Transplantable canine glioma model for use in experimental neuro-oncology

The need for a large animal tumor model in experimental neuro-oncology led us to re-evaluate and to modify the transplantable canine glioma of Wodinsky and Walker. Successive passages of the original tumor brei were made in purebred beagles, from beagle to mongrel, and between various mongrel strains until an intracerebral injection of 0.1 cc on Days 1 to 3 of life produced a 93% incidence of tumor take in all breeds. The mean survival was 13.5 +/- 1.9 days after injection (range, 10 to 19 days) in 10 litters. The tumor was invariably fatal and possessed many of the histological characteristics of human glioblastoma (i.e., capillary proliferation, pseudopallisading, frequent mitotic figures, and multinucleated giant cells). The animals were large enough to be scanned on the Pfizer 450 scanner, and the tumors were visualized in vivo as typical "ring" lesions after the injection of contrast agent. Intravital staining with Evans blue outlined the areas of contrast enhancement observed in the same tumors by computed tomography. The apparent defect in the blood-brain barrier could be explained in part by the absence of endothelial tight junctions on electron microscopy. Stability in the histology and activity of the tumor could be demonstrated after more than 14 months of storage at -70 degrees C. The transplantable canine glioma model has many advantages including low cost, reproducible morphology, a short survival time, and relative safety for the investigator. The large size of the animal preparation allows the use of complex surgical instrumentation and radiographic study, as well as repeated sampling of cerebrospinal and other fluids.