Preconditioning of Rabbit Mesenchymal Stem Cells in Polyglycolic Acid (PGA) Scaffold using Low-Intensity Ultrasound Improved Regeneration of Cartilage in Rabbit Articular Cartilage Defect Model.

Abstract

This study investigated the effect of low intensity ultrasound (LIUS) stimulation of mesenchymal stem cells (MSCs) in vitro on the repair of cartilage defect after implantation of the construct in vivo. Rabbit MSCs were cultured in the polyglycolic acid (PGA) scaffold and preconditioned with (MSCs/US+) or without (MSCs/US-) LIUS stimulation during the chondrogenic differentiation for 1 week in vitro. The LIUS stimulation was carried out at the intensity of 200 mW/Cm2 every day for 20 min over a week. The constructs were implanted into the cartilage defects created in the rabbit femoral trochlea. The defect only was used as a negative control and rabbit chondrocytes seeded in PGA was used as a positive control, respectively. The repair of cartilage defect was examined at 2, 4, 8 and 12 weeks after implantation, respectively. The gross observation showed that the articular cartilage defects were filled with the repaired tissue in all groups. Histological and immunohistochemical analyses revealed, however, more intensive and widespread expression of proteoglycans and type II collagen in the MSCs/US+ group than in the MSCs/US- group. Fibrous tissues were observed mainly in the defect only group. The chondrocytes groups showed efficient repair of the defect by hyaline cartilage. In conclusion, this study suggested that LIUS preconditioning of MSCs in vitro could be an effective method to promote chondrogenesis of MSCs and repair of cartilage defect in vivo.