AR Coomer, JP Farese, RJ Milner, DW Siemann, D Rajon, ME Salute, D Taylor, FJ Bova, A Pozzi.
University of Florida, Gainesville, Florida, United States

ACVS Abstract 2007

Several murine models for canine osteosarcoma have been associated with various complications. The purpose of this study is to describe the protocol and technique for successful use of an intramuscular murine xenograft model for radiation therapy and canine osteosarcoma. Intramuscular Highly Metastasizing Primary Osteosarcoma (HMPOS) xenografts were initiated in twenty-seven 5-week old athymic BALB/c AnNCrl-nuBR mice.

Mice were randomly divided in 3 groups: 1) no radiation, 2) 10Gy, 3) 15Gy radiation treatments. Conscious mice were restrained in customized plastic jigs and tumor irradiations were performed using a 6-MV Clinac 600 c linear accelerator. The behaviour and development of the IM HMPOS tumor xenograft model was studied in detail using: Initial Tumor Growth (t8mm), Tumor Growth (t8–13mm), tumor vasculature with CD31 immunohistochemistry, histomorphology, percent tumor necrosis, morbidity. Tumor diameter of 8mm was achieved within 7–10 days of inoculation. Tumor growth from 8 to 13mm diameter was significantly slower in both radiation therapy groups than in the control group (P<0.05), but no significant difference was found between radiation therapy groups.

Tumors were highly vascular based on both subjective scoring and CD31 micro-vessel density. No significant difference was evident in percent tumor necrosis between groups. Morbidity was minimal. This intramuscular xenograft model for in vivo assessment of canine osteosarcoma is reliable, repeatable and easily useable. We can recommend this model for future investigations of canine osteosarcoma and for its radiation therapy.