Biomedical scientists at University of Texas (UT) Southwestern Medical Center and nanotechnology researchers from UT Dallas are testing a new way to kill cancer cells selectively by using a trio of tools: antibodies, nanotubes, and light.
The researchers used monoclonal antibodies that target specific sites on lymphoma cells to coat carbon nanotubes, small cylinders of graphite carbon. “Once the carbon nanotubes have bound to the tumor cells, an external source of near-infrared light can be used to safely penetrate normal tissues and kill the tumor cells,” said Dr. Ellen Vitetta, director of the Cancer Immunobiology Center at UT Southwestern and senior author of the study. Nanotubes coated with an unrelated antibody neither bound to nor killed the tumor cells.
The team used nanotubes for several reasons. “We chose them because they are commercially available, relatively inexpensive, are the right size, and can be made biocompatible,” Dr. Vitetta said, adding that the short, single-walled nanotubes are very effective at converting near-infrared light into heat. “This does not mean that five other things would have not worked as well,” she explained, “But we had to start somewhere.”
This transmission electron microscopy image of individual biotinylated carbon nanotubes show uniform coverage of biotin after immunodetection with gold-labeled antibiotin.
Near-infrared light can penetrate human tissue up to about 1½ in.; living tissues do not strongly absorb radiation in this range.
“We have worked with targeted therapies for many years, and even when this degree of specificity can be demonstrated in a laboratory dish, there are many hurdles to translating these new therapies into clinical studies,” said Vitetta. “We’re just beginning to test this in mice, and although there is no guarantee it will work, we are optimistic.”
The use of carbon nanotubes to destroy cancer cells with heat is being explored by several research groups, but this study is the first to show that the antibody and the carbon nanotubes retained their physical properties and their functional abilities—binding to and killing only the targeted cells, even when the antibody-nanotube complex was placed in a setting designed to mimic conditions inside the human body. –BG