A Sound You Can’t Hear but May One Day Change Your Life

Undergoing clinical trials around the world is a brain surgery that doesn’t need an incision or produce any blood yet drastically improves the lives of people with essential tremor, depression and more. The procedure, known as a focused ultrasound, aims sound waves at parts of the brain to disrupt faulty brain circuits causing symptoms.

Pictured are scans of a 80-year-old patient's brain. Focused ultrasound signficantly improved the tremors.

Focused ultrasound is a noninvasive therapeutic technology,” said Dr. Neal Kassell, founder and chairman of the Focused Ultrasound Foundation. “We’ve said that focused ultrasound is the most powerful sound you will never hear, but sound that someday could save your life.

Kassell describes the way it works as “analogous to using a magnifying glass to focus beams of light on a point and burn a hole in a leaf.” “With focused ultrasound, instead of using an optical lens to focus beams of light,” he added, “an acoustic lens is used to focus multiple beams of ultrasound energy on targets deep in the body with a high degree of precision and accuracy, sparing the adjacent normal tissue.”

You must be logged in to view this content.

Ultrasound to Command Bacteria to Nuke Tumors

Scientists at Caltech have genetically engineered, sound-controlled bacteria that seek and destroy cancer cells. In a new paper appearing in the journal Nature Communications, researchers from the lab of Mikhail Shapiro, professor of chemical engineering and Howard Hughes Medical Institute investigator, show how they have developed a specialized strain of the bacteria Escherichia coli (E. coli) that seeks out and infiltrates cancerous tumors when injected into a patient’s body. Once the bacteria have arrived at their destination, they can be triggered to produce anti-cancer drugs with pulses of ultrasound.

The goal of this technology is to take advantage of the ability of engineered probiotics to infiltrate tumors, while using ultrasound to activate them to release potent drugs inside the tumor,” Shapiro says.

The starting point for their work was a strain of E. coli called Nissle 1917, which is approved for medical uses in humans. After being injected into the bloodstream, these bacteria spread throughout the body. The patient’s immune system then destroys them—except for those bacteria that have colonized cancerous tumors, which offer an immunosuppressed environment.

To turn the bacteria into a useful tool for treating cancer, the team engineered them to contain two new sets of genes. One set of genes is for producing nanobodies, which are therapeutic proteins that turn off the signals a tumor uses to prevent an anti-tumor response by the immune system. The presence of these nanobodies allow the immune system to attack the tumor. The other set of genes act like a thermal switch for turning the nanobody genes on when the bacteria reaches a specific temperature.

By inserting the temperature-dependent and nanobody genes, the team was able to create strains of bacteria that only produced the tumor-suppressing nanobodies when warmed to a trigger temperature of 42–43 degrees Celsius. Since normal human body temperature is 37 degrees Celsius, these strains do not begin producing their anti-tumor nanobodies when injected into a person. Instead, they quietly grow inside the tumors until an outside source heats them to their trigger temperature.

But how do you heat bacteria that are located in one specific location, potentially deep inside the body where a tumor is growing? For this, the team used focused ultrasound (FUS). FUS is similar to the ultrasound used for imaging internal organs, or a fetus growing in the womb, but has higher intensity and is focused into a tight point. Focusing the ultrasound on one spot causes the tissue in that location to heat up, but not the tissue surrounding it; by controlling the intensity of the ultrasound, the researchers were able to raise the temperature of that tissue to a specific degree.

Source: https://www.caltech.edu/