAMP (dBcAMP) were not increased, whereas dBcAMP increased steady-state levels of mRNA encoding the major myelin protein, P0. We have also shown that expression of PLP, unlike that of P0, is regulated in SC in vitro at a posttranscriptional level. Finally, the steady-state levels of P0 mRNA are much more dramatically reduced than those of PLP mRNA during Wallerian degeneration of the peripheral nerve. Thus PLP expression in the PNS is probably controlled by different molecular mechanisms from P0, and may not be part of the coordinate program of myelin gene expression. In contrast to its expression in the PNS, transcription of PLP in the CNS is coordinately regulated along with the other myelin protein genes, suggesting there may be differences in the cis-acting elements and transacting factors involved in the regulation of PLP transcription in SC and oligodendrocytes (OC). Consistent with this notion, we have found that most PLP transcripts are initiated at the more proximal of two start sites in the PNS, while in the CNS proportionally more PLP transcripts are initiated from the distal start site. We propose that the proximal site, utilized predominantly in SC, is responsible for maintenance expression of PLP and is not inducible, while the distal site is responsible for the rapid, inducible increase of PLP message during brain development.

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.

Myelin/oligodendrocyte-specific protein: a novel surface membrane protein that associates with microtubules

Only a few proteins are known to be exclusively expressed in central nervous system (CNS) myelin. A novel surface membrane protein expressed only in CNS myelin and oligodendrocytes of higher vertebrates has been identified by a monoclonal antibody. This CNS myelin/oligodendrocyte-specific protein, MOSP, has a molecular weight of 48 kDa and a pI of approximately 6.7. In the presence of the monoclonal antibody, MOSP remains on the surface of cultured oligodendrocytes but becomes associated with cytoplasmic microtubules. Our results suggest that MOSP plays an important role in membrane/cytoskeleton interactions during the formation and maintenance of CNS myelin. MOSP also may play a critical role in the pathogenesis of diseases of CNS myelin.

Antibodies to interleukin-1 inhibit cytokine-induced proliferation of neonatal rat Schwann cells in vitro

Unfractionated cytokines have been shown to induce in vitro proliferation of neonatal rat Schwann cells but the nature of the mitogen(s) is not known. A mixture of rabbit antibodies specific for recombinant interleukin-1 alpha (IL-1 alpha) and interleukin-1 beta (IL-1 beta) inhibited Schwann cell proliferation induced by unfractionated human cytokines whereas antibodies to interleukin-2 (IL-2) and control IgG did not. However, purified human IL-1 and recombinant human IL-1 alpha or beta did not induce Schwann cell proliferation on their own.

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.

Low uptake of [3H]2-deoxy-D-glucose by cultured rat Schwann cells

[3H]2-Deoxy-D-glucose (2-DG) was used to investigate the glucose uptake in cultured rat Schwann cells from postnatal Sprague-Dawley rat sciatic nerves. The glucose uptake of Schwann cells slightly increased in a time- and dose-dependent manner. However, the maximal uptake level was much lower than that of ethylnitrosourea (ENU)-induced transformed rat schwannoma-like cells and fibroblasts. By autoradiography of the cultured system, we were able to visualize the accumulation of [3H]2-DG grains in the schwannoma-like cells and fibroblasts, but not in Schwann cells.

Human fetal Schwann cells in culture: phenotypic expressions and proliferative capability

In this report we examined the phenotypic expressions and the proliferative capability of cultured human fetal Schwann cells. Antigens that were expressed included laminin, nerve growth factor receptor, neural cell adhesion molecule, S-100 protein, and that recognized by the monoclonal antibody HNK-1. In addition, HLA-A,B,C and HLA-DR, respectively, class I and class II antigens of the major histocompatibility complex, were demonstrated on Schwann cells. Mitotic capability was high, with an average of 34% of Schwann cells undergoing proliferation over a 2-day period.