A team of U.S. researchers has developed nano-sized 'cargo ships' to target and destroy tumors. They say that these 'ships can sail throughout the body via the bloodstream without immediate detection from the body's immune radar system and ferry their cargo of anti-cancer drugs and markers into tumors that might otherwise go untreated or undetected.' So far, these nano-cargo-ships have only been tested on mice. But it is possible that they could be used one day to more effectively deliver toxic anti-cancer drugs to tumors. But read more...
You can see above that "the nanometer-sized cargo ships look individually like a chocolate-covered nut cluster, in which a biocompatible lipid forms the chocolate shell and magnetic nanoparticles, quantum dots and the drug doxorubicin are the nuts." (Credit for picture: Ji-Ho Park, UCSD) Here is a link to the original version of this illustration.
The team, which was composed of scientists at UC San Diego (UCSD), UC Santa Barbara and MIT, "report that their nano-cargo-ship system integrates therapeutic and diagnostic functions into a single device that avoids rapid removal by the body's natural immune system."
One of these researchers is Michael Sailor, a professor of chemistry and biochemistry at UCSD who headed the team of chemists, biologists and engineers who developed these devices. He worked with other members of his research group. Here is how he describes the concept. "The idea involves encapsulating imaging agents and drugs into a protective 'mother ship' that evades the natural processes that normally would remove these payloads if they were unprotected. These mother ships are only 50 nanometers in diameter, or 1,000 times smaller than the diameter of a human hair, and are equipped with an array of molecules on their surfaces that enable them to find and penetrate tumor cells in the body."
Another researcher involved in this project is Sangeeta Bhatia, , a physician, bioengineer and professor of Health Sciences and Technology at MIT who also is the director of the MIT's Laboratory for Multiscale Regenerative Technologies. Here are some of her own explanations. "Many drugs look promising in the laboratory, but fail in humans because they do not reach the diseased tissue in time or at concentrations high enough to be effective. These drugs don't have the capability to avoid the body's natural defenses or to discriminate their intended targets from healthy tissues. In addition, we lack the tools to detect diseases such as cancer at the earliest stages of development, when therapies can be most effective."
So how were these ships designed? "The researchers designed the hull of the ships to evade detection by constructing them of specially modified lipids--a primary component of the surface of natural cells. The lipids were modified in such a way as to enable them to circulate in the bloodstream for many hours before being eliminated. This was demonstrated by the researchers in a series of experiments with mice. The researchers also designed the material of the hull to be strong enough to prevent accidental release of its cargo while circulating through the bloodstream. Tethered to the surface of the hull is a protein called F3, a molecule that sticks to cancer cells. Prepared in the laboratory of Erkki Ruoslahti, a cell biologist and professor at the Burnham Institute for Medical Research at UC Santa Barbara, F3 was engineered to specifically home in on tumor cell surfaces and then transport itself into their nuclei.
And how were tested these devices? "The researchers loaded their ships with three payloads before injecting them in the mice. Two types of nanoparticles, superparamagnetic iron oxide and fluorescent quantum dots, were placed in the ship's cargo hold, along with the anti-cancer drug doxorubicin. The iron oxide nanoparticles allow the ships to show up in a Magnetic Resonance Imaging, or MRI, scan, while the quantum dots can be seen with another type of imaging tool, a fluorescence scanner. 'The fluorescence image provides higher resolution than MRI,' said Sailor. 'One can imagine a surgeon identifying the specific location of a tumor in the body before surgery with an MRI scan, then using fluorescence imaging to find and remove all parts of the tumor during the operation.'"
This research work has been published by the chemistry journal Angewandte Chemie International Edition under the title "Micellar Hybrid Nanoparticles for Simultaneous Magnetofluorescent Imaging and Drug Delivery" (Volume 47, Issue 38, Pages 7284-7288, Published Online on August 11, 2008). Here is a link to the references of this paper -- there is no abstract.
Finally, if you want to see how this system works, here is a link to a short video (59 seconds, 13.7 MB).
Sources: Kim McDonald, UC San Diego, September 11, 2008; and various websites
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