A new long-term in vitro invasion assay using fibrous connective tissue matrices maintaining architectural characteristics of connective tissue.

A long-term invasion assay using fibrous connective tissue matrices was developed. The matrices were prepared by treating murine skin or human dura mater with 25 mM ammonium hydroxide containing proteinase inhibitors at 4 degrees C for 7 days. They could be maintained almost indefinitely without the degeneration and necrosis. Electron micrographs of them revealed the preservation of native collagen fibers, and sequential enzyme digestion showed the presence of glycoprotein in the matrices. Local dissolution of extracellular matrix by cultured human rectal adenocarcinoma cell line, RCM-1, was observed morphologically and confirmed by a quantitative assay using radiolabeled matrices. The destruction of extracellular matrix occurred associated with membrane vesicle-shedding from the cells. Both the advantages and disadvantages of this assay were discussed.