Design and characterization of a dynamic vibrational culture system

To engineer a functional vocal fold tissue, the mechanical environment of the native tissue needs to be emulated in vitro. We have created a dynamic culture system capable of generating vibratory stimulations at human phonation frequencies. The novel device is composed of a function generator, a power amplifier, an enclosed loudspeaker and a circumferentially-anchored silicone membrane. The vibration signals are translated to the membrane aerodynamically by the oscillating air pressure underneath. The vibration profiles detected on the membrane were symmetrical relative to the centre of the membrane as well as the resting position over the range of frequencies (60-300 Hz) and amplitudes tested (1-30 µm). The oscillatory motion of the membrane gave rise to two orthogonal, in-plane strain components that are similar in magnitude (0.47%) and are strong functions of membrane thickness. Neonatal foreskin fibroblasts (NFFs) attached to the membrane were subjected to a 1 h vibration at 60, 110 and 300 Hz, with the displacement at the centre of the membrane varying in the range 1-30 µm, followed by a 6 h rest. These regimens did not cause morphological changes to the cells. An increase in cell proliferation was detected when NFFs were driven into oscillation at 110 Hz with a normal displacement of 30 µm. qPCR results showed that the expression of genes encoding some extracellular matrix proteins was altered in response to changes in vibratory frequency and amplitude. The dynamic culture device provides a potentially useful in vitro platform for evaluating cellular responses to vibration.