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Ultrasound-guided nanobubbles could enhance cancer treatments
Widely available, portable, and relatively inexpensive, ultrasound is well established as a powerful imaging technique for diagnosing disease. Increasingly, though, researchers are exploring ultrasound as a therapeutic tool in the fight against cancer and other maladies.
At the University of Illinois, Bioengineering Professor Joseph Irudayaraj and his team have recently demonstrated a new nanotechnology- and ultrasound-based cancer treatment approach that could enhance existing chemotherapy and radiation regimens while reducing negative side effects for patients.
It's well known that hypoxic tumor cells, which are starved of oxygen, become resistant to conventional radiation and chemotherapy treatments. When this happens, doctors typically increase the radiation dose or concentration of chemotherapy drug, which often adversely affects the patient.
To combat this, Irudayaraj and his recently graduated student Pushpak Bhandari, along with researchers from Purdue University used a Doppler ultrasound beam to precisely guide tiny oxygen-laden nanobubbles (about 100-300 nanometers in diameter) to hypoxic regions of a bladder cancer tumor in a mouse. At the same time, the researchers were using the ultrasound to image the process and determine the penetration depth of nanobubbles inside the tumor.
By altering the power of the ultrasound beam, the researchers could control the nanobubble speed, which they were able to move at up to 40 millimeters per second. They steered the nanobubbles by altering the angle of the beam.
As a result of their experiment, the hypoxic tissue was reoxygenated and the tumor's ability to grow was significantly suppressed.
"The dose of the chemotheraphy drug, mitomycin-C, which is commonly used to treat bladder cancer, could be reduced by 50% and yet still be effective in reducing the tumor size," said Irudayaraj, a Founder Professor of Bioengineering. "Our unconventional approach provides an injectable, nanoscale delivery platform that significantly enhances the efficacy of chemotherapeutic agents by precise drug delivery and targeted re-oxygenation of hypoxic tumor regions."
The team is currently working on closely examining the ultrasound-nanobubble interaction to impart precise guidance for enhanced localization utilizing model systems that mimic tissues. They also plan to precisely tune the nanobubbles to carry appropriate therapeutic payloads and to enhance their stability.
This work was funded by the National Institutes of Health through the Purdue University Center for Cancer Research and Indiana Clinical and Translational Sciences Institute, and by a W.M. Keck Foundation grant.
The full title and authors of the paper are: “Ultrasound beam steering of oxygen nanobubbles for enhanced bladder cancer therapy,” Pushpak Bhandari, Gloriia Novikova, Craig Goergen, and Joseph Irudayaraj, Nature Scientific Reports. Irudayaraj holds appointments in the Carl Woese Institute for Genomic Biology, Beckman Institute, and Micro + Nanotechnology Lab on campus.