ABSTRACT
Objective To investigate the effects of vitamin D on synthesis and secretion of lubricin in chondrocytes at the cellular level. Methods Rat articular chondrocytes were stimulated by TNF-α. Normal and inflammatory chondrocytes were treated by different doses of vitamin D respectively. ELISA and Western Blot were used to detect the secretion of lubricin in the supernatant and the synthesis level in the cells. Results TNF-α significantly reduced the activity of both normal chondrocytes and chondrocytes in inflammatory state. TNF-α also significantly reduced the expression of lubricin in the cells and supernatant. 1α,25(OH)2D3 increased the activity of both normal chondrocytes and chondrocytes in inflammatory state. 1α,25(OH)2D3 significantly elevated the secretion and expression of supernatant and intracellular lubricin only in chondrocytes stimulated by TNF-α in a dose-dependent manner, but not in normal chondrocytes. Conclusions Vitamin D can promote the secretion and expression of lubricin in inflammatory state chondrocytes, which may act as one of the mechanisms of vitamin D protecting the cartilage surface in osteoarthritis.
ABSTRACT
Objective To investigate the effects of vitamin D on synthesis and secretion of lubricin in chondrocytes at the cellular level. Methods Rat articular chondrocytes were stimulated by TNF-α. Normal and inflammatory chondrocytes were treated by different doses of vitamin D respectively. ELISA and Western Blot were used to detect the secretion of lubricin in the supernatant and the synthesis level in the cells. Results TNF-α significantly reduced the activity of both normal chondrocytes and chondrocytes in inflammatory state. TNF-α also significantly reduced the expression of lubricin in the cells and supernatant. 1α,25(OH)2D3 increased the activity of both normal chondrocytes and chondrocytes in inflammatory state. 1α,25(OH)2D3 significantly elevated the secretion and expression of supernatant and intracellular lubricin only in chondrocytes stimulated by TNF-α in a dose-dependent manner, but not in normal chondrocytes. Conclusions Vitamin D can promote the secretion and expression of lubricin in inflammatory state chondrocytes, which may act as one of the mechanisms of vitamin D protecting the cartilage surface in osteoarthritis.
ABSTRACT
Objective To investigate the effect of hypoxia on the proliferation of nucleus pulposus-derived mesen-chymal stem cells ( NPMSCs) in vitro and explore its possible mechanism .Methods NPMSCs were isolated from nucleus pulposus of Sprague-Dawley rats.Cellular morphology was observed and expression of CD 11b, CD45, CD73, CD90 and CD105 was detected using flow cytometry .The third generation NPMSCs were cultured under nor-moxia (20%O2) and hypoxia (2%O2) for 14 days.Cell viability was determined by the annexin-V-FITC/propidi-um iodide doublestaining assay and cell proliferation was measured by MTT assay .The expressions of hypoxia-in-ducible factor-1α( HIF-1α) , glucose transporter 1( GLUT-1) , vascular endothelial growth factor ( VEGF) , silent information regulator protein 1( SIRT1) and silent information regulator protein 6 ( SIRT6) at the mRNA level were examined by semi-quantitative reverse transcription polymerase chain reaction ( RT-qPCR ).Results NPMSCs formed sunflower-like colony and the third passage NPMSCs became homogeneous and exhibited spindle -like mor-phology .Meanwhile , high expression level of stem cell-related positive antigen molecules and low expression levels of negative antigen molecules .Hypoxia promoted proliferation of NPMSCs and promoted gene expression of HIF-1α, GLUT-1, VEGF, SIRT1 and SIRT6 significantly(P<0.05).Conclusions Hypoxia has a significant impact on the proliferation of NPMSCs and SIRT 1, SIRT6 mediated HIF-1αpathway is potentially involved in the mechanism .