Scientists build cell-sized robots to treat cancer

Thursday, April 29th, 2004

Margaret Munro

Scientists who dream of someday unleashing tiny computers in the body to diagnose and treat disease have produced their first minuscule prototypes.

A team of researchers at Israel‘s Weizmann Institute of Science reports in the journal Nature Wednesday that they have created biological computers that can diagnose cancer and produce drugs to combat the invasive disease. The computers have so far worked only in the test tube, but even that is seen as a major accomplishment.

“This work represents the first actual proof of the concept and the first actual demonstration of a possible real-life application for this kind of computer,” says Dr. Ehud Shapiro, head of the research team.

Shapiro and his colleagues hope to eventually create “a ‘doctor in a cell” able to operate inside a living body, spot disease and apply the necessary treatment before external symptoms even appear.”

Their computers are so tiny, several trillion can fit in a drop of water. They are not made of silicon chips but of such biologically active molecules as the DNA normally found in genes. One computer was able to identify the molecules that indicate the presence of prostate cancer and release short DNA strands designed to kill the cancer cells, according to the Nature report. In another experiment, a computer detected lung cancer.

But, Shapiro says researchers have a long way to go before such computers roam through people’s bodies.

“It may take decades before such a system operating inside the human body becomes reality,” says Shapiro, who presented the findings at a meeting of Nobel laureates in Brussels on Wednesday. “Nevertheless, only two years ago we predicted that it would take another 10 years to reach the point we have reached today.”

Dr. Kirk Schultz, a cancer specialist at B.C. Children’s Hospital in Vancouver, says such computers may sound like something out of Star Trek, but the technology is moving ahead quickly.

“That they could do this is very exciting,” says Schultz. He says miniaturized diagnostic and treatment devices that could be implanted or worn just outside the body are not far off. He envisions devices for diabetics that could monitor and manage the disease, and others to check for the molecular markers of prostate cancer and administer agents to inhibit the malignancy.

Schultz is working on a Canadian research initiative to bring such microtechnologies to the bedside and doctor’s office. He says they would be tiny but not invisible.

The Israeli scientists are operating on a much smaller nanoscale and the cancer-detecting computers are just the team’s latest creation. In 2001, they built a biomolecular computer that could do simple mathematical calculations in the test tube. Last year, they created what was dubbed the smallest biological computing device on the planet. It used DNA as its source of energy.

The scientists say the beauty of biological computers is that they should be able to function where silicon-based machines cannot — inside the body.

The computers developed for the latest experiments have “software” that is composed of DNA, while DNA-manipulating enzymes make up their “hardware.” They work by assessing concentrations of specific molecules, which are known to be over-produced or under-produced in prostate and lung cancer. The computers make a diagnosis based on the detected levels of these compounds. In response to a prostate cancer diagnosis, it initiates the controlled release of a single-stranded DNA molecule that is known to interfere with the cancer cell’s activities, causing it to self-destruct.

“Our medical computer might one day be administered as a drug and be distributed throughout the body by the bloodstream to detect disease markers autonomously and independently in every cell,” says Shapiro.

“In this way, a single cancer cell could be detected and destroyed before the tumour develops.”

© The Vancouver Sun 2004

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