In vitro investigations on cellular damage induced by high energy shock waves

Single-cell suspensions of the prostate carcinoma cell line PCA were exposed to electromagnetically generated ultrasound shock waves (source and focusing lens identical to those used in the commercially available lithotripor Lithostar Plus). Cell loss of up to 40% occurred in sample tubes containing air. To expose multicellular tumor spheroids and cells growing on a microcarrier, an experimental setup was developed that prevented motion of the specimen. Intracellular damage of intact spheroids was analyzed by laser scanning microscopy following specific fluorescence staining. Different sensitivities of individual cell components with respect to the applied energy density of the pulses were found, namely defects on cell membranes (0.12 mJ/mm2), vimentin (0.21 mJ/mm2), mitochondria (0.33 mJ/mm2) and nuclear membranes (0.5 mJ/mm2). Loss of cells growing on a microcarrier was found after application of 200 pulses with 0.21 mJ/mm2.