Bioreactor cultivation and mechanical stimulation for regeneration of tissue-engineered cartilage / 中国组织工程研究

ABSTRACT

BACKGROUND:Cartilage tissue engineering has been widely used to achieve cartilage regeneration in vitro and repair cartilage defects. Tissue-engineered cartilage mainly consists of chondrocytes, cartilage scaffold and in vitro environment. OBJECTIVE:To mimic the environment of articular cartilage development in vivo, in order to increase the bionic features of tissue-engineered cartilage scaffold and effectiveness of cartilage repair. METHODS: Knee joint chondrocytes were isolated from New Zealand white rabbits, 2 months old, and expanded in vitro. The chondrocytes at passage 2 were seeded onto a scaffold of articular cartilage extracelular matrix in the concentration of 1×106/L to prepare cel-scaffold composites. Cel-scaffold composites were cultivated in an Instron bioreactor with mechanical compression (1 Hz, 3 hours per day, 10% compression) as experimental group for 7, 14, 24, 28 days or cultured staticaly for 1 day as control group. RESULTS AND CONCLUSION:Morphological observations demonstrated that the thickness, elastic modulus and maximum load of the composite in the experimental group were significantly higher than those in the control group, which were positively related to time (P < 0.05). Histological staining showed the proliferation of chondrocytes, formation of cartilage lacuna and synthesis of proteoglycan in the experimental group through hematoxylin-eosin staining and safranin-O staining, which were increased gradualy with mechanical stimulation time. These results were consistent with the findings of proteoglycan kit. Real-time quantitative PCR revealed that mRNA expressions of colagen type I and colagen type II were significantly higher in the experimental group than the control group (P < 0.05). The experimental group showed the highest mRNA expression of colagen type I and colagen type II at 21 and 28 days of mechanical stimulation, respectively (P < 0.05). With the mechanical stimulation of bioreactor, the cel-scaffold composite can produce more extracelular matrix, such as colagen and proteoglycan, strengthen the mechanical properties to be more coincident with thein vivo environment of cartilage development, and increase the bionic features. With the progress of tissue engineering, the clinical bioregeneration of damaged cartilage wil be achieved.