A news items from Science@NASA ("Voyage of the Nano-Surgeons", by Patrick L. Barry, 15 January 2002), a news service of the U.S. National Aeronautics and Space Administration (NASA), describes work at the NASA Ames Research Center to develop "nanoparticles" and "nanocapsules" that will hunt down diseased cells and penetrate their membranes to deliver precise doses of medicines. The hope is that the tiny capsules may someday be injected into people's bloodstreams to treat conditions ranging from cancer to radiation damage.
Read more for details of the project and web links to other resources. The research, sponsored jointly by NASA and the U.S. National Cancer Institute (NCI), will focus on a problem related to cancer — the high radiation doses experienced by astronauts in space, especially on journeys to the Moon or to Mars, when spacecraft leave the protection of Earthís magnetic field. Radiation shielding on spacecraft can't fully insulate astronauts from the high-energy radiation of space. The nanoparticles also hold great potential for many fields of medicine, particularly cancer treatment. The tantalizing promise of delivering tumor-killing poisons directly to cancerous cells, thus averting the ravaging side-effects of chemotherapy, has generated a lot of interest in nanoparticles among the medical community. "The purpose of these nanoparticles is to introduce a new type of therapy — to actually go inside individual cells … and repair them, or, if there's a lot of damage, to get rid of those cells," explains James Leary of the University of Texas Medical Branch.
These drug-delivery nanocapsules are tiny — only a few hundred nanometers. A simple injection could release thousands or millions of these capsules into a person's bloodstream, and use the body's natural cellular signaling system to find radiation-damaged cells. When cells become damaged by radiation, they produce markers in a particular class of proteins called "CD-95" and place these on their outer surfaces. By implanting molecules in the outer surface of the nanoparticles that bind to these CD-95 markers, scientists can "program" the nanoparticles to seek out these radiation-damaged cells. If the radiation damage is very bad, nanoparticles can enter the damaged cells and release enzymes that initiate the cell's "auto-destruct sequence," known as apoptosis. Otherwise, they can release DNA-repair enzymes to try to fix the cell and return it to normal functioning. A similar scheme to use radioactive atoms to target cancer cells was announced in November 2001.
More on the Biomolecular Sensor Development program at the NASA Ames center is available at the project website, which is scheduled to be launched on 25 January 2002.
According to a NASA press release (21 November 2001), the research project is just one of several projects to receive grants totaling approximately US$11 million over three years to develop new biomedical technologies to detect, diagnose and treat disease inside the human body. The selected proposals will develop and study nanoscale biomedical sensors that can detect changes at the cellular and molecular level and communicate irregularities to a device outside the body. The joint NASA/NCI research initiative was announced in April 2000.