THE EFFECTS OF CALCIUM-PHOSPHATE PARTICLES ON THE GROWTH OF OSTEOBLASTS

With advances in ceramics technology, calcium phosphate bioceramics ha ve 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 calc ium phosphate powders, including beta-tricalcium phosphate (beta-TCP), hydroxyapatite (HA), beta-dicalcium pyrophosphate (beta-DCP), and sin tered beta-dicalcium pyrophosphate (SDCP), were tested by osteoblast c ell culture. The results were analyzed by cell count, concentration of transforming growth factor-beta 1 (TGF-beta 1), alkaline phosphatase (ALP), and prostaglandin E-2 (PGE(2)) in culture media. The changes we re most significant when osteoblasts were cultured with beta-TCP and H A bioceramics. The changes in cell population of the beta-TCP and HA w ere quite low in the first 3 days, then increased gradually toward the seventh day. The changes in TGF-beta 1 concentration in culture mediu m inversely related to the changes in cell population. The ALP titer i n the culture media of the beta-TCP and HA were quite high in the firs t 3 days, then decreased rapidly between the third and seventh days. T he concentrations of PGE(2) in the culture media tested were quite hig h on the first day, decreased rapidly to the third day, and then gradu ally until the seventh day. The changes in the beta-DCP and SDCP were quite similar to those of HA and beta-TCP but much less significant. W e conclude that HA and beta-TCP have an inhibitory effect on the growt h of osteoblasts. The inhibitins effects of the HA and beta-TCP powder s on the osteoblast cell cultures possibly are mediated by the increas ed synthesis of PGE(2). (C) 1997 John Wiley & Sons, Inc.