Primary bovine synoviocyte cultures: a useful tool for in vitro drug testing?

The aim of the study was to evaluate bovine synoviocyte culture as an in vitro model to test new intra-articular drugs. The inflammatory reaction pattern of synoviocytes as compared to fibroblasts was studied over nine passages. Expression of pro-inflammatory cytokines was assessed after stimulation with lipopolysaccharide. Immunohistochemical markers were used to identify synoviocyte populations. Primary synoviocytes expressed markedly higher amounts of interleukin-1beta mRNA and tumour necrosis factor-alpha mRNA than fibroblasts after stimulation. This difference was lost over two passages. CD68-positive macrophage-like synoviocytes diminished over three passages, which may explain the reduced pro-inflammatory cytokine response. Primary bovine synoviocytes appear to be an appropriate and optimised model for testing novel drugs for cattle, because their response may more closely reflect in vivo tissue responses compared to cultured cell lines.