Enforcing Homogeneity in a Complex and Heterogeneous System: "It Always Seems Impossible until It Is Done." (Nelson Mandela)

We tend to think of cell lines in a bioreactor as a number of cells that, given that they are derived from a clone and live in a controlled and constant environment, behave in the same way, each and every one of them. However, this is not the case: each gene and each pathway in each individual cell behaves in a stochastic way that may, in combination, lead to large diversity. In addition, cells that divide at high rates accumulate a large number of variants and mutants, including SNPs, indels and structural variants such as translocations that lead to large heterogeneity within a population. It has been shown that subclones of the same parent behave in diverse ways, and re-subcloning a subclone results in similar diversity in the next generation of subclones again. Nevertheless, subcloning is a standard procedure in cell line development to obtain “stability” and “reliability” in behavior for production processes. This presentation will i) investigate our current knowledge of population diversity as seen in genome and karyotype variation, and how these impact cell behavior; ii) discuss other factors, such as epigenetics, that contribute to population phenotype and explore how these can be controlled and manipulated and iii) scout our options to achieve a higher level of homogeneity, stability and of control.