Type I collagen-induced osteoblastic differentiation of bone-marrow cells mediated by collagen-alpha 2 beta 1 integrin interaction

Bone marrow cells are multipotent cells. When bone marrow cells were cultur ed with type I collagen matrix gels, they showed high alkaline phosphatase activity, collagen synthesis, and formed mineralized tissues. Furthermore, cells expressed osteocalcin and bone sialoprotein genes, which are osteobla st-specific genes. These findings indicate that type I collagen matrix gels induce osteoblastic differentiation of bone marrow cells. Type I collagen interacts with the a 2 beta 1 integrin receptor on the cell membrane and me diates extracellular signals into cells. DGEA peptide is a cell-binding dom ain of type 1 collagen molecule. When collagen-integrin interaction was int errupted by the addition of Asp-Gly-Glu-Ala (DGEA) peptide to the culture, the expression of osteoblastic phenotypes of bone marrow cells was inhibite d. Furthermore, anti-alpha 2 integrin antibody, which interacts with a subu nit of integrin and blocks the binding of integrin with collagen, suppresse d the expression of osteoblastic phenotypes. These findings imply that coll agen-alpha 2 beta 1 integrin interaction is an important signal for the ost eoblastic differentiation of bone marrow cells. J. Cell. Physiol. 184:207-2 13, 2000. (C) 2000 Wiley-Liss, Inc.