Resolution of intervertebral disc (IVD) degeneration-associated inflammation is a prerequisite for tissue regeneration and could possibly be achieved by strategies ranging from pharmacological to cell-based therapies. In this study, a proinflammatory disc organ culture model was established. Bovine caudal disc punches were needle punctured and additionally stimulated with lipopolysaccharide (10 μg/mL) or interleukin-1β (IL-1β, 10-100 ng/mL) for 48 h. Two intradiscal therapeutic approaches were tested: (i) a nonsteroidal anti-inflammatory drug, diclofenac (Df) and (ii) human mesenchymal stem/stromal cells (MSCs) embedded in an albumin/hyaluronan hydrogel. IL-1β-treated disc organ cultures showed a statistically significant upregulation of proinflammatory markers (IL-6, IL-8, prostaglandin E2 [PGE2]) and metalloproteases (MMP1, MMP3) expression, while extracellular matrix (ECM) proteins (collagen II, aggrecan) were significantly downregulated. The injection of the anti-inflammatory drug, Df, was able to reduce the levels of proinflammatory cytokines and MMPs and surprisingly increase ECM protein levels. These results point the intradiscal application of anti-inflammatory drugs as promising therapeutics for disc degeneration. In parallel, the immunomodulatory role of MSCs on this model was also evaluated. Although a slight downregulation of IL-6 and IL-8 expression could be found, the variability among the five donors tested was high, suggesting that the beneficial effect of these cells on disc degeneration needs to be further evaluated. The proinflammatory/degenerative IVD organ culture model established can be considered a suitable approach for testing novel therapeutic drugs, thus reducing the number of animals in in vivo experimentation. Moreover, this model can be used to address the cellular and molecular mechanisms that regulate inflammation in the IVD and their implications in tissue degeneration.

Introduction Resolution of intervertebral disc (IVD) degeneration-associated inflammation is a pre-requisite for tissue regeneration. Here, a pro-inflammatory disc organ culture model from bovine origin was established,1 and a therapy based on the intra-discal delivery of an anti-inflammatory drug (diclofenac). Material and Methods Bovine caudal IVD punches were needle-punctured and additionally stimulated with lipopolysaccharide (10 µg/mL) or interleukin-1β (IL-1β, 10–100 ng/mL) for 48 hours. An intradiscal therapeutic approach was tested based on a non-steroidal anti-inflammatory drug, diclofenac (Df), alone or incorporated into nanoparticles, previously developed.2 Results IL-1β-treated IVD organ cultures showed a statistically significant up-regulation of pro-inflammatory markers (IL-6, IL-8, PGE2) and metalloproteases (MMP1, MMP3) expression while ECM proteins (Collagen II, Aggrecan) were significantly down-regulated. The injection of the anti-inflammatory drug was able to reduce the levels of pro-inflammatory cytokines and MMPs and surprisingly increased ECM protein levels. Conclusion These results point the intradiscal application of anti-inflammatory drugs as promising therapeutics for disc degeneration. Moreover, the organ culture model established could be used to address cellular/molecular mechanisms that regulate inflammation and IVD degeneration, and moreover to test novel therapeutic drugs, thus reducing the number of animals in in vivo experimentation. Acknowledgments This work was supported by European funds from FP7-EU-project GENODISC (HEALTH-F2–2008–201626), by German funds from the German Spine Foundation (Deutsche Wirbelsäulenstitung), by the Luso-German Integrated Actions Program (DAAD/CRUP, ref. A20/12), by FEDER funds through the Programa Operacional Factores de Competitividade – COMPETE, by Portuguese funds through QREN (project NORTE-07–0124-FEDER-000005) co-financed by North Portugal Regional Operational (ON.2-O Novo Norte). Graciosa Q. Teixeira and Catarina L. Pereira also acknowledge FCT for their PhD grants (SFRH/BD/88429/2012 and SFRH/BD/85779/2012, respectively). References Teixeira GQ, et al. Tissue Eng 2015; (Part C). Accepted for publication Gonçalves RM, et al. J Mater Sci Mater Med 2015