Low-intensity pulsed ultrasound stimulates a bone-forming response in UMR-106 cells

Low-intensity (<100 mW/cm(2)) pulsed ultrasound (US) is an established ther apy for fracture repair. In both animal and human trials, such US has been shown to facilitate fresh fracture repair and initiate healing in fractures with repair defects. However, the mechanism by which US achieves these out comes is not clear. One possible mechanism is the direct stimulation of bon e formation. To investigate this hypothesis, the current study investigated the mRNA response of isolated bone-forming cells (UMR-106 cells) to a sing le 20-min dose of low-intensity pulsed US. Using a novel US-cell coupling m ethod, US was found to stimulate expression of the immediate-early response genes c-fos and COX-2 and elevate mRNA levels for the bone matrix proteins ALP and OC. These findings suggest that low-intensity pulsed US has a dire ct effect on bone formation. This may contribute to the beneficial effect o f low-intensity pulsed US on fracture repair. (C) 2001 Academic Press.