P01-34 Low-intensity pulsed ultrasounds produces an increase of IGF-I gene expression during fibula bone repair in rats

Abstract

Pulsed ultrasounds(PUS) is a form of non-invasive mechanical energy that can be transmitted through the skin as a sound wave of high pressure. This type of mechanical energy has been employed with therapeutic purposes to improve the bone healing. The aim of this study was to measure the temporal expression of IGF-I gene during the process of bone healing in both control and lowintensity pulsed ultrasound (LIPUS) treated fibula fracture in rats. A non-critical size bone fragment was surgically removed from both f ibulas. After 24 hours of surgery, the treated animals received 0.5 W/cm2, 3 min/day LIPUS. On days 2, 5, 10, 15, 20 and 28 postinjury 6 rats per group were sacrificed and bone callus were isolated and processed to obtain total RNA. For the purpose of this study, we examined the expression of IGF-I involved in bone repair and remodelling. Quantitative real-time polymerase chain reaction (RT-qPCR) showed an upregulation of IGF-I gene at days 5 and 15 and then declined gradually until day 28 postsurgery. Our results indicate that ultrasounds therapy may improve bone repair by increasing IGF-I; a powerful stimulator of osteogenesis, since IGF-I induces cell proliferation, osteoblast differentiation, type I collagen biosynthesis, osteoclastogenesis, and interaction osteoblast-osteoclast.