History of CHO

The use of the Chinese hamster in research dates back to 1919 where they were used in place of mice for typing pnumococci. They were subsequently found to be excellent vectors for transmission of kala-azar (also known as black fever or visceral leishmaniasis), facilitating research in epidemiology. In 1948, the Chinese hamster was brought to the United States for breeding in research laboratories. This immigration of the Chinese hamster to the United States during the cold war era spurred much political controversy, resulting in the arrest of two scientists who assisted in their journey. It was thought that the United States would use these animals in biological warfare by infecting the hamsters with cholera or the plague and parachuting them over enemies.

Rather than being used as an agent in biological warfare, the Chinese hamster became noteworthy for the cell lines that were derived from its tissues. Having a very low chromosome number (2n=22) f or a mammal, the Chinese hamster is an ideal model for radiation cytogenetics and tissue culture. In 1957, Theod ore.T. Puck obtained a female Chinese hamster from Dr. Ge orge Yerganian’s laboratory at the Boston Cancer Research Foundation and used it to derive the original Chinese hamster ovary (CHO) cell line. In 1980, Urlaub and Chasin isolated a CHO cell line deficient in DHFR enzyme activity through mutagenesis and selection of thymidine auxotrophs. These mutants have become the most widely used host for recombinant protein production, churning out billions of dollars in therapeutics per annum.

Although relatively few labs still breed Chinese hamsters (aside from Dr. Yerganian who still breeds them in his lab orat ory at Cytogen), the species is still of great economic value in biomedical research and in the biotechnology industry. As a host for expression of recombinant proteins, CHO cells have become the mammalian equivalent of E. coli in research and biotechnology today.