BIODEGRADATION OF SYNTHETIC BIPHASIC CALCIUM-PHOSPHATE BY HUMAN MONOCYTES IN-VITRO - A MORPHOLOGICAL-STUDY

Biodegradation processes (both intra- and extracellular) occur immedia tely after implantation of calcium phosphate (CaP) ceramics. Monocytes and macrophages, among the first cells to appear in wound healing, ar e largely implicated in phagocytosis and may be involved in CaP degrad ation because of their sensitivity to secreted cytokines. We tested th e behaviour of human monocytes placed on the surface of hydroxyapatite (HA) and biphasic calcium phosphate (BCP) tablets in the presence of vitamin D-3 (VD3) and interferon gamma (INF gamma). After short-term c ulture (6 days), morphological events were observed in histological an d scanning electron microscopy studies, and degradation lacunae were c haracterized. There were cell prints but no pits on the HA surface, bu t pits appeared near cells on the BCP surface. Preincubation of biomat erial in culture medium was essential. Variations in cell morphology w ere observed in different culture types. In the presence of VD3, degra dation was greater than in the control, and cells were more polarized and rounded. With INF gamma, cells were extensively spread out on the sample surface, and the biomaterial seemed to be extracted from the su rface by cells. Thus, monocytes are clearly influenced by soluble fact ors (vitamins, cytokines) and could be key cells in initiating the deg radation of biomaterial. (C) 1996 Elsevier Science Limited