To clarify b-FGF expression in different types of herniated nucleus pulposus (HNP) as angiogenesis marker, and to identify the novel vasculature in avascular nucleus pulposus.

Twenty-seven disc specimens removed surgically from patients who underwent discectomy for L4-5 HNP. The control disc specimens were obtained from five patients who underwent surgery for spine fracture or idiopathic scoliosis. According to MRI and operative findings, HNP was classified into 3 groups; protruded, extruded and sequestrated. The study involved; 7 protruded cases, 10 extruded cases and 10 sequestrated cases. Specimens were analyzed by western quantitative comparisons were performed upon the different bands. H-E stain and immunohistochemistry of CD 34 were performed to identify vessels in the avascular nucleus pulposus.

The expression of b-FGF was not significantly increased in the protruded disc (p>0.05), but was significantly increased in the extruded disc as compared with the protruded disc (p<0.05) and in the sequestrated disc in compared with the extruded disc (p<0.05). Immunohistochemical study revealed novel vasculature at the periphery of the sequestrated disc.

It is possible to confirm that sequestrated HNP is exposed to more vigorous regression via new vessel infiltration into the avascular nucleus pulposus tissue.