New form of ultrasound therapy selectively neutralizes cancer cells, sparing healthy cells

Illustration showing the functioning of an ultrasound therapy (different from that of the study): sonodynamic therapy. | BAI Lixin

In a new experiment to test a new method of cancer treatment using ultrasound, American doctors used focused ultrasound to destroy tumors without invasive surgery. This method aims, among other things, to remedy a major drawback of this type of treatment: the ultrasonic therapies offered to date in clinics, which are imprecise, also damage healthy cells. The newly proposed technique targets cancer cells and thus spares healthy cells.

Most forms of ultrasound therapy use high intensity beams to heat and destroy cells, or special contrast agents injected before the ultrasound, which can neutralize nearby cells. But the high heat generated can harm healthy cells (along with cancer cells), and contrast agents only work for a minority of tumors.

Recently, researchers from the California Institute of Technology and the City of Hope Beckman Research Institute (United States) have developed a low-intensity ultrasound approach that exploits the unique physical and structural properties of tumor cells, in order to target and provide them. a more selective and safer option.

By reducing the intensity and carefully adjusting the frequency to match the target cells, the research group was able to eliminate several types of cancer cells without harming healthy blood cells.

Targeted pulsed ultrasound takes advantage of the unique mechanical properties of cancer cells to destroy them while sparing healthy cells. This diagram compares the impact of high intensity ultrasound therapy (left) with the new type of therapy offered, low intensity ultrasound (right). In the latter case, healthy cells are spared. Credit: David Mittelstein

Oncotripsy, a new area of ​​research for the treatment of cancer

The scientists' findings, reported in the journal Applied Physics Letters , mark a new step in an emerging area of ​​research called oncotripsy, which distinguishes and aims to kill cancer cells based on their physical properties.

"This project shows that ultrasound can be used to target cancer cells based on their mechanical properties," said David Mittelstein, lead author of the study. "This is an exciting proof of concept for a new type of cancer therapy, which does not require that the cancer has unique molecular markers or that it be located separately from healthy cells to be targeted."

A solid mechanics laboratory at the California Institute of Technology (Caltech) first developed the theory of oncotripsy, based on the idea that cells are vulnerable to ultrasound at specific frequencies - a bit like a soprano singer breaking a wine glass by emitting a specific note (frequency).

The Caltech team discovered that at certain frequencies, low intensity ultrasound caused the breakdown of the cell skeleton of cancer cells, while healthy cells nearby were unharmed.

"Just by adjusting the stimulation frequency, we saw a dramatic difference in the response of cancer and healthy cells," said Mittelstein. "There are many aspects to study on the precise mechanism, but our results are very encouraging."

The researchers hope their work will inspire other scientists to explore oncotripsy as a potential treatment, which may someday be used in conjunction with chemotherapy, immunotherapy, radiation therapy and surgery. They are now planning to better understand what exactly is happening in a cell affected by this form of ultrasound.


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Appl. Phys. Lett. 115, 102902 (2019);

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