Fig. 1

Upregulated HIF1α signaling in EP and AF tissues of degenerative IVD. (a) Real-time PCR analysis of HIF1A, HIF2A and HIF3A expression in degenerative lumbar EP from patients with DDD. b–e Immunohistochemical detection of HIF1A expression was performed in normal and degenerative lumbar EP and AF tissues. f–h Histological analysis of IVD samples harvested at 2 and 4 weeks post LSI (lumbar spine instability) surgery and by Safranin O/Fast green staining. The arrowheads indicate EP ossifications. IHC staining for HIF1α was performed in the IVD of wild-type mice. (i) Sham mice, (j, k) 2 weeks and 4 weeks after LSI surgery. l Quantitative analysis of the areas of HIF1α immunoreacted positive cells in LSI surgery. m–o Caudal vertebrae were harvested at 0, 1, and 3 weeks after tail-looping surgery and analyzed histologically by Safranin O/Fast green staining. p–r Immunohistochemical analysis of HIF1α⁺ cells in tail-looping surgery. The black arrow indicates AF degeneration. s Quantitative analysis of HIF1α⁺ cells. Scale bar: 100 µm (b–e), 50 µm (f–k), 100 µm (m–r). Data are expressed as the percent expression relative to controls. Values represent the mean (symbols) ± SD (error bars). *P < 0.05; **P < 0.01; ***P < 0.001.