Figure 2.

Chondrocytes secrete FGF2 to induce angiogenesis

The conditioned media (CM) of chondrocytes cultured with TNF-α, IFN-γ, or IL-17 for 7 days were collected separately and then applied to HUVECs.

(A–D) Tube-formation (A) and transwell migration (C) assays were performed on HUVECs cultured in CM. The numbers of branches (B) and migratory cells (D) were calculated and quantified using ImageJ software. Scale bar, 100 μm.

(E and F) Matrigel plugs containing chondrocyte CM, TNF-α-treated chondrocyte CM, INF-γ-treated chondrocyte CM, and IL-17-treated chondrocyte CM with or without an FGF-2-neutralizing antibody were subcutaneously injected into nude mice. The plugs were collected on day 7. Paraffin sections of Matrigel plugs were stained with H&E (E), and vessel structures containing red blood cells were quantified (F) (n = 6 mice per group). Scale bar, 100 μm.

Bars show the means ± SD. ∗p < 0.05 and ∗∗p < 0.01, 2-tailed Student's t-test.