Serum-free medium for cultures of the postnatal mouse cerebellum: only insulin is essential

Serum-free culture conditions for dissociated postnatal mouse cerebellar cells were investigated. This study demonstrates that among various supposed growth-promoting factors only insulin is required as an additive to the basic medium. If viewed by phase contrast microscopy, cultures kept in insulin-supplemented basic medium looked identical to those maintained in the presence of a mixture of growth-promoting factors (insulin, putrescine, transferrin, progesterone, triiodothyronine, selenium). In addition, quantitative evidence is provided indicating that cellular survival is supported to the same extent by insulin as by this admixture. Insulin concentrations required ranged between 0.3-20 micrograms/ml. By contrast to serum-supplemented culture conditions, no significant proliferation of non-neuronal cells was observed in serum-free culture media. It is expected that by these findings attention will be focused again to the exact role insulin plays in the central nervous system.