Effect of ciprofloxacin on the proliferation of osteoblast-like MG-63 human osteosarcoma cells in vitro

Locally applied antibiotic therapy is gaining popularity for the treatment of infections associated with open fractures and posttraumatic osteomyelitis. With use of local techniques, ciprofloxacin levels as high as 1,300 μg/ml, or over 200 times the bone levels achieved with intravenous administration, have been reported. To study the possible effects of ciprofloxacin on bone, osteoblast-like cells from the MG-63 human osteosarcoma cell line were studied. The cells were grown in antibiotic-free media and exposed to concentrations of ciprofloxacin at 0, 10, 100, 200, and 1,000 μg/ml to establish an initial dose-response curve. Media containing the appropriate dose of ciprofloxacin were changed every 24 hours. Cell number and [³H]thymidine incorporation per cell were determined at 0, 24, and 72 hours. A second dose-response curve was performed at concentrations of 0, 10, 20, 40, and 80 μg/ml. Three experiments, each with four observations, were performed. The results of this study demonstrated that ciprofloxacin caused significant decreases (p<0.05) in cell number at 40 μg/ml at 24 hours and 20 μg/ml at 72 hours. [³H]thymidine incorporation per cell decreased significantly at levels of 80 μg/ml at 24 hours and 20 μg/ml at 72 hours. The authors conclude that reported local levels of ciprofloxacin seen in vivo inhibit the proliferation of human osteoblast-like cells in vitro.