Standardization of human diploid cell cultivation

Determination of toxin-induced leakage of different-size nucleotides through the plasma membrane of human diploid fibroblasts

Human diploid lung fibroblasts were treated with cytolytic bacterial toxins and the nature of the membrane damage was investigated. [3H] uridine was used for differential labeling of cytoplasmic components of small or large molecular size. Two principal size categories were achieved by labeling the fibroblasts in either early growth phase or stationary phase, a high-molecular weight ribonucleic acid label and a low-molecular-weight nucleotide label. The size of the labeled molecules was determined by perchloric acid precipitation and gel chromatography. Leakage of labeled molecules of different size indicated the size of the "functional pores" in the plasma membrane caused by the test substance. The nonionic detergent Triton X-100 produced large functional pores in the fibroblast membrane as evidenced by rapid leakage of both large and small labeled molecules. Theta-toxin from Clostridium perfringens and the polyene antibiotic filipin both gave rise to considerably small functional pores in the plasma membrane. Although small molecules easily passed the treated membrane, large molecules could not escape from the cells even after prolonged treatment with these substances or by increasing their concentration. By the contrast, the leakage profiles obtained with melittin from bee venom or with delta-toxin from Staphylococcus aureus in each case suggested the formation initially of pores of intermediate size that increased upon prolonged incubation or when higher concentrations were used.

Effects of staphylococcal alpha-, beta-, delta-, and gamma-hemolysins on human diploid fibroblasts and HeLa cells: evaluation of a new quantitative as say for measuring cell damage

Human diploid embryonic lung fibroblasts and HeLa cells were cultivated in Eagle minimaĺ essential medium supplemented with 10% calf serum. Monolayer cultures were labeled with (3)H-uridine and treated with highly purified staphylococcal alpha-, beta-, delta-, or gamma-hemolysin. The release of soluble radioactive substances into the medium was used as an indicator of damage to the cell membrane after treatment with each hemolysin. The assay method described is simple, sensitive, and rapid. It allows quantitative estimation of changes in membrane permeability to be detected before a morphological damage is observed microscopically. Upon incubation for up to 30 min with highly purified staphylococcal hemolysins, only delta-hemolysin caused release of a significant amount of tritiated substances from fibroblasts. Such leakage occurred immediately after addition of delta-lysin and was independent of temperature. With minor exceptions, this was similar to the release of isotopes after treatment of the cells with the nonionic detergent Triton X-100. Treatment of fibroblasts with combinations of two or three of these toxins gave neither a synergistic nor an antagonistic effect. Evidence is presented which indicates that delta-hemolysin is the only important fibroblast damaging activity in crude preparations of extracellular proteins of four strains of S. aureus, whereas HeLa cells are susceptible also to purified alpha-toxin.

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.