Removal of trace metals from culture media and sera for in vitro deficiency studies

Culture media and sera contain substantial quantities of trace metals such as zinc and copper, so that they cannot be used for cell culture studies of trace metal deficiencies unless the element in question is first removed. By coupling the chelator iminodiacetate to an insoluble agarose matrix, we have been able to extract zinc selectively from both media and sera, without exposing cells directly to the chelator. The procedure reduced the zinc concentration of media to unmeasurably low levels, and serum zinc concentration by approximately 90%. The development of zinc deficiency in vitro was demonstrated by a reduced lymphocyte blastogenic response, which could be prevented by the addition of zinc to the extracted culture medium. The extraction procedure is potentially applicable to a range of trace elements (e.g., Zn, Cu, Mn, Fe) and to virtually any cell type that can be cultured.