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New molecular imaging techniques may lead to advances in disease treatment
June 17, 2008Researchers present a promising cell engineering technique at the SNM 55th Annual Meeting, June 14-18
NEW ORLEANS, La.- A promising new technique has been developed that will enable more accurate non-invasive positron emission tomography (PET) imaging of new cells injected into the body, according to researchers at SNM's 55th Annual Meeting. The new technique, which involves engineering antibody fragments to act as reporter genes-or markers that signal cells of interest for PET imaging purposes-could significantly advance the study of genetically engineered cells to treat diseases.
"Genetic cell engineering is the focus of intense research in almost all areas of medicine and shows great promise for treatment of common illnesses such as heart disease, diabetes, and Parkinson's disease and other neurodegenerative disorders," said Wolfgang Weber, lead researcher of the study, Cell Surface Expression of an Engineered Antibody as a PET Reporter Gene for In Vivo PET Imaging, which was performed at the Department of Molecular and Medical Pharmacology at UCLA in collaboration with the Department of Chemistry at UC Davis.
However, despite intense efforts, researchers have few solid, noninvasive methods for accurately tracking the location, function and viability of small numbers of transplanted cells. "Our research shows that using antibodies as reporter genes in PET imaging provides these capabilities and could contribute to improved treatment of a number of potentially devastating diseases," added Weber, now professor of nuclear medicine at the University of Freiburg, Germany.
To improve PET imaging in this area, researchers have been studying the use of reporter gene-probe combinations. With this technique, cells are created to synthesize a protein that binds to or metabolizes radioactive reporter probes that are injected into the body and detected with PET imaging technology. However, most available reporter gene combinations are not aptly sensitive or specific and have significant limitations in terms of tracking the cells of interest to researchers.
In this new research, Weber and his team explored using cell surface-bound antibody fragments as reporter genes. These engineered antibody fragments, developed by the group of Claude Meares at Davis, bind irreversibly to low-molecular-weight antigens, which act as reporter probes. Cell culture and animal studies demonstrated intense and highly specific uptake of the probes in cells expressing the antibody fragment on the cell surface. These data indicate that antibody-based reporter genes represent a promising new platform for the development of new reporter gene and probe combinations.
Antibody-based reporter genes have several potential advantages over other combinations. For example, the pharmacokinetics of the reporter probe can easily be optimized, and probes can identify antibodies with much higher specificity, thus improving the accuracy of PET imaging. In addition, the number of antibodies that can be used as reporter genes is virtually unlimited compared with available viral or mammalian reporter genes. Antibody-based reporter genes have low immunogenicity and are better suited for imaging the expression of several genes.
Society of Nuclear Medicine
However, despite intense efforts, researchers have few solid, noninvasive methods for accurately tracking the location, function and viability of small numbers of transplanted cells. "Our research shows that using antibodies as reporter genes in PET imaging provides these capabilities and could contribute to improved treatment of a number of potentially devastating diseases," added Weber, now professor of nuclear medicine at the University of Freiburg, Germany.
To improve PET imaging in this area, researchers have been studying the use of reporter gene-probe combinations. With this technique, cells are created to synthesize a protein that binds to or metabolizes radioactive reporter probes that are injected into the body and detected with PET imaging technology. However, most available reporter gene combinations are not aptly sensitive or specific and have significant limitations in terms of tracking the cells of interest to researchers.
In this new research, Weber and his team explored using cell surface-bound antibody fragments as reporter genes. These engineered antibody fragments, developed by the group of Claude Meares at Davis, bind irreversibly to low-molecular-weight antigens, which act as reporter probes. Cell culture and animal studies demonstrated intense and highly specific uptake of the probes in cells expressing the antibody fragment on the cell surface. These data indicate that antibody-based reporter genes represent a promising new platform for the development of new reporter gene and probe combinations.
Antibody-based reporter genes have several potential advantages over other combinations. For example, the pharmacokinetics of the reporter probe can easily be optimized, and probes can identify antibodies with much higher specificity, thus improving the accuracy of PET imaging. In addition, the number of antibodies that can be used as reporter genes is virtually unlimited compared with available viral or mammalian reporter genes. Antibody-based reporter genes have low immunogenicity and are better suited for imaging the expression of several genes.
Society of Nuclear Medicine
Molecular Imaging Current Events and Molecular Imaging News RSSUCLA researchers create 'fly paper' to capture circulating cancer cells
Just as fly paper captures insects, an innovative new device with nano-sized features developed by researchers at UCLA is able to grab cancer cells in the blood that have broken off from a tumor.
PET imaging response a prognostic factor after thoracic radiation therapy for lung cancer
A rapid decline in metabolic activity on a PET scan after radiation therapy for non-small cell lung cancer is correlated with good local tumor control, according to a study presented by researchers at Thomas Jefferson University Hospital at the 51st ASTRO Annual Meeting.
Bioluminescence imaging used for eye cancer detection
At the moment, doctors rely on biopsy analysis to determine the progression of eye cancer. However, researchers now believe that a new technology, bioluminescence imaging (BLI), will allow doctors to detect tumors earlier and quickly choose a method of treatment that doesn't necessarily involve eye surgery.
Hyper-SAGE boosts remote MRI sensitivity
A new technique in Magnetic Resonance Imaging dubbed "Hyper-SAGE" has the potential to detect ultra low concentrations of clincal targets, such as lung and other cancers.
Molecular imaging holds promise for early intervention in common uterine cancer
A promising new molecular imaging technique may provide physicians and patients with a noninvasive way to learn more information about a type of cancer of the uterus lining called "endometrial carcinoma"-one of the most common malignant female tumors.
Worldwide isotope shortage continues to pose significant challenges
SNM recently conducted a survey of nuclear pharmacies-pharmacies that supply the critical radioisotope Technetium-99m, which is used in more than 16 million nuclear medicine tests each year in the United States-to assess, anecdotally, the impact of the worldwide medical isotope shortage.
PET/CT scans may help detect recurring prostate cancer earlier
A new study published in the September issue of The Journal of Nuclear Medicine shows that positron emission tomography (PET)/computer tomography (CT) scans with the imaging agent choline could detect recurring prostate cancer sooner than conventional imaging technologies in some patients who have had their prostates surgically removed.
New microchip technology performs 1,000 chemical reactions at once
Flasks, beakers and hot plates may soon be a thing of the past in chemistry labs. Instead of handling a few experiments on a bench top, scientists may simply pop a microchip into a computer and instantly run thousands of chemical reactions, with results - literally shrinking the lab down to the size of a thumbnail.
Study shows PET can measure effectiveness of novel breast cancer treatment
A new study published in the July issue of The Journal of Nuclear Medicine shows that positron emission tomography (PET) scans in mice can be used to determine whether a novel type of breast cancer treatment is working as intended.
Prototype Breast Cancer Imaging System May Improve Patient Care
A prototype breast imaging system combining positron emission tomography (PET) and magnetic resonance imaging (MRI) technologies could greatly improve breast cancer imaging capabilities, according to researchers at SNM's 56th Annual Meeting.
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