Identification of candidate serum biomarkers for intervertebral disk degeneration in an animal model.

Abstract

OBJECTIVE: To examine serum markers of matrix turnover in an animal model of disk degeneration. DESIGN: Randomized prospective in vivo study. SETTING: Laboratory for Orthopaedic and Spine Research and Department of Large Animal Research. PARTICIPANTS: Twenty-one New Zealand White rabbits. INTERVENTION: Rabbits were randomly grouped into control (n = 8), sham surgery (n = 5), or stab surgery (n = 8). The stab surgical group underwent annulotomy of L2-3, L3-4, and L4-5 to induce intervertebral disk degeneration. The sham surgical group underwent surgical exposure without annulotomy, and the control group received no intervention. OUTCOME MEASUREMENTS: Lumbar spine magnetic resonance imaging (MRI) and serum samples were obtained before intervention and at 0, 3, 6, and 12 weeks thereafter. MRIs were analyzed for evidence of intervertebral disk degeneration via measurement of MRI index. The serum was assayed at 0, 3, 6, and 12 weeks for the aggrecan biosynthesis marker CS846 and the C-telopeptide of collagen II (CTX-II). RESULTS: The stabbed disks demonstrate degeneration apparent by MRI criteria. CTX-II increased with time in the stabbed group compared to the control and sham surgery groups regardless of baseline levels. Aggrecan showed no statistically significant difference among groups. CONCLUSIONS: CTX-II shows promise as a useful serum biomarker for intervertebral disk degeneration.