Fig. 5

Coculturing tumor necrosis factor (TNF)-α-treated nucleus pulposus mesenchymal stem cells (NPMSCs) with notochordal cell (NC)-rich nucleus pulposus (NP) explants significantly promotes proliferation. After NPMSCs were treated with different test compounds for 7 days, cell proliferation assays (resulting in optical density (OD) values) were performed. Proliferation in TNF-α-treated NPMSCs was significant decreased on days 1, 3, 5, and 7, whereas coculturing with NC-rich NP explants attenuated the inhibitory effects of TNF-α on NPMSC proliferation, with significant differences on days 5 and 7 (a). In addition, NPMSC numbers were similar but were associated with a significant decline on days 5 and 7; however, coculturing with NC-rich NP explants attenuated this trend on day 7 (b). Data are expressed as mean ± SD values (n = 4). *P < 0.05