Evaluation Of Stem Cells' Potential For New Ways To Treat Disease -
Aided By PET And Bioluminescent Imaging
Main Category: Medical Devices News
Article Date: 09 Dec 2007 - 6:00 PST
Using positron emission tomography (PET) imaging with
bioluminescence - the light produced by a chemical reaction within an
organism - researchers are starting to understand the behavior of
transplanted or implanted stem cells that may one day be used to
develop new treatments for disease.
According to a study in the December Journal of Nuclear Medicine,
scientists have found that using the unique combination of
noninvasive PET imaging and optical (bioluminescent) imaging is "an
ideal method for tracking stem cell transplantation in small animal
models," said Zhenghong Lee, an associate professor of nuclear
medicine/radiology and biomedical engineering departments at Case
Western Reserve University in Cleveland, Ohio. Researchers were able
to use these two imaging techniques to "follow" stem cells for a
longer time than previously had been achieved to determine
their "fate," explained Lee.
Human mesenchymal stems cells or multipotent marrow stromal cells
(hMSCs) are self-renewing adult stem cells that are found in adult
donor bone marrow. These stem cells, the body's blank or "master"
cells, may differentiate (or change) into bone, fat tissue and
cartilage, said Lee. "The promise of MSC therapies - derived from
adult bone marrow and used as a viable and renewable source of stem
cells - mandates research leading to a better understanding of the
long-term fate and trafficking of transplanted MSCs in animal and
human subjects," said the investigator at Case Western's Center for
Stem Cell and Regenerative Medicine. These progenitor cells may have
great potential in providing future treatments for heart diseases,
brain disorders and cancer and greatly reduce the need to use
embryonic stem cells or other fetal tissues.
Specifically, this imaging research could help optimize treatments
for individuals with graft-versus-
condition where immune cells from donated marrow or cord blood attack
the body of a bone marrow transplant patient, said Lee. Additionally,
bone marrow stem cells may help regenerate cells in individuals with
heart disease (heart attacks) or brain disorders (strokes, multiple
sclerosis) or bone fractures. They could act as a drug delivery
vehicle for cancer patients, he added. Much research in these areas
still needs to be done "since there are many things that we don't
know about stem cell biology," noted Lee.
For this study, researchers used a fusion protein combining firefly
luciferase (a light-emitting substance) for optical imaging, a red
fluorescent protein for cell separation and a virus enzyme thymidine
kinase for PET imaging in mice to visualize biological processes at
the molecular level. "The triple-fusion reporter approach resulted in
a reliable method of labeling stem cells for investigation by use of
both small-animal PET imaging and bioluminescent imaging," said Lee.
PET is a powerful molecular imaging procedure that noninvasively
demonstrates the function of genes, cells and organs/tissues,
providing information about the biochemistry processes, metabolic
activities and body functions. PET scans use very small amounts of
radioactive pharmaceuticals that are detected or "traced" by a
special type of camera that works with computers to provide
quantitative pictures of the area of the body being imaged. To image
dim light from bioluminescence - the process of light emission in
living organisms - researchers use an ultra-sensitive camera from an
external vantage point. This research is detailed in "Imaging of
Mesenchymal Stem Cell Transplant by Bioluminescence and PET."
In a related Journal of Nuclear Medicine article, the growing number
of exciting animal and preclinical studies are explored, revealing
the "immense potential in stem cell-based therapies, particularly in
the area of treating cardiovascular diseases," said Joseph C. Wu,
assistant professor of cardiovascular medicine and radiology at
Stanford University School of Medicine in Stanford, Calif. Wu and co-
author Sarah J. Zhang review the basic principles of current
techniques for cardiac stem cell tracking, compare the relative
advantages and disadvantages of these imaging modalities and discuss
the future prospect of cardiac stem cell trafficking. "Comparison of
Imaging Techniques for Tracking Cardiac Stem Cell Therapy" is the
first article in the journal's new monthly feature called "Focus on
Molecular Imaging."
"The unique information obtained from molecular imaging techniques is
particularly helpful in evaluating cell engraftment and may shed
light on the mixed findings regarding stem cell-based therapy," said
Wu. "The current noninvasive imaging approaches for tracking stem
cells in vivo include imaging with magnetic particles, radionuclides,
quantum dots, reporter genes, and fluorescence and bioluminescence
imaging," he added. "It is possible that a tailored combination of
two or more techniques may provide the most ideal information profile
for clinical applications,
------------
Article adapted by Medical News Today from original press release.
------------
Additional co-authors of "Imaging of Mesenchymal Stem Cell Transplant
by Bioluminescence and PET" include Zachary Love, nuclear
medicine/radiology department; Fangjing Wang and Nicholas Salem,
biomedical engineering department; Amad Awadallah, orthopedics
department, James Dennis, orthopedics department and Center for Stem
Cell and Regenerative Medicine, and Yuan Lin, hematology/oncology
department, all at Case Western Reserve University in Cleveland,
Ohio; and Andrew Weisenberger and Stan Majewski, Thomas Jefferson
National Accelerator Facility, Newport News, Va.
"Comparison of Imaging Techniques for Tracking Cardiac Stem Cell
Therapy" was co-written by Wu and Sarah J. Zhang, Stanford University
School of Medicine, Stanford, Calif.
About SNM - Advancing Molecular Imaging and Therapy
SNM is an international scientific and professional organization of
more than 16,000 members dedicated to promoting the science,
technology and practical applications of molecular and nuclear
imaging to diagnose, manage and treat diseases in women, men and
children. Founded more than 50 years ago, SNM continues to provide
essential resources for health care practitioners and patients;
publish the most prominent peer-reviewed journal in the field
(Journal of Nuclear Medicine); host the premier annual meeting for
medical imaging; sponsor research grants, fellowships and awards; and
train physicians, technologists, scientists, physicists, chemists and
radiopharmacists in state-of-the-
SNM members have introduced - and continue to explore - biological
and technological innovations in medicine that noninvasively
investigate the molecular basis of diseases, benefiting countless
generations of patients. SNM is based in Reston, Va.; additional
information can be found online at http://www.snm.
Source: Maryann Verrillo
Society of Nuclear Medicine
http://www.medicaln
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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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