Cooking cancer cells

Covered in antibodies and bathed in laser light, carbon nanotubes kill malignant cells with heat. The new technique may one day enable physicians to target and kill cancerous growth without surgery, radiation or chemotherapy.

After the team shone near-infrared light over a cell culture with antibody-coated carbon nanotubes attached to cancer cells, the diseased cells died, while non-cancerous cells went unharmed, researchers report online June 16 in the Proceedings of the National Academy of Sciences.

If this technique works in living tissue, “it might be possible to cook tumors rather than to surgically remove them,” says Ellen Vitetta, an immunologist at the University of Texas Southwestern in Dallas and coauthor of the new study.

Should future tests show this method is safe to use in humans, doctors could inject antibody-coated carbon nanotubes into a breast lump and then pass near-infrared light laser light over the skin. That would, in theory, kill the tumor without invasive surgery.

“This research is at a very early stage,” Vitetta says, “so moving it from a tissue culture setting to an animal and then a human is going to take time. It might or might not work. It is too early to say.”

Vitetta and her colleagues coated carbon nanotubes with leukemia-specific antibodies that seek out and bind to particular molecules on human leukemia cells. They then created lymphoma-specific antibodies and did the same in human lymphoma cells. Each antibody type fits to only one kind of cancer cell, like a key fitting only one lock, Vitetta explains.

Once the antibodies clicked into their targets, scientists passed laser light over the cell culture. Like radio antennae, the carbon nanotubes picked up the laser light’s frequency and converted the light to heat, which heated, and ultimately killed, the cancer cells.

To make sure only diseased cells felt the heat, the team conducted two control tests on healthy cells — one with a cell culture treated only with laser light and one that also included the antibody-covered nanotubes. In these trials, no cells were damaged.

“The controls are good. They serve as a rigorous test,” says Eric Wickstrom, a biochemist at ThomasJeffersonUniversity, in Philadelphia, who studies how to use nanotubes and near-infrared light to destroy breast cancer tissue but was not involved in the current study. “They answer whether a specific antibody goes to a specific cancer cell, or whether any antibody will do.”

The new study confirms Wickstrom’s team’s 2007 results, which showed breast cancer cells could be killed with a similar method that didn’t rely on specific antibodies. This team’s study shows that, using cancer-specific antibodies, researchers could one day target and kill particular types of cancer cells, Wickstrom adds.

That “proof of specificity” is the most significant aspect of this work, Vitetta says.

Current cancer treatments, such as chemotherapy and radiation, kill both diseased and healthy cells, Vitetta explains. This method could cook only diseased cells, both dividing and dormant ones. According to Vitetta, standard treatments do not kill dormant cancer cells.

These cells are not dividing at the time of treatment but can do so at a later time and cause a relapse, Vitetta says. “Antibody-carbon nanotubes would not care if a cell is dividing,” she says.