Abstract
Anterior cruciate ligament injury is the most common and economically costly sport injuries, frequently requiring expensive surgery and rehabilitation. Post-operative knee septic arthritis represents a serious complication with an incidence rate between 0.14% and 1.7%. A common practice to avoid septic arthritis is the “vancomycin wrap”, consisting in the soaking of the graft for 10–15 minutes within a sterile gauze swab previously saturated with 5 mg/mL vancomycin. Even though several studies have been conducted to investigate vancomycin toxicity on different musculoskeletal tissues or cells, little is known about the effect of such antimicrobial on tendon-derived cells.
The aim of this study was to determine the in vitro toxicity of different concentrations of vancomycin at different time points on human primary tenocytes (hTCs).
hTCs were isolated from hamstring grafts of patients undergoing anterior cruciate ligament reconstruction. After expansion, cells were treated with different concentrations of vancomycin (2.5, 5, 10, 25, 50 and 100 mg/mL) for 10, 15, 30 and 60 minutes. In vitro toxicity was evaluated measuring: metabolic activity through the reduction of 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT Assay); cytotoxicity (Live/Dead assay); and cell apoptosis (Annexin V apoptosis kit).
The metabolic activity of hTCs was affected by vancomycin treatment starting from 10 mg/mL at all time points (p < 0.05) and dropped down at 100 mg/mL at all time points (0.05 < p < 0.001). Cells viability resulted to be unaffected only by 2.5 mg/mL vancomycin at all time points. Vancomycin resulted to be cytotoxic starting from 10 mg/mL after 15 minutes of treatment and at all higher concentrations under study at all time points. Cells died when treated with vancomycin concentrations higher than 5 mg/mL but not through apoptosis, as confirmed by negative staining for Annexin V.
In our experimental conditions, vancomycin resulted to be toxic on hTCs at concentrations higher than 5 mg/mL. The use of this antibiotic on tendons to prevent infections could be useful and safe for resident cells if used at a concentration of 2.5 mg/mL up to 1 hour of treatment.
