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Measurements of Proteoglycan and Water Content Distribution in Human Lumbar Intervertebral Discs

Iatridis, James C., PhD*; MacLean, Jeffrey J., MS*; O’Brien, Mary, BA; Stokes, Ian A. F., PhD*

doi: 10.1097/BRS.0b013e318067dd3f
Basic Science
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Study Design. Study of regional variations in composition in a sample of 9 mildly to moderately degenerated human intervertebral discs.

Objective. The aim of this study was to obtain proteoglycan distribution in human lumbar discs with high position resolution in the: 1) sagittal, 2) coronal, and 3) axial directions.

Summary of Background Data. Regional variation in disc proteoglycan content has only been reported in coronal sections in a small number of discs and with low spatial resolution in the sagittal direction, and has not been reported in the axial direction.

Methods. Each of 9 human L2–L3 or L3–L4 lumbar discs (age, 53–56 years) were dissected into 36 to 41 specimens using a rectangular cutting die, measured for water content and analyzed for glycosaminoglycan content using the dimethylmethylene blue dye binding assay.

Results. The intervertebral discs were mildly to moderately degenerated. They had glycosaminoglycan content ranging ∼40 to 600 μg/mg dry tissue, with largest values in the nucleus and lowest in the outer anulus. In general, posterior regions had greater glycosaminoglycan content than anterior regions, although values were not as high as in the nucleus. Small variations in glycosaminoglycan content in the axial direction were observed with the largest values in the center, although this variation was small compared with radial variations. Water content results followed similar trends as glycosaminoglycan content with average values ranging from ∼66% to 86%.

Conclusions. A refined map of proteoglycan content is presented with 3 important findings. First, sagittal variations were distinct from coronal variations. Second, the proteoglycan content was not uniform across the nucleus regions. Third, some specimens had localized variations in proteoglycan and water contents suggestive of focal damage and degeneration.

Refined measurements of spatial distributions of proteoglycan and water content were made on moderately degenerated human lumbar intervertebral discs. Results indicated sagittal variations were distinct from coronal variations, proteoglycan content was not uniform across the nucleus, and localized variations in proteoglycan contents of individual specimens were suggestive of focal damage.

From the *University of Vermont, Burlington, VT; and †Saint Michael’s College, Colchester, VT.

Acknowledgment date: August 24, 2006. First revision date: October 26, 2006. Second revision date: November 28, 2006. Acceptance date: November 28, 2006.

Supported by NIH Grant No. R01 AR 049370. Discs were provided by the National Disease Research Interchange.

The manuscript submitted does not contain information about medical device(s)/drug(s).

Federal funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

Address correspondence and reprint requests to James Iatridis, PhD, University of Vermont, 201 Perkins, 33 Colchester Ave, Burlington, VT 05405; E-mail: james.iatridis@uvm.edu

© 2007 Lippincott Williams & Wilkins, Inc.