Deep digital flexor tendon (DDFT) injuries including those accompanying degenerative changes of navicular bone are a major cause of lameness associated with navicular disease. Injection of corticosteroids into the navicular bursa are frequently administered due to the anti-inflammatory effects, but their effect on DDFT cell biosynthesis are unknown.
In osteoarthritis therapy, intra-articular corticosteroid administration reduces joint inflammation and pain; however, corticosteroids can impair cartilage metabolism, resulting in altered extracellular matrix (ECM) composition and subsequent detrimental changes to articular cartilage structure.
Researchers at Ohio State University have performed an in-vitro study to investigate the effects of the corticosteroid most commonly used, methylprednisolone acetate (MPA), on cells isolated from forelimb DDFTs (DDFT-derived cells) of 5 horses (aged 11–17 years).
Cell cultures were established and treated with medium containing 0 (control), 0.05 and 0.5 mg/mL MPA for 24 h. Tendon and cartilage extracellular matrix (ECM) related gene expression, cell aggregate and culture medium glycosaminoglycan (GAG) contents, culture medium collagen and inflammatory marker MMP-3 and−13 concentrations were measured.
After 24 h of treatment, only the higher MPA concentration (0.5 mg/mL) significantly down-regulated tendon ECM related genes; whereas, both MPA doses significantly down-regulated cartilage ECM related genes. MPA treatment did not affect the total GAG content of DDFT-derived cells or total GAG, soluble collagen and MMP-3 and−13 contents in culture medium compared to untreated controls.
The study's hypothesis that in vitro MPA treatment of DDFT-derived cells under non-inflammatory conditions would have negative effects was largely not supported by the results of this study. The low number of horses and the in vitro experimental environment used may have precluded detection of small differences. Future studies to determine the response of DDFT-derived cells with longer exposure times to corticosteroids and in the presence of inflammatory mediators is warranted.
References
Sullivan et al. Front. Vet. Sci., 05 August 2020 |Available HERE