Biomaterial calcification without direct material-cell interaction.

This report summarizes 1) features of the local redistribution of calcium ions and formation of complexes with calcium (Ca) in the presence of polymer samples; 2) the adsorption of Ca ions and Ca containing complexes onto biomaterial surfaces; 3) the character and composition of Ca containing deposits; and 4) the role of cellular and humoral factors in calcification. All experiments were done with three types of medical grade polymer material (from USSR): silicone rubber (SR), polyurethane "Vitur" (PU), and polyethylene (PE). Biochemical, radioisotopic, SEM, and EDAX methods were used in in vitro and in vivo experiments. The diffusion chamber model was used in animal experiments. SR was shown to induce greater changes in complex formation processes and to adsorb more Ca containing complexes than PE or PU. In addition to the degree of SR calcification seen after 21 days, implantation accentuated these findings. The possibility of calcification of polymer materials without direct contact of material and cells was observed. Combining the in vitro and in vivo experimental data, the authors propose a hypothetical scheme of biomaterial calcification.