Abstract:

BACKGROUND: Dexamethasone is a common drug for cell proliferation. However, it remains unclear whether dexamethasone can promote the proliferation of nucleus pulposus cells.
OBJECTIVE: To investigate the effects of dexamethasone on the proliferation of nucleus pulposus cells in rabbit intervertebral disk and the expression of type Ⅱ collagen secreted by nucleus pulposus cells.
METHODS: The rabbit intervertebral disk was extracted in sterile processing. After conventional separation and digestion, nucleus pulposus cells were cultured and passaged for 7 days, and then dexamethasone with the concentration of 1, 10, 100,    1 000, 10 000 nmol/L was added. After that, the nucleus pulposus cells were cultured for 1-5 days, and the absorbance values at 490 nm of the cells were detected by 3-(4, 5)-dimethylthiahiazo (-z-y1)-3, 5-di-phenytetrazoliumromide (MTT) assay every day and the growth curve was drawn. In addition, 100 nmol/L dexamethasone was selected for culture of nucleus pulposus cells, and the nucleus pulposus cells cultured with no dexamethasone was as controls.
RESULTS AND CONCLUSION: MTT assay results showed that dexamethasone had the proliferative effects on the cultured nucleus pulposus cells. The optimal action time was 48 hours and the optimal action concentration was 100 nmol/L. Reverse transcription-PCR results showed that dexamethasone could up-regulate the mRNA expression of type Ⅱ collagen which was significantly higher than that in the control group (P < 0.05). These suggest that dexamethasone can promote the proliferation of nucleus pulposus cells of rabbit intervertebral disk and up-regulate the expression of type Ⅱ collagen in rabbit nucleus pulposus cells.