A new assay system for quality control testing of a chemically defined medium

Abstract

SUMMARY: Mouse NCTC clone 929 L (L-929) cells were propagated continuously over 2 yr in protein-free Eagles's minimal essential medium (EMEM). The cells designated L-929-WS were used for quality-control testing of protein-free EMEM as a model for more general medium quality tests. The parameter for the suggested quality control assay was the growth-promoting activity of the medium for L-929-WS cells. As an example of quality tests we assayed the growth promoting activity of EMEM exposed to various conditions of storage time and temperature. We established the sensitivity of the new assay by comparing it to the original ceils L-929 grown in EMEM supplemented with 10% fetal bovine serum (FBS). The assay system using L-929-WS cells propagated continuously in protein-free medium proved to be much more sensitive. The sensitivity, however, was abolished by the addition of FBS in a concentration as low as 1% to a culture medium.Key words: protein-free medium; quality control testing; growth-promoting activity. I. INTRODUCTION II. MATERIALSQuality control testing of media and cell culture medium constituents depends on highly sensitive assay procedures. In this context, tests for growth-promoting activity of a chemically defined medium deserve special attention. To detect significant deviations from the designated formula, the presence of chemical contaminants, or a negative influence of storage conditions the use of sensitive cell lines grown in serum-free media has been suggested 19,10). To achieve sustained cell growth, however, such media usually have to be supplemented with various protein growth factors and hormones (1,2) that possibly prevent the effect of contaminants.Several cell lines, including mouse NCTC clone 929 L {L-929) cells, have been established in chemically defined media without any protein supplement (3,6,7,(12)(13)(14)20,22,23). The present study shows that L-929 cells grown continuously in such a medium can be used as a highly sensitive and simple cell culture system for quality control testing. IV. DISCUSSION This procedure demonstrates that L-929-WS cells grown continuously in a protein-free medium may be used as a highly sensitive and simple cell culture system for testing the growth-promoting activity of a chemically defined medium, of different medium constituents, or the influence of storage conditions. We showed previously that L-929 cells may be easily adapted to protein-free growth using commercially available cell culture media and supplies (4). In addition, L-929-WS cells are available in our laboratory for common use.Experimental results are shown in Figs (Figs. 4 A, B and 5}. The decreased quality of a chemically defined medium can easily be demonstrated by microscopic examination of the cells for typical changes in cell morphology (Fig. 6L We routinely use this aspect of the method for rapid orientation when the quality of a culture medium is being tested. The deleterious effect of a medium on cell morphology may, however, be masked by the addition of FBS in a concentration as low...

HeLa Cells Grown Continuously in Protein-Free Medium: A Novel Model for the Study of Virus Replication

“…Neverthe less, such cells have not had general applica tion. It has been repeatedly suggested that suc cessful growth of the cells in a protein-free medium depends on several factors including high quality chemicals, pure water and chemi cally clean glass or plastic ware [14,[22][23][24]. It is possible that the quality of these factors was difficult to obtain in the past and, thus, the culture technique could only be used in a few laboratories.…”