The effects of calcium phosphate particles on the growth of osteoblasts

With advances in ceramics technology, calcium phosphate bioceramics have been applied as bone substitutes for several decades. The focus of this work is to elucidate the biocompatibility of the particulates of various calcium phosphate cytotoxicities. Four different kinds of calcium phosphate powders, including β-tricalcium phosphate (β-TCP), hydroxyapatite (HA), β-dicalcium pyrophosphate (β-DCP), and sintered β-dicalcium pyrophosphate (SDCP), were tested by osteoblast cell culture. The results were analyzed by cell count, concentration of transforming growth factor-β1 (TGF-β1), alkaline phosphatase (ALP), and prostaglandin E₂ (PGE₂) in culture media. The changes were most significant when osteoblasts were cultured with β-TCP and HA bioceramics. The changes in cell population of the β-TCP and HA were quite low in the first 3 days, then increased gradually toward the seventh day. The changes in TGF-β1 concentration in culture medium inversely related to the changes in cell population. The ALP titer in the culture media of the β-TCP and HA were quite high in the first 3 days, then decreased rapidly between the third and seventh days. The concentrations of PGE₂ in the culture media tested were quite high on the first day, decreased rapidly to the third day, and then gradually until the seventh day. The changes in the β-DCP and SDCP were quite similar to those of HA and β-TCP but much less significant. We conclude that HA and β-TCP have an inhibitory effect on the growth of osteoblasts. The inhibitins effects of the HA and β-TCP powders on the osteoblast cell cultures possibly are mediated by the increased synthesis of PGE₂.