Abstract
Nerve Growth Factor (NGF) is a signalling molecule for pain and inflammation. NGF is increased in synovial fluid from osteoarthritic humans and animals, compared to healthy controls. Monoclonal antibody therapy directed against NGF has been approved to treat pain in osteoarthritic dogs but despite many years of trialling, therapy has not been approved for human use. One reason for this is that adverse reactions with rapidly progressing osteoarthritis has occurred in some individuals. More detailed knowledge of NGF expression in joints is needed. In this study, capillary-based Simple Western was used to analyse NGF in cultured equine chondrocytes. Chondrocytes were collected post mortem from three macroscopically healthy intercarpal joints and three intercarpal joints with mild osteoarthritic changes. The chondrocytes were expanded to passage one and seeded in chondrogenic medium to maintain the phenotype. On day four, cells were either stimulated with LPS or kept untreated in medium. All cells were harvested on day five. Wes analysis of lysates did not show mature NGF but two proforms, 40 and 45 kDa, were identified. Results were confirmed with western blot. The same proforms were expressed in chondrocytes from healthy and osteoarthritic joints. Acute inflammation induced by LPS stimulation did not change the forms of expressed NGF. Capillary Simple Western offers a sensitive and sample-sparing alternative to traditional western blot. However, confirmation of peaks is imperative in order to avoid misinterpretation of findings. In addition, in this case the method did not offer the possibility of quantification advertised by the manufacturers.