Effects of ferrous iron and transferrin on cell proliferation of human diploid fibroblasts in serum-free culture.

Iron-free RITC 80-7 defined medium was used to examine effects of ferrous iron and transferrin on cell proliferation of human diploid fibroblasts. Both ferrous iron and holo-transferrin stimulated cell proliferation in the medium, but apotransferrin did not. When 5 g/l human serum albumin (HSA) was added to the defined medium, excellent growth was obtained under hypoxic conditions, whereas a reduction of cellular growth during the culture periods was observed under aerobic conditions. When ferrous iron was added to the HSA medium alone, the reduction in growth increased in proportion to the concentrations, whereas the addition of transferrin prevented this reduction in a concentration-dependent manner. This suggests that the ferrous iron concentration in media causes a reduction in growth under aerobic conditions and transferrin prevents this reduction because it decreases the ferrous iron concentration. Further, serum albumin seems to be a source of iron in media.