Evaluation of the effect of three calcium phosphate powders on osteoblast cells

The aim of the present study was to assess the effect of three calcium phos phate powders entering in the composition of bone substitute materials on o steoblast-cells activity. These powders were hydroxyapatite (HA) widely use d as a biomaterial, nanocrystalline carbonate apatite (C A) very close to b one mineral crystals, and an experimental one: calcium phosphate cement-1 ( CPC-1) composed of an amorphous Ca-P phase and brushite. The powders were p hysico-chemically characterized. The very reactive CPC-1 powder became tran sformed in cell culture medium: recrystallization of amorphous precursors a nd hydrolysis of brushite into poorly crystalline apatite occurred. Osteobl ast-cells activity was evaluated: for low level of calcium phosphates (> 10 0 mug/ml) CPC-1 enhanced proliferation and, to a lesser degree, differentia tion on alkaline phosphatase activity. For 100 mug/ml of powders we observe d a great alteration of biological activity of the osteoblasts: evaluation of proliferation indicated an inhibition for all samples, and a decrease of two differentiation markers: alkaline phosphatase activity and osteocalcin release were noticed, suggesting a down regulation due to the presence of large amount of mineral powder. (C) 2001 Kluwer Academic Publishers.