PRODUCTION AND CHARACTERIZATION OF 2 EPENDYMOMA XENOGRAFTS

Childhood ependymomas exhibit epidemiologic, anatomic, histologic, and biologic features that distinguish them from other gliomas. Because o f their propensity to grow in functionally sensitive regions of the br ain, adequate tumor sampling for basic and therapeutic research is lim ited. We have established xenografts in both subcutaneous and intracra nial nude mouse systems (D528 EP-X, D612 EP-X) from the ependymomas of two nonrelated children. Median subcutaneous growth rates (reported i n days to grow from 200 mm(3) to 1000 mm(3)) are 82 days for D528 EP-X (n=10) and 50 days for D612 EP-X (n=10). D528 EP-X grows intracranial ly 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 pseudop alisading is found in both xenografts, true ependymal rosette formatio n 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 gl ial fibrillary acidic protein, vimentin, and nestin. Karyotypically D5 28 EP exhibits 46,XX,del(6)(q22q26)/46,XX while D612 EP exhibits er(5) t(4;5)(q12;q35),+der(5)t(4;5)(q12;q35),-6,+9, +9,-16,+der(17)t(6;17)(p 11;p11),+mar. Restriction fragment length polymorphism studies compari ng the primary brain tumor tissue from each patient against multiple p assages of the resulting xenografts confirm the origin of both xenogra fts. These xenografts represent models on which future studies into th e oncogenesis, progression and therapy of ependymomas can be performed .