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Spine. 2006 Jul 1;31(15):1658-65
Disc distraction shows evidence of
regenerative potential in degenerated intervertebral discs as evaluated by
protein expression, magnetic resonance imaging, and messenger ribonucleic acid
Guehring T, Omlor GW, Lorenz H,
Engelleiter K, Richter W, Carstens C, Kroeber M. Department of Orthopaedic
Surgery, University of Heidelberg, Germany.
STUDY DESIGN: An animal model of
degeneration was used to determine the effects of disc distraction, and was
evaluated with magnetic resonance imaging (MRI) as well as gene and protein
OBJECTIVE: To investigate gene expression
and MRI effects of distraction.
SUMMARY OF BACKGROUND DATA: Disc
degeneration can result from hyper-physiologic loading. Distracted discs with
degeneration showed histologic signs of tissue recovery.
METHODS: There were 18 rabbits that
underwent 28 days of compression (200 N) to induce moderate disc degeneration
followed by 28 days of distraction (120 N; attached and loaded distraction
device) or sham distraction (attached but unloaded distraction device).
Comparison was performed with 56 days of compressed discs without distraction.
Quantitative outcome measures were MRI signal intensity and gene expression
analysis to determine: messenger ribonucleic acid levels for extracellular
matrix genes, including collagen 1, collagen 2, biglycan, decorin, aggrecan,
fibromodulin, and osteonectin; and matrix-regulative genes, including matrix
metalloproteinase-13, tissue-inhibitor of matrix metalloproteinase-1, and bone
morphogenetic protein (BMP)-2. Immunohistology was performed for collagen 2 and
BMP-2 to label cells semiquantitatively by staining of the cell-surrounding
RESULTS: A total of 28 days of compression
decreased signal intensity. Distraction over the same period reestablished
physiologic signal intensity, however, a persistent reduction was found in sham
distraction. Distraction resulted in gene expression up-regulation of collagen
1 (5.4-fold), collagen 2 (5.5-fold), biglycan (7.7-fold), and decorin
(3.4-fold), while expression of fibromodulin (0.16-fold), tissue-inhibitor of
matrix metalloproteinase-1 (0.05-fold), and BMP-2 (0.15-fold) was decreased, as
compared with 56 days compression. Distracted discs showed more BMP-2 (19.67
vs. 3.67 in 56 days compression) and collagen 2 (18.67 vs. 11.33 in 56 days
compression) positive cells per field.
CONCLUSIONS: Distraction results in disc
rehydration, stimulated extracellular matrix gene expression, and increased
numbers of protein-expressing cells.
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