Carbon Micro-Spaghetti Offers Hope For Fighting Cancer
(4/29/2010) by Abram Katz
If a new Yale discovery is confirmed, the microscopic spaghetti of carbon could provide a new way to fight cancer and other diseases.
The discovery came from research done at Yale on carbon nanotubes (or CNTs). CNTs are super-light and super-strong rolled-up sheets of graphite just one atom thick. They’re used in high-end tennis rackets and bicycle frames.
Now Yale scientists have used carbon nanotubes to multiply the body’s cellular defenders—meaning a nanomaterial previously known primarily for boosting consumer products may have work in medicines, too. Until now, few researchers have consider nanotubes a biological assistant. And fears have arisen among some researchers that the nanotubes could cause health problems for people working with them in the manufacturing process, because they might have properties similar to asbestos fibers.
Nanotubes, as the name suggests, are similar to tunnels of chicken wire made out of carbon. The nanotubes used in the Yale research are a mere 1 to 2 nanometers in diameter.
A nanometer is one-billionth of a meter, or roughly 17 times smaller than the smallest virus. A hair is about 100,000 nanometers wide.
Nanotubes are stiff, until they grow to about 4 to 10 microns. A micron is still pretty small. E. Coli bacterium is about 2 microns long. As the nanotubes grow, they start to become floppy.
Tarek Fadel, a graduate student in the Yale department of biomedical engineering, led the nanotubes research at Yale, as part of work on his doctoral thesis. He said that currently, tumors can be excised through surgery, bombarded with damaging radiation, or assaulted with toxic chemicals.
Many groups of scientists have been searching for ways to boost the immune system of cancer patients so that the body can eliminate malignancies in its own way.
This “adoptive immunotherapy” is already being done, but generating sufficient T-cells takes weeks.
Fadel apparently uncovered a way to rapidly multiply defensive cells outside of the body. The new method prompts T-cell production and activation three times faster than other methods.
Once these cells are activated and begin to proliferate, they could be injected back into the patient and go about their highly selective onslaught.
Results of a successful “proof of concept” experiment were published this month in the American Chemical Society journal Langmuir.
Yale researchers showed that a specially treated spaghetti-like glob of nanotubes can stimulate a rapid increase in T-cells, a type of white blood cell that, when activated, secretes a brew of proteins that can chop up and digest unwelcome cancer cells or pathogens.
Tarek M. Fahmy, associate professor of biomedical and chemical engineering, Fadel’s mentor, and senior author of the study, said the idea was to see if antigens, or invading cells, could be stuck on the strands of nanotubes.
This is important because T-cells exposed to clusters of antigen become active, and multiply, much faster.
However, nanotubes are smooth; not much sticks to them. The solution was to treat the tangles with acids and other chemicals to create tiny tears in the nanotubes.
Antigen proteins will “stick” to these intentional defects. In fact, the nanotube blob will hold many antigen proteins because it has an absolutely enormous surface area.
If one gram of this tangled material could be spread out, it would cover 1,600 square meters, or around a quarter of an acre.
T-cells respond strongly to clusters of antigens. Using nanotube tangles, Yale researchers found that the carbon thicket spiked with antigens produced three times more T-cells than a substrate such as tiny plastic spheres.
Stimulating production of white blood cells is important because tumors tend to suppress the immune system, Fadel said.
How would the process work in a patient?
A sample of cancer cell surface proteins would be obtained and then reproduced. These targets would then be mixed into the nanotube matrix.
Some of the patient’s T-cells would be added, and within a day or two, there would be a large number of T-cells ready to find and attack the cancer.
Separating the T-cells from the nanotubes is not a complicated process. The T-cells are then injected into the patient, where they start to make cytokines, lymphokines, and other cell-killing proteins, and attracting macrophages to engulf and digest the resulting debris.
The system avoids the need to place nanotubes in the patient, eliminating the concerns of some physicians that the nanotubes could cause harm, such as embolisms.
Fahmy said the nanotubes seem to mimic the physiology of lymph nodes, where some of the body’s T-cells reside.
Other Yale scientists involved in the research are Michael Look, Peter Stafffier, Gary L. Haller, and Lisa D. Pfefferle.
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