Noninvasive molecular imaging technology helps track stem cells in
tumors
Using noninvasive molecular imaging technology, a method has been
developed to track the location and activity of mesenchymal stem
cells (MSCs) in the tumors of living organisms, according to
researchers at the Society of Nuclear Medicine's 55th Annual Meeting.
This ability could lead to major advances in the use of stem cell
therapies to treat cancer.
"Stem cell cancer therapies are still in the early stages of
development, but they offer great promise in delivering personalized
medicine that will fight disease at the cellular level," said Hui
Wang, a postdoctoral fellow from Prof. Xiaoyuan (Shawn) Chen's group
of the Molecular Imaging Program at Stanford (MIPS), Department of
Radiology at Stanford University, Stanford, Calif., and lead
researcher of the study, Trafficking the Fate of Mesenchymal Stem
Cells In Vivo. "Our results indicate that molecular imaging can play
a critical role in understanding and improving the process of how
stem cells migrate to cancer cells. Eventually, this technique could
also be used to determine if gene-modified stem cells are effective
in fighting cancer."
MSCs are adult stem cells that have the ability to transform into
many different types of cells, such as bone, fat or cartilage. Many
scientists believe that stem cells show great promise in treating
different types of diseases-and a few stem cell therapies are already
used to fight some types of cancer. Leukemia patients who haven't
responded to chemotherapy, for example, may receive bone marrow
transplants, through which stem cells of a healthy bone marrow donor
are injected into the patient's blood stream. If the transplant is
successful, the stem cells will migrate to the patient's bone marrow
and begin producing healthy cells that will replace the cancer cells.
For other types of cancer, researchers are experimenting with
modifying stem cells that could be engineered to deliver chemotherapy
more precisely to specific tumor sites.
For these types of treatments to be successful, the ability to track
what happens to stem cells after they are injected into a living
organism is essential. Currently, three different tracking techniques
are used: radiolabeling, which consists of using a radioactive
substance to tag the cells; magnetic labeling, or using magnetic
nanoparticles to tag cells for magnetic resonance imaging; and
reporter-gene tracking, which involves engineering genes that can
adhere to cells and be tracked with molecular imaging technologies.
Of these, reporter gene techniques are highly sensitive and able to
monitor cell migration, survival and proliferation over time in
living organisms.
In their research, Wang and her team isolated stem cells from adult
mice and engineered a reporter gene that would be both luminescent
and green under a special microscope. Two tumor models were also
tagged with reporter genes that were luminescent and red. The tumor
cells were injected into live mice either intravenously or under the
skin, followed days later by injection of the engineered stem cells.
The study produced solid evidence that the injected stem cells
migrate to the tumors and don't begin to differentiate into other
types of cells until they are at the tumor sites. In some of the
mice, the breast cancer cells had begun to spread to the lungs.
Researchers found that the injected stem cells also migrated to the
lung cancer tumors. In addition, the stem cells that migrated to lung
tumors differentiated into bone cells, while the stem cells that
migrated to breast cancer tumors differentiated into fat cells. The
results indicate that stem cells can migrate both to breast cancer
cells and their lung metastasis. In addition, the MSCs differentiate
into distinctly different cells. "The next logical step of this study
is to incorporate therapeutic genes into MSCs and use multimodality
molecular imaging techniques to follow the distribution, homing,
survival, proliferation and cell/gene therapy efficacy of the MSC
platform," said Wang.
http://www.snm.
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StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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