student research day - Case Western Reserve University School of ...

Joshua Bear
The Role of Angiogenesis in Tumor Maturation: Oxygen Delivery or Waste Elimination?
Joshua Bear, Dr. Hanping Wu and Dr. John Haaga
Department of Radiology, University Hospitals Case Medical Center
Although the process of angiogenesis in tumor growth has been defined and studied for decades, recent
advances in our understanding of the process are being realized through the use of computed
tomography (CT) to study blood perfusion patterns. New questions regarding the actual role of
angiogenesis in the life cycle of tumors have stimulated further research to investigate whether the role
of tumor angiogenesis is to provide the lesions with nutrients or merely to offer a way to dispose of
metabolic wastes. This study examines the changes in tumor perfusion over four weeks of growth using
a rabbit model to support concurrent studies exploring the role of tumor angiogenesis.
Tumors were injected into the livers of nine rabbits and allowed to grow for five weeks. Blood
perfusion measurements using a high-resolution CT scanner were taken every week. The measurements
were analyzed using Siemens Medical Solutions’ syngo® MultiModality Workplace to calculate
perfusion values in the following regions of interest (ROIs): aorta, tumor center, tumor ring, adjacent
liver, remote liver. The data were entered into Microsoft Office Excel 2008 in order to calculate the time
to start (T0), time to perfusion (TP), and tissue blood ratio (TBR).
Although the study is ongoing, current analyses demonstrate that the slope of enhancement for both the
tumor ring and the tumor center decreases over time while the slope of washout for both ROIs increase
over time (p < 0.05). In contrast, the enhancement and washout for both adjacent and remote liver
controls do not change over time.
The results obtained are inconclusive by themselves, but lend support to the hypothesis that tumor
angiogenesis is more important as a means to eliminate wastes than as a means to obtain nutrients.
Concurrent and future studies are underway to elaborate on this hypothesis.
Student research funded by the National Institutes of Health (NIH) T35 grant.
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