Immunohistochemical detection of Schwann cells in innervated and vascularized human intervertebral discs.
METHODS
The ingrowth of nerves, blood vessels, and Schwann cells into human intervertebral discs was examined using immunohistochemistry for cell-type-specific markers.


OBJECTIVE
To determine whether Schwann cells may contribute to disc innervation, and to assess the relation between disc innervation and vascularization.


BACKGROUND
Intervertebral disc degeneration was associated previously with ingrowth of blood vessels and nerves. Schwann cells are known to play an important role in regulating nerve growth and survival in other tissues, but they have not been examined in human pathologic intervertebral discs.


METHODS
Serial sections of human intervertebral discs were immunostained for the neuronal markers (neurofilament 200, peripherin, protein gene product 9.5), for the Schwann cell marker (glial fibrillary acidic protein), and for the endothelial cell marker (CD34).


RESULTS
Glial fibrillary acidic protein-immunopositive cells colocalized with nerves in degenerate discs, but were absent or rarely observed in nondegenerate, aneural discs. These also were seen in the disc matrix, independently of nerves. Much of the nerve and Schwann cell ingrowth was found in vascularized areas of disc tissue, where the lamellar structure of the anulus fibrosus was disrupted. Blood vessels were observed deeper into the discs than nerves or Schwann cells.


CONCLUSIONS
The appearance of glial fibrillary acidic protein-immunopositive cells in diseased intervertebral discs was closely associated with nerve ingrowth. This novel finding suggests that Schwann cells have a role to play in regulating disc innervation and nerve function in the disc. Because blood vessels were observed furthermost into the disc, it is possible that degenerate disc vascularization occurs before innervation.
Johnson
W E
WE
J.P. O'Brien Laboratory, Centre for Spinal Studies, Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, Shropshire SY10 7AG, United Kingdom. w.e.b.johnson@keele.ac.uk
Evans
H
H
Menage
J
J
Eisenstein
S M
SM
El Haj
A
A
Roberts
S
S
D000293:Adolescent; D000328:Adult; D018952:Antigens, CD34 / Q000378:metabolism; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007403:Intervertebral Disc / Q000098:blood supply / Q000166:cytology* / Q000294:innervation; D008297:Male; D008875:Middle Aged; D016900:Neurofilament Proteins / Q000378:metabolism; D012583:Schwann Cells / Q000166:cytology* / Q000378:metabolism
D018952:Antigens, CD34; D005904:Glial Fibrillary Acidic Protein; D016900:Neurofilament Proteins; C051774:neurofilament protein H