Generation of High-Producing CHO Cell Lines by Piggybac Transposition

CHO cells expressing a human IgG or a TNFR:Fc fusion protein were generated either by piggybac (PB) transposon-mediated gene transfer or by conventional transfection techniques. Polyclonal populations were cultivated at small scale as batch cultures and analyzed for transgene expression over time. Afterwards, clonal cell lines were recovered by limiting dilution. When compared to controls, cell populations generated by transposition showed improved recombinant protein yield and stability. In addition, the frequency of high-producer cell lines was up to 4-fold higher when cells were sorted from cell pools generated by transposition. Analysis of the specific productivity of selected clones confirmed the improved productivity of transposed cell lines, which also correlated with an increased number of integrated transgene copies. The results indicated that PB-transposition is a valuable tool to generate cell clones with stable and enhanced transgene expression at high frequency, and thus sensibly reducing screening, development timelines, and costs.