Mammalian Cell Systems for Recombinant Protein Production

Mammalian cell systems, chiefly Chinese hamster ovary (CHO) and human embryonic kidney (HEK293) lines, constitute the principal platforms for the manufacture of therapeutic proteins. Their capacity to perform complex post-translational modifications, including human-like glycosylation and correct disulfide bonding, underpins the safety and efficacy of biopharmaceuticals ranging from monoclonal antibodies to cytokines. Host cell engineering strategies have evolved from classical gene amplification and random integration to precision genome editing, enabling the creation of isogenic cell lines with stable transgene expression. Vector design now incorporates synthetic selection markers and multicistronic cassettes to enrich high producers and streamline cell line development. Bioprocess optimisation—spanning media formulation, feeding strategies and bioreactor control—further enhances titre, quality and consistency. Together, these advances have accelerated timelines, reduced variability and supported the global demand for increasingly complex recombinant therapeutics.

Research from Nature Portfolio

Foundational work has demonstrated precise insertion of therapeutic transgenes into defined genomic loci using CRISPR/Cas9 coupled with homology-directed repair. This approach yields isogenic CHO populations with uniform transgene copy number and markedly reduced expression variability. By targeting safe-harbour sites and employing compact donor templates, researchers have generated stable cell lines that maintain consistent protein productivity over extended culture. Such methodologies pave the way for rapid generation of production candidates with predictable performance and simplify regulatory evaluation by minimising clone-to-clone heterogeneity.

Mammalian Cell Systems for Recombinant Protein Production publication trend

The graph below shows the total number of articles in mammalian cell systems for recombinant protein production across all publications each year (not limited to Nature Index journals).

Technical terms

CRISPR/Cas9: A programmable nuclease system that introduces site-specific DNA double-strand breaks to facilitate targeted genome modification.

Homology-directed repair (HDR): A cellular mechanism for precise DNA repair using a homologous template to guide accurate sequence insertion.

Split intein: A pair of protein fragments that reassemble in vivo to catalyse peptide bond formation, enabling post-translational ligation of functional domains.

Glutamine synthetase selection: A metabolic marker system that confers growth advantage in glutamine-free medium, used to enrich transfected cells.

Post-translational modification: Chemical or structural alterations of a protein after synthesis, such as glycosylation or disulfide bond formation, critical for function.

References

1. SiMPl‐GS: Advancing Cell Line Development via Synthetic Selection Marker for Next‐Generation Biopharmaceutical Production. Advanced Science (2024).
2. Comprehensive genome-scale CRISPR knockout screening of CHO cells. Scientific Data (2025).
3. Site-specific integration in CHO cells mediated by CRISPR/Cas9 and homology-directed DNA repair pathway. Scientific Reports (2015).