[cdn-nucl-l] Tiny gold shells may help battle cancer; absorb radiation, heat kills cancer

["Adam McLean" <adam.mclean@utoronto.ca>]

Posted on the Canadian Press on November 3, 2003 and at:
http://www.canada.com/health/fromthewires/story.html?id=5CCE9839-B629-428C-9
FD5-3D1E9AD8C62D

Adam

----------------

Tiny gold shells may help battle cancer; absorb radiation, heat kills cancer
  
RANDOLPH E. SCHMID   
Canadian Press  
  
WASHINGTON (AP) - Tiny gold shells that absorb certain types of radiation
may become a new weapon in the ongoing battle against cancer. 

Called nanoshells, the golden balls have a bit of mica in their centre and
can be designed to absorb radiation at various frequencies. A group of Texas
researchers injected the nanoshells - so small it would take 5,000 of them
to reach the size of a poppy seed - into tumours in mice. They then exposed
the tumours to near infrared radiation, heating them enough to kill the
cancer but without injuring nearby normal tissue. 

Their results are reported in this week's online issue of Proceedings of the
National Academy of Sciences. 

Nanoshells should work in most soft tissue tumours but would be most
effective on cancers that can't be removed surgically because they're in an
awkward location, such as in the brain, the researchers said. 

"Nanoshells can be directly injected," said Jennifer L. West of Rice
University, "or, our most recent study shows that you can inject nanoshells
intravenously and they will accumulate in tumour sites because the blood
vessels in tumours are leakier than elsewhere in the body." 

West said patients could be treated in two ways. 

"Near infrared light can be applied from outside of the body for most
applications, but if necessary, fibre optics can be run through catheters,"
said West, who led the team from Rice and the University of Texas M.D.
Anderson Cancer Center. 

Near infrared light is a type of low-energy radiation not absorbed by living
tissues. However, the nanoshells can be designed to absorb this light, which
heats them up. 

Andrei Laszlo of the Washington University School of Medicine in St. Louis
said that although the method is a novel approach for removing tumours, it
"will require a considerable amount of further work" to overcome the problem
of directing the nanoshells to the specific tumour sites. 

The Texas researchers first experimented with cultured human breast cancer
cells in a solution containing nanoshells and then turned to tumors in mice.


In both cases, temperatures inside the tumours reached levels high enough to
damage cells within four to six minutes, killing the tumours but leaving
surrounding tissue unharmed. 

The researchers will monitor the long-term health of the treated mice. 

West said a company called Nanospectra Biosciences has licensed the
technology and plans to do studies in people, which could occur within 12 to
18 months. 
- 
On the Net: 
Proceedings of the National Academy of Sciences: pnas.org 

C Copyright 2003 The Canadian Press