Grant: Operating Grant

Current ultrasound contrast agents are limited in their applications because 1) they are confined to the microcirculation, 2) they are unstable, and 3) they have limited ability to image specific molecular targets. A new paradigm for ultrasound contrast based on naturally occurring nanoscale gas vesicles (GVs) will be investigated. These fascinating protein nano-structures provide vertical mobility for a wide range of halo- and cyanobacteria. GVs are approximately a fifth of a micron in size and with a wide range of shapes depending on species. Unlike artificial microbubbles, GVs are not pressurized and allow gases to freely exchange with the surrounding medium. This results in a very stable configuration that is ideal for high frequency ultrasound detection. In addition, GVs are genetically coded, opening up the remarkable possibility that they could act as a reporter gene analogous to green fluorescent protein. The advantage of the GV system is that the reporter could be localized at depth with ultrasound resolution whereas GFP cannot be effectively imaged beyond a depth of a few millimetres. Applications of these new contrast agents to preclinical imaging studies could answer many important questions that will guide decision making in the development of new cancer, cardiovascular and other therapies.