Glioma cell interactions with fetal rat brain aggregates in vitro and with brain tissue in vivo.

Two malignant rat neurogenic cell lines have been confronted with reaggregation cultures of fetal rat brain in a stationary culture system. In this organ culture system several morphological aspects of the developing brain are imitated. The malignant cell lines showed invasive and progressive growth into the brain tissue, ending with a completely destroyed aggregate within 10 days of coculture. One cell line (BT5C) showed solid invasion with groups of cells replacing different layers of the brain tissue. A considerable degree of normal cell lysis was seen, both at the edge of invasion and at distant parts of the aggregate. This cell line seemed to activate macrophages in the aggregates. In addition, conditioned medium from these cultures caused degeneration of the brain aggregates. The other cell line (BT4Cn) showed invasion by single cells where the replacement and destruction of the tissue was not accompanied by distant lysis. Both cell lines showed the same pattern of invasion in vitro as was seen in the brains of isogeneic animals in vivo, showing that the individual tumor characteristics were also reflected during invasive growth in organ culture.