Effects of low-intensity pulsed ultrasound on proliferation and chondroitin sulfate synthesis of cultured chondrocytes embedded in Atelocollagen((R))gel

The effects of low-intensity pulsed ultrasound (US) on the proliferation an d chondroitin sulfate synthesis of cultured chondrocytes embedded in Ateloc ollagen (R) gel in vitro were examined. Articular cartilage was harvested f rom the hip, knee, and shoulder joints of 10-week-old Japanese white rabbit s. Chondrocytes isolated by collagenase digestion were embedded in type I c ollagen gel, Atelocollagen gel, and were cultured in Dulbecco's modified ea gle's medium for 3 weeks. The US apparatus, SAFHS (R), was used to deliver an ultrasound signal with spatial and temporal average intensities of 30 mW /cm(2) (US group). The frequency was 1.5 MHz with a 200-microsecond tone bu rst repeated at 1.0 kHz. US treatments were administered for 20 min per day under culture dishes, with the medium replaced twice a week. Another group of cells was exposed to sham ultrasound as a control. Cell number, histolo gical findings, synthesis of isomers of chondroitin sulfate, and stiffness of the chondrocyte-collagen gel composites were analyzed. US exposure promo ted synthesis of chondroitin sulfate, especially chondroitin 6-sulfate, alt hough it did not significantly enhance cell number and stiffness. In this t hree-dimensional culture model, these results suggest that US exposure may be clinically useful in improving the quality of chondrocyte-Atelocollagen implants for transplantation into articular cartilage defects. (C) 2001 Joh n Wiley & Sons, Inc.