Prolonged hyperthermia eliminates mycoplasma from cultured human and rat brain tumor cell lines.
Mycoplasma infection of mammalian cells in culture is a common occurrence that can affect the results of experimental protocols. Current methods of eliminating mycoplasma from cell cultures are usually tedious, time-consuming, and sometimes unsuccessful. In the present study, four cultured brain tumor cell lines (human U-251 MG, U-87 MG, SF-126, and rat 9L) were heavily contaminated with Mycoplasma orale. Heating the cultures to 41 degrees C for at least 96 h eliminated the contamination for up to 7 months, the maximum period of observation. The time chosen to assay for the presence of mycoplasma in cultures was critical: in some cultures heated for less than 96 h that initially appeared to be free of contamination, mycoplasma began to appear after 2 weeks. Heat-treated cells grew at the same rate as unheated control cells. Infected cells were more sensitive to X rays than uncontaminated cells, but the sensitivity reverted to normal after mycoplasma was eliminated by hyperthermia. The heating method does not require a cell cloning procedure or the use of exogenous materials. Treated cell cultures exhibit normal growth and radiation sensitivity, and the technique seems to be reliable and efficient.
Ho
J T
JT
Department of Neurological Surgery, School of Medicine, University of California, San Francisco 94143-0520.
Deen
D F
DF
D000818:Animals; D001932:Brain Neoplasms; D006358:Hot Temperature; D006801:Humans; D009174:Mycoplasma; D051381:Rats; D013997:Time Factors; D014407:Tumor Cells, Cultured / Q000382:microbiology*