Nanoparticles deliver triple blow to tumors

Nanoparticles deliver triple blow to tumors

New chemo delivery system allows for more effective cancer treatment

Article by Hudson Lofchie

Image Courtesy UCSB Engineering

Published in The California Aggie (theaggie.org) on February 1, 2012

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The fight against cancer has been long and arduous. Researchers have made the occasional advance in treatment, but as of yet, cancer is still at large. However, a group of researchers based at UC Davis has made a major advance in cancer treatment that will dramatically augment our ability to fight cancerous tumors.

This advance is not a new drug or medication, but instead a new delivery method. Researchers created a nanoparticle, called a micelle, that holds cancer medications inside and will only release the drug once it is inside a tumor. Since the medications are only released within the tumor, doctors can administer far higher dosages of cancer drugs without having to worry about toxicity to the rest of the body.

“We [could] only give 15mg [of chemo] per kilogram of weight, otherwise the subject dies because too much [medication] goes into their system and is toxic,” said Kit Lam, professor and chair of the department of biochemistry and molecular medicine at UC Davis.

The micelles are conglomerations of smaller molecules that each have a hydrophobic (water-avoiding) and hydrophilic (water-attracted) end. The molecules are specifically designed by the researchers to have these properties and are constructed through a basic peptide chemistry process. When these small molecules are dispersed into a water-based solution, they automatically assemble into micelles. Depending on how the molecules are constructed, they can be “tuned” to respond to changes in pH (acidity).

“The micelles … are stable during blood circulation and release the [medication] quickly when triggered by the acidic micro-environment of a tumor,” said Yaunpei Li, a postdoctoral fellow in Lam’a lab, and first author of the study. “Our micelle could prevent premature drug release [into the body].”

While chemotherapy remains a very effective treatment for cancer, it is limited by its toxicity to the rest of the body. In high concentrations, it will not only kill cancer cells, but all of your healthy cells as well once it disperses throughout the body. Since these new micelles are tuned to the specific pH of a tumor, they ensure that nearly 100 percent of the drugs go directly to the tumor and not to the rest of the body.

“With this micelle, we can deliver up to three times the dosage because all of it goes directly to the tumor,” Lam said.

Micelles have been used in the past as a drug delivery system, but until now, they were relatively unstable and bore the risk of prematurely releasing the medications.

“We used cross-linking to improve over past micelles,” said Juntau Lau, an assistant professor of pharmacology at State University of New York (SUNY) Upstate Medical University and one of the authors of the study. “The new micelles better maintain their chemical structure to prevent disassociation (breaking apart).”

As of now, the micelles are only effective against solid tumors, and not against blood cancers like leukemia or lymphoma. However, the researchers were confident that with a little more work, they can make micelles that will be effective against not only blood cancers, but against many other diseases and even inflammation.

Perhaps the most important part of this advance is that since the micelles deliver most of the medication to the tumor, there is very little dispersed within your system to cause negative side effects such as nausea and hair loss.

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