Insulin-like growth factor-1 upregulates the expression of aggrecan and collagen type Ⅱ in nucleus pulposus cells via PI3K/Akt signaling pathway / 中国组织工程研究

ABSTRACT

BACKGROUND: Growth factors and other biological methods have become very popular in the repair of degenerative interevrtebral disc. Insulin-like growth factor-1 (IGF-1) can promote the proliferation of nucleus pulposus cells, and synthesis of functional extracellular matrix, but the mechanisms remain unclear.OBJECTIVE: To investigate the effect of IGF-Ⅰ on the expressions of aggrecan and collagen type Ⅱ in nucleus pulposus cells, and to explore its signal transduction mechanism.METHODS: The human nucleus pulposus cells were isolated and cultured. Passage 3 nucleus pulposus cells were induced in different concentrations of IGF-1 (0, 20, 50, 100 and 200 μg/L), respectively. The expressions of aggrecan and collagen type Ⅱ were detected by reverse transcription PCR and western blot assay. Western blot assay was adopted to observe the effect of 100 μg/L IGF-1 on the activation of PI3K/Akt signaling pathway in nucleus pulposus cells,and the expression of aggrecan and collagen type Ⅱ was detected after the inhibition of PI3K/Akt pathway by LY294002.RESULTS AND CONCLUSION: With the increase of IGF concentration, the expression levels of aggrecan and collagen type Ⅱ were increased gradually. 100 μg/L IGF-1 could significantly promote the expressions of p-PI3K and p-Akt (P <0.01), while LY294002 reversed this effcet (P < 0.01). 100 μg/L IGF-1 significantly upregulated the expression levels of aggrecan and collagen type Ⅱ in nucleus pulposus cells (P < 0.01); in contrast, LY294002 significantly downregulated the expression levels of aggrecan and collagen type Ⅱ promoted by IGF-1(P < 0.01). These results indicate that IGF-1 can promote the expression levels of aggrecan and collagen type Ⅱ in nucleus pulposus cells via the PI3K/Akt signaling pathway.