Flow cytometry analysis of effects of glass on response of osteosarcoma cells to plasma-sprayed hydroxyapatite/CaO-P2O5 coatings

Multilayered coatings composed of mixtures of hydroxyapatite (HA) and P2O5- based bioactive glasses offer potential clinical benefits in orthopedic and dental surgery. In this study double-layer plasma-sprayed coatings were pr epared and the biological response evaluated in tissue culture using two hu man osteosarcoma cell lines, MG63 and HOS TE85 (HOS). The cells were cultur ed on the materials and the effects on cell growth were determined using a spectrophometric assay of a mitochondrial enzyme that is active in viable c ells. While none of the materials influenced the growth of the MG63 cells, the HOS cells appeared to undergo less proliferation on all the HA material s. Flow cytometry analysis was carried out using rabbit antibodies against osteonectin, osteopontin, bone sialoprotein, fibronectin, and collagen type I to measure the effects of the materials on key cellular functions. The r esults showed that the materials downregulated the expression of these extr acellular matrix antigens by MG63 cells whereas they had less effect on the HOS cells compared to the same cells incubated on a plastic surface. Notab ly, with both cell lines the composite with the higher percentage of glass restored the production of connective tissue proteins to levels that were m ore similar to those present in the control cells. (C) 1999 John Wiley & So ns, Inc.