PHENOTYPIC-EXPRESSION OF MARROW-CELLS WHEN GROWN ON VARIOUS SUBSTRATA

Our aim was to study the role of various extracellular matrices (ECM) on growth and differentiation of marrow stromal cells in vitro. Morpho logy changes, gene expression, and enzymatic activities were monitored in stromal osteoblastic MBA-15 and adipocytic 14F1.1 cells. These str omal cells were plated on dishes precoated with different substrata, s uch as matrigel (basement membrane), collagen type I, and endothelial ECM, and compared with cells plated on protein-free dishes. Striking m orphological differences were observed when the cells grew on these di fferent substrata. Changes in cell shape and growth also led to differ ential mRNA expression and enzymatic activities. When MBA-15 cells wer e plated on collagen, there was a decrease in mRNA for alkaline phosph atase (ALK-P), osteopontin (OP), and osteonectin (ON), and an increase in mRNA for procollagen (I). A differential effect was noted on 14F1. 1 cells, the mRNA for ALK-P increased, the expressions of OP and ON lo wered, and no expression for procollagen (I) was monitored. MBA-15 cel ls cultured on matrigel had decreased mRNA for ALK-P and OP, while the y had increased ON mRNA expression and remained unchanged for procolla gen I. No change in mRNA expression by 14F1.1 cells was monitored when cultured on matrigel. Functional enzymatic activities of ALK-P marked ly decreased in MBA-15 cells cultured on various substrata, and increa sed or were unchanged in 14F1.1 cells. An additional enzyme, neutral e ndopeptidase (CD10/NEP), altered differentially in both cell types; th is enzymatic activity increased or was unchanged when cells were cultu red on these matrices. The results indicate a specific role for differ ent ECM on various stromal cell types and their function. (C) 1996 Wil ey-Liss, Inc.