Invasion Test

Abstract

In cases of malignant brain tumors, the histological diagnosis may be of prognostic value, but the clinical course is sometimes unpredictable. Malignant brain tumors are destructive mainly through their invasive tendency and the pressure they exert as they grow. It is difficult to evaluate a tumor's invasive capacity in a two-dimensional culture system such as monolayer culture. Although threedimensional culture systems have been used for testing the invasive patterns of some malignant tumors, little is known about the invasive mechanisms of neurogenic tumors. Using a modified “invasion test, ” the authors examined the invasive characteristics of four neurogenic cell lines (T1, 9L, T1A, and T1B). Multicellular tumor spheroids (MTS) were produced from tumor cell colonies consisting of 20 to 30 cells by shake culture. With this method, MTS of constant shape and size were obtainable. Pulsating heart tissue obtained from 9-day-old chick embryos was minced and also shake cultured. The MTS and cultured embryonic chick heart (ECH) fragments were placed together in semisolid agar medium for 2 hours, then cultured in a gyratory shaker for 7 days. Tumor invasiveness was examined by hematoxylin-eosin staining and anti-ECH antibody immunostaining. All cell lines examined were able to form MTS and all proved highly invasive.