COMPARISON OF EXTRACELLULAR-MATRIX IN HUMAN OSTEOSARCOMAS AND MELANOMAS GROWING AS XENOGRAFTS, MULTICELLULAR SPHEROIDS, AND MONOLAYER-CULTURES

Background: The composition of extracellular matrix in human xenograft s and spheroids were compared with the monolayer cultures from which t hey originated Collagen I, fibronectin, acetylglucosamine, and acetylg alactosamine were quantitated in two osteosarcomas and one melanoma. M ethods: Using fluorescence microscopy, extracellular matrix constituen ts in the cellular and extracellular compartment were measured, wherea s flow cytometry measured the extracellular matrix constituents bound to the cell surface as well as the total cellular amount including int racellular and surface bound constituents. Results: The fluorescence m icroscopy measurements, demonstrated that the xenografts contained mor e or equal quantities of the extracellular matrix constituents compare d with the spheroids. Flow cytometric measurements of total cellular a mounts, showed that cells fi om xenografts usually contained more or e qual amounts as the spheroid cells, which contained less or equal amou nts as the monolayer cells. The surface expression of the extracellula r matrix constituents increased or there were no significant differenc es, comparing cells grown as monolayers, spheroids, and xenografts. Co nclusions: The data shows that multicellular spheroids being an in vit ro system of intermediate complexity between monolayer cultures and tu mours, contain an extracellular matrix corresponding to some degree to this intermediate position.