[Over-expression of platelet-derived growth factor-BB in degenerative hypertrophied ligamentum flavum].

OBJECTIVE: To investigate the role of platelet-derived growth factor-BB (PDGF-BB) in the degeneration of the hypertrophied ligamentum flavum (LF) in the lumbar spine. METHODS: Surgical specimens of degenerative hypertrophied LF were obtained from 11 patients with lumbar spinal stenosis (LSS, mean age 57.8 years), with those from 10 age-matched patients with lumbar disc herniation (LDH, mean age 53.5 years) as the normal controls. The thickness of the LF was measured preoperatively by axial T1-weighted magnetic resonance imaging (MRI) at the facet joint level. Immunohistochemistry was employed to determine the expression of PDGF ß and PDGF-BB in the LF. The mRNA and protein expressions of PDGF-BB in the LF were detected using real-time PCR and Western blotting, respectively. RESULTS: The thickness of the LF was 5.30±1.12 mm in the degenerative group and 2.80±1.53 mm in the control group, showing a significant difference between the two groups (P<0.001). PDGF-ß and PDGF-BB were positive in the fibroblasts in hypertrophied LF. The mRNA and protein expressions of PDGF-BB were significantly higher in the degenerative group than in the control group (P=0.013 and 0.023, respectively). CONCLUSION: The high expression of PDGF-BB in the hypertrophied LF suggests its important role in the development of hypertrophy of LF in lumbar spinal canal stenosis.