Widespread Inhibition of Neuroblastoma Cells in the 13- to 17-Day-Old Mouse Embryo1

Previous experiments have demonstrated specific inhibition of tumor formation after neuroblastoma cells were injected into fragments of 8.5to 9.5-day embryonic tissue (A. H. Podestà et ai. Proc. Nati. Acati. Sci. USA, 81: 7608-7611, 1984). The effect was localized to the somite and appeared specific for neuroblastoma as opposed to a variety of other tumor types. This regulation of neuroblastoma cells was believed to reflect an underlying event in the development of migrating embryonic neuroblasts. The current experiments were done to determine the effect on regulation with further embryonic development. The results indicated that later embryos (13 to 17 days of gestation) have a widespread inhibitory effect in all tissues tested, including the adrenal gland, testis, kidney, liver, limb bud, and heart. In contrast a leukemia cell line was not affected by any of these tissues. In organ culture demonstrable colony formation by neuroblastoma was likewise inhibited, and conditioned media from one of these embryonic sources (limb bud) slowed but did not abrogate growth of neuroblastoma cells.