nbsp; Gas vesicles
nbsp; Achievements
Addition of synthetic lipid microbubbles improved the responsiveness of cells to low-power ultrasound. Gas vesicle-forming proteins were expressed in mammalian cells where they improved sensitivity of cells to the ultrasound. Combination of the ectopic expression of mechanosensing bacterial channel MscS and gas vesicles-forming proteins sensitized cells to mechanical stimulation.
nbsp; Motivation
For activation of mechanoreceptors TRPC1 or MscS, a high-power ultrasound wave (900 Vpp) is required. Our aim was to improve responsiveness of cells to respond to the lower power of ultrasound as this would increase the selectivity, avoiding stimulation of endogenous channels and prevent cell damage. We decided to test gas-filled lipid microbubbles, since it has been reported that microbubbles can amplify the ultrasonic signal
Microbubbles are small gas-filled lipid vesicles which are used as contrast agents in medicine. Their size is in the range of micrometers. They work by resonating in an ultrasound beam, rapidly contracting and expanding in response to the pressure changes of the sound wave
nbsp; Results
Properties of microbubbles, such as for example rigidity, are affected by the composition of the lipid membrane and the gas core. We prepared our lipid microbubbles from a mixture of DSPC:DSPE. Before sonication we added gas perfluorohexane (as described in the Protocols section), which facilitates compression and expansion of the microbubbles upon ultrasound stimulation (3.3.1.A). A heterogeneous mixture of microbubbles in the range from 5 to 100 m in size were generated by this procedure (3.3.1.B ). Microbubbles are most effective in the size range corresponding to the resonance frequency of the ultrasound. However care has to be taken in the applied energy to prevent cavitation, that can sonoporate cell membranes.