Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10692027 | Ultrasound in Medicine & Biology | 2014 | 12 Pages |
Abstract
To establish the therapeutic potential of low-intensity ultrasound, it is important to characterize its biophysical interactions with living cells. Here, through a series of single-cell direct observations, we show that low-intensity ultrasound pulsing would give rise to a dynamic course of cytomechanical perturbations at both the membrane and nucleus levels. Our investigation was conducted using a composite platform that coupled a 1-MHz ultrasound exposure hardware to a confocal microscopy system. Short ultrasound pulses (5 cycles, 2-kHz pulse repetition frequency) with a spatial-peak time-averaged intensity of 0.24 W/cm2 (0.85-MPa peak positive acoustic pressure) were delivered over a 10-min period to adherent Neuro-2a neuroblastoma cells, and live imaging of cellular dynamics was performed before, during and after the exposure period. Bright-field imaging results revealed progressive shrinkage of cellular cross-sectional area (25%-45%, N = 7) during low-intensity ultrasound pulsing; the initial rate of size decrease was estimated to be 8%-14% per minute. This shrinkage was found to be transient, as the sonicated cells had recovered (at a rate of size increase of 0.4%-0.9% per minute) to their pre-exposure size within 30 min after the end of exposure. Three-dimensional confocal imaging results further revealed that (i) ultrasound-induced membrane contraction was volumetric in nature (21%-45% reduction), and (ii) a concomitant decrease in nucleus volume was evident (12%-25% reduction). Together, these findings indicate that low-intensity ultrasound pulsing, if applied on the order of minutes, would reversibly perturb the physical and subcellular structures of living cells.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Acoustics and Ultrasonics
Authors
Yaxin Hu, Jennifer M.F. Wan, Alfred C.H. Yu,