Objective To construct adeno-associated virus (AAV) expression system for transforming growth factor β3 (TGFβ3) and detect its biological effect on proteoglycan synthesis of the earlier and later dedifferentiated rabbit lumbar disc nucleus pulpous (NP) cells, which was compared with that of adenovirus (AV) expression system for TGFβ1.Methods TGFβ3 gene was obtained using PCR. Its upstream contained restriction enzyme site Kpn Ⅰ, and its downstream contained restriction enzyme site Sal Ⅰ. Using the restriction enzyme sites of PCR product of TGFβ3 and the corresponding multiple cloning site (MCS) in plasmid AAV, TGFβ3 was subcloned into AAV. The recombinant plas-mid AAV-TGFβ3 was transfected into H293 cells with Lipofectamine(tm) 2000, and the expression of TGFβ3 gene was detected using immunofluorescent analysis. After AAV-TGFβ3 virus particle with infectious activity was packaged, TGFβ3 expression in NP cells was detected by immunoblotting, and its biological effect on proteoglycan synthesis was detected by antonopulos method and compared with that of AV-TGFβ, in the earlier and later dedifferentiated NP cells.Results For the earlier dedifferentiated NP cells, AAV-TGFβ slowly and stably enhanced proteoglycan synthesis, but AV-TGFβ, rapidly and transiently enhanced its synthesis. For the later dedifferentiated NP cells, AAV-TGFβ3 stably enhanced proteoglycan synthesis, but AV-TGFβ, inhibited its synthesis.Conclusion AAV expression system can mediate TGFβ3 gene to be expressed stably, and AAV-TGFβ3 can enhance proteoglycan synthesis of the earlier and later dedifferentiated NP cells.