Lentivirus‑mediated transfer of gene encoding fibroblast growth factor‑18 inhibits intervertebral disc degeneration
Sheng Lu, Chaowei Lin
Abstract
Fibroblast growth factor 18 (FGF‑18) is a well‑characterized anabolic growth factor involved in cartilage homeostasis. However, the effect of FGF‑18 on intervertebral disc (IVD) degeneration has not been investigated. The present study aimed to investigate the role of FGF‑18 in the process of rabbit IVD degeneration. <em>In vitro</em>, primary nucleus pulposus cells (NPs) were cultured and transfected with a lentivirus. Tert‑butyl hydroperoxide (TBHP) was used to induce apoptosis in NPs on the second passage, while overexpression of FGF‑18 in NPs attenuated TBHP‑induced apoptosis. A rabbit annular puncture model was generated to induce IVD degeneration in vivo. The discs were injected with an FGF‑18‑overexpression lentivirus or a negative control lentivirus. In the sham group, the discs were exposed and not punctured. Disc degeneration was evaluated using H&E staining and a histological grading system. Reverse transcription‑quantitative PCR was used to detect the expression of the extracellular matrix‑degrading enzymes matrix metalloproteinase‑3 (MMP‑3) and A disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS‑5). Nucleus pulposus apoptosis was detected via western blotting, immunohistochemical methods and TUNEL staining. Histologic examination showed that disc degeneration was attenuated after FGF‑18 overexpression treatment. At 8 weeks after surgery, the expression of MMP‑3 and ADAMTS‑5 in the annular puncture groups was higher compared with in the sham group. FGF‑18 treatment inhibited the expression of MMP‑3 and ADAMTS‑5 at the mRNA level. Western blot assays indicated that the expression level of Bax was significantly reduced in the FGF‑18 groups, and that the expression level of Bcl‑2 was significantly increased compared with those in the control group. Moreover, immunohistochemical analysis indicated that the FGF‑18 group exhibited a lower percentage of cleaved caspase 3‑positive NPs. Quantification of the TUNEL staining demonstrated that the FGF‑18 group had fewer apoptotic NPs than the control group. These findings indicated that FGF‑18 could delay IVD degeneration by inhibiting the apoptosis of NPs and the expression of matrix‑degrading enzymes.