Ex vivo effects of corticosteroids on equine deep digital flexor and navicular fibrocartilage explant cell viability.

This study examines the impact of two types of corticosteroids, triamcinolone acetonide (TA) and methylprednisolone acetate (MPA), on the health of cells in the fibrocartilage within a horse’s deep digital flexor tendon and navicular bone. The research suggests that TA is less harmful to these cells than MPA, but also suggests further research is required to fully understand the effects of these drugs.

Methods

• The researchers used 12 to 14 explants of fibrocartilage from the deep digital flexor tendon (FC-DDFT) and the navicular bone (FC-NB) from the forelimbs of 5 horses aged 9 to 15 years. These horses didn’t show any evidence of musculoskeletal disease.
• The fibrocartilage explants were incubated in a control culture medium, or in a medium supplemented with either TA (0.6 or 6 mg/mL) or MPA (0.5 or 5 mg/mL) for 6 or 24 hours.
• At each time point, researchers assessed fibrocartilage explants for metabolic activity (using a resazurin-based assay) and for the percentage of dead cells (using live-dead cell staining).
• The effects of the drugs on the explants were assessed in comparison with the control group.

Findings

• For FC-DDFT explants, TA did not significantly affect cell viability at either concentration.
• However, for FC-NB explants, TA at a concentration of 6 mg/mL significantly reduced metabolic activity and increased the percentage of dead cells at both 6 and 24 hour time points.
• With MPA at either concentration, both FC-DDFT and FC-NB explants showed a decrease in metabolic activity and an increase in dead cells at the 24 hour time point. At the 6 hour time point, only a higher concentration of MPA (5 mg/mL) showed cytotoxic effects.

Conclusions

• Ex vivo (outside the living body) studies showed that TA was less harmful to the cells of equine FC-DDFT and FC-NB than MPA.
• The study suggests that further research is needed to understand how these drugs affect cellular transcription and translation. It is also suggested to investigate their cytotoxicity at lower concentrations.