Implantation of human meningiomas into the subrenal capsule of the nude mouse. A model for studies of tumor growth.

To develop a reproducible in vivo model for the growth of human meningiomas, meningiomas from 16 patients were implanted into the subrenal capsule of the nude mouse. In eight experiments solid tumor implants taken directly from surgical specimens were used, in four experiments the implants were made from early-passage monolayer cell cultures, and in four experiments both techniques were used. Successful tumor growth was observed in 10 (83%) of the 12 solid tumor implants and in six (75%) of the eight implants from cell cultures. The size and neovascularization of these tumors were serially determined over a 3-month period. Tumor doubling occurred in 1 to 3 weeks in all of the solid tumor implant group. In the group of six tumors successfully implanted from cell cultures, three doubled in 1 to 3 weeks and three grew more rapidly, reaching 10 to 20 times their original volume. Neovascularity occurred in the tumors within 3 weeks of implantation. Each of the solid tumor implants had a histological pattern similar to that of the corresponding original specimen. Only three of those implanted from cell cultures were similar to the original tumor; the other three displayed features characteristic of malignant meningioma. These studies suggest that implantation of human meningiomas in the subrenal capsule of the nude mouse is a feasible model that may be useful for evaluating hormonal or genetic modulation of tumor growth and for testing potential treatment regimens.