Comparison of invasiveness and non-invasiveness of two epithelial cell lines in vitro.

Two epithelial cell lines of urological origin have been compared for their invasiveness in an in vitro three-dimensional culture system, using embryonic chick cardiac muscle as host tissue. Cells from the Nara bladder tumor line (NBT-II), an invasive tumor in the rat, invaded and progressively occupied the cardiac muscle which degenerated. Cells from a dog kidney line (MDCK), which are of low tumorigenicity in nude mice, failed to invade into the cardiac muscle in vitro. MDCK cells formed a structurally polarized epithelium around the heart tissue. MDCK is the first established epithelial cell line that has been found to grow in this invasion assay culture system and yet did not invade the heart fragment.