HEK293 and CHO cells are two widely used mammalian cell lines in research and biotechnology. Both cell lines have distinct characteristics that make them suitable for different applications, such as protein production, gene expression studies, and drug development.

HEK293 cells: HEK293 (Human Embryonic Kidney 293) cells are derived from human embryonic kidney cells. They were first generated in the early 1970s by transforming the primary kidney cells with sheared fragments of adenovirus type 5 DNA. HEK293 cells are easy to culture, grow rapidly, and have a high transfection efficiency, making them a popular choice for various applications, including:

1. Gene expression studies: Due to their high transfection efficiency, HEK293 cells are frequently used for transient transfection experiments to study the function of genes, promoters, and other regulatory elements.
2. Protein production: HEK293 cells can be used to produce recombinant proteins, particularly those requiring complex post-translational modifications like glycosylation. Specialized sublines, such as HEK293T or HEK293E, have been developed to improve protein production yield and quality.
3. Viral vector production: HEK293 cells are often used to produce viral vectors, such as lentivirus or adenovirus, for gene therapy or gene delivery applications.

CHO cells: CHO (Chinese Hamster Ovary) cells are derived from the ovary of the Chinese hamster. First established in the late 1950s, CHO cells have become one of the most widely used mammalian cell lines for the production of recombinant proteins and biopharmaceuticals. Some key advantages of CHO cells include:

1. High protein production yield: CHO cells can grow to high densities in suspension culture and are capable of producing large amounts of recombinant proteins.
2. Post-translational modifications: Like other mammalian cells, CHO cells can perform complex post-translational modifications, such as glycosylation, which are crucial for the proper function of many therapeutic proteins.
3. Safety: CHO cells have a long history of use in biopharmaceutical production and have been well characterized in terms of safety, reducing the risk of contamination with human pathogens or endogenous retroviruses.

Both HEK293 and CHO cells have been instrumental in advancing biological research and biotechnology. They each offer unique advantages for different applications, and the choice between the two cell lines often depends on the specific goals and requirements of a particular experiment or bioprocess.