The Study Of Engineered Cartilage Constructed By Co-culture Of Chondrocytes And Bone Mesenchymal Stem Cells

Objective:To explore the effects of co-culture of chondrocytes and bone mesenchymal stem cells (BMSCs) on constructing engineered cartilages, and confirm the best ratio of chondrocytes to BMSCs.Methods:Chondrocytes and BMSCs were isolated from rabbit (1 month old) articulars cartilages and expanded respectively in vitro. They were mixed at six different ratios ( chondrocytes to BMSCs: 4:1, 2:1, 1:1, 1:2, 1:4, and chondrocytes alone ) after the first passage, and co-cultured for another passage. The mixed cells (40μl, 4×107/ml ) were seeded into a polyglycolic acid/polylactic acid (PLGA) scaffold ( 4mm×4mm×2mm ) and cultured statically for 2 days. They were transferred into the cyclic pressures system, and cultured under cyclic pressures ( pressure: 0～200kPa, frequency: 0.1Hz, time: 8h/d ) for 3 weeks. The engineered cartilages were harvested and examined by gross observation, histological staining, immunohistochemisty of collagenⅡ, the content of GAG, DNA and the percentage of collagenⅡdyeing area.Results:The engineered cartilages of the co-cultured groups grew bigger than those of the chondrocytes alone group, and their surfaces were smooth and glossy. The distributions of cartilaginous extracellular matrices in the co-cultured groups were more homogenous than those of the chondrocytes alone group. Cartilage lacunas were found in the 2:1 group only. The contents of GAG, DNA and the percentages of collagenⅡdyeing area of the co-cultured groups were higher than those of the chondrocytes alone group. The contents and the percentages of the 2:1 group were the highest, and the differences were statistically significant (P<0.05).Conclusions:Co-culture of chondrocytes and BMSCs can improve the quality of engineered cartilages, and 2:1 ratio for rabbit chondrocytes and rabbit BMSCs is of the best co-cultured effect.