Mitogenic response of adult rat olfactory ensheathing glia to four growth factors

Olfactory ensheathing glia (EG) from adult rat proliferate slowly in vitro without added mitogens. The potential future use of EG in transplantation w ithin the central nervous system to improve neural repair is dependent on i dentifying mitogens that will effectively expand EG without altering their phenotype. The mitogenic effects of heregulin (HRG), fibroblast growth fact or 2 (FGF-2), platelet-derived growth factor BE (PDGF-BB), insulin-like gro wth factor 1 (IGF-1), and forskolin (FSK) on cultured adult-derived rat EG were monitored by tritiated-thymidine labeling and p75 immunostaining. In s erum-containing medium, HRG, FGF-2, PDGF-BB, IGF-1, and FSK were capable of stimulating EG proliferation, and the stimulation by these growth factors was potentiated by FSK. The combinations of HRG + FGF-2, HRG + PDGF-BB, HRG + IGF-1, FGF-2 + PDGF-BB, and FGF-2 + IGF-1 all promoted EG proliferation in an additive manner. In serum-free medium, HRG and FGF-2 were mitogenic, but PDGF-BB, IGF-1 and FSK were not; however, FSK potentiated the stimulati on by HRG and FGF-2, and the combination of HRG + FGF-2 promoted EG prolife ration in an additive manner. This new information will be useful for the d esign of protocols to achieve sufficient numbers of adult-derived EG for cl inical purposes. This study also further establishes similarities between E G and Schwann cells. GLIA 33:334-342, 2001. (C) 2001 Wiley-Liss Inc.