The effects of REV5901 on chondrocyte viability following mechanical trauma

Eleanor Parker, Stephen J. Getting, Frank Hucklebridge, Veronica E. Vleck, Mark J.P. Kerrigan. University of Westminster, London, United Kingdom.

Mechanical trauma through repetitive, high-impact sport contributes to the onset of osteoarthritis. Hypertonicity protects chondrocytes from mechanical trauma1 suggesting a role for cell volume in this process. Since the 5-lipoxygenase inhibitor REV5901 inhibits chondrocyte volume regulation, this study was designed to investigate whether this compound exerts a chondro-protective effect following mechanical trauma.

Cartilage explants were dissected from the joints of 18-21 month old steers, weighed and added to DMEM. Explants were incubated for 1h in either: isotonic (280mOsm), hypertonic (380 mOsm), DMSO supplemented (5μl/ml) or 50μM REV 5901 DMEM and subsequently subjected to a single impact as previously described2. Chondrocyte viability was determined by confocal microscopy2 and data expressed as mean ± s.e.m; *p<0.05. n = 5 distinct experiments.

Explants in isotonic or DMSO supplemented DMEM exhibited a decrease in cell viability from 79.0 ± 0.1% and 83.0 ± 1.6% for isotonic to 45.0 ± 2.5% and 50±3.45% for DMSO supplemented following 48h post impact; *p<0.05 and *p<0.05 respectively. Conversely, when incubated with hypertonic DMEM prior to impact, there was no decrease in chondrocyte viability at 48h (89.0 ± 3.7% to 90.0 ±4.5%) when compared to controls. A pre-incubation with 50μM REV 5901 also prevented cell death following impact whereby cell viability was measured at 93±2.63% to 86±3.34% respectively. Pre-incubation with 50 μM REV 5901 resulted in a sustained decrease in cell volume (p<0.01) from 1547 ± 61 μm3 to 1011 ±19 μm3, which was not significantly different when compared to cells in hypertonic DMEM.

These data suggest that REV5901 exhibits a chondro-protective effect in an in vitro model of mechanical trauma by causing a decrease in cell volume potentially via activating a volume-regulatory pathway.

1.Bush, P., et al., Osteoarthritis and Cartilage, 2005. 13(1): p. 54-65.
2.From the University of Brighton, Winter 2008 Meeting: Proceedings of the British Pharmacological Society at http://www.pa2online.org/abstracts/Vol6Issue4abst148P.pdf.