Adeno-Associated Vector mediated gene transfer of Transforming Growth Factor -beta1 to normal and osteoarthritic human chondrocytes stimulates cartilage anabolism

Abstract

The objective of the present study was to investigate whether cartilage anabolism in human primary osteoarthritic chondrocytes could be improved by adeno-associated virus (AAV) vector-mediated gene transduction of transforming growth factor TGF-beta1 (TGF-beta1). A bi-cistronic AAV-TGF-beta1-IRES-eGFP (AAV-TGF-beta1) vector was generated and used for transduction of a normal human articular chondrocyte cell line (tsT/AC62) and primary human osteoarthritic articular chondrocytes harvested from 8 patients receiving total knee joint arthroplasty. Transduction efficiency was detected by fluorescent microscopy for gene expression of enhanced green fluorescent protein (eGFP). TGF-beta1 synthesis was determined by ELISA. To assess the influence of TGF-beta1 gene therapy on chondrocyte cartilage metabolism, mRNA expressions of type II collagen, aggrecan, and matrix metalloproteinase 3 (MMP-3) were determined by quantitative real-time PCR. AAV-TGF-beta1 transduction resulted in increased synthesis of TGF-beta1 in both osteoarthritic chondrocytes and the normal articular chondrocyte cell line. The expression levels of the transduced genes were correlated to "multiplicity of infection" (MOI) and post-infectious time. In both osteoarthritic chondrocytes and the normal articular chondrocyte cell line, AAV-TGF-beta1 treatment increased mRNA expression of both type II collagen and aggrecan, but decreased MMP-3 mRNA expression. Osteoarthritic chondrocytes and the normal articular chondrocyte cell line could be transduced with equal efficiencies. In conclusion, it was demonstrated that AAV-TGF-beta1 gene transfer stimulates cartilage anabolism and decreases expression of enzymes responsible for cartilage degradation in human osteoarthritic chondrocytes. The results indicate that the AAV vector is an efficient mediator of growth factors to human articular chondrocytes, and that it might be useful in future chondrocyte gene therapy.