Angioma fusiform cells stimulated by conditioned medium from melanoma cells secrete a neomatrix which plays a role in "in vitro metastasis".

The rebuilt tumor model is a three dimensional mass of tumoral cells and angioma fusiform cells in collagen. Rebuilt tumors can give rise to "in vitro metastases" and these metastases depend on the presence of a neomatrix secreted in vitro by rebuilt tumor cells. This study defines the origin of the neomatrix and its role in "in vitro metastasis". Fusiform cells of angioma origin (AF3cells) were stimulated ten-fold by growing them in conditioned medium from a human melanoma cell line (MM2). The stimulated AF3 cells produced a dense neomatrix that was firmly attached to the culture flask. The AF3 cells were removed and MM2 cells were grown on this neomatrix. They gave rise to tumorous nodules very like the "in vitro metastases" produced by rebuilt tumors. The MM2 conditioned medium contained basic fibroblast growth factor, which could account for the angiogenetic activity of the tumoral cells. The fusiform cells of angioma origin that are stimulated by cancerous conditioned medium, are responsible for secretion of the neomatrix which plays a role in "in vitro metastasis".