EXTRACELLULAR-MATRIX PENETRATION BY EPITHELIAL-CELLS IS INFLUENCED BYQUANTITATIVE CHANGES IN BASEMENT-MEMBRANE COMPONENTS AND GROWTH-FACTORS

We have previously shown that isolated mouse fetal choroid plexus epit helial (CPE) cells penetrate a basement membrane matrix (Matrigel) sub strate in vitro to form single-layered epithelial vesicles embedded wi thin the matrix. To determine which properties of the matrix are impor tant for inducing or permitting cells to penetrate the substrate and o rganize into multicellular vesicles we have made quantitative changes to the basement membrane components and growth factors in cell culture s. Matrigel diluted to 33 or 10% with a collagen I gel was not permiss ive to cell invasion, and CPE cells formed a polarized epithelial mono layer on the substrate surface which had ultrastructural characteristi cs similar to those of CPE vesicles. Cells in these monolayers prolife rated more rapidly than cells in epithelial vesicles. When deliberatel y embedded within a 33 or 10% Matrigel matrix, CPE cells were able to form vesicles, indicating that a dilute matrix is nonpermissive to cel l invasion but promotes epithelial polarization and organization into vesicles. Cells embedded within a 100% collagen I matrix did not proli ferate or form epithelial vesicles and the majority of cells did not r emain viable. Addition of laminin to the collagen I gel promoted cell adhesion and cell survival, but did not promote the formation of exten sive monolayers on the substrate nor the formation of epithelial vesic les within the matrix. Cell invasion into the 33% Matrigel matrix was induced by addition of laminin, nidogen, or a laminin-nidogen complex to the substrate or by addition of TGF beta 2 to the culture medium, b ut not TGF beta 1 or PDGF. These studies show that CPE cells are sensi tive to quantitative changes in matrix composition, which influences t heir survival and proliferation and also their ability to penetrate th e matrix and organize into multicellular epithelial vesicles. (C) 1996 Academic Press, Inc.