Distribution of the basic fibroblast growth factor and its receptor gene expression in normal and degenerated rat intervertebral discs.

Abstract

Using a rat spondylosis model, the distributions of cells expressing the basic fibroblast growth factor and its receptor were investigated in normal and degenerated intervertebral discs. Cell-proliferating activity in degenerated discs was also assessed. This study was conducted to determine whether basic fibroblast growth factor is related to intervertebral disc degeneration. Basic fibroblast growth factor stimulates proliferation and matrix synthesis of cultured intervertebral disc cells. Immunohistochemistry and in situ hybridization histochemistry were conducted to detect cells with basic fibroblast growth factor-like immunoreactivity and fibroblast growth factor receptor messenger RNA, respectively. Cell-proliferating activity was evaluated by AgNOR staining. In degenerated discs, round chondrocytes with basic fibroblast growth factor-like immunoreactivity and fibroblast growth factor receptor messenger RNA are scattered instead of spindle-shaped cells in the normal anulus (normal anular cells), which are devoid of basic fibroblast growth factor-like immunoreactivity and fibroblast growth factor receptor messenger RNA. The proliferating activity of these chondrocytes is suggested to exceed that of normal anular cells. Basic fibroblast growth factor is suggested to promote proliferation of chondrocytes in degenerated discs in an autocrine or paracrine manner. Basic fibroblast growth factor may be related to intervertebral disc degeneration as a proliferation-stimulating factor of chondrocytes that replace normal anular cells during disc degeneration.