Longitudinal live animal micro-CT allows for quantitative analysis of tumor-induced bone destruction

Abstract

The majority of breast cancer and prostate cancer patients with metastatic disease will go on to develop bone metastases, which contribute largely to patient morbidity and mortality. Numerous small animal models of cancer metastasis to bone have been developed in order to study tumorinduced bone destruction, but the advancement of imaging modalities utilized for these models has lagged significantly behind clinical imaging. Therefore, there is a significant need for improvements to live small animal imaging, particularly when obtaining high resolution images for longitudinal quantitative analyses. Recently, live animal micro-Computed Tomography (μCT) has gained popularity due to the ability to obtain high resolution, 3-dimensional images. However, the utility of μCT in bone metastasis models has been limited to end-point analyses due to offtarget radiation effects on tumor cells. We hypothesized that live animal in vivo μCT can be utilized to perform reproducible and quantitative longitudinal analyses of bone volume in tumor bearing mice, particularly in a drug treatment model of breast cancer metastasis to bone. To test this hypothesis we utilized the MDA-MB-231 osteolytic breast cancer model in which the tumor cells are inoculated directly into the tibia of athymic nude mice and imaged mice weekly by Faxitron (radiography), Imtek μCT (in vivo), and Maestro (GFP-imaging). Ex-vivo μCT and histology were performed at end-point for validation. After establishing a high resolution scanning protocol for the Imtek CT, we determined whether clear, measurable differences in bone volume were detectable in mice undergoing bisphosphonate drug treatments. We found that in vivo μCT can be used to obtain quantifiable and longitudinal images of the progression of bone destruction over time without altering tumor cell growth. Additionally, we found that we could detect lesions as early as week one and that this approach could be used to monitor the effect of drug treatment on bone. Taken together, these data indicate in vivo μCT is an effective and reproducible method Corresponding Author: Julie A. Sterling, PhD, Vanderbilt Center for Bone Biology, 2215B Garland Avenue, 1235 MRBIV, Nashville, TN 37232, P. 1+ (615) 322-4364 F. 1+ (615) 343-2611, julie.sterling@vanderbilt.edu. * These authors contributed equally to this work.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errorsmaybe discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptBone. Author manuscript; available in PMC 2012 January 1. BackgroundNearly 70% of breast cancer and 90% of prostate cancer patients with metastatic disease will develop bone meta...

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