High Quality Content by WIKIPEDIA articles! High Quality Content by WIKIPEDIA articles! Chinese hamster ovary (CHO) cells are a cell line derived from the ovary of the Chinese hamster. They are often used in biological and medical research and commercially in the production of therapeutic proteins. They were introduced in the 1960s and grow as a cultured monolayer. They require the amino acid proline in their culture medium.CHO cells are used in studies of genetics, toxicity screening, nutrition and gene expression, particularly to express recombinant proteins. Today, CHO cells are the most commonly used mammalian hosts for industrial production of recombinant protein therapeutics.The use of the Chinese hamster in research began in 1919 where they were used in place of mice for typing pneumococci. They were subsequently found to be excellent vectors for transmission of kala-azar (also known as visceral leishmaniasis), facilitating research in epidemiology.