Characterization and improvement of cell line performance via flow cytometry and cell sorting

The improvement of specific productivity is a continuous challenge for bioprocesses involving mammalian cells, and hence, high-throughput methods and low-cost strategies are needed for the selection of high producers. The aim of this study was the productivity improvement of the hybridoma cell line IV F 19.23. For this purpose, a cell surface affinity matrix assay was established to identify and select high producers. This assay is based on the binding of secreted monoclonal antibodies to an affinity matrix assembled on the outer cell membrane. A protein microarray approach was used to investigate and optimize the functionality of the affinity matrix. The protein microarray was particularly useful to identify critical steps of the staining method, such as unspecific binding, before it was applied to the hybridoma cell line. Secreting hybridomas were treated with the affinity matrix and then selected via flow-cytometric cell sorting in four consecutive bulk sort rounds. The applied bulk strategy, allowing low screening costs, resulted in a 125% increase in specific productivity of the cell line in comparison to the initial population.