LONG-TERM BFGF NEURONAL CULTURE - REINTRODUCTION INTO SERUM MEDIUM YIELDS NEURONS AND NONNEURONAL CELLS WITH NEURONAL CHARACTERISTICS

The potential use of bFGF immortalized cells as hosts for delivering f oreign genes into nervous tissue led us to examine the effect of maint aining E-18 hippocampal neurons for extended periods in bFGF culture p rior to transfer into a standard, serum-containing, medium. We found: (1) many, if not most, precursors seen in bFGF, mature into glia and n ot into primary neurons after medium exchange; (2) the electrophysiolo gy of the neurons which do mature after medium transfer and replating, is similar to that of neurons in standard cultures; (3) extended cult ure in bFGF prior to cell harvesting and replating into standard mediu m generates neurons from the precursors that possess proper neuronal p olarization, morphology, and electrophysiology; and (4) extended bFGF also induces the expression, on transfer into standard medium, of an a dditional cell type with a distinct non-neuronal morphology that stain s with the neuronal marker MAP-2, These results illustrate the need fo r additional characterization of long-term growth factor effects on ma intained progenitor cells prior to their use in gene therapy and trans plantation.