Matrikine stimulation of equine synovial fibroblasts and chondrocytes results in an in vitro osteoarthritis phenotype.

Osteoarthritis (OA) is a debilitating disease that impacts millions of individuals and has limited therapeutic options. A significant hindrance to therapeutic discovery is the lack of in vitro OA models that translate reliably to in vivo preclinical animal models. An alternative to traditional inflammatory cytokine models is the matrikine stimulation model, in which fragments of matrix proteins naturally found in OA tissues and synovial fluid, are used to stimulate cells of the joint. The objective of this study was to determine if matrikine stimulation of equine synovial fibroblasts and chondrocytes with fibronectin fragments (FN7-10) would result in an OA phenotype. We hypothesized that FN7-10 stimulation of equine articular cells would result in an OA phenotype with gene and protein expression changes similar to those previously described for human chondrocytes stimulated with FN7-10. Synovial fibroblasts and chondrocytes isolated from four horses were stimulated in monolayer culture for 6 or 18 h with 1 µM purified recombinant 42 kD FN7-10 in serum-free media. At the conclusion of stimulation, RNA was collected for targeted gene expression analysis and media for targeted protein production analysis. Consistent with our hypothesis, FN7-10 stimulation resulted in significant alterations to many important genes that are involved in OA pathogenesis including increased expression of IL-1β, IL-4, IL-6, CCL2/MCP-1, CCL5/RANTES, CXCL6/GCP-2, MMP-1, MMP-3, and MMP13. The results of this study suggest that the equine matrikine stimulation model of OA may prove useful for in vitro experiments leading up to preclinical trials.