Improving Bioprocess Expression Systems: A Clean Alternative to CRISPR/Cas9

Chinese hamster ovary (CHO) cells have emerged as a robust platform for bioprocessing serving both early and late-stage biotherapeutic drug supply. However, these cells and other hosts (e.g., HEK293), can be optimized for even greater potential through advanced gene editing. For example, when the endogenous glutamine synthetase (GS) gene is knocked out in CHO cells, a sixfold increase in high-producing cell lines is achieved (1). In another study, CHO with annexin A2 (ANXA2) and cathepsin gene (CTSD) knockouts were introduced to eliminate CHO host-cell proteins that complicate downstream processing and can contribute to immunogenicity (2).

In this BPI supplier-side article, Demeetra AgBio introduces the Cas-CLOVER gene-editing technology, a dimeric nuclease system that, unlike CRISPR/Cas9, does not result in detectable off-target mutagenesis. Fill out the form below to read the full article now.



References
1 Fan L, et al. Improving the Efficiency of CHO Cell Line Generation Using Glutamine Synthetase Gene Knockout Cells. Biotech. & Bioeng. 109(4) 2012: 1007–1015; https://www.ncbi.nlm.nih.gov/pubmed/22068567.

2 Fukuda N, Senga Y, Honda S. ANXA2-and CTSD-Knockout CHO Cell Lines to Diminish the Risk of Contamination with Host-Cell Proteins. Biotech. Prog. 35(4) 2019: e2820; https://www.ncbi.nlm.nih.gov/pubmed/30972970.

3 Fu Y, et al. High-Frequency Off-Target Mutagenesis Induced By CRISPR-Cas Nucleases in Human Cells. Nat. Biotech. 31(9) 2013: 822–826; https://www.ncbi.nlm. nih.gov/pmc/articles/PMC3773023/.

4 Lee JS, et al. Site-Specific Integration in CHO Cells Mediated By CRISPR/Cas9 and Homology-Directed DNA Repair Pathway. Sci. Reports 5, 2015: e8572; https://www.nature.com/articles/srep08572.

5 Li X, et al. Cas-CLOVER™: A High-Fidelity Genome Editing System for Safe and Efficient Modification of Cells for Immunotherapy. Poster: 2018 Precision CRISPR Congress, Boston, MA: 2018; https://www.herabiolabs.com/wp-content/uploads/2019/11/CRISPR-Congress-Poster-Cas-CLOVER-1.pdf.

Jack Crawford is CEO of Demeetra AgBio, Inc., 2277 Thunderstick Drive #500, Lexington, KY 40505; jcrawford@ demeetra.com; 1-315-351-9115.

This article will appear in BPI’s September 2020 print issue.

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