Fibroblast proliferation dependence on insonification of low intensity ultrasounds at different duty cycles

We designed and fabricated an ultrasound insonification system able to generate magnitudes and duty cycles of the tone bursts to drive a 1 MHz transducer. Human fibroblasts of the same passage cultured in a six-well plate were both incubated and insonified at 37°C temperature. Pilot studies were performed to explore fibroblast proliferation dependency on the ultrasound insonification time in which a 20% duty cycle of ultrasound at a 1 ms repetition period, ultrasonic intensity measured to be 7.5 mW/cm² (I_SATA), was insonified to cultured cells ranged from 1 to 10 minutes per day. It demonstrated that three minutes insonification time tends to result the highest fibroblast proliferation in which it will be saturated after the fifth cultured day. The dependency of the fibroblast proliferation on duty cycle was carried out using different insonifications ranged from 0 (control group) to 100% (continuous wave) duty cycles of the same ultrasound intensity at 7.5 mW/cm² (I_SATA) for three minutes per day.