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Animal Model Used to Study Disc Degeneration in Humans

Many people suffer from disc-related back pain. How the disc is damaged and degenerates is still under study. Researchers in Sweden are using animal models to understand the chemical and biological changes that occur with disc damage and repair.

The disc is made up of two main parts. There's the outer covering called the annulus and the gel-like center called the nucleus. In this study, they damaged the discs of six pigs by poking a hole through the disc. After puncturing the discs, the pigs were returned to the lab for three months. Then the scientists looked at the effect of increasing constant loads on the healing discs.

There was a delayed response in the damaged disc when the spine was loaded and unloaded. The scientists also studied what happened to both parts of the disc. The annulus lost its water content, and the nucleus lost its gel-like structure. The nucleus became brown and discolored. Sub-units of protein called proteoglycans also shifted toward the back of the disc. Looking closely at the fibers of the disc, both parts showed a change in the way the collagen fibers were lined up.

Other changes included a loss of disc height. The border between the annulus and the nucleus disappeared. And many of the layers of the annulus were separated. Pressure within the damaged disc was much lower compared to the disc next to it.

The authors report that the changes from disc injury in a pig are much like the changes that happen in a damaged human disc. Pigs provide a useful model for understanding human disc degeneration. Some differences exist, but several changes that happen with disc damage are similar between pigs and humans.

References: Sten Holm, PhD, et al. Experimental Disc Degeneration Due to Endplate Injury. In Journal of Spinal Disorders & Techniques. February 2004. Vol. 17. No. 3. Pp. 64-71.

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