The effects of AAV-TGFbeta(1) and AAV-TGFbeta(3) on promoting synthesis of glycosaminoglycan and collagen type II of dedifferentiated rabbit lumbar disc NP cells were studied in this work. The rabbit lumbar disc NP cells were isolated and cultured. The earlier and later dedifferentiated NP cells were established by subculture. The AAV transfection efficiency to dedifferentiated NP cells was analyzed with AAV-EGFP in vitro. After dedifferentiated NP cells were transfected by AAV-TGFbeta(1) or AAV-TGFbeta(3), their biological effects on promoting synthesis of glycosaminoglycan or collagen type II were detected and compared by the methods of (35)S incorporation or immunoblotting. The experimental results showed that AAV could transfect efficiently the earlier dedifferentiated NP cells, but its transfection rate was shown to be at a low level to the later dedifferentiated NP cells. Both AAV-TGFbeta(1) and AAV-TGFbeta(3) could promote the earlier dedifferentiated NP cells to synthesize glycosaminoglycan and collagen type II, and the effect of AAV-TGFbeta(1) was better than that of AAV-TGFbeta(3). For the later dedifferentiated NP cells, the AAV-TGFbeta(3) could promote their synthesis, but AAV-TGFbeta(1) could slightly inhibit their synthesis. Therefore, AAV-TGFbeta(1) and AAV-TGFbeta(3) could be used for the earlier dedifferentiated NP cells, and the TGFbeta(3) could be used as the objective gene for the later dedifferentiated NP cells.