Production and characterization of two ependymoma xenografts.

Childhood ependymomas exhibit epidemiologic, anatomic, histologic, and biologic features and distinguish them from other gliomas. Because of their propensity to grow in functionally sensitive regions of the brain, adequate tumor sampling for basic and therapeutic research is limited. We have established xenografts in both subcutaneous and intracranial nude mouse systems (D528 EP-X, D612 EP-X) from the ependymomas of two nonrelated children. Median subcutaneous growth rates (reported in days to grow from 200 mm3 to 1000 mm3) are 82 days for D528 EP-X (n = 10) and 50 days for D612 EP-X (n = 10). D528 EP-X grows intracranially with a median postimplantation survival of 85 days (n = 10); D612 EP produces a median postimplantation survival of 72.5 days (n = 10). Both xenografts grow as well-formed masses with no evidence of infiltration into either brain or subcutaneous tissues. While perivascular pseudopalisading is found in both xenografts, true ependymal rosette formation is absent. Ultrastructurally, neither xenograft exhibits cilia, but both produce abundant intermediate filaments. By light microscopy, the neoplastic cells are immunoreactive for the intermediate filaments glial fibrillary acidic protein, vimentin, and nestin. Karyotypically D528 EP exhibits 46,XX,del(6)(q22q26)/46,XX while D612 EP exhibits 50,XX, +X,t(1;8)(p11;q11),t(1;8)(p11;q11), +1,-4, der(5)t(4;5)(q12;q35), +der(5)t(4;5)(q12;q35),-6, +9, +9,-16, +der(17)t(6;17)(p11;p11), +mar. Restriction fragment length polymorphism studies comparing the primary brain tumor tissue from each patient against multiple passages of the resulting xenografts confirm the origin of both xenografts. These xenografts represent models on which future studies into the oncogenesis, progression and therapy of ependymomas can be performed.