A Comparative study on MMP-2 activity and GAG concentration during subsequent stages of degenerated canine intervertebral discs.

Abstract

Since 2006 intervertebral disc degeneration is defined as: ”The process of disc degeneration is an aberrant, cell-mediated response to progressive structural failure. A degenerated disc is one with structural failure combined with accelerated or advanced signs of aging”[1]. In order to come up with a justifiable model for intervertebral disc degeneration in humans, one has to quantify changes that take place on cellular and extracellular level inside the nucleus pulposus of the intervertebral disc during subsequent stages of intervertebral disc degeneration. The different stages of degeneration are graded using the five-category grading scheme according to Thompson[2]. A total of 123 individual nuclei pulposi samples were used, obtained from 13 randomly selected dogs older than one year of age, none of the 13 dogs was euthanized for reasons related to intervertebral disc degeneration. For the quantification of the sulphated glycosaminoglycan content in the tissue samples, the Farndale (Dimethylmethylene Blue) assay was used. Two groups can be identified based on the GAG content. In Group A al samples that came from intervertebral discs with either a I or II on the Thompson scale are combined, whereas in group B holds all the samples that were graded III, IV or V. The Farndale assay showed that GAG concentration is significantly higher in group A when compared to in group B. For MMP-2 concentration a gelatin zymogram was used. For the MMP-2 activity there is a rise in activity for each step upwards on the Thompson scale, until samples that were graded with a III on the Thompson scale. The MMP-2 activity in samples originating from discs with a grade IV is significantly lower than those originating from discs with grade III.