Ultrasound Effect on Gene Expression of Sex Determining Region Y-box 9 (SOX9) and Transforming Growth Factor β Isoforms in Adipose Stem Cells

Background Cartilage tissue engineering is a promising method for repair of cartilage defects. Induction of chondrogenesis in mesenchymal stem cells (MSC) is currently used in cartilage tissue engineering. Among growth factors, transforming growth factor β (TGF-β) is common chondrogenic inducer but toward hypertrophic chondrocyte. However, mechanical factors such as ultrasound could stimulate chondrogenesis. Objectives We aimed to investigate stimulation of endogenous TGF-β genes expression by low intensity pulsed ultrasound (LIPUS) in MSC. Materials and Methods In this experimental study, adipose tissue stem cells (ASC) cultures were treated with or without LIPUS (30 mW/cm², 20 min/day) and with or without TGF-β3 (10 ng/mL) for 4 or 14 days. Chondrogenic gene expression of SOX9 and members of TGF-β family (β1, β2 and β3) was assessed in ASC cultures at day 4 and 14 by real time PCR. Results The gene expression of SOX9 significantly increased by LIPUS and TGF-β treatment versus control cultures. Exogenous TGF-β3 treatment stimulated endogenous TGF-β1 and β2 gene expressions more than LIPUS treated cultures at day 4. LIPUS, TGF-β and LIPUS plus TGF-β treated cultures expressed same TGF-β3 gene expression at day 4. The expression of TGF-β1 and β2 decreased by LIPUS in comparison to TGF-β treated cultures at day 14. Conclusions Our results suggest that LIPUS might initiate differentiation of ASC without enhancing endogenous TGF-β genes in in-vitro.