Nanodiamonds Show Promise As Safe Chemo Boosters For Breast And Liver Cancer

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Academic Journal
Main Category: Cancer / Oncology
Also Included In: Breast Cancer;  Liver Disease / Hepatitis
Article Date: 16 Mar 2011 - 12:00 PDT


Using nanodiamonds, tiny particles of carbon, as a drug delivery system, researchers have developed a promising approach to treating breast and liver cancer tumors that are resistant to chemotherapy.

Led by Dr Dean Ho, an associate professor of biomedical engineering at Northwestern University in Evanston, Illinois, US, the researchers used lab mice to test how effectively and safely the nanodiamonds released the cancer drugs over time.

You can read how they did this online in the 9 March issue of Science Translational Medicine.

Finding ways to make chemotherapy drugs more efficient is a continual challenge, particularly for the treatment of cancers that are resistant to chemotherapy, such as recurring breast and liver tumors.

One way to do this, is through the use of nanoparticles to deliver the drugs. One example that researchers have been looking at recently is the nanodiamond, a particle of carbon that is between 2 and 8 microns thick; about 10,000 times thinner than a human hair.

The advantage of using such tiny particles is that you can get the drug to stick to their surfaces, use them to enter cancerous cells and release the drug slowly over time, exit the cell when they are finished, then leave the body altogether.

Ho told the press that in this study, they were able to boost the efficiency of the cancer drug they tested 70 times while still maintaining safety.

"It's the best of both worlds," he said.

If you could see a nanodiamond you would understand why it has that name, it looks like a diamond, and it is not just its size that makes it useful, but also its shape.

"They're called truncated octahedrons," explained Ho.

"They're shaped like a soccer ball but the faces are more angled."

It's the faces of the nanodiamonds that allow the drugs to bind tightly to their surface and release slowly.

Ho said sustained release was an important feature because by their very nature, chemotherapy drugs are toxic.

Sustained release over time also reduces side effects of very toxic chemotherapies.

"The surface chemistry, coupled with the architecture of the surface, allows for a very sustained interaction with drugs," said Ho.

The drugs can be bound tightly to the surface with a chemical bond, or temporarily with an electrostatic bond. It is useful to have these options because some drugs can do their job without letting go of the surface, while others have to come away to be effective.

Another advantage of nanoparticles as drug delivery systems is that you can make them seek out particular molecules or tumor sites by attaching a unique chemical compound or antibody to one end.

For this study, Ho and colleagues tested the nanodiamonds as a delivery system for doxorubicin, a common chemotherapy drug that is very efficient at killing cancer cells but as Ho explained, "it is also very effective at killing everything else".

"We found that if you bind the drugs to the diamond, the efficiency is even enhanced compared to using the drug alone," he added.

The advantage of targeting liver cancer with nanodiamonds is that the liver is where the body metabolizes drugs and detoxifies blood.

"A lot of this stuff ends up at the liver anyways and it takes some time to get there, but it also takes even a little bit longer to come off the diamond," said Ho.

This is what he meant by "the best of both worlds". The nanoparticle travels through the bloodstream, gradually shedding the drug, but most of that comes off in the tumor.

An important worry with nanoparticles is the potential side effects, coming from the material the nanoparticles are made of, especially in the liver, where toxins are removed and filtered out of the body.

Ho and colleagues found that even at high dosage, the nanodiamond system does not appear to affect liver toxicity.

"We also find that it doesn't seem to cause blood toxicity, systemically. It appears to be a relatively biocompatible system," he added.

In fact, the nanodiamond delivery system appears to reduce the side effects from chemotherapy.

One of the main side effects of chemotherapy is reduction in white blood cells, the main tools of the immune system, and this is often the main reason for limiting the dose patients can have at one time, to stop them getting infections.

"One of the things we find is that when you bind the diamond to the drug, from our studies, it doesn't drop the white blood cell count, yet it still has efficacy to reduce tumor size," said Ho.

"Nanodiamond Therapeutic Delivery Agents Mediate Enhanced Chemoresistant Tumor Treatment."
Edward K. Chow, Xue-Qing Zhang, Mark Chen, Robert Lam, Erik Robinson, Houjin Huang, Daniel Schaffer, Eiji Osawa, Andrei Goga, and Dean Ho.
Sci Transl Med, 9 March 2011: Vol. 3, Issue 73, p. 73ra21
DOI: 10.1126/scitranslmed.3001713

Main source: Medill Reports Chicago.

Written by: Catharine Paddock, PhD
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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