Upregulation of CD44 expression in the spinal cords of rats with clip compression injury.

The expression of the extracellular matrix phosphoglycoprotein CD44 after compression injury of the spinal cord was examined in rats. Western blot analysis of tissues harvested on days 0 (sham), 1, 4 and 7 post-injury showed significant increases in CD44 expression from 1 to 7 days after compression injury compared to sham-operated controls. Immunohistochemistry revealed that CD44 was constitutively expressed in some astrocytes in sham-operated controls. At days 4-7 post-injury, CD44 was intensely expressed in astrocytes in the periphery of lesions, and in myelin sheaths, vessels, and the majority of inflammatory cells including macrophages in core lesions. The finding that expression of CD44 was upregulated after spinal cord injury suggests that CD44 contributes to cell adhesion and glial cell attraction during the early stages after spinal cord injury, and may thus promote remodeling of injured spinal cords.