Basic fibroblast growth factor expression in hypertrophic ligamentum flavum of lumbar spinal stenosis

Background: Lumbar spinal canal stenosis is the most common spinal disorder in elderly patients. Canal narrowing is partly the result from hyperthrophy of ligamentum flavum (LF), which mechanically compresses nerve roots. Basic fibroblast growth factor (bFGF) is a potent regulator of many cellular functions including proliferation, differentiation, wound healing, and angiogenesis.

Objective: We examined the pattern of bFGF expression in the ligamentum flavum of lumbar spinal stenosis patients.

Methods: We quantified and localized bFGF expression in LF tissues obtained during surgery from nineteen patients with lumbar spinal stenosis. bFGF expression was determined using quantitative real-time polymerase chain reaction (real-time PCR). The concentration of bFGF was analyzed by enzyme-linked immunosorbent assay.

Results: The bFGF expression was significantly higher in hypertrophic LF of spinal stenosis than that in nonpathologic LF of controls. In real-time PCR, the expression of bFGF was substantially higher in the hypertrophic LF than in controls (P<0.001). The average concentration of bFGF in the hypertrophic LF (mean, 256.7 pg/mg protein) was markedly elevated compared with that of controls (mean, 75.7 pg/mg protein) (P=0.003). There was greater bFGF expression in lumbar spinal stenosis patients as quantified by real-time PCR and enzyme-linked immunosorbent assay.

Conclusion: Our study reveals that increased bFGF expression may be associated with degenerative changes of hypertrophic LF. This suggests that bFGF may contribute to pathogenesis of lumbar spinal stenosis.