The Role of Cells in the Calcification Process

Although the vertebrate body contains an abundance of potential sites for mineralization, not every tissue calcifies, which indicates that regulatory processes are operative. The mechanisms responsible for stimulating and inhibiting the initiation and progression of mineralization are likely to be cell-mediated, and various experimental systems have been used to study the involvement of cells, the function of which may be regulated systemically or locally. In this chapter, we will discuss experiments in which we studied the role of vitamin D metabolites as regulators of bone matrix calcification in rats in vivo and experiments designed to analyse the factors involved in regulation of de novo mineralization of bone formed in vitro. First, however, we present a brief overview of the matrix constituents associated with calcification.