[extropy-chat] nanotech bones

[spike]

http://www.foxnews.com/story/0,2933,194857,00.html


Nanotechnology May Help Grow Replacement Bone 
Wednesday, May 10, 2006
By Scott Fields


Scientists have developed a technique that someday may let doctors create
customized bones. 

Such bones could come in handy in circumstances where chunks of bone in the
human body go missing.

Bones can be lost, for example, in brutal accidents, from in-depth
dentistry, or during surgery, especially when certain kinds of tumors are
removed.

Bone grafts can help span a gap, but current sources of fill-in bone are
less than perfect.

Bone can be swiped from someplace else on the patient - and home-grown bone
is the stuff that the body is least likely to reject - but that means an
extra incision, extra pain and an extra risk of complications.

Bone from cadavers is sometimes used, but imported bone doesn't grow as well
as the domestic model. And artificial bones made from materials such as
ceramics aren't good for much more than extending natural bone grafts.

Perhaps the ideal solution, says Laura Zanello, an assistant biochemistry
professor at the University of California in Riverside, would be a
substitute bone fragment that matched the gap and the patient perfectly.

Her group has developed a system in which bone cells grow onto scaffolds
built of carbon nanotubes, which are extraordinarily strong and stiff
structures usually no more than a few nanometers in diameter. Currently the
group is using bone cells from lab rats.

The idea is that when the technique is refined, the nanotubes could be
formed so that when layered with the patient's bone cells, they would fit
perfectly into a gap in a damaged bone. Over time, the bone cells would
merge with the surrounding bone, just as would a conventional graft.

The body would be unlikely to reject such a contraption, she says, because
carbon is bio-friendly and the bone would be grown from the patient's own
cells.

Many other researchers have attempted to combine carbon nanotubes with
various types of living cells, Zanello says, but until recently the cells
have died quickly, poisoned by the tubes themselves.

"What happens," she said, "is during the fabrication of carbon nanotubes,
there is deposition of heavy metals into the nanotubes."

These metals are toxic to most living cells. But a member of Zanello's group
- Bin Zhao, then a graduate student in the university's chemistry department
and now a researcher at Oak Ridge National Laboratory - produced nanotubes
that are purer than previous models.

"Apparently that is the reason our bone cells can grow on these carbon
nanotubes," Zanello said. "The most fascinating part was that they will not
only grow and proliferate, but they secrete a bone matrix."

Such a matrix would allow the cells to fuse with existing bone.

The research was detailed in a recent issue of the journal Nano Letters.

Although these results are promising, they are just the first step in a long
journey toward treating damaged human bones, Zanello cautions.

Especially important will be to test how well the body tolerates the
nanotube structures, which, although buried in bone, would be permanent.

Wednesday, May 10, 2006
By Scott Fields