title: Optimizing a novel method for low intensity ultrasound in chondrogenesis induction.
abstract: BACKGROUND
  Hyaline cartilage tissue of joints is susceptible to injuries due to avascularity. Mesenchymal stem cells (MSCs) are used for cartilage tissue engineering. Among MSCs, adipose stem cells (ASCs) are attractive because of accessibility, their large number, and rapid growth. Common in vitro protocols successfully induce chondrogenic differentiation by expression of multiple cartilage-specific molecules. However, transforming growth factor β (TGFβ) promotes chondrogenesis to terminal stages. Despite much attention being given to the influences of biochemical factors on chondrogenesis of MSCs, few studies have examined the chondrogenic effect of mechanical factors such as ultrasound as a feasible tool.
  
  
  METHODS
  In this study, we focused on inducing chondrogenesis in the early stages of differentiation by using low-intensity ultrasound (LIUS). Four groups of ASC pellets (control, ultrasound, TGFβ, and ultrasound/TGF) were cultured under chondrogenic (10 ng/ml of TGFβ3) and ultrasound conditions (200 mW/cm(2), 10 min/day). After 2 weeks, differentiation was evaluated by histology, quantitative gene expression analysis, and immunohistochemistry.
  
  
  RESULTS
  Our data demonstrated that ultrasound differentiated pellets showed increased expression of early chondrogenesis marker, Col2A, than those in TGFβ groups (P < 0.001), and Col2B and Col10 expression were more prominent in TGFβ groups. Immunostaining of sections showed Col2 fibrils around lacuna in LIUS and TGFβ treated groups.
  
  
  CONCLUSIONS
  Using LIUS resulted in early chondrogenesis in comparison with terminally differentiated chondrocytes by TGFβ. Therefore, LIUS might provide an applicable, safe, efficient, and cheap tool for chondrogenic differentiation of ASCs in cartilage tissue engineering.
authors: Department of Anatomical Sciences, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
authors: Hajar
authors: H
authors: Shafaei
authors: Department of Anatomical Sciences and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors: Ebrahim
authors: E
authors: Esfandiari
authors: Department of Biology, Faculty of Science, University of Isfahan, Isfahan, Iran.
authors: Abolghasem
authors: A
authors: Esmaeili
authors: Department of Anatomical Sciences and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors: Shahnaz
authors: S
authors: Razavi
authors: Department of Anatomical Sciences and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors: Batool
authors: B
authors: Hashemibeni
authors: Department of Embryology, Royan Institute, Isfahan, Iran.
authors: Mohammad Hossien
authors: MH
authors: Nasr Esfahani
authors: Department of Medical Physics, Tehran University of Medical Sciences, Tehran, Iran.
authors: Mohammad Bagher
authors: MB
authors: Shiran
authors: Department of Embryology, Royan Institute, Isfahan, Iran.
authors: Sayed Hamid Zarkesh
authors: SH
authors: Isfahani
authors: Department of Anatomical Sciences and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors: Mohammad
authors: M
authors: Mardani
keywords: Adipose stem cell; cartilage tissue engineering; chondrocyte; chondrogenesis; low intensity ultrasound