Comparative effects of nacre water-soluble matrix and dexamethasone on thealkaline phosphatase activity of MRC-5 fibroblasts

In this study we demonstrate, for the first time, that dexamethasone and BM P-2 stimulated alkaline phosphatase (ALP) activity in MRC-5 fibroblasts, a cell line derived from human fetal luna. Previously we reported that the wa ter-soluble matrix (WSM) of nacre obtained from the inner shell laver of th e oyster Pinctada maxima, promoted an increase in ALP activity that was dos e-dependent. In this work, we show that the effect of WSM is also time-depe ndent. As a comparison, the effect of WSM was also tested in bone marrow st romal cells because marrow and other bone surface-derived osteoblast stem c ells have the inherent direct potential for osteogenesis. WSM promotes cell proliferation and ALP activity when tested with bone marrow cells in conce ntrations between 135 and 540 mug protein/mL. The effect of WSM on ALP acti vity of bone marrow stromal cells is similar to that obtained by dexamethas one. These results imply that MRC-5 fibroblasts respond to differentiating factors that promote osteoblastic phenotype in bone-derived cell cultures. (C) 2001 John Wiley & Sons, Inc.