Figure 1.

Strain-dependent vascular endothelial growth factor (VEGF) expression in C-28/I2 cells. Chondrocytes were strained in a FX-4000T system for 12 h. Using square waveforms and 0.5 Hz at 0%, 1%, 4%, 8%, 12% and 16% of strain (A and B, respectively), VEGF expression was quantified immediately (t₀) (A and C, respectively) or 24 h post stretching (B and D, respectively) using a VEGFA-specific enzyme-linked immunosorbent assay (ELISA). The experiment was repeated at 1 Hz using only 0%, 1%, 4%, and 8% of strain (C and D, respectively). All values are normalized to the unstrained, parallel controls (set to 1). *, **, and *** indicate significance levels of p ≤ 0.05, p ≤ 0.01, and p ≤ 0.001 respectively, n = 5.