Nanotech Trojan Horse That Kills Cancer

An anonymous reader writes "University of Michigan scientists have created the nanotechnology equivalent of a Trojan horse to smuggle a powerful chemotherapeutic drug inside tumor cells - increasing the drug's cancer-killing activity and reducing its toxic side effects." From the article: "The drug delivery vehicle used by U-M scientists is a manmade polymer molecule called a dendrimer. Less than five nanometers in diameter, these dendrimers are small enough to slip through tiny openings in cell membranes. One nanometer equals one-billionth of a meter, which means it would take 100,000 nanometers lined up side-by-side to equal the diameter of a human hair."

Comments

Nanoparticles?

[Raindance]

The real news here, if I can interpret the press release correctly, is not that the nanoparticle is the trojan horse, but that its small size *allowed* the researchers to construct the trojan horse.

The article summary is a bit brief- basically, cancer needs a lot of folate. Moreso than normal cells. These folks attached both an anti-cancer drug and a bunch of folate to a nanoparticle, which, due to both its small size and tasty-looking folate, is able to enter cells and deliver the anti-cancer payload rather than slowly diffuse it through the cell wall.

This is still a bit of a shotgun approach, as normal cells still get targetted to some extent, but *much* less so than previous methods.

Re:How do they determine cancer/non cancer cells?

[TripMaster Monkey]

From TFA:

Dendrimers have a tree-like structure with many branches where scientists can attach a variety of molecules, including drugs. In experiments reported in Cancer Research, U-M scientists attached methotrexate, a powerful anticancer drug, to branches of the dendrimer. On other branches, they attached fluorescent imaging agents and their secret ingredient - a vitamin called folic acid.

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.

Wow, really wow.

[borkus]

Most folks know someone either in their family or circle of friends who's had chemotherapy. Depending on the level of treatment, it can be grueling. The impressive quote from the story is this -

the nanoparticle-based therapy using folic acid and methotrexate was 10 times more effective at delaying tumor growth than the drug given alone. Nanoparticle treatment also proved to be far less toxic to mice in the study than the anticancer drug alone

Less toxic and 10 times more effective (possibly requiring fewer treatments). I wonder if that could make it a viable treatment alternative for inoperably cancers.

Lastly, some folks asked about what happens to all those dendrimers when they've done their job.

The results showed that the kidneys quickly filtered free nanoparticles from blood and eliminated them in urine. The researchers found no evidence that nanoparticles were able to leave the bloodstream and enter the brain.

Re:How it works

[dannyitc]

Folate is a molecule needed for DNA synthesis. Cancer cells need more of it because they are multiplying uncontrolled and therefore are synthesizing much more DNA than regular cells. Folate in itself, however, is not a mutagen, which is required to disrupt the DNA in a healthy cell to make it become cancerous. Actually, increased folate intake has shown to decrease instances of many types of cancer because folate deficiency is a main cause of error in DNA synthesis.

Re:yuck...

[iamlucky13]

"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

According to that passage, it's not quite as simple as slipping through the cell membrane, like osmosis of water. It sounds like they're taking advantage of facilitated transport. Your cells need some molecules that are too large to fit through your cell membrane, so instead there are "gates" for them to pass through that are essentially proteins embedded in the membrane. Each gate can bond to a particular molecule, so you theoretically don't have stuff getting through that shouldn't. When the molecule bonds to the protein, it changes shape, taking the molecule in, typically without the expenditure of ATP (cell energy).

I'm curious, what exactly about this makes you feel uncomfortable?