Enhanced proliferation of WI38 cells in the presence of glucocorticoid-conditioned medium.
The addition of hydrocortisone (HC) or dexamethasone (DEX) to WI38 cells at subcultivation is known to result in increased saturation densities (20-40%). We report that maximal increases in saturation density are, however, only observed if HC is added to the culture shortly after subcultivation. We have found that the proliferative response of WI38 cells to glucocorticoids is mediated by a secondary stimulatory factor(s) present in medium-conditioned by cells in the presence of the hormone. Control cultures refed with medium conditioned in the presence of HC for the first 24 h after seeding (24 h HC-CM) achieve saturation densities 20-40% higher than cultures refed with either medium conditioned in the absence of the hormone (24 h CM) or 24 h CM supplemented with fresh HC. Furthermore, WI38 cultures remain responsive to the stimulatory activity present in 24 h HC-CM throughout the growth cycle. The stimulatory effects of 24 h HC-CM are enhanced by repeatedly refeeding cultures; WI38 cells refed every 2 days with 24 h HC-CM demonstrate an extended period of logarithmic growth and achieve densities 2-3 times higher than controls. A preliminary characterization of this activity shows it to be of low molecular weight (MW) (dialyzable using 12 000 MW cut-off tubing) and heat-stable (75 degrees C).
D002455:Cell Division / Q000187:drug effects*; D002460:Cell Line; D003470:Culture Media; D003907:Dexamethasone / Q000494:pharmacology; D006133:Growth Substances / Q000494:pharmacology*; D006358:Hot Temperature; D006801:Humans; D006854:Hydrocortisone / Q000494:pharmacology*; D007700:Kinetics; D008970:Molecular Weight
D003470:Culture Media; D006133:Growth Substances; D003907:Dexamethasone; D006854:Hydrocortisone