EVALUATION OF IMPLANT MATERIALS (HYDROXYAPATITE, GLASS-CERAMICS, TITANIUM) IN RAT BONE-MARROW STROMAL CELL-CULTURE

Bone marrow stromal cells of femora from young adult rats produce bone -like mineralized tissue in culture. We evaluated three implant materi als (hydroxyapatite (HA), glass-ceramics (GC) and commercial pure tita nium (Ti)), as to their ability to provide an environment for marrow c ells to differentiate into osteoblasts and function as suitable for mi neralized tissue formation. We did this by measuring the DNA content, alkaline phosphatase (ALP) activity and calcium (Ca) content in cultur e, and the expression of osteopontin and bone sialoprotein by means of analysis of gene expression using Northern hybridization. DNA measure ment showed no difference between each material, but ALP activity and Ca content in the culture on HA and GC were higher than on Ti and the control. An analysis of the gene expression revealed the highest expre ssion of osteopontin and bone sialoprotein in the culture on HA. Miner alized nodule formation (both in area and number) was the most predomi nant on HA, followed by that on GC. These results showed that HA and G C provided a favourable situation for marrow cells to differentiate os teoblasts, resulting in a large amount of mineralized tissue formation on these surfaces. Present in vitro results could explain the rapid b one bonding of HA and GC in vivo.