Gene expression levels of brain-derived neurotrophic factor in cultured human annulus cells versus Thompson grades. Graphical presentation of relative gene expression levels of brain-derived neurotrophic factor (BDNF) in cultured human annulus cells versus Thompson grades. Intervertebral discs of grades II and III were pooled (n = 6) and compared with intervertebral discs of grade IV (n = 5). Relative gene expression is significantly greater in the grade IV specimens (P = 0.037). Data presented as the mean ± standard error of the mean.
Gruber et al. Arthritis Research & Therapy 2008 10:R82 doi:10.1186/ar2456