Treatment of cartilage defects by Low-intensity pulsed ultrasound in a sheep model.

Abstract

Aim of this study was to evaluate effects of Low-intensity pulsed ultrasound on repair of articular cartilage defects. Low-intensity pulsed ultrasound (Lipus) can induce the differentiation and activation of chondrocytes. This study was designed to evaluate the effect of Lipus on articular cartilage defects in a sheep. Eight sheep were divided in to two groups. The animals received bilateraly, articular cartilage defects 4mm in diameter and 2mm in deep on the patellar groove and experimental groups were treated with intensity 200 mW/cm2, 20min/day with low-intensity pulsed ultrasound for 2month. Then both knee joints underwent surgery for remove of formed tissue sample from defects.The samples were evaluated by Quantitative real-time polymerase chain reaction (qRT-PCR), Safranin-o staining, Immunofluorescence Staining and Morphological characterization. The best and worst sample per group according to Macroscopic and micriscopic scoring were icentified. The results showed that the operated groups with-Lipus-treatment and without-Lipus treatment had considered statistically significant. Gross photography revealed that the defects in experimental groups were filled with proliferative tissue, while in control groups, a thin layer of proliferative tissue was formed in defects. qRT-PCR results showed the expression of coll2, sox9, aggrecan and Osteocalcin in experimental groups. Intense safranin-O staining show the formation cartilage tissue in ultrasound treated group, while loose safranin-o-staining were observed at the control groups. Immunofluorescence staining showed the type 2 Collagen protein expression. We suggest that low-intensity pulsed ultrasound provide the mechanistic basis force for articular cartilage repair and effective treatment modality for improving of articular cartilage defects.