We propose to purchase a commercial bioluminescent imaging (BLI) system, specifically, the Caliper (Xenogen) IVIS SpectrumTM. It will primarily serve six NIH-funded research teams to undertake biomedical research. In addition, through a Small Animal Imaging Research Program (U24- SAIRP) it will support 12 other current research investigations and serve as a catalyst for new research. It is widely recognized that imaging enhances biomedical research, particularly in oncology. Tumors exhibit substantial heterogeneity, and thus, it is advantageous for each tumor to serve as its own control. Longitudinal studies in individual tumors enjoy three primary benefits: i) the need for fewer animals, ii) as a corollary, the need for less reagent (therefore, rare and costly drugs and antibodies can be screened more efficiently), iii) more robust statistics. Bioluminescent imaging is particularly effective for high throughput screening of tumors at small volumes (including sub palpable) growing in nude mice. Whole mice may be observed and the development of remote metastasis is readily assessed without a priori assumptions about location (in contrast to the requirements for effective pathology). BLI does require introduction of a reporter gene (typically, firefly luciferase), but this is reliably accomplished and is routine at UT Southwestern Medical Center. BLI has the additional advantage that specific promoters (e.g., hypoxia, clusterin, estrogen, or other stress elements) may be included to regulate luciferase expression. This can also be achieved using fluorescent reporters and the Spectrum can also undertake fluorescent imaging, with spectral unmixing to reliably remove autofluorescence or differentiate reporters with distinct wavelengths. The Spectrum offers 3-dimensional capabilities for both bioluminescent and fluorescence imaging, which greatly enhances the ability to distinguish the location of developing tumors. Hitherto, we provided a BLI service using home built instrumentation, but we believe it is important to add a capability using a standard commercial platform. Commercial systems are more user friendly allowing diverse investigators to be rapidly trained to conduct imaging studies. Furthermore, UT Southwestern is establishing a specific pathogen free (SPF) facility including a small animal tumor model core resource, which requires imaging capabilities. While BLI instruments are relatively cheap, they are beyond the scope of individual investigators, and this shared instrument will facilitate new experiments while being efficiently used. BLI has become established as the premiere screening tool for small tumor volumes and metastatic spread. The new instrument will accelerate development of new therapies in our institution, which will be directly translatable to the clinic, and thus, provide more effective future therapy for patients. While the reporter gene is only relevant in the preclinical setting, the results achieved should provide insight into optimizing therapy protocols for patients. ? ? ?
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