Introduction
Chinese hamster ovary (CHO) cells are the most widely used expression system for therapeutic antibody production.
Over several decades, they have become the industry standard for manufacturing monoclonal antibodies, supported by a combination of biological suitability, process flexibility, and regulatory familiarity.
Understanding why CHO cells are so widely used helps provide context for how biologics are developed, optimised, and scaled.
What Are CHO Cells?
CHO cells are mammalian cells derived from the ovary of the Chinese hamster. They are commonly used to produce recombinant proteins, particularly complex biologics such as monoclonal antibodies.
Because they are mammalian, CHO cells are capable of:
- Proper protein folding
- Post-translational modifications
- Human-like glycosylation patterns
These characteristics are essential for producing functional therapeutic antibodies.
Why CHO Cells Are Widely Used
Compatibility with Complex Proteins
Antibodies require correct folding and glycosylation to function properly. CHO cells are well suited to producing these complex proteins in a form that is both active and stable.
Established Manufacturing Platform
CHO-based production is:
- Well understood
- Highly optimised
- Widely adopted across industry
This means:
- Established protocols exist
- Scaling processes are well characterised
- Knowledge is transferable between projects
This established foundation is one reason CHO cells remain widely used in antibody production workflows.
Regulatory Acceptance
CHO cells have a long history of use in approved therapeutics. As a result:
- Regulatory expectations are well defined
- Safety profiles are well understood
- Manufacturing processes are easier to justify
This reduces risk during development and approval.
Flexibility in Cell Line Development
CHO cells can be engineered and selected to:
- Improve productivity
- Enhance stability
- Optimise product quality
This makes them highly adaptable to different antibody formats and production requirements.
Challenges Associated with CHO Systems
Despite their advantages, CHO cells also introduce challenges that need to be managed.
Variability Between Clones
Different CHO clones can show significant variation in:
- Expression levels
- Growth behaviour
- Product quality
This makes cell line development (CLD) a critical step in identifying suitable production candidates.
Host Cell Proteins (HCPs)
CHO cells produce a wide range of endogenous proteins that can be co-expressed with the target antibody.
These host cell proteins:
- Need to be removed during downstream processing
- Can impact product quality if not controlled
- Are monitored throughout development
This makes HCP monitoring an important part of developing a robust and controlled antibody production process.
Process Complexity
Producing antibodies in CHO cells involves:
- Optimising culture conditions
- Managing cell health and productivity
- Ensuring consistent product quality
This requires careful process development and monitoring.
CHO Cells in the Development Workflow
CHO cells are used throughout the biologics development pipeline:
- Cell line development
→ screening and selection of high-producing clones - Process development
→ optimisation of culture and purification conditions - Manufacturing
→ large-scale production under controlled conditions
At each stage, measurements such as antibody titre and impurity levels are used to guide decisions.
Supporting CHO-Based Workflows in Practice
Established analytical methods—such as ELISA, affinity-based assays, and HCP analysis—remain central to monitoring antibody production in CHO systems.
At the same time, there is increasing interest in approaches that:
- Support faster feedback during development
- Reduce variability in measurement
- Enable more consistent comparison across samples
Platforms such as Amperia™ are being explored in this context to support protein quantification within streamlined workflows.
Conclusion
CHO cells have become the industry standard for therapeutic antibody production due to their ability to produce complex, functional proteins at scale.
While they offer significant advantages, they also introduce variability and complexity that must be carefully managed. Understanding how CHO systems behave—and how they are monitored—helps support more efficient and reliable biologics development.