Introduction
Chinese Hamster Ovary (CHO) cells are a widely used mammalian cell line in biotechnology and pharmaceutical industries. These cells were first isolated from the ovary of the Chinese hamster (Cricetulus griseus) in the 1950s and have since been adapted for large-scale production of therapeutic proteins. CHO cells are the preferred host for producing recombinant proteins, monoclonal antibodies, and biosimilars due to their ability to perform post-translational modifications, particularly glycosylation, which is crucial for maintaining the stability and efficacy of therapeutic proteins.

Characteristics of CHO Cells
1. Adaptability and Scalability
CHO cells can adapt to growth in both adherent and suspension cultures, which makes them highly suitable for scaling up in industrial bioreactors. In suspension, they can be grown to high densities, optimizing production efficiency for biopharmaceutical manufacturing. 2. Post-Translational Modifications
CHO cells perform human-like glycosylation, ensuring that recombinant proteins, particularly antibodies, maintain appropriate structure and function. These modifications improve protein stability, bioactivity, and pharmacokinetics, making CHO-derived products viable for clinical applications.
3. Genetic Stability
CHO cells can stably integrate transgenes, allowing for the creation of stable cell lines that express recombinant proteins consistently over time. This makes them a reliable choice for long-term commercial production of biologics.
4. Resistance to Viral Infection
Compared to other mammalian cell lines, CHO cells exhibit low susceptibility to viral infections, enhancing the safety of pharmaceutical production. This is one reason regulators favor CHO-based systems for biologics manufacturing.

Mechanisms of CHO Cell Utilization
1. Stable vs. Transient Transfection
• Stable Transfection: DNA encoding the target protein is integrated into the CHO cell genome, creating a cell line that can express the protein consistently over many generations. This is ideal for large-scale production.
• Transient Transfection: DNA is introduced temporarily, leading to short-term protein expression. Transient expression is used for rapid protein production in early-stage research but is less efficient for commercial manufacturing.
2. Fed-Batch and Perfusion Cultures
• Fed-Batch: Nutrients are added at intervals during the production process, extending the productivity of the culture. This is a common method for CHO-based antibody production.
• Perfusion: The medium is continuously refreshed, and waste is removed. Perfusion systems allow for extended production cycles but are more complex and costly to operate.
3. Cell Line Engineering
Genetic modifications can improve CHO cell productivity by:
• Enhancing growth rates and cell viability.
• Modifying glycosylation pathways to produce consistent therapeutic protein.
• Reducing lactate accumulation, which can impair cell growth and protein expression.

Applications of CHO Cells
1. Therapeutic Protein Production
CHO cells are the leading platform for producing monoclonal antibodies (mAbs) and other therapeutic proteins, such as erythropoietin (EPO) and coagulation factors.
2. Biosimilars
The versatility of CHO cells makes them ideal for producing biosimilars—affordable alternatives to original biologics—without compromising on quality.
3. Vaccine Development
CHO cells are also used for vaccine production, especially for subunit vaccines, due to their ability to express complex proteins with high fidelity.
4. Diagnostics
CHO cells are employed in the development of diagnostic tools, such as enzyme-linked immunosorbent assays (ELISA) and immunoassays, for detecting biomarkers in clinical settings.

GenScript Solutions for CHO Cell Applications
GenScript provides a suite of products and services to optimize CHO cell-based workflows:
• TurboCHO™ Stable Cell Line Development: Accelerates the creation of high-yield stable cell lines.
• Custom Culture Media: Tailored formulations to improve CHO cell growth and protein expression.
• Antibody Purification Tools: Resins and purification kits for efficient recovery of high-quality proteins.
• Gene Synthesis and Vector Construction: Optimized vectors to enhance transfection efficiency and expression levels.
These services streamline the production process, ensuring high yields and consistent product quality for commercial-scale biologics production.

Conclusion
CHO cells play an essential role in the production of therapeutic proteins, particularly monoclonal antibodies. Their ability to perform complex post-translational modifications, maintain genetic stability, and grow in scalable culture systems makes them a preferred platform for biologics manufacturing. Continuous advancements in cell line engineering, media optimization, and bioreactor technologies will further enhance CHO cell applications, meeting the growing demand for safe, effective, and affordable therapeutics.