A simple and effective method for the removal of trace metal cations from a mammalian culture medium supplemented with 10% fetal calf serum.

Direct batch addition of sterile Chelex ion-exchange resin to Dubecco's modified Eagle's medium supplemented with 10% fetal calf serum with gentle stirring removed a very wide variety of trace metal ions from the medium to varying extents dependent upon Chelex content (between 0.01 and 4% w/v), exposure time (between 5 min and 10 days) and temperature (4, 25 and 37 degrees C). Prolonged treatment (10 days) with 4% w/v Chelex at 4 degrees C reduced the concentration of zinc, strontium, aluminum, copper, manganese, nickel and chromium from 100 to 2.7, 12.1, 7.7, 22.6, 13.0, 14.7 and 53.3% of their original concentrations, respectively. Re-supplementation of the metal depleted medium with a defined cocktail of metals restored the growth potential of the medium which was then capable of supporting growth over at least three subcultures without a decrease in fibroblast cell yield, demonstrating its suitability in cell culture studies on trace metal ions.