Chinese hamsters were first used in medical research in 1919, when Dr. E.T. Hsieh of the
Peking Union Medical College used captured hamsters from the local fields for typing
pneumococci. They were subsequently found by Jocelyn Smyly and Charles Young, two other doctors at the same institute, to be excellent vectors for transmission of kala-azar (
visceral leishmaniasis), facilitating
Leishmania research. Unsuccessful attempts were made to breed the rodents in captivity, first at the Peking Union Medical College in 1928, and subsequently in the United States at the
Harvard Medical School with a colony of 150 hamsters, which also failed; despite the researchers constructing extensive naturalistic mating burrows in the basement of the Harvard Comparative Pathology building, and then the grassy yard outside, the hamsters survived the harsh New England winter but did not reproduce. In 1943, Italian geneticist Guido Pontecorvo counted only 14 comparatively large chromosomes in Chinese hamster cells, compared to 40 in mice and 42 in rats - the fewer and larger chromosomes were easier to isolate, characterize, and map, making the rodents sought after for genomic research. In 1948, under the shadow of the
Chinese Civil War, and weeks before the
fall of Beijing, Dr. Hu Zhengxiang sent 20 Chinese hamsters, 10 male and 10 female, to Dr. Robert Briggs Watson, an American studying malaria in Nanjing, who took an 11-hour drive through blinding rain, narrowly avoiding roving bands of Communist troops, to deliver the animals to Shanghai and onto one of the last
Pan-Am flights to the United States. The hamsters were shipped to Victor Schwentker, a skilled rodent breeder in upstate New York, from whom a Harvard graduate student, George Yerganian, purchased several animals and began his own breeding program and determined the correct number of chromosomes (2n=22). All modern CHO cells are descended from the 20 individuals provided by Dr. Hu in 1948; for his cooperation with American scientists, he was persecuted as a "reactionary academic authority" for aiding American germ warfare in the
Korean War, and sentenced to a reeducation camp for six months. Decades later, during the
Chinese Cultural Revolution in August 1966, these accusations resurfaced, leading to a vicious beating in his home at the hands of the Red Guard, shortly after which he and his wife committed suicide. In 1957,
Theodore T. Puck obtained a female Chinese hamster from now Dr. George Yerganian's laboratory at the Boston Cancer Research Foundation and used it to derive the original Chinese hamster ovary (CHO) cell line. Since then, CHO cells have been a cell line of choice because of their rapid growth in
suspension culture, high protein production, and ability to produce proteins with mammalian post-transcriptional glycosylation. The thrombolytic medication against myocardial infarction
alteplase (Activase) was approved by the US
Food and Drug Administration in 1987. It was the first commercially available recombinant protein produced from CHO cells. CHO cells continue to be the most widely used manufacturing approach for recombinant protein therapeutics and prophylactic agents. In 2019, six of the 10 best-selling drugs were made in CHO cells. ==Properties==