title: Identification of growth factors that promote long-term proliferation of olfactory ensheathing cells and modulate their antigenic phenotype.
abstract: Olfactory ensheathing cells can develop into distinct subtypes in culture after incubation in serum-free medium conditioned by astrocytes, which have Schwann cell-like and astrocyte-like properties. It has not been possible so far to modulate and grow large numbers of these olfactory ensheathing cell subtypes. In this study, we have shown that astrocyte-conditioned medium, although promoting differentiation of the two olfactory ensheathing cell types, is growth-restrictive after 14 days, probably due to the upregulation of p16 and p27. Growth arrest can be overridden and cells maintained for a further 11 weeks, by a mitogen mix of fibroblast growth factor 2, forskolin, and heregulin (olfactory mitogen medium) combined with astrocyte-conditioned medium. In the absence of astrocyte-conditioned medium, combinations of the same factors can also override growth arrest but to a lesser extent. Olfactory mitogen medium combined with astrocyte-conditioned medium upregulates O4 and low-affinity nerve growth factor receptor expression on olfactory ensheathing cells, leading to a 100% Schwann cell--like phenotype. If cells are maintained in olfactory mitogen medium alone, or if they are treated with forskolin or fibroblast growth factor 2 diluted in serum-free medium, O4 and low-affinity nerve growth factor receptor expression remains at 100%, but there is also an increase in expression of E-NCAM, the astrocyte-like marker. Medium containing serum also overrides growth arrest, but for only 4 weeks, during which time most differentiation-specific markers disappear. These studies have allowed us to define conditions to modulate the olfactory ensheathing cell phenotype.
authors.affiliation: Department of Neurology, University of Glasgow, Glasgow, UK.
authors.forename: Claire L
authors.initials: CL
authors.lastname: Alexander
authors.forename: Una F
authors.initials: UF
authors.lastname: Fitzgerald
authors.forename: Susan C
authors.initials: SC
authors.lastname: Barnett
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000954:Antigens, Surface / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D016380:Brain Tissue Transplantation / Q000379:methods*; D018797:Cell Cycle Proteins / Q000187:drug effects / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D017077:Culture Media, Conditioned; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000187:drug effects / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D006133:Growth Substances / Q000494:pharmacology*; D008934:Mitogens / Q000494:pharmacology; D009416:Nerve Regeneration / Q000187:drug effects / Q000502:physiology*; D020890:Neuregulin-1 / Q000494:pharmacology; D009457:Neuroglia / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009830:Olfactory Bulb / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D025521:Tumor Suppressor Proteins / Q000187:drug effects / Q000378:metabolism
chemical_list: D000954:Antigens, Surface; C493962:Cdkn1b protein, rat; D018797:Cell Cycle Proteins; D017077:Culture Media, Conditioned; D019941:Cyclin-Dependent Kinase Inhibitor p16; D006133:Growth Substances; D008934:Mitogens; D020890:Neuregulin-1; D025521:Tumor Suppressor Proteins; D016222:Fibroblast Growth Factor 2; D050760:Cyclin-Dependent Kinase Inhibitor p27; D005576:Colforsin