Collagen synthesis and types I, III, IV, and VI collagens in an animal model of disc degeneration.
METHODS
The present study sought to elucidate the changes that occur in collagen chemistry in the early phases of disc degeneration.


OBJECTIVE
To monitor the healing process of the injured anulus fibrosus and the secondary degenerative reactions in the nucleus pulposus.


BACKGROUND
Despite the importance of collagen chemistry under pathologic conditions in the intervertebral disc, knowledge of this aspect is very limited.


METHODS
Fourteen pigs were stabbed with a scalpel blade in the anterior part of the anulus fibrosus of a lumbar disc. The animals were killed 2 weeks to 5 months after injury. The activities of prolyl 4-hydroxylase and galactosylhydroxylysyl glucosyltransferase, the total collagen content, and staining patterns for Types I, III, IV, and VI collagens were analyzed from different parts of the disc.


RESULTS
The most active phase of the healing process, assessed from the activities of enzymes involved in collagen biosynthesis, took place during the first month postoperatively. The anular lesion was found to cicatrize through formation of disorganized granulation tissue in which Type I, III, and, IV collagens were deposited. In the nucleus pulposus, activities of prolyl 4-hydroxylase and galactosylhydroxylysyl glucosyltransferase and total collagen content increased, and the originally rounded cells became more elongated, resembling fibroblasts.


CONCLUSIONS
The results of this study suggest that the altered composition of collagens observed in the degenerate porcine nucleus pulposus results from changes in cell phenotype: Notochondral cells were replaced by fibroblast-like cells. It is likely that trauma to the anulus fibrosus can initiate a progressive degenerative process in the disc tissue.
Kääpä
E
E
Department of Physical Medicine and Rehabilitation, Oulu University, Finland.
Han
X
X
Holm
S
S
Peltonen
J
J
Takala
T
T
Vanharanta
H
H
D000818:Animals; D003094:Collagen / Q000096:biosynthesis*; D004195:Disease Models, Animal; D005260:Female; D005455:Fluorescent Antibody Technique; D005964:Glucosyltransferases / Q000378:metabolism; D007403:Intervertebral Disc / Q000201:enzymology* / Q000473:pathology; D008159:Lumbar Vertebrae / Q000201:enzymology / Q000473:pathology; D008297:Male; D011393:Procollagen-Proline Dioxygenase / Q000378:metabolism; D013122:Spinal Diseases / Q000201:enzymology* / Q000473:pathology; D013552:Swine
D003094:Collagen; D011393:Procollagen-Proline Dioxygenase; D005964:Glucosyltransferases; C023247:UDP glucose-collagen glucosyltransferase