Growth of Trypanosoma cruzi in human heart tissue cells and effects of aminonucleoside of puromycin, trypacidin and aminopterin.

Abstract

SYNOPSIS. Development of a suitable tissue cell system for the growth of T. cruzi required the production of infective metacyclic trypanosomes and tissues which these forms could infect. Human heart was selected from a range of serially‐cultured tissue cell lines as the most suitable for intracellular growth. Most metacyclic forms occurred when the growth medium had an initial pH of 7.2 and the cultures were gassed with 5% CO2/95% air before closure and then incubated at 33 C.During the first 4 days of incubation ∼ 10% of tissue cells in cultures were infected with 1–5 leishmanial forms of T. cruzi. During the next 4 days, the number of infected cells about doubled and many contained 10 or more leishmanias. The effects of drugs were studied on this 2nd 4‐day period of incubation. The aminonucleoside of puromycin affected growth of the intracellular but not the extracellular parasites whereas trypacidin had the opposite effect, inhibiting growth of the extracellular but not the intracellular forms. Aminopterin inhibited the growth of both extracellular and intracellular forms. The selective effects of the aminonucleoside of puromycin against intracellular forms might be due to it being metabolized by the host cells to a more active trypanocide.A method for isolating intracellular forms of T. cruzi from the tissue cells is described. Dihydrofolate reductase activity was found in these preparations and in similar preparations of the culture and blood forms. The reductase was sensitive to inhibition by aminopterin and a 2, 4‐diaminopyrimidine.