Cytokine‐Mediated Responses Across Endplate Subregions in Intervertebral Disc Multi‐Tissue Explants

ABSTRACT Background The endplate (EP) is essential for maintaining intervertebral disc (IVD) homeostasis by regulating nutrient transport to the nucleus pulposus (NP). Structural or biochemical alterations in the EP can impair this function and contribute to disc degeneration and low back pain (LBP). While most studies focus on the NP and annulus fibrosus (AF), increasing evidence suggests that early EP degeneration is a key initiator of disc pathology. Aims This study combined in silico modeling with a novel ex vivo multi‐tissue culture system to investigate cytokine‐driven degeneration across the intact IVD‐vertebral interface. A previously validated signal‐transduction network model predicted that degenerative environmental conditions alone, without cytokine stimulation, are limited in inducing chondrocyte degeneration. Materials & Methods To experimentally corroborate this, intact bovine explants comprising NP, AF, cartilaginous EP, and bony EP were maintained in a composite culture system, preserving tissue interfaces, an approach not previously reported. Explants were cultured for 14 days under standard, degenerative, and cytokine‐stimulated conditions using tumor necrosis factor (TNF) or interleukin‐1‐beta (IL‐1β). Tissue responses were assessed using computed tomography, glycosaminoglycan‐to‐DNA (GAG/DNA) ratios, GAG release, histological grading, cell density, and immunohistochemistry. Results In silico predictions were supported experimentally, whereby degenerative conditions alone induced limited changes associated with degeneration, whereas cytokine exposure induced broader and more pronounced degenerative changes. Reduced proteoglycan staining in the CEP and NP/AF tissues was seen under cytokine conditions without complete structural disruption. Furthermore, staining for anabolic and catabolic markers in the CEP was altered within 14 days. Discussion & Conclusion These findings suggest that cytokine signaling is an important driver and amplifier of EP‐associated degeneration with distinct, tissue‐specific responses. The development of a multi‐tissue ex vivo culture system provides a novel platform to study degenerative mechanisms under physiologically relevant investigation of tissue interactions.