Objectives: To establish a mouse orthotopic bladder cancer model with consistent tumor-take rate. This orthotopic model was subsequently used to evaluate small animal imaging techniques and investigate new therapeutic agents for bladder cancer treatment. / Materials and Methods: Different orthotopic implantation techniques have been tested. MBT-2 cells and syngeneic C3H/He mice were used in all experiments. Chemical bladder pre-treatment with different agents (saline, hydrochloric acid, trypsin and poly-L-lysine) and different concentration of instilled tumor cells (1 x 10⁶ or 2 x 10⁶) were investigated. In the second part of the experiment, trans-abdominal micro-ultrasound imaging (MUI) technique was investigated and validated. Bladder tumor growths were monitored with longitudinal measurement. Mice were killed at every MUI session. Bladder tumor volumes were measured and correlated with gross stereomicroscopy. Using the optimized orthotopic bladder cancer model, targeted contrast enhanced micro-ultrasound imaging has been investigated. VEGFR2 targeted contrast agent was prepared and injected intravenously before imaging sessions. The intra-tumoral perfusion, VEGFR2 expression and blood volume in real time were quantified. Contrast enhanced MUI was performed on Days 14 and 21. The feasibility of targeted contrast enhanced micro-ultrasound imaging was confirmed. After the establishment of orthotopic model and in vivo molecular imaging techniques, this robust platform was used for investigating new treatment agent in localized bladder cancer. Tumor-bearing mice were randomized into control and sunitinibtreated (40 mg/kg) groups. Tumor volume, intra-tumoral perfusion, and in vivo VEGFR2 expression were measured using a targeted contrast-enhanced micro-ultrasound imaging system. The effects of sunitinib malate on angiogenesis and cellular proliferation were measured by CD31 and Ki-67 immunohistochemistry. The clinical outcomes including total bladder weight, tumor stage, and survival were evaluated. / Results: A consistent tumor take-rate of over 90% was achieved by using poly-L-lysine pretreatment with 2 x 10⁶ MBT-2 cells in all of the experiments. MUI identified all tumors that were present on final histology. Measurements of tumor size by MUI and gross microscopy had a high correlation coefficient (r = 0.97). Measurements of intra-tumoral perfusion and in vivo VEGFR2 expression were also proved to be feasible. After the technical refinement and modification, complete measurements could be performed in all mice (n = 10) at 2 consecutive imaging sessions. No adverse effects occurred due to anesthesia or the ultrasound contrast agent. This is the first report of applying targeted contrast enhanced MUI in orthotopic bladder cancer model. Finally, sunitinib was found to have significant tumor growth inhibition in both in vitro and in vivo experiments. In the orthotopic model, tumors in sunitinib-treated mice had reduced tumor volume and stage, lower proliferation index and micro-vessel density. Sunitinib prolonged survival in tumor-bearing mice as compared to control group. / Conclusions: The development of reliable orthotopic animal models assists in the discovery of novel therapeutic agents. The establishment in the methods of implantation with improved tumor-take rate and the advances in imaging technology form the important foundation of basic research in bladder cancer. Trans-abdominal MUI is proven to be a valuable tool for translational studies involving orthotopic mouse bladder cancer models. Furthermore, the first report of the application of targeted contrast enhanced MUI in deep-seated tumor in bladder has been published. It enables investigators to monitor tumor angiogenesis and vascular changes after treatment. It will be useful for direct, noninvasive, in vivo evaluation of anti-angiogenesis therapeutic agents. The preclinical study has demonstrated the activities of a new class of targeted therapy against localized bladder cancer in an orthotopic mouse model. Sunitinib inhibits tumor growth and thus decreases the tumor burden and prolongs survival compared with placebo. These results provide a rationale for future clinical trials using VEGFR-targeted treatments of localized bladder cancer in the neo-adjuvant and adjuvant settings. / Chan, Shu Yin Eddie. / Thesis (M.D) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 189-212).
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_1077689 |
| Date | January 2014 |
| Contributors | Chan, Shu Yin Eddie (author.), Chinese University of Hong Kong Graduate School, (degree granting institution.) |
| Source Sets | The Chinese University of Hong Kong |
| Language | English |
| Detected Language | English |
| Type | Text, bibliography, text |
| Format | electronic resource, electronic resource, remote, 1 online resource (214 leaves) : illustrations (some color), computer, online resource |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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