The influence of basic fibroblast growth factor (bFGF), a central nervous system (CNS)-derived molecule, on survival of trunk neural crest cells was investigated. As previously shown (C. Kalcheim and N. M. Le Douarin, 1986, Dev. Biol. 116, 451-466), the interposition of untreated silastic membranes between neural tube and neural crest cells of the dorsal root ganglion (DRG) anlage led to selective death of neural crest cells that remained distally located with respect to the implants. Membranes were then treated with laminin and bFGF (100 ng/ml) and implanted. Under these conditions, rescued cells were observed for over 30 hr after grafting in 15 of 19 embryos. In contrast, no surviving cells could be found in any of 10 control embryos implanted with laminin-treated silastic membranes. We have also investigated the effects of bFGF on survival of identified subpopulations of trunk neural crest cells cultured with somite cells in a serum-free, chemically defined medium. bFGF promoted a dose-dependent increase in the number of HNK-1-positive nonneuronal cells in 1- to 4-day-old cultures (1.8- to 8.2-fold over controls using FGF at concentrations of 10 pg/ml to 1 ng/ml, respectively). FGF had no mitogenic effect on the neural crest-derived nonneuronal cells since the number of HNK-1-immunoreactive nonneuronal cells having incorporated [3H]thymidine into their nuclei remained unchanged in control as compared to treated cultures. However, the same concentrations of FGF were found to stimulate the incorporation of [3H]thymidine into acid-insoluble material in somite cultures devoid of neural crest. Moreover, bFGF significantly enhanced survival of nonneuronal cells in pure neural crest cultures established from neural crest clusters, thus demonstrating a direct effect of bFGF on survival and/or differentiation of neural crest-derived nonneuronal cells. These data support the hypothesis that CNS-derived molecules influence early development of selective subsets of neural crest cells developing into sensory ganglia.
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The author is grateful to Professor Israel Vlodavsky for helpful suggestions. The excellent technical assistance of Ms. Chana Carmeli is warmly acknowledged. We also thank Ms. Mindy Slupski for the preparation of the typescript and the Takeda Co. (Japan) for kindly providing recombinant bFGF. This work was supported by grants from the Muscular Dystrophy Association (MDA) and the Israel Academy for Sciences and Humanities.