Disorganization and Disruption of Mammalian and Amoeboid Cells by Acoustic Microstreaming

Abstract

Single-cell suspensions of mouse Ehrlich ascites carcinoma and the amoeba Hartmanella castellanii were subjected to the small-scale acoustic microstreaming field set up around a partially submerged transversely oscillating wire. A resonant length (1.69 cm) of thin steel wire (0.023-cm diam) was driven transversely from one end at 20 kHz and a system of flexural standing waves developed. The free end of the wire was immersed in 0.3 ml of the dilute cell suspension and the maximum displacement amplitude of the submerged portion measured with a traveling microscope. The amoebae and mouse cells were disrupted in a reproducible manner when the maximum wire displacement amplitude exceeded the critical values of about 10 and 28 μm respectively. Electron micrographs of amoebae sonicated for 5 min at displacement amplitudes close to the critical value for disruption suggest that some form of intracellular streaming might have occurred. However, this is unlikely in the mouse cells where intracellular adhesion is so strong that the cell membrane may be partially or completely removed without dispersing the cell contents. Intact sonicated mouse cells exhibit a variety of changes which suggest that a small alteration in fluid transport has occurred.