MONOCYTE CHEMOATTRACTANT PROTEIN-1 IN THE INTERVERTEBRAL DISC - A HISTOLOGIC EXPERIMENTAL-MODEL

Study Design. Monocyte chemoattractant protein-1 was investigated in a n experimental rat model using immunohistochemistry. Objective. To asc ertain the precise mechanism of macrophage recruitment in the early ph ase of disc resorption. Summary of Background Data. In previous studie s, many investigators reported that disc herniation was resorbed by mo nocytic phagocytosis. However, how the recruitment of monocytes was tr iggered is still unknown. Methods. The autologous intervertebral discs from tails of Wistar rats were subcutaneously implanted into the abdo men. These discs were obtained on days 2, 3, 7, and 14 after implantat ion and were used for immunohistochemical study and for quantitative a nalysis of monocyte chemoattractant protein-1 by sandwich enzyme-linke d immunosorbent assay. Results. Monocyte chemoattractant protein-1-pos itive granulocytes and macrophages were observed surrounding the inter vertebral disc, and monocyte chemoattractant protein-1-positive disc c hondrocytes were observed in the nucleus pulposus and the inner anulus fibrosus on day 3. By day 7, monocyte chemoattractant protein-1-posit ive and TRPM-3-positive macrophages appeared in the granulation tissue , and some of these cells invaded the nucleus pulposus and inner anulu s fibrosus. The concentration of monocyte chemoattractant protein-1 wa s highest on day 3. Conclusion. Intervertebral disc chondrocytes have chemotactic properties and play an active role in the recruitment of m onocytes involved in disc resorption.