Comparison the cytotoxicity of hydroxyapatite measured by direct cell counting and MTT test in murine fibroblast NIH-3T3 cells

The worldwide growing interest to biomaterials over the last years results from their irreplaceable role in medical clinic. Hydroxyapatite is used in bone reconstruction because of its similar chemical structure compared to the inorganic composition of human bone and it is basic building component of many newly prepared biomaterials. In this study, we evaluated cytotoxic/antiproliferative activity of hydroxyapatite extract using murine fibroblast cell line NIH-3T3 and two in vitro different cytotoxic assays: growth inhibition assay and MTT assay. Hydroxyapatite extract after 72 h of incubation manifested the significant in vitro cytotoxic/antiproliferative effect only at the highest concentration tested (100 %). The antiproliferative effect of hydroxyapatite extract at the other concentrations tested (75 %, 50 %, 25 %, 10 %, 5 % and 1 %) was directly proportional to the concentration and the time of influence. The inhibition of cell proliferation was 86.8 - 0 %. The sensitivity of cell growth inhibition assay (direct counting of viable cells) to the extract influence was higher than that of MTT test.