Structural analysis of random transgene integration in CHO manufacturing cell lines by targeted sequencing

Area of Science:

• Biotechnology and Genetic Engineering
• Cell Line Development for Biopharmaceutical Production
• Genomics and Molecular Biology

Background:

• Chinese hamster ovary (CHO) cell lines are crucial for biopharmaceutical manufacturing.
• Precise understanding of transgene integration sites and genomic alterations in CHO cells is limited.
• Next-generation sequencing (NGS) offers powerful capabilities for cellular genotype analysis.

Purpose of the Study:

• To investigate the utility of Targeted Locus Amplification (TLA) coupled with NGS for characterizing transgene integration in CHO cell lines.
• To analyze genomic alterations and integration site numbers in CHO production clones, including those from supertransfection.
• To evaluate TLA as a tool for distinguishing and evaluating CHO production cell lines during development.

Main Methods:

• Application of Targeted Locus Amplification (TLA) to generate comparative genomic fingerprints of CHO production cell lines.
• Combined use of TLA and next-generation sequencing (NGS) for detecting transgene integration positions and structural genomic changes.
• Analysis of supertransfected CHO cell lines to assess integration site integrity and copy number.

Main Results:

• TLA-NGS enabled detailed genetic characterization of transgene integration regions, identifying single sites with concatenated copies and associated genomic rearrangements (e.g., deletions, translocations).
• Supertransfection led to increased biopharmaceutical titer, correlated with an additional integration site per clone.
• TLA fingerprints effectively distinguished CHO cell lines, even those derived from the same mother clone, although genetic and phenotypic differences were observed in some cases despite identical fingerprints.

Conclusions:

• TLA combined with NGS provides accurate genetic characterization of transgene integration sites in CHO cells, surpassing conventional methods.
• This approach is a valuable tool for comprehensive evaluation of CHO production clones early in cell line development.
• Understanding transgene integration is critical for optimizing biopharmaceutical production and ensuring cell line stability.