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Stem Cell News
Personalized Therapy for Cancer, Self-Targeting
Stem Cell from Fat
American Association for Cancer Research, July 5,
2007
Capable of seeking out tumors and destroying theme
like tiny homing missiles, mesenchymal stem cells
derived from adipose, or fat tissue, have been
engineered by researchers in Slovakia. The modified
cells have been called, "suicide genes". In
a journal of the American Association for Cancer
Research, the July 1 issue of Cancer Research,
the Slovakian scientists concluded that this gene
therapy approach was a novel way to attack small tumor
metastases that evade current detection techniques and
treatments.
"These fat-derived stem cells could be
exploited for personalized cell-based
therapeutics," said the study's lead
investigator, Cestmir Altaner, Ph.D., D.Sc., an
associate professor in the Cancer Research Institute
of the Slovak Academy of Sciences in Bratislava.
"Nearly everyone has some fat tissue they can
spare, and this tissue could be a source of cells for
cancer treatment that can be adapted into specific
vehicles for drug transport."
By renewing injured cells, mesenchymal stem cells
help repair damaged tissue and organs. Solid tumors
are also made up of a mix of cancer cells and normal
cells, some of which are mesenchymal stem cells. The
cells may be able to find both small metastases as
well as primary tumors because mesenchymal stem cells
are believed to be able to "see" a tumor as
a damaged organ and migrate to it. For this reason,
researchers believe that the cells can be used as a
vehicle for treatment.
The standard therapy for colon cancer is to use a
chemotherapy agent called 5-fluorouracil (5-FU), which
can produce toxic side effects in normal cells. With
this in mind, the researchers worked to find a less
toxic way to treat colon cancer with the stem cells
they extracted from human fat tissue. The gene
cytosine deaminase was inserted into the cell using a
retrovirus vector after the mesenchymal stem cells
were expanded in a laboratory. A lethal bystander
effect can be produced by the gene, which can convert
a less toxic drug, 5-fluorocytosine (5-FC), to 5-FU
inside the stem cells, and the chemotherapy can then
seep out into the tumor.
The researchers injected the engineered mesenchymal
stem cells, then 5-FC, into mice with inhibited immune
systems who were engrafted with human colon cancer.
None of the mice exhibited any signs of toxic side
effects while up to a 68.5 percent inhibition of tumor
growth was observed in the animals.
However, none of the animals remained tumor-free.
"The procedure was quite effective even though we
applied the stem cells just once. Obviously, repeated
treatment will increase the efficacy, as would using
this strategy in combination with other
treatments," Altaner said.
The yield of normal mesenchymal stem cells from fat
tissue is far greater than when the cells are derived
from other sources such as bone marrow.
Altaner said that the, "removal of fat tissue
during surgery to remove a tumor would be
simple."
Mesenchymal stem cells can also be gathered and
isolated through liposuction, and the cells frozen in
liquid nitrogen for future therapeutic use. Both
processes would be easier than taking bone marrow from
a patient, Altaner said.
The Slovakian national cancer genomics program
supported the study and the League Against Cancer
along with the Slovak Academy of Sciences provided
grants for funding.
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