A small wireless implant could help kill deadly brain tumors

The implant, which was tested in mice, is a success.
Deniz Yildiran
3D illustration of the human brain with tumor.
3D illustration of the human brain with tumor.

Stanford University 

Researchers at Stanford Medicine developed and tested a wireless device in mice that is small enough to be inserted into a mouse's brain to kill cancerous cells. This, in the long run, could put an end to unpleasant and prolonged cancer treatments that patients with brain tumors have to undergo.

The implant in question is activated remotely and heats up nanoparticles injected into the tumor to start off the killing spree of cancer cells.

The research was published in Nature Nanotechnology in August.

The researchers treated mice with brain tumors for 15 minutes of daily treatment for over 15 days, and recorded significantly increased survival times.

"The nanoparticles help us target the treatment to only the tumor, so the side effects will be relatively less compared with chemotherapy and radiation," said Hamed Arami, Ph.D., co-lead author of the paper.

Photothermal treatments, which use light to heat up nanoparticles while fighting brain tumors, are nothing new; however, they can only be applied during surgeries while the tumor is exposed to the light source.

The late Sam Gambhir, MD, former chair of radiology at Stanford Medicine and a pioneer in molecular imaging contacted Ada Poon, Ph.D., a Stanford University associate professor of electrical engineering to come up with a new fashion that'll help fight brain tumors without baring the brain.

"When I got that email from Sam, I saw that what he wanted to do was really aligned with what our lab is focusing on, which is using electronics to treat diseases," Poon said.

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How does it work?

After a four-year hard work, researchers developed a system that can generate heat precisely at the site of tumors to defeat them. The wireless implant is implanted between the skin and the skull; then the gold nanoparticles are injected into the tumor through a tiny hole in the skull. The implant emits infrared light, which penetrates brain tissue to activate the nanoparticles that increase in temperature by up to 5 degrees Celsius. Various sizes of tumors can be killed by adjusting the power and wavelength of light.

"We think this short amount of heating, which is in the clinically acceptable range, is not affecting normal activities," Arami said.

According to the researchers, mice that received the treatment lived longer than untreated mice. The survival times doubled, even tripled on average. Combined with chemotherapy, the treatment was a success in making the mice even longer.

"Glioblastoma patients don't often live more than two to three years after diagnosis because you can't get rid of every part of the tumor, and the tumor can become drug-resistant or radiation-resistant," Arami said. "The goal is to combine this with other treatments to extend survival."

Abstract:

Current clinical brain tumour therapy practices are based on tumour resection and post-operative chemotherapy or X-ray radiation. Resection requires technically challenging open-skull surgeries that can lead to major neurological deficits and, in some cases, death. Treatments with X-ray and chemotherapy, on the other hand, cause major side-effects such as damage to surrounding normal brain tissues and other organs. Here we report the development of an integrated nanomedicine–bioelectronics brain–machine interface that enables continuous and on-demand treatment of brain tumours, without open-skull surgery and toxicological side-effects on other organs. Near-infrared surface plasmon characteristics of our gold nanostars enabled the precise treatment of deep brain tumours in freely behaving mice. Moreover, the nanostars’ surface coating enabled their selective diffusion in tumour tissues after intratumoral administration, leading to the exclusive heating of tumours for treatment. This versatile remotely controlled and wireless method allows the adjustment of nanoparticles’ photothermal strength, as well as power and wavelength of the therapeutic light, to target tumours in different anatomical locations within the brain.

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