Figure 2From: Expression and regulation of neurotrophic and angiogenic factors during human intervertebral disc degenerationNeuropeptide and angiogenic factor expression within native intervertebral disc tissue. Percentage expression is represented as the number of disc samples in each cohort that expressed the target gene, shown by the number above the bars. Bars represent the levels of mRNA expression seen in these samples. Expression of pain-related peptides substance P (A) and calcitonin gene-related peptide (CGRP) (B) and angiogenic factors vascular endothelial growth factor (VEGF) (C) and pleiotrophin (D) in human intervertebral discs graded histologically: grade 0 to 3, n = 8; grade 4 to 6, n = 12; grade 7 to 12, n = 20; infiltrated, n = 12. GAPDH, glyceraldehyde-3-phosphate dehydrogenase. *Statistical significance: P ≤ 0.05.Back to article page