Standardization of human diploid fibroblast cultivation: centrifugation procedure.

The effect of varying centrifugal forces on the growth rate, longevity, and adsorption on glass of human embryonic diploid lung fibroblasts was studied. Cells centrifuged at 120, 500, or 1,500 x g at each passage had similar growth rates but their longevity decreased slightly with increasing force. These forces had no influence on the proportion of cells attaching to the glass. When the material in the first supernatant was recentrifuged at 2,000 x g for 30 min and added to the cells precipitated in the first centrifugation, the longevity of these cells was increased by several cell divisions. Cells which were not centrifuged but added directly from the cell suspension in trypsin to the new culture grew at a slightly slower rate than the centrifuged cells and became senescent at an earlier time. However, the noncentrifuged cells adsorbed to glass better than those centrifuged.