Ultrasound can help radiologists non-invasively image internal body structures, becoming a window into looking for abnormalities in the abdomen, pelvis, heart, and even muscles. Over the past few years, scientists have tapped into ultrasound technologies beyond their traditional diagnostic role to explore their applications in cancer therapy.
Tune in to learn about recent research that shows how sound waves can be leveraged to attack malignant cells, guide and boost targeted drug delivery, and power devices implanted during surgery to treat tumors.
Acoustic Drug Delivery Advances Cancer Therapy
Carolyn Schutt Ibsen, a biomedical engineer at Oregon Health and Science University, works at the intersection of bioengineering and nanomedicine. Her research involves developing ultrasound-responsive liposomes encapsulating therapeutic materials like DNA. Exposing these to ultrasound when they reach the target site triggers cargo release, which attacks the tumor. She also expanded this ultrasound approach to develop energy-responsive bioink to control where gene therapy gets delivered.
Ultrasound Powers Implanted Devices for Tumor Treatment
In 2022, Bingzhe Xu, then a biomedical engineer at Sun Yat-sen University, and colleagues designed a chip-sized wireless device that can be implanted into a tumor site during surgery. This tool, called ultrasound-powered tumor treating device, converts ultrasound radiation into electrical energy. In vitro tests using the ultrasound-activated device and patient-derived glioblastoma cells slowed cell growth significantly. The researchers also implanted the device into rats with brain tumors and observed that the tumors shrank after six days of ultrasound treatments, offering targeted therapy approaches for cancer treatment.
A wireless device implanted inside a rat brain shrank cancer cells remaining after surgery. When triggered by ultrasound, the implant produces an electrical tumor-treating field that interferes with proteins involved in cell division and triggers apoptosis in tumor cells. Healthy cells such as astrocytes, meanwhile, aren’t disrupted by the electrical frequency emitted by the device, while neurons are unaffected because they don’t divide.
© Ikumi Kayama, Studio Kayama
Microscopic Robots Deliver Drugs Against Bladder Cancer
Bladder cancer treatment involves delivering chemotherapy directly into the bladder via a catheter. Despite this localized approach, drugs do not always penetrate the tissue sufficiently, limiting treatment outcomes. To overcome this problem, Qi Zhou and his colleagues developed a biohybrid microrobot by engineering natural microalgae with a synthetic coating. The researchers used ultrasound to track the microrobots in real time and fed this information into an AI algorithm to pinpoint both the bladder tumor and moving robots. This enabled precise and targeted delivery and improved tissue penetration of chemotherapeutic drugs compared to conventional methods.
Ultrasound Beams Open Up Blood-Brain Barrier for Drug Delivery
Treating brain tumors is technically challenging because the drugs have to cross the blood-brain barrier. Over a decade ago, researchers discovered that they could use ultrasound to permeabilize the blood-brain barrier in animals. Building on this, neurosurgeon Nir Lipsman at Sunnybrook Research Institute and his colleagues found focused ultrasound enables a drug to enter brain tumors and possibly even shrink them in humans. The researchers treated four patients with a labeled anticancer monoclonal antibody before exposing them to ultrasound. Imaging revealed increased radioactivity in brain lesions of the patients after receiving ultrasound treatment, indicating that the drug got into the brain. Magnetic resonance imaging tests over the following months showed that all of the participants’ tumors shrank significantly, suggesting that ultrasound-aided drug delivery was effective.
Ultrasound Exposes Oral Cancer Tumor Core
Fluorescence microscopy revealed that ultrasound treatment reduced cancer-associated fibroblasts (magenta) cocultured with patient-derived oral cancer cells (green).
Rashmita Luha, Indian Institute of Science
Ajay Tijore, a mechanobiologist at the Indian Institute of Science, investigated whether low-frequency ultrasound could be effective against oral cancer based on previous knowledge that ultrasound waves triggered mechanical stress that killed several invasive cancer cell types. By exposing patient-derived oral cancer cells to low-frequency ultrasound, the researchers found that the cells’ distinct biomechanical properties rendered them susceptible to the sound waves. Ultrasound-exposed cancer cells showed lower migration and invasion properties compared to control cells. When they exposed patient-derived oral cancer cells cocultured with cancer-associated fibroblasts to ultrasound, this reduced the numbers of the latter cells and exposed the tumor core. These findings demonstrated that ultrasound mechano-stimulation could loosen the barrier enveloping the tumor to enhance drug permeability.
