in vitro evaluation of equine fibroblast-like synoviocytes viability treated with doxycycline

Objective- the purpose of the present study was to investigate the viability of equine fibroblast-like synoviocytes (flss) treated with doxycycline. design- experimental study. animals - flss from metacarpophalangeal joints of six skeletally mature horses. methods- flss were established from synovial fluids of healthy joints. the cells were treated with varoius concentrations (1, 5, 10, 50, 100, 150, 300, 400 μg/ml) or without doxycycline for 48-hour. viability of flss was determined using mtt assay and the trypan blue dye exclusion method. results- no significant differences were observed between viability of flss cultures treated with doxycycline until 150 μg/ml and control group (p>0.05). doxycycline at 300 and 400 μg/ml significantly decreased flss viability (p<0.05). flss viability was 74.28% and 59.07% in 300 and 400 μg/ml, respectively, when measured by the mtt assay. also flss viability at 300 and 400 μg/ml of doxycycline were 68.10% and 43.26%, respectively, with trypan blue exclusion method. conclusion and clinical relevance- these findings demonstrated that doxycycline was not toxic for equine flss at concentration ≤150 μg/ml in vitro. further studies are needed to investigate the safety, efficacy and detrimental effects of doxycycline in equine joints.