Cytotoxicity of local anaesthetics and protective effects of platelet rich plasma on equine tenocytes: An in vitro study

Local anaesthetics (LAs) can have detrimental effects on rat, bovine, canine, and human tendon tissues and cells. Currently, there has been no available data on the impact of these drugs on equine tenocytes. Even if LA injection for managing painful tendon conditions in horses is limited, it is usually used via intra-articular, intrasynovial, perineural, and intrathecal as well as for lameness examinations. In this in vitro study, the cytotoxic effects of LAs, including lidocaine, mepivacaine, and bupivacaine on equine tenocytes, in the presence and absence of platelet rich plasma (PRP), were investigated. PRP accelerates tissue healing and can exert cytoprotective effects on different cell types exposed to different stressful conditions, including drugs. Results indicated that the exposure to LAs significantly reduced tenocytes viability in dose- and time-dependent manners while PRP was able to counteract their cytotoxic effects. Furthermore, microscopy and flow cytometry analyses revealed apoptosis and necrosis in equine tenocytes exposed to these drugs, that were both reduced when PRP was in the medium. These findings highlight the importance of considering the tenocyte toxicity associated with intrathecal and intraneural LA injections, as they might affect tenocytes or reduce the efficacy of associated therapies. Moreover, this study also highlights the protective effects of PRP, which could make LA injections safer.