Ultrasonic treatment of Chinese hamster cells at high intensities and long exposure times

Abstract

Monolayers of single Chinese hamster cells growing on 0.036 mm Melinex film in specially constructed irradiation vessels were treated to continuous 990.5 kHz focused ultrasound. After treatment, cells were incubated until they formed small microcolonies (48 h) or until confluent growth was obtained (96 h). Damage was assessed by scoring a focal area of 5 mm2 for a reduction in colony number or multiplicity after 3 generations or for a cell-free area after 7 generations. Mammalian cells withstood up to 30 times greater intensities and up to 1000 times higher exposure times than any treatments shown to produce pathological lesions in mammalian tissues. When damage was observed it was generally associated with the production of cavitation events. A non-cavitation or non-thermal effect leading to cell death was not demonstrated.