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

Overview

• This study investigated how local anaesthetics (LAs) affect the viability of equine tendon cells (tenocytes) in vitro and assessed whether platelet rich plasma (PRP) can protect these cells from LA-induced damage.

Background

• Local anaesthetics (LAs) like lidocaine, mepivacaine, and bupivacaine are commonly used to manage pain in various clinical settings.
• Previous research has shown these LAs can be harmful to tendon tissues and cells in species such as rats, cows, dogs, and humans.
• There was no prior data on the effects of LAs on equine tenocytes, despite these drugs being used in horses mainly for intra-articular (within joints), intrasynovial (within synovial sheath), perineural (around nerves), and intrathecal (within spinal canal) injections during lameness exams or treatments.
• Platelet Rich Plasma (PRP) is known to facilitate tissue healing and can protect various cell types from injury or stress caused by drugs or adverse conditions.

Objectives

• To evaluate the cytotoxic (cell-damaging) effects of three common LAs—lidocaine, mepivacaine, and bupivacaine—on cultured equine tenocytes.
• To determine if PRP can reduce or prevent the damage caused by these LAs to the tenocytes.

Methods

• Equine tenocytes were cultured in vitro (outside the body, in lab conditions).
• Cells were exposed to different concentrations and durations of exposure to lidocaine, mepivacaine, and bupivacaine to measure dose- and time-dependent cytotoxicity.
• Experiments were performed with and without the addition of PRP in the culture medium.
• Cell viability was assessed using appropriate assays to quantify living versus dead cells.
• Microscopy and flow cytometry analyses were conducted to identify the mode of cell death, specifically apoptosis (programmed cell death) and necrosis (cell death due to injury), in the treated cells.

Key Findings

• Exposure to LAs significantly reduced the viability of equine tenocytes, and this effect was dependent on both drug concentration and exposure time.
• The presence of PRP in the culture medium effectively counteracted the cytotoxic effects of all tested LAs, maintaining higher tenocyte viability.
• Microscopy and flow cytometry showed that apoptosis and necrosis were induced by LA treatment, but these effects were both significantly reduced when PRP was included.

Implications and Conclusions

• This study highlights that LAs can be harmful to equine tendon cells, which is important because certain injection techniques (intrathecal or perineural) might inadvertently expose tendons or their cells to these drugs.
• Potential cytotoxicity may compromise tendon health or reduce the effectiveness of concurrent regenerative treatments (like PRP or stem cell therapies) if LAs are used carelessly.
• The demonstrated protective effects of PRP suggest it could be used clinically to make LA injections safer, reducing tendon cell damage during pain management protocols in horses.
• Overall, the findings provide a scientific basis for reevaluating the use of LAs in equine musculoskeletal treatments and support the therapeutic benefits of PRP in mitigating drug-induced cellular damage.