WASHINGTON, Jan. 9 (UPI) -- Researchers said Tuesday they have developed tiny nano-particles that can home in on tumors, making the cancer more visible to doctors while also clogging the tumors and hindering their growth.
Animal studies have demonstrated that the nano-particles can choke off as much as 20 percent of the tumor's blood supply, said Erkki Ruoslahti, professor of medicine at the Burnham Institute for Medical Research at the University of California in Santa Barbara.
"Having identified the principle of self-amplification, we are now optimizing the process, hoping to obtain a more complete shut-down of blood flow into the tumor to strangle it," Ruoslahti said in a report in the online edition of the Proceedings of the National Academy of Sciences.
"We are also in the process of adding a drug delivery function to the particles. These two approaches are synergistic; the more particles we bring into the tumor, the greater the obstruction of the blood flow and more of the drug is delivered into the tumor," Ruoslahti said.
"Nano systems have the potential to become the prime way drugs are delivered to cancer tumors because we can target the cancer without damaging healthy tissue," said Amanda Lowery, a researcher in nanomedicine and biomedical engineering at Rice University in Houston.
"We expect to be seeing some of these nano-particle systems being used in the clinic in a few years," she told United Press International. Approval of the particles as either a drug or a device, depending on Food and Drug Administration definitions, could occur within a decade, she suggested.
The development of the nano-particle by Ruoslahti first required bioengineers to figure out a way of protecting the nano-particles from being attacked as a foreign body by the host immune system. To do that, the particle is coated with decoy molecules.
Then, the particle was constructed of superparamagnetic amino dextran-coated iron oxide -- a substance often used to enhance the ability of magnetic resonance imaging devices to visualize soft-tissue structures in the body. In addition, Ruoslahti's team manipulated the nano-particle to fluoresce, making it even more visible.
Using a screening technique developed previously in his laboratory, the researchers identified a peptide that homed to the blood vessels inside the breast cancer tumors. The peptide was comprised of five amino acids: Cysteine-Arginine-Glutamic acid-Lysine-Alanine, abbreviated CREKA. Cancer tumors develop blood vessels in order to feed nutrients to the growing lesions. These blood vessels often have clotted blood in their linings -- unlike normal blood vessels - and the nano-particle is attracted to these sickly blood vessels and bind to that clot.
The binding action allows better visualization of the cancer and also tends to shut down blood passage in the vessel. When the nano-particle locates and binds to the site, it also creates additional binding sites for more nano-particles.
Ruoslahti said that a 20-percent shutdown of the blood supply may not be sufficient to kill or regress the cancer, but it gives researchers insight to adding further attacks on the tumor.
Rice University's Lowery told UPI, "It is likely that it is going to take several different payloads to defeat most solid tumors."
