[A new, in vitro technique for estimating the invasive potential of brain tumors].

  The authors previously reported a new, in vitro technique for determining the invasiveness of four rat neurogenic tumor cell lines. Now this method has been modified and applied to the analysis of the invasiveness of human brain tumors.   Eighty-seven tumors, including 61 gliomas, six metastatic brain tumors, 10 meningiomas, four neurinomas, one melanoma, one hemangioblastoma, two craniopharyngiomas, one chemodec toma, and one pituitary adenoma, were studied. Since gliomas were of primary interest, their in vasiveness was studied more extensively. Fresh tumor specimens obtained during craniotomy were immediately minced in Dulbecco's modified Eagles's minimum essential medium containing 20% fetal calf serum to obtain fragments of 300-500 μm in size. These tumor fragments and precultured embryonic chick heart fragments were placed together on semisolid agar (0.35%) for 2 hours at 37°C. These fused tissues were then cultured in a gyratory shaker at 100 rpm for 7 days. From hematoxylin-eosin stained and immunostained serial sections, the degree of invasiveness was deter mined according to the “classification of i vasiveness.” Although there were discrepancies between the histologic findings and the degree of invasiveness in 22.5% of high-grade astrocytomas, con ventional histological diagnosis was well correlated with invasiveness in almost all low-grade astrocytomas. This in vitro technique appears to be a simple and useful means of evaluating the in vasive potential of brain tumors.