Combination of cytomegalovirus enhancer with human cellular promoters for gene-induced chondrogenesis of human bone marrow mesenchymal stem cells

The sCMV IE enhancer/promoter system for high-level expression and efficient functional studies of target genes in mammalian cells and zebrafish

Human and simian cytomegalovirus immediate-early (IE) enhancer/promoter (hCMVp and sCMVp) are the most widely used system for high-level gene expression; however, studies on detailed comparative analyses of the promoters are scarce. Using GFP reporter gene and immunoblotting assays, we have shown that the transcriptional activity of sCMVp was two to four fold higher than those of hCMVp in human-, monkey-, mouse-originated cell lines, and zebrafish as a vertebrate animal model. Notably, HtrA1 driven by the sCMVp induced cell death at relatively high-levels in HEK293 cells, but HtrA1 driven by the hCMVp had almost no effect on cell death, as shown by more than 4-fold increase in the expression levels of HtrA1. Our data may provide a valuable tool for functional studies of target genes that are expressed at extreme low level under standard transfection conditions and for development of new gene therapeutic systems.

Ex vivo cartilage defect model for the evaluation of cartilage regeneration using mesenchymal stem cells

An ex vivo cartilage defect model for the evaluation of cartilage regeneration using mesenchymal stem cells (MSCs) was developed. Porcine chondrocytes and human MSCs were transplanted into cartilage defects created on the porcine osteochondral and chondral discs and cultivated for 3 weeks. Although the regeneration of cartilage-like tissues was observed after the transplantation of chondrocytes to defects on both of the osteochondral and chondral discs, the transplanted MSCs formed cartilage-like tissues only in the defect on the chondral disc, in which an in vivo cartilage-like structure was partly observed, and a degraded tissue was observed in the defect on the osteochondral disc. The effects of medium additives such as serum, transforming growth factor-β3 (TGF-β3), and fibroblast growth factor-2, and the transfection of TGF-β3 gene to MSCs could be clearly estimated using the cartilage defect model. In conclusion, a chondral disc with defects is useful for evaluating cartilage regeneration using MSCs.