AsianScientist (Apr. 25, 2016) – Scientists in Singapore have invented a new way to deliver cancer drugs deep into tumor cells using tiny drug-coated gas bubbles. Their work, published in NPG Asia Materials, may help provide a promising alternative to chemotherapy with fewer side effects.
The main issue with chemotherapy is that current chemotherapy drugs are largely non-targeted. Drug particles flow freely in the bloodstream, damaging both healthy and cancerous cells. Typically, these drugs are flushed away quickly by organs such as the lungs and liver, limiting their effectiveness. The remaining drugs are unable to penetrate deep into the core of the tumor, leaving some surviving cancer cells—which could lead to a resurgence in tumor growth.
“For anticancer drugs to achieve their best effectiveness, they need to penetrate into the tumor efficiently in order to reach the cystoplasm of all the cancer cells that are being targeted without affecting the normal cells,” said Clinical Associate Professor Chia Sing Joo, senior consultant at Tan Tock Seng Hospital and one of the consultants for the present study.
“Currently, these can be achieved by means of a direct injection into the tumor or by administering a large dosage of anticancer drugs, which can be painful, expensive, impractical and might have various side effects.”
Instead, the researchers used magnets to pull the micro-sized gas bubbles, coated with cancer drug particles and iron oxide nanoparticles, to gather around a specific tumor. Then, ultrasound is employed to make the bubbles vibrate, directing the drug particles to the target area.
This technique was developed by a multidisciplinary team of scientists led by Assistant Professor Xu Chenjie from the School of Chemical and Biomedical Engineering and Associate Professor Claus-Dieter Ohl from the School of Physical and Mathematical Sciences at Nanyang Technological University.
“The first unique characteristic of our microbubbles is that they are magnetic. After injecting them into the bloodstream, we are able to gather them around the tumour using magnets and ensure that they don’t kill the healthy cells,” Xu said.
“More importantly, our invention allows drug particles to be directed deep into a tumor in a few milliseconds. They can penetrate a depth of 50 cell layers or more, which is about 200 micrometers—twice the width of a human hair. This helps to ensure that the drugs can reach the cancer cells on the surface and also inside the core of the tumor.”
Chia added that if the research team’s technology proves to be viable, clinicians might be able to localize and concentrate the anticancer drugs around a tumor and then introduce the drugs deep into tumor tissues in just a few seconds using a clinical ultrasound system.
“Most prototype drug delivery systems on the market face three main challenges before they can be commercially successful: they have to be non-invasive, patient-friendly and yet cost-effective,” explained Ohl.
“Using the theory of microbubbles and how their surface vibrates under ultrasound, we were able to come up with our solution that addresses these three challenges.”
Moving forward, the team will be adopting this new drug delivery system in studies on lung and liver cancer using animal models, and eventually clinical studies. They estimate that it will take another eight to ten years before it reaches human clinical trials.
The article can be found at: Gao et al. (2016) Controlled Nanoparticle Release from Stable Magnetic Microbubble Oscillations.
Source: Nanyang Technological University.
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