What is the Difference Between CHO-S and CHO-K1

The key difference between CHO-S and CHO-K1 is the manner in which the cells proliferate and grow. While CHO-S is adapted for growth in suspension liquid cultures, CHO-K1 is a cell line that could be genetically manipulated to grow as suspension cells or adherent cells.

CHO stands for Chinese Hamster Ovary cells. It is an epithelial cell line. This epithelial cell line is derived from the ovary of the Chinese hamster. CHO is used in medical and biological research studies. It is also widely used in the production of commercially available therapeutic recombinant proteins. The scientific research studies where CHO and CHO-derived cell lines are used include studies in toxicity screening, genetic studies, nutrition, and gene expression related to the expression of recombinant proteins.


1. Overview and Key Difference
2. What is CHO-S  
3. What is CHO-K1
4. Similarities – CHO-S and CHO-K1
5. CHO-S vs CHO-K1 in Tabular Form
6. Summary – CHO-S and CHO-K1

What is CHO-S?

CHO-S is a type of cell line lineage derived from the CHO cell line. The importance of CHO-S cells in research studies is the adaptation of the cell line in serum-free suspension culture to grow to high cell density. Hence, the CHO-S cell line is ideal for the growth of large-scale industrial bioreactors. They are important in the process of protein expression in biomanufacturing. The growth of the CHO-S cell line in serum-free suspension depends on several factors. They are media composition, proper cell maintenance, and cell culture format. At present, CHO-S cells utilize modern media formulations for growth. These include Expression Medium from Mirus Bio and CHOgro®. These media allow the CHO-S cells to reach a cell density of 1-2×107 cells/ml. In addition to the above media types, a few other types of media, including Hams’s F10, Ham’s F12, ProCHO, and PowerCHO™ for the growth CHO-S cells recommended.

Figure 01: CHO

The only drawback in using these types of media is that CHO-S cells quickly consume the available nutrients in the medium. Hence, to overcome this challenge to cell maintenance, the suspension should be split to lower cell densities and provide a fresh growth medium regularly.

What is CHO-K1?

CHO-K1 is a cell line lineage derived from CHO cell line as a subclone from parental CHO cell line derived from the ovary of an adult Chinese hamster. It is important to provide proline as a supplement to the growth medium when growing CHO-K1 cells. This is due to the fact that CHO-K1 cells lack a chromosome that is necessary for proline biosynthesis. This results in the blockage of the biosynthetic chain during the conversion of glutamic acid to glutamine gamma seri-aldehyde.

CHO-K1 cells are widely applied in nutritional and gene expression studies, cell culture, growth conditions, stable cell transfection, transient transfection, and protein expression. CHO-K1 cells grow as suspension cells or adherent cells after genetic manipulation. Hence, CHO-K1 cells are widely used in therapeutic recombinant protein production and in-vitro cancer studies related to ovarian cancer. CHO-K1 cells demonstrate viral susceptibility and show resistance to poliovirus. CHO-K1 cells also act as a host expression system for growth factors, monoclonal antibodies, interferons, and enzymes. The role of CHO-K1 cells in these aspects is dominant.

What are the Similarities Between CHO-S and CHO-K1?

  • CHO-S and CHO-K1 are two cell lines derived from Chinese Hamster Ovarian epithelial cells.
  • Both types are grown in suspension media.
  • These types are used in biological and medical research studies.
  • Moreover, both CHO-S and CHO-K1 are used in a wide range of commercially available therapeutic studies.

What are the Difference Between CHO-S and CHO-K1?

The key difference between CHO-S and CHO-K1 is that CHO-S grow as suspension cells only, but CHO-K1 grows as both suspension and adherent cells. Both CHO-S and CHO-K1 are derived from the same ancestral CHO but possess differences when it comes to applications. CHO-K1 lacks a proline-synthesizing gene, unlike CHO-K1. Hence, proline is added to the media when culturing.

The below infographic presents the differences between CHO-S and CHO-K1 in tabular form for side by side comparison.

Summary – CHO-S vs CHO-K1

CHO-S and CHO-K1 cell lines are derived from the Chinese Hamster Ovary (CHO) epithelial cells. Both types are important for various research studies, both medical and biological. CHO-S is a suspension cell line, while CHO-K1 is either a suspension or adherent cell line. The important feature of CHO-K1 is that it lacks the proline-synthesizing gene. CHO-S is widely used in industrial bioreactor systems. CHO-K1 applications lie more on gene expression studies. So, this summarizes the difference between CHO-S and CHO-K1.