Acoustotaxis – in vitro stimulation in a wound healing assay employing surface acoustic waves

A novel, ultrasound based approach for the dynamic stimulation and promotion of tissue healing processes employing surface acoustic waves (SAW) on a chip is presented for the example of osteoblast-like SaOs-2 cells. In our investigations, we directly irradiate cells with SAW on a SiO2 covered piezoelectric LiNbO3 substrate. Observing the temporal evolution of cell growth and migration and comparing non-irradiated to irradiated areas on the chip, we find that the SAW-treated cells exhibit a significantly increased migration as compared to the control samples. Apart from quantifying our experimental findings on the cell migration stimulation, we also demonstrate the full bio compatibility and bio functionality of our SAW technique by using LDH assays. We safely exclude parasitic side effects such as a SAW related increased substrate temperature or nutrient flow by thoroughly monitoring the temperature and the flow field using infrared microscopy and micro particle image velocimetry. Our results show that the SAW induced dynamic mechanical and electrical stimulation obviously directly promotes the cell growth. We conclude that this stimulation method offers a powerful platform for future medical treatment, e.g. being implemented as a implantable biochip with wireless extra-corporal power supply to treat deeper tissue.