Chinese Hamster Ovary (CHO) cells are a foundational element in modern biotechnology, widely adopted for producing complex biological therapeutics. These specialized cells act as microscopic factories to manufacture many protein-based medicines. Their reliability and efficacy in developing treatments for various human diseases underscore their widespread use. CHO cells are often referred to as the “workhorse” of biomanufacturing due to their consistent performance and adaptability.
Understanding CHO Cells
CHO cells originate from the ovary of a Chinese hamster (Cricetulus griseus), a small rodent native to northern China and Mongolia. Theodore T. Puck first isolated these cells in 1957, observing their ability to proliferate indefinitely in a laboratory. This classifies them as an “immortalized” cell line, meaning they can be cultured continuously over long periods.
Their biological characteristics make them suitable for industrial applications. CHO cells exhibit robust growth, with a doubling time of 16 to 22 hours, allowing for rapid expansion. They can be grown in large quantities and adapt to various conditions, including suspension cultures in chemically defined, serum-free media. This adaptability simplifies culturing and reduces contamination risk from animal-derived components.
Why CHO Cells Are Indispensable in Medicine
CHO cells are indispensable in biopharmaceutical production due to several advantages. Primary is their ability to perform human-like glycosylation, where sugar molecules are added to proteins. This modification is important for the function, stability, and therapeutic effectiveness of many protein-based drugs, ensuring they behave correctly within the human body.
Another advantage is their favorable safety profile. They present a low risk of carrying human viruses, a substantial concern when producing medicines for human use. This, coupled with their non-tumorigenic nature, makes them a safer option compared to human cell lines. Their long history of safe use has also led to broad regulatory acceptance by agencies worldwide, including the FDA and EMA, which streamlines the approval process for new drug candidates.
CHO cells also offer high productivity and scalability, allowing for efficient production of large quantities of complex proteins. They can be grown in vast bioreactors, enabling industrial-scale manufacturing of biopharmaceuticals. This capability makes them a preferred choice for producing therapeutic proteins.
Major Therapeutic Products from CHO Cells
CHO cell lines produce a wide array of complex protein-based therapeutics. Monoclonal antibodies (mAbs) represent a significant category, accounting for a large portion of biopharmaceutical sales. These antibodies treat various conditions, including cancers, autoimmune diseases like rheumatoid arthritis and Crohn’s disease, and other inflammatory disorders. An example is rituximab, approved for treating non-Hodgkin’s lymphoma, chronic lymphocytic leukemia, and rheumatoid arthritis.
Beyond monoclonal antibodies, CHO cells produce other recombinant proteins. These include erythropoietin (EPO), a hormone used to treat anemia by stimulating red blood cell production. Clotting factors, used in hemophilia treatment, are also manufactured using CHO cells. Additionally, certain vaccine components are produced in these cell lines, contributing to global health initiatives. The ability of CHO cells to produce these complex proteins makes them essential for modern medicine.
Ensuring Quality and Consistency
Ensuring the quality and consistency of biopharmaceuticals produced using CHO cells involves carefully controlled processes. Cell line development begins with selecting and engineering specific CHO cell lines to optimize protein production. This involves introducing genetic material into host cells to enable them to produce the desired proteins. Scientists continuously work to improve these cell lines for higher yields and better product quality.
Bioprocess optimization is another aspect, involving the careful control of growth conditions within bioreactors. Parameters such as temperature, nutrient supply, and pH are monitored and adjusted to maximize cell growth and product yield. This optimization helps maintain consistent product quality throughout large-scale manufacturing.
Quality control measures are implemented throughout the production process. This includes extensive testing and purification steps to ensure the final biopharmaceutical product is pure, potent, and free from contaminants. These measures are important for meeting regulatory standards and ensuring patient safety. Research efforts also focus on improving CHO cell lines for enhanced productivity, product quality, and cost-effectiveness.