Originally created 05/07/02

'Bad-cell bomber' could help wipe out ailments like cancer



Disease-fighting drugs that can specifically target damaged cells could be a reality in the next 10 to 20 years, thanks in part to a recent Sandia National Laboratories discovery.

Sandia scientists have confirmed that a chemical process in cells could be manipulated to create microscopic drug-delivery vehicles that drop their cargo only on diseased cells.

The discovery could create drug treatments that can more effectively fight many diseases, including cancer, leukemia and arthritis.

"Usually, when you take a drug, it exposes itself to every cell in your system," said Darryl Sasaki, a Sandia scientist. "The nice thing about this type of system is you can target only specific cells, and you can use more potent drugs. That opens up a whole new area of medicine for doctors."

In the past, scientists had theorized such a system was possible, but a recent Sandia test with a device called an Atomic Force Microscope - which can see processes at the atomic scale - was able to verify those beliefs.

Drug companies have been experimenting with delivering drugs through microscopic organisms called vesicles, which can hold drugs as they float throughout the blood system.

The companies add antibodies to the vesicles, which can be engineered to fit only into a specific type of damaged cell - holding the vesicle in place.

"You could think of a vesicle as a tiny drug bag that delivers drugs directly to the cell," Sasaki said.

The problem is, when the drug bag gets to its destination, it doesn't automatically open, Sasaki said.

"They're just hoping if the vesicle is around these cell systems long enough, it will release the drug on its own," he said. "We're hoping with our discovery we can trigger it to open when it gets to the cell."

Scientists can chemically design a vesicle to only bind with the unique properties of a diseased cell. Once the vesicle binds to the cell, its structure would change, dropping the drug in place. Once the drug interacted with the diseased cell, the chemical properties of the vesicle would return it to its original form.

"It could essentially function like an on-off switch," Sasaki said.

Studying microscopic cellular structures could also help scientists find easier pathways for drugs to travel through the body.

Various chemicals that bind with a cell's surface - like a key in a lock - can be designed to create specific surface properties on a cell. For instance, Sasaki said a chemical could be used to create a track along which a vesicle could travel to more rapidly deliver its cargo.

The body already naturally creates these tracks to deliver protein inside individual cells. But experimentation could help scientists use the natural processes to their advantage.

"We can make molecules organize in straight rows and give them the ability to bind with specific proteins," Sasaki said. "It's like generating a railroad track so you can move molecules. With different chemicals, you can use a pathway, erase it and rebuild it."

Some scientists hope to use the discovery in other ways, including the creation of molecule-sized wires or circuits from organic materials or metals.

That could create a microscopic computer smaller than the width of a human hair. Such computers would have many applications in the microsystems industry. Microsystems are tiny machines that can sense, think, move and interact with microscopic environments.