Bone marrow mesenchymal stem cells combined with calcium alginate gel modified by hTGF-β1 for the construction of tissue-engineered cartilage in three-dimensional conditions

The aim of this study was to investigate the feasibility of Ad-hTGF-β1-transfected bone marrow mesenchymal stem cells (BMMSCs) combined with calcium alginate gel for the construction of tissue-engineered cartilage under three-dimensional conditions. Rat BMMSCs were divided into three groups: the Ad-hTGF-β1 transfection group, the Ad-EGFP transfection group and the control group. The BMMSCs in the Ad-hTGF-β1 transfection group were continually grown. The compound of cell-calcium alginate gel was cultured in a constant temperature incubator. The morphology of cells was examined, and the proliferation of cells was detected by MTT assay. The results from real-time PCR showed that the average relative ratio of TGF-β1 and transcriptional coactivator with PDZ-binding motif (TAZ) in the Ad-hTGF-β1 group was comparable to that of the control group (P<0.05). Using western blotting and immunohistochemistry, strong expression of collagen II in the Ad-hTGF-β1 group was detected. The results from western blotting showed that the expression of TGF-β1 in the Ad-hTGF-β1 group was significantly increased compared with that of the other two groups. The differentiation of BMMSCs was induced by Ad-hTGF-β1 transfection into chondrocytes. TGF-β1 may promote the differentiation of BMMSCs into chondrocytes by TAZ. BMMSCs transfected by Ad-hTGF-β1 could be induced into chondrocytes. These three-dimensional conditions could preferably mimic cell growth patterns in vivo.