Alkaline phosphatase and type I collagen gene expressions were reduced by hydroxyl radical-treated fibronectin substratum.

The influence of fibronectin (FN) substratum treated with hydroxyl radicals (.OH) generated by the H2O2-Cu2+ systems on osteoblast cells was studied. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that FN was degradated and/or modified by .OH treatment. The calcified bone nodule formation of osteoblast cells cultured on .OH treated FN-coated wells was significantly lower compared to those on intact FN-coated wells. Alkaline phosphatase (ALP) activity and the secretion of type I collagen were reduced by .OH-treated FN. By RT-PCR mRNA levels of ALP and type I collagen genes were also diminished. These findings suggested that the .OH damaged FN molecules and reduced the bone formation of osteoblast cells via inhibition of proliferation and/or differentiation of osteoblast progenitors and the calcification process. Copyright 1998 Academic Press.