Sprifermin (rhFGF18) modulates extracellular matrix turnover in cartilage explants ex vivo

Abstract

BackgroundSprifermin (recombinant human fibroblast growth factor 18) is in clinical development as a potential disease-modifying osteoarthritis drug (DMOAD). In vitro studies have shown that cartilage regenerative properties of sprifermin involve chondrocyte proliferation and extracellular matrix (ECM) production. To gain further insight into the process of sprifermin in the cartilage tissue, this study aimed at investigating the ECM turnover of articular cartilage explants in a longitudinal manner.MethodsBovine full-depth articular cartilage explants were stimulated with sprifermin or placebo at weekly intervals, similar to the dosing regimen used in clinical trials. Pre-culturing with oncostatin M and tumour necrosis factor-α, was also used to induce an inflammatory state before treatment. Metabolic activity was measured using AlamarBlue, and chondrocyte proliferation was visualized by immuno-histochemical detection of proliferating cell nuclear antigen. ECM turnover was quantified by biomarker ELISAs; ProC2 reflecting type II collagen formation, CS846 reflecting aggrecan formation, active MMP9, C2M and AGNx2 reflecting matrix metalloproteinase activity, and AGNx1 reflecting aggrecanase activity.ResultsSprifermin was able to reach the chondrocytes through the extracellular matrix, as it increased cell proliferation and metabolic activity of explants. ProC2 and CS846 was dose-dependently increased (P < 0.05) by sprifermin compared to placebo, while C2M and AGNx2 were unaffected, active MMP9 was slightly decreased, and AGNx1 was slightly increased. Over the course of treatment, the temporal order of ECM turnover responses was AGNx1, then ProC2, followed by CS846 and MMP9. Pro-inflammatory activation of the explants diminished the ECM turnover responses otherwise observed under non-inflammatory conditions.ConclusionsThe data suggest that sprifermin has chondrogenic effects on articular cartilage ex vivo, exerted through a sequential process of ECM turnover; aggrecan degradation seems to occur first, while type II collagen and aggrecan production increased at a later time point. In addition, it was observed that these chondrogenic effects are dependent on the inflammatory status of the cartilage prior to treatment.Electronic supplementary materialThe online version of this article (10.1186/s12967-017-1356-8) contains supplementary material, which is available to authorized users.

Sprifermin (rhFGF18) versus vehicle induces a biphasic process of extracellular matrix remodeling in human knee OA articular cartilage ex vivo

“…In the early phase of culturing, the chondrocytes of sprifermin-treated explants seemed to exhibit a catabolic phenotype, with decreased PIIBNP release and increased NITEGE release. The NITEGE release was previously seen in bovine articular cartilage, where it was suggested to be part of a coordinated process to expand the lacunae and allow proliferation of chondrocytes 12 . In the present study, it was not possible to monitor the temporal changes in cell proliferation.…”

“…To summarize, the cartilage explants permanently stimulated with sprifermin had continuously increased metabolic activity throughout the culture period (day 0-70). Duringearly-phase culturing (day 7-28) www.nature.com/scientificreports www.nature.com/scientificreports/ the explants had increased aggrecanase-mediated aggrecandegradation (NITEGE) and decreased type II collagen formation (PIIBNP), whereas the late-phase showed increased type II collagen formation.This investigation builds on a previous study that investigate the effect on human and porcine monolayer chondrocyte cultures 11 and bovine cartilage explants 12 . In current model we use OA human cartilage which is known to be more heterogenous than that of healthy bovine cartilage cultures.…”

“…This ELISA recognizes all cleavage fragments that contain an exposed NITEGE epitope, thus including the 32 mer fragment (described by Lees et al 23 ), fragments with the G1 domain and even larger fragments with hyaluronic acid still linked to the G1 domain. The assay was performed as previously described 12 .…”

Recombinant human FGF18 preserves depth-dependent mechanical inhomogeneity in articular cartilage

“…There have been numerous attempts to preserve or promote AC phenotype during in vitro culture of living AC, with varying degrees of success. Early studies in this field, employing mechanical loading systems and supplementation of media with growth factors, have demonstrated an anabolic effect and have explicated many of the key factors that regulate AC homeostasis (Fitzgerald et al, 2004;Guilak et al, 1994;Hall et al, 1991;Hascall et al, 1983a;Luyten et al, 1988;Sah et al, 1994;Sah et al, 1989). Towards the practical application of preserving implant properties prior to OCT procedures, these media formulations have been increasingly well defined, with some making their way to clinical and commercial application (Mickevicius et al, 2015;Teng et al, 2008).…”

“…To that end, studies have recently shown that fibroblast growth factor 18 (FGF18) stimulates chondrocyte proliferation and matrix production in vitro and reduces AC degeneration and increases de novo matrix formation by osteoarthritic AC in vivo (Ellsworth et al, 2002;Moore et al, 2005). A recombinant version of this protein, known as sprifermin, currently a non-approved drug candidate and in clinical development for osteoarthritis treatment, also has positive effects in vitro, in vivo and in several recent pre-clinical and clinical trials in humans (Dahlberg et al, 2016;Lohmander et al, 2014;Mori et al, 2014;Power et al, 2014;Reker et al, 2017). Sprifermin decreases collagen type I expression in monolayer culture and decreases collagen type II expression at dosing concentrations > 100 ng/mL.…”