Nanoparticles carry cancer-killing drugs into tumor cells

It strikes me as somewhat ironic that one of the first practical and profitable uses for nanotechnology will be making delivery vehicles for chemotherapeutic agents. No, not itsy-bitsy submarines, but molecules that are designed to have an affinity for cancer cells. The idea is get more chemo to cancer cells and less to normal cells. From Eureka Alert:

"This is the first study to demonstrate a nanoparticle-targeted drug
actually leaving the bloodstream, being concentrated in cancer cells,
and having a biological effect on the animal’s tumor," says James R.
Baker Jr., M.D., the Ruth Dow Doan Professor of Biologic Nanotechnology
at the University of Michigan, who directed the study.

"We’re very optimistic that nanotechnology can markedly improve cancer
therapy," says Baker, who directs the Michigan Nanotechnology Institute
for Medicine and the Biological Sciences. "Targeting drugs directly to
cancer cells reduces the amount that gets to normal cells, increases
the drug’s anti-cancer effect and reduces its toxicity. By improving
the therapeutic index of cancer drugs, we hope to turn cancer into a
chronic, manageable disease."

It turns out cancer cells need their vitamins: specifically, folic acid. So:

Folic acid, or folate, is an important vitamin required for the
healthy functioning of all cells. But cancer cells, in particular, seem
to need more than average amounts. To soak up as much folate as
possible, some cancer cells display more docking sites called folate
receptors on their cell membranes. By taking advantage of a cancer
cell’s appetite for folate, U-M scientists are able to prevent the
cells from developing resistance to chemotherapeutic drugs.

"It’s like a Trojan horse," Baker explains. "Folate molecules
on the nanoparticle bind to receptors on tumor cell membranes and the
cell immediately internalizes it, because it thinks it’s getting the
vitamin it needs. But while it’s bringing folate across the cell
membrane, the cell also draws in the methotrexate that will poison it."