In vitro analysis of the oligodendrocyte lineage in mice during demyelination and remyelination

Since PDGF, IGF-I, and bFGF can each induce proliferation of neonatal O-2A progenitor cells in the developing rat CNS (reviewed in Dubois-Dalcq and Armstrong, 1990), we assayed the mitogenic effect of these growth factors in our cultures of adult mouse spinal cord (see protocol outlined in Fig. 1 C) . We tested each growth factor at 1, 3, 4, 5, and 8 wpi since the effect of a particular growth factor may vary during the course of the disease. In cultures of demyelinating and remyelinating tissue, none of these three growth factors caused a significant increase in the percentage of O-2A lineage cells which incorporate pH]thymidine during a 20-h terminal pulse (p = 0.691 for the difference between treatments, as determined by ANOVA). Similarly, preliminary data from control cultures indicated that treatment with PDGF, IGF-I, or bFGF did not enhance the proliferation of O-2A lineage cells from normal adult mice. Thus, exogenous growth factors influenced phenotype expression ( Fig. 9 ) but did not enhance the proliferation of O-2A lineage cells in our cultures.