Influence of Strontium on Vascular Endothelial Growth Factor and Fibroblast Growth Factor 2 Expression in Rat Chondrocytes Cultured In Vitro.

Strontium (Sr) can reduce cartilage degeneration and stimulate cartilage matrix formation. Angiogenesis plays a developmental role in chondrogenesis, and was stimulated by growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2). However, the direct influence of Sr on VEGF and FGF2 expressions in chondrocytes is not entirely clear. The objective of this study was to investigate the effects of different Sr concentrations on VEGF and FGF2 expressions in rat chondrocytes in vitro. Chondrocytes were isolated from Wistar rat articular by enzymatic digestion. As a Sr source, strontium chloride hexahydrate (SrCl2·6H2O) was added to the culture solution at final concentrations of 0, 0.5, 1.0, 2.0, 5.0, 20.0, and 100.0 μg/mL. After 72 h of continuous culture, mRNA abundance and protein expression levels of VEGF and FGF2 in the chondrocytes were determined by real-time polymerase chain reaction (real-time PCR) and Western blot, respectively. The results showed that VEGF and FGF2 expressions were dose-dependently elevated with Sr concentration in chondrocytes. The mRNA abundance and protein expression levels of VEGF were extremely significantly higher than those in the control group (P < 0.01) at 1.0 μg/mL Sr treatment. For FGF2, there were markedly significant differences in mRNA and protein expression from control group (P < 0.01) when the Sr-treated concentration exceeded 5.0 μg/mL and 20.0 μg/mL, respectively. These results indicated that Sr might involve in the cartilage angiogenesis via regulating expression of VEGF and FGF2z.