Methods of study of the invasion of malignant C3H-mouse fibroblasts into embryonic chick heart in vitro.

Methods of study of tumour invasiveness in vitro were investigated using the interactions between malignant virally transformed C3H mouse fibroblasts (MO4) with fragments from embryonic chick heart. Invasion of MO4 cells into the heart tissue could be demonstrated in all three-dimensional cultures. On the contrary, seeding of MO4 cells on top of a monolayer of heart cells did not mimic invasion. Precultured heart fragments were more suitable for the study of the early phase of invasion than freshly cut ones because they presented healthy well-delineated borders. Aggregates of MO4 cells proved more suitable than suspensions or monolayer fragments because they were amenable to quantitation, were not traumatized or treated with enzymes during harvest. They allowed precise control of the initial site of contact with the heart tissue. The nature of the culture medium predominantly affected the growth of the MO4 population. This factor influenced the pattern of invasion quantitatively, but did not alter the invasive capacity of the MO4 cells itself. In cultures on adhesive substrates the interaction between the MO4 cells and the heart tissue was complicated by the fact that both also interacted with the aritficial substrate. Shaker cultures appeared better than comparable static cultures because they allowed better aeration and so delayed central necrosis.