MYELINATION IN-VITRO OF RODENT DORSAL-ROOT GANGLIA BY GLIAL PROGENITOR CELLS

Oligodendrocytes synthesize myelin in the mammalian central nervous system; they develop from glial progenitors which, at least in vitro, are bipotential and also differentiate into astrocytes. Maturation of these 0-2A progenitors is known to be influenced by growth factors and by extracellular matrix molecules. We investigated the effect of neurons on glial development by co-culturing highly purified rodent embryonic dorsal root ganglia with neonatal 0-2A progenitors. Neurons produce signals, including platelet-derived growth factor BE and basic fibroblast growth factor, which stimulate progenitor cells to synthesize DNA; axonal contact is associated with down-regulation in the expression of complex ganglioside surface molecules on 0-2A progenitors; with maturation, many of these cells develop into oligodendrocytes allowing the normal process of myelination to take place, but neurons also promote the differentiation of type 2 astrocytes. This orchestration of proliferation and differentiation in 0-2A progenitor cells favours the development of glial-neuronal interactions needed for saltatory conduction of the nerve impulse.