Injection of (Un)loaded Hydrogels and Microspheres in Intervertebral Discs of Laboratory Beagle Dogs

Introduction
Elevated pGE2 levels have been described in degenerated intervertebral discs (iVDs) and are associated with negative effects on iVD matrix metabolism1.the objective of this pilot study was to assess the effect of controlled release (Cr) of an anti-inflamma- tory drug (celecoxib, CXB) on the pGE2 content of spontaneous early stage degenerated lumbar iVDs of Beagles.

Materials and methods
A volume of 30 μl of 3 Cr systems (i.e. hydrogels and microspheres) unloaded or loaded with 7.7*10-6 CXB were randomly injected into lumbar Beagle iVDs and compared to a single injection of CXB and naCl 0.9%.

Results
Degeneration of all iVDs was confirmed by pfirrmann scores2, thompson scores and his- topathology; pfirrmann scores remained unchanged at 4 weeks follow up. there were no signs of inflammation on histology. Control iVDs had a broad range in pGE2 content (6 - 33*10-4 pg pGE2/ng Dna); pGE2 levels in the injected iVDs were inconclusive as n=3. no significant changes were observed on GaG/Dna content of the nucleus pulposus.

Conclusion
This pilot study only concentrated on the direct effects of CXB, i.e. pGE2 tissue levels. pGE2 levels and iVD matrix metabolism can be influenced by direct and indirect effects of CXB3. additional gene expression profiling and measurement of the CXB tissue con- centration enables evaluation of both effects.