Monocyte chemoattractant protein-1 was investigated in an experimental rat model using immunohistochemistry.
To ascertain the precise mechanism of macrophage recruitment in the early phase of disc resorption.
In previous studies, many investigators reported that disc herniation was resorbed by monocytic phagocytosis. However, how the recruitment of monocytes was triggered is still unknown.
The autologous intervertebral discs from tails of Wistar rats were subcutaneously implanted into the abdomen. These discs were obtained on days 2, 3, 7, and 14 after implantation and were used for immunohistochemical study and for quantitative analysis of monocyte chemoattractant protein-1 by sandwich enzyme-linked immunosorbent assay.
Monocyte chemoattractant protein-1-positive granulocytes and macrophages were observed surrounding the intervertebral disc, and monocyte chemoattractant protein-1-positive disc chondrocytes were observed in the nucleus pulposus and the inner anulus fibrosus on day 3. By day 7, monocyte chemoattractant protein-1-positive and TRPM-3-positive macrophages appeared in the granulation tissue, and some of these cells invaded the nucleus pulposus and inner anulus fibrosus. The concentration of monocyte chemoattractant protein-1 was highest on day 3.
Intervertebral disc chondrocytes have chemotactic properties and play an active role in the recruitment of monocytes involved in disc resorption.
From the *Department of Orthopaedic Surgery, and †the Second Department of Pathology, Kumamoto University School of Medicine, Kumamoto, Japan.
Acknowledgment date: June 5, 1997.
First revision date: August 18, 1997.
Acceptance date: November 3, 1997.
Device status category: 1.
Address reprint requests to: Taro Kikuchi, MD; Department of Orthopaedic Surgery; Kumamoto University School of Medicine; 1-1-1 Honjo, Kumamoto, 860; Japan; E-mail: email@example.com.