Our bodies are home to tiny organisms called microbes that play a big role in health, and scientists have developed a new way to track these organisms using sound. They’ve only tested the technique in mice so far, but it could one day be used to enhance treatments for gut disease and cancer.
In mammals, the microbiome consists of an ecosystem of various bacteria and fungi that live inside our bodies. More and more, research finds that microbes affect everything from digestion to infection to birth, and one promising application is to send special microbes inside the body to deliver medicine. In a study published today in the journal Nature, scientists engineered microbes to make specific sounds when they come into contact with ultrasound. This makes it possible to easily track these microbes, which could come in handy when doctors need to figure out whether they’ve reached the right location to deliver medicine.
To use microbes to deliver medicine, you need to know exactly where these organisms are. That’s a challenge because microbes usually live deep inside our bodies, and our usual imaging techniques use light and can’t see through that much tissue. One alternative is ultrasound, which works by sending sound waves and analyzing the echoes that come back. (The echoes are different based on the density of the tissue that the sound wave goes through, and different patterns will tell you where something is.)
Some bacteria have hollow structures inside called gas vesicles. These vesicles scatter sound waves in a particular way, so they can be used with ultrasound to track where the organism is. For today’s study, scientists added gas vesicles to cells that don’t normally have them. They injected this engineered bacteria in a mouse gut and, separately, in a mouse tumor. In both cases, they were able to track with ultrasound.
Today’s study proves that this technique is possible, but also shows enormous promise that it can be used to monitor drug delivery in cancer patients, write biologists Ricard Solé and Nuria Conde-Pueyo, in an accompanying News & Views. It could help us study the mysteries of the microbiome in general, and perhaps even move beyond the body, to study ecosystems of microbes in the environment.