Pandia: Gold Nanorods and Their Applications in Cancer Therapy and In Vivo Imaging in Companion Animals and Their Potential Application to Humans - Nanotechnology for Biomedical Imaging and Diagnostics - page 358

In Reference [69], PeG-coated gold nanoparticles (492.5 µg/g body weight)
were used, and biodistribution showed an accumulation of the liver (64.4% Id) at
3 d, spleen (9.7% Id), small intestine (4.3% Id), lymph nodes (1.9% Id), large
intestines (1.6% Id), muscle (1.3% Id), and kidneys (~1% Id), minimal in the
brain, heart, and lung. In this study, mice showed normal hematology and blood
chemistry at days 3 and 14. histological examination of nine major organs and
tissues 3 days after injection showed no evidence of inflammatory cell infiltration,
cell swelling, or tissue necrosis in any mice. No signs of sickness were observed in
the mice up to 6 months.
In Reference [70], the authors evaluated the bioaccumulation and toxic effects of
different doses (40, 200, and 400 µg/kg/day) of 12 nm gold nanoparticles upon intra-
peritoneal administration in mice every day for 8 days. The gold levels in blood did
not increase with the dose administered, whereas in all the organs examined, there
was a proportional increase on gold, indicating efficient tissue uptake.
No evidence of toxicity was observed in any of the diverse studies performed,
including survival, behavior, animal weight, organ morphology, blood biochemistry,
and tissue histology. The results indicate that tissue accumulation pattern of GNPs
depends on the doses administered and the accumulation of the particles does not
produce subacute physiological damage.
In Reference [71], the cytotoxicity in vitro and biodistribution in vivo of Au-Au2S
nanoparticles were studied by using NIh3T3 cells and KM mice, respectively.
Au-Au2S nanoparticles (<300 µg/ml) showed good biocompatibility. In this study,
Au-Au2S nanoparticles were preferentially taken up by the liver and spleen and
ultimately eliminated mostly in the feces.

12.5 summary

Cancer is the major cause of death for companion animals. As we noted earlier, 45%
of all dogs over 10 years of age and 23% of all dogs and 32% of all cats succumb to
cancer [1]. Skin cancer, mastocytomas, is the number 1 cancer killer in dogs accounting
for 23% of all cancers. Cats have a higher prevalence of cancer than all other
companion animals. Skin cancer is the second most prevalent cancer in cats occurring
in 7% of all cancer cases [72]. Mouth cancers occur in 3-4% of all cat cancer cases. It
is estimated that four million dogs and four million cats will be diagnosed with cancer
each year. Current methods of cancer treatment are similar to humans. These include
complete surgical removal, burning or freezing, radiation therapy, chemotherapy, hor-
mone therapy, and immunotherapy. These methods can result in incomplete removal,
reduced efficacy, scarring, and other deleterious side effects.
The presented technology incorporates the use of gold nanoparticles as a method
for inducing localized thermal therapy, thereby aiding destruction of cancer tumors
without surgery. In use, our gold nanoparticles are injected intravenously into the
animal where they target cancer tumors due to the ePR effect inherent difference
between cancer tissue and healthy tissue. A laser tuned to the absorption peak of
the gold nanoparticles is used to heat the area of the tumor. Only where the gold