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A team of researchers, including a group at the Massachusetts Institute of Technology, has developed what is called a "cocktail" of extremely tiny particles that work in concert in the bloodstream to locate, stick and kill cancerous tumors.
This study, co-authored by Sangeeta Bhatia, a physician, bioengineer and a professor of health sciences and technology at the Koch Institute for Integrative Cancer Research at MIT, is considered important because it is reportedly the first example of a two-part nanosystem that can reduce tumor volume in live animals.
In their study, the University of California, San Diego chemists, bioengineers at MIT and cell biologists at UC Santa Barbara, developed a system containing two nanomaterials a thousand times smaller than the diameter of a human hair that can be injected into the bloodstream. One nanomaterial was designed to find and adhere to tumors in mice, while the other was intended to kill the tumors.
These scientists and others had previously designed nanometer-sized devices to attach to diseased cells or deliver drugs specifically to them while ignoring healthy cells. But the functions of those devices, the researchers discovered, often worked in conflict.
"For example, a nanoparticle engineered to circulate through a cancer patient's body for a long period of time is more likely to encounter a tumor," said Bhatia.
"However, that nanoparticle may not be able to stick to tumor cells once it finds them. Likewise, a particle that is engineered to adhere tightly to tumors may not be able to circulate in the body long enough to encounter one in the first place."
The researchers pointed out that when a single drug does not work, a doctor commonly administered "a cocktail" containing several drug molecules.
The strategy can be very effective in treating cancer, where the rationale is to attack the disease on as many fronts as possible.
Drugs may sometimes work together on a single aspect of the disease, or they may attack separate functions. In either case, drug combinations can provide a greater effect than either drug alone.
Treating tumors with nanoparticles has been challenging because immune cells called mononuclear phagocytes identify them and yank them from circulation, preventing the nanomaterials from reaching their target.
"This study represents the first example of the benefits of employing a cooperative nanosystem to fight cancer," said Michael Sailor, a professor of chemistry and biochemistry at the University of California, San Diego.
The results of the study are being published in a forthcoming issue of the Proceedings of the National Academy of Sciences.
Ji-Ho Park, a graduate student in Sailor's UC San Diego laboratory, and Geoffrey von Maltzahn, a graduate student in Bhatia's MIT laboratory, headed the effort to develop the distinct nanomaterials that would work to overcome that and other obstacles.
"Think of them (the nanomaterials) like soldiers attacking an enemy base," Sailor explained.
"The gold nanorods are the special forces, who come in first to mark the target. Then the air force flies in to deliver the laser-guided bomb. The devices are designed to minimize collateral damage to the rest of the body."
Image: Physician and researcher Sangeeta Bhatia
