Development and application of a cultivation platform for mammalian suspension cell lines with single-cell resolution (MaSC)

In bioproduction processes cellular heterogeneity can cause unpredictable process outcomes or even provoke process failure. Still, cellular heterogeneity is not examined systematically in bioprocess research and development. One reason for this shortcoming are the applied average bulk analyses, which are not able to detect cell-to-cell differences. In this work we present a microfluidic tool for single-cell cultivation of mammalian suspension cells (MaSC). The design of our platform allows long-term cultivation at highly controllable environments. As model system CHO K1 cells were cultivated over 150 h. Growth behavior was analyzed on single-cell level and resulted in growth rates between 0.85 - 1.16 d-1, which are comparable to classical cultivation approaches such as shake flask and labscale bioreactor. At the same time, heterogeneous growth and division behavior, e.g., unequal division time, as well as rare cellular events like polynucleation or reversed mitosis were observed, which would have remained undetected in a standard population analysis based on average measurements. Therefore, MaSC will open the door for systematic single-cell analysis of mammalian suspension cells. Possible fields of application represent basic research topics like cell-to-cell heterogeneity studies, clonal stability, pharmaceutical drug screening and stem cell research, as well as bioprocess related topics such as media development and novel scale-down approaches.