In Vivo Administration of an Inflammatory Stimulant can Trigger Loss of Biomechanical and Biochemical Properties of the Intervertebral Disc

Human intervertebral disc (IVD) degeneration is accompanied by chronic inflammation, particularly seen in the elevated levels of pro-inflammatory cytokines IL-1β and TNF-α [1–3]. Animal models of disc degeneration (DD) using stab or laceration of the disc generally reproduce morphological changes of IVD degeneration. However, inflammatory changes in these models are thought to be acute and transient post injury [4–6]. The goal of this study is to explore the effect of direct inflammatory stimulation of the IVD on disc biochemical and biomechanical properties in vivo. We utilize lipopolysaccharide (LPS), an inflammatory stimulant that provokes secretion of multiple cytokines by disc cells. We have previously shown that direct injection of LPS into the disc results in significantly higher protein levels of IL-1β, TNF-α, HMGB-1 and MIF vs. sham injection up to 7 days post administration [7]. The goal of this study is to explore the dose-dependent response of this inflammatory stimulation on the biochemical and biomechanical properties of IVD in vivo. We hypothesize that LPS stimulation mimics the pathophysiology of DD by triggering a group of cytokines that are associated with IVD degeneration. LPS is administered using micro needles (<10% disc height) in order to minimize the potential disruption by needle injection.