Abstract
We have reported several acidic noncollagenous proteins in the acetic acid extract of bovine femoral cortical bone, characteristic of their acidity and high affinity to collagen. In this study, we investigated effects of the collagen-high affinity proteins (C-HAP) on the process of bone formation using osteoblast-like MC3T3-E1 cells. To the calcification-promoting medium for MC3T3-E1 cells were added the excess amount of endogenous protein fractions containing C-HAP or exogenous polyglutamic acid (PGA). The process of bone formation of MC3T3-E1 cells were evaluated by the change of cell shape, ALP activity, accumulation of protein and calcification of bone matrix. Thus, it concluded that (1) PGA stimulated ALP activity, accumulation of protein and calcification of bone matrix, (2) C-HAP inhibited ALP activity but stimulated accumulation of protein and calcification of bone matrix, and (3) PGA maintained a polygonal shape in cell structure and C-HAP modulated a cells to a spindle shape. We discussed also whether the collagen-high affinity proteins may play some important roles in the calcification process of bone formation.
