SOX17 is expressed in regenerating oligodendrocytes in experimental models of demyelination and in multiple sclerosis.

We have previously demonstrated that Sox17 expression is prominent at developmental stages corresponding to oligodendrocyte progenitor cell (OPC) cycle exit and onset of differentiation, and that Sox17 promotes initiation of OPC differentiation. In this study, we examined Sox17 expression and regulation under pathological conditions, particularly in two animal models of demyelination/remyelination and in post-mortem multiple sclerosis (MS) brain lesions. We found that the number of Sox17 expressing cells was significantly increased in lysolecithin (LPC)-induced lesions of the mouse spinal cord between 7 and 30 days post-injection, as compared with controls. Sox17 immunoreactivity was predominantly detected in Olig2(+) and CC1(+) oligodendrocytes and rarely in NG2(+) OPCs. The highest density of Sox17(+) oligodendrocytes was observed at 2 weeks after LPC injection, coinciding with OPC differentiation. Consistent with these findings, in cuprizone-treated mice, Sox17 expression was highest in newly generated and in maturing CC1(+) oligodendrocytes, but low in NG2(+) OPCs during the demyelination and remyelination phases. In MS tissue, Sox17 was primarily detected in actively demyelinating lesions and periplaque white matter. Sox17 immunoreactivity was co-localized with NOGO-A+ post-mitotic oligodendrocytes both in active MS lesions and periplaque white matter. Taken together, our data: (i) demonstrate that Sox17 expression is highest in newly generated oligodendrocytes under pathological conditions and could be used as a marker of oligodendrocyte regeneration, and (ii) are suggestive of Sox17 playing a critical role in oligodendrocyte differentiation and lesion repair.

Haplotype matching is not an essential requirement to achieve remyelination of demyelinating CNS lesions.

Transplantation of oligodendrocyte precursor cells (OPCs) results in efficient remyelination in animal models of demyelination. However, the experiments so far undertaken have not addressed the need for tissue-type matching to achieve graft-mediated remyelination. Examination of MHC expression (main determinant of allograft rejection) by OPCs showed nondetectable levels under standard culture conditions and upregulation of MHC Class I expression only upon exposure to interferon gamma. We therefore hypothesized that MHC matching of OPC grafts may not be crucial to achieve transplant-mediated remyelination. Transplant experiments performed using a nonself repairing toxin-induced demyelination model showed that, similarly to allogeneic neurons, survival of allogeneic oligodendrocyte lineage cells is influenced by donor-host haplotype combination and graft composition. Transplantation of allogeneic mixed glial cell cultures resulted in remyelination failure by 1 month postengraftment due to a rejection response targeting both myelinating oligodendrocytes and OPCs, suggesting that inflammation-induced upregulation of OPC MHC I expression results in susceptibility to cytotoxic T cell attack. In contrast, remyelination persisted for at least 2 months following transplantation of OPC-enriched cultures whose overall MHC expression level was significantly decreased. While OPC-enriched preparations elicited delayed type hypersensitivity responses in hosts sensitized to alloantigens, allografting of such preparations into a central nervous system demyelinating lesion did not result in recipient priming. We conclude that while allografted oligodendrocyte lineage cells become targets of a graft rejection response once this response has been initiated, transplantation of OPC-enriched preparations can evade priming against alloantigens and graft rejection. This finding indicates that close tissue matching may not be an essential requirement for successful transplant-mediated remyelination.

Glial grafting for demyelinating disease.

Remyelination of demyelinated central nervous system (CNS) axons is considered as a potential treatment for multiple sclerosis, and it has been achieved in experimental models of demyelination by transplantation of pro-myelinating cells. However, the experiments undertaken have not addressed the need for tissue-type matching in order to achieve graft-mediated remyelination since they were performed in conditions in which the chance for graft rejection was minimized. This article focuses on the factors determining survival of allogeneic oligodendrocyte lineage cells and their contribution to the remyelination of demyelinating CNS lesions. The immune status of the CNS as well as the suitability of different models of demyelination for graft rejection studies are discussed, and ways of enhancing allogeneic oligodendrocyte-mediated remyelination are presented. Finally, the effects of glial graft rejection on host remyelination are described, highlighting the potential benefits of the acute CNS inflammatory response for myelin repair.

Isolation, characterization, and propagation of rat conjunctival goblet cells in vitro.

PURPOSE: To isolate, culture, and characterize goblet cells from the conjunctiva of rats. METHODS: Conjunctival tissue was surgically removed from Sprague-Dawley rats. Goblet cells were then isolated from the nictitating membrane and fornix using explant cultures. Cells derived from the explants were grown and propagated in RPMI medium supplemented with 10% fetal bovine serum. They were characterized using an enzyme-linked lectin assay (ELLA) with the lectin Ulex europaeus agglutinin-1 (UEA-1), Western blot analysis, PCR, light and electron microscopy, specialized histochemistry and indirect immunofluorescence microscopy. RESULTS: Goblet cells were successfully isolated from conjunctival explants by scraping nongoblet cells from the culture vessel. To date, cultures have been passaged a minimum of three times without the loss of their specific cellular markers. Cells identified as goblet cells fulfilled the following criteria: positive staining for alcian blue/periodic acid Schiff reagent, cytokeratin (CK)-7, the lectins UEA-I and Helix pomatia agglutinin (HPA), MUC5AC, and M(3) muscarinic receptor; detection of MUC5AC mRNA using RT-PCR; and negative staining for CK-4, M(1) muscarinic receptor, and Banderia simplicifolia lectin. The authors also measured, using the ELLA, substantial amounts of UEA-I-detectable high-molecular-weight glycoproteins and MUC5AC released into the medium. CONCLUSIONS: Cultured goblet cells retain many characteristics of goblet cells in vivo and thus may serve as a useful tool in delineating the pathobiology of the ocular surface.