Abstract
The use of transposase in cell line development (CLD) programs has
experienced increased popularity over the past decade. However, few
studies have described the mechanism of action and the genomic and
phenotypic characteristics of clones derived from transposase.
Additionally, how these traits impact long-term bioproduction is
unknown. Here, we use chromosome painting, deep sequencing, and ddPCR to
characterize the unique fingerprints associated with transposase-derived
clones. Transposase reduces the cellular pool of transient vector as
early as three days post transfection following transfection and
expedites stable pool establishment by up to two weeks. Furthermore, ,
recombinant DNA expression is significantly improved up to
~3 fold along with a greater balance of antibody heavy
and light chain transcripts, resulting in higher titers in transposase
generated pools. Transposase derived pools contained an often
innumerable number of integration sites, representing a vast increase in
integration site diversity over randomly generated pools, which were
bottlenecked at 1-3 integration sites per pool. These transposase
mediated integrations typically occurred in clean singlets, free of
genomic scars such as deletions, inversions, and other modifications
associated with legacy transfection methods which exhibited higher copy
numbers per integration site. Also we observed a relative decline in
gene expression with copy number increase in the randomly generated, but
not the transposase derived clones. Furthermore, transposase-derived
clones were more likely to exhibit enhanced a long term stability
profile, including product quality attributes such as Mannose-5. This
improved stability may result from circumventing mechanisms associated
with the silencing of tandem repeats. Thus, transposase-mediated
approaches can provide multifaceted molecular and phenotypic advantages
in cell line development when compared to legacy random-integration
methods.