Qualitative and quantitative aspects of animal cell in vitro systems.

The evaluation of sublethal cellular damage is shown to be important for the performance of experiments and bioproduction with animal cells. Detailed information on the fate of single cells in colony pedigrees from untreated and irradiated mammalian cells was obtained in vitro with cinematography recordings. It can be demonstrated that in generations two, three, and four the cells are more sensitive because of higher death rates and increased generation times induced by the handling of the cells during passaging or by the damaging agent. It is obvious that chemical agents can act in the same way. Also poor medium quality induces similar effects. Growth curves of single colony cell populations render much better information on the proliferation of a cell population than the determination of cells per ml (= particle counting). Examples are given for such growth curves and for colony size distribution curves based on individual cell countings. The advantages of the use of flow-cytofluorometry for the control of cell cycle phases are shown. As an example for the relevance of qualitative and quantitative data on cell substrate and medium conditions for bioproduction the in vitro mass replication of an insect pathogenic virus (baculovirus) is presented. Baculoviruses are potentially important biological pesticides which can replace chemical insecticides partially.