Growth factor responses of enriched bipotential glial progenitors.
Responses of oligodendrocyte/type 2 astrocyte (O-2A) glial progenitors from neonatal rat brains to different growth factors were studied by a new, serum-free method. Enriched tertiary cultures of O-2A progenitors were produced after 6-7 days in vitro using the growth-promoting factors from the B104 CNS neuronal cell line, heparin, and mechanical separation. These cultures contained about 75-90% A2B5+ cells with less than 10% type 1 astrocytes, and the yield was 4.4 x 10(5) cells/brain. B104 conditioned medium (CM) factors increased both O-2A progenitor number and [3H]thymidine-labeling indices after three days. However, type 1 astrocyte CM was required for continued survival of enriched progenitors beyond 1 day in tertiary culture. Platelet-derived growth factor (PDGF) and glia maturation factor also showed growth-promoting action, but were less effective than B104 CM at tested doses. PDGF-neutralizing antibodies had no effect on progenitor survival or response to B104 CM factors. Thus, type 1 astrocyte-derived PDGF was not required for this response, B104 CM is not likely to contain PDGF, and B104 CM factors act directly on O-2A progenitors. Fibroblast growth factor, transforming growth factor beta, interleukin 2, epidermal growth factor, and triiodothyronine showed no growth-promoting activity; moreover, interleukin 2, epidermal growth factor, transforming growth factor beta, and 0.5% fetal bovine serum inhibited B104 CM action. Enriched progenitors exhibited bipotentiality by slowly differentiating into oligodendrocytes in serum-free medium, whereas culture in 10% fetal bovine serum increased type 2 astrocytes. Thus, this new method selects or produces progenitors which are similar to those from mature brains.
Hunter
S F
SF
Department of Pharmacology-Toxicology, University of Texas Medical Branch, Galveston 77550.
Bottenstein
J E
JE
D000818:Animals; D001253:Astrocytes / Q000166:cytology* / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D046508:Culture Techniques / Q000379:methods*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D006133:Growth Substances / Q000494:pharmacology*; D007150:Immunohistochemistry; D007376:Interleukin-2 / Q000494:pharmacology; D009836:Oligodendroglia / Q000166:cytology* / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D013234:Stem Cells / Q000187:drug effects*
D006133:Growth Substances; D007376:Interleukin-2; D005346:Fibroblast Growth Factors; D004815:Epidermal Growth Factor