Al2O3 doped apatite-wollastonite containing glass ceramic provokes osteogenic differentiation of marrow stromal stem cells

Fresh marrow cells were obtained from femora of Fischer rats and cultured i n a medium containing 15% fetal calf serum (FCS) until confluence. After tr ypsinization, cells were subcultured at a cell density of 100 x 10(3)/35-mm well in the presence of FCS, beta-glycerophosphate, and ascorbic acid phos phate on four different culture substrata. The period of subculture was 2 w eeks; the substrata used were the culture dish, ayatite-wollastonite contai ning glass ceramic (AW), hydroxyapatite coated AW (HA/AW), and Al2O3 doped AW (Al/AW). The HA coating was attained by the incubation of AW in simulate d physiological solution. The glass matrix of AW and HA/AW contained MgO, C aO, P2O5, and SiO2; Al/AW contained Al2O3 in addition to these components. The subculture on Al/AW substratum showed many alkaline phosphatase (ALP) p ositive nodules and the highest ALP activity. On a Northern blot analysis t he housekeeping gene of beta-actin mRNA was evenly detected from the cells cultured on all substrata; however, bone-specific osteocalcin mRNA was only detected from the cells on Al/AW. These results indicate that Al/AW provok es the osteoblastic differentiation of marrow stromal stem cells. (C) 1999 John Wiley & Sons, Inc.