UTILIZATION OF ACTIVATED U937 MONOCYTIC CELLS AS A MODEL TO EVALUATE BIOCOMPATIBILITY AND BIODEGRADATION OF SYNTHETIC CALCIUM-PHOSPHATE

The use of calcium phosphate biomaterials as a bone substitute necessi tates the use of normative biocompatibility and biodegradation techniq ues which must be fast, simple and reproducible. In the present study, we have developed an in vitro model to study and to compare different calcium phosphate ceramics. After activation with 1,25-dihydroxy-vita min D-3 and phorbol 12,13-dibutyrate, the monoblastic U937 cells becam e multinucleated, expressed tartrate-resistant acid phosphatase and se veral markers of monocyte/macrophage differentiation. Activated U937 c ells did not express the vitronectin receptor (VNR) (as revealed using monoclonal antibodies 23C6 or 13C2) but around 25% of the cells were strongly reactive with 211D, a novel monoclonal antibody that recogniz es an osteoclast-specific membrane antigenic determinant. These cells remain active/viable with hydroxyapatite (HA) or beta-tricarcium phosp hate (beta-TCP) ceramics. In conclusion, activated U937 cells are good candidates to use in a normative in vitro method to evaluate new biom aterials.