Objectives　To observe the gene expression of rat osteoblasts treated with titanium particles and to identify the novel genes which may be related to the periprosthetic osteolysis.　Methods　Neonatal rat osteoblasts were grown in DME medium with 10% bovine serum, and 0.1% titanium particles were added to the medium when the cells reached 80% confluency.After 24 hours，the total RNA was isolated.Messenger RNA differential display techniques were used to compare the differences between the treated and the control group. Furthermore，the differentially displayed gene fragments were isolated，reamplified，and cloned for reverse northern hybridization，northern hybridization and sequencing. The sequences were compared with GenBank database using the BLAST network service at the National Center for Biotechnology Information（NCBI）.　Results　35 fragments were differentially displayed between tho two groups. Of the 35 fragments that were analyzed by reverse northern hybridization，the 5 positive genes were sequenced and compared with NCBI.One of the five positive genes, named G46T, showed 92% homology with mouse macrophage-derived monocyte chemotactic protein-3. The other 4 positives were unknown genes.　Conclusions　Titanium particles may alter the gene expression of rat osteoblasts.G46T gene may be related with periprosthetic osteolysis.

Objectives　To observe the gene expression of rat osteoblasts treated with titanium particles and to identify the novel genes which may be related to the periprosthetic osteolysis.　Methods　Neonatal rat osteoblasts were grown in DME medium with 10% bovine serum, and 0.1% titanium particles were added to the medium when the cells reached 80% confluency.After 24 hours，the total RNA was isolated.Messenger RNA differential display techniques were used to compare the differences between the treated and the control group. Furthermore，the differentially displayed gene fragments were isolated，reamplified，and cloned for reverse northern hybridization，northern hybridization and sequencing. The sequences were compared with GenBank database using the BLAST network service at the National Center for Biotechnology Information（NCBI）.　Results　35 fragments were differentially displayed between tho two groups. Of the 35 fragments that were analyzed by reverse northern hybridization，the 5 positive genes were sequenced and compared with NCBI.One of the five positive genes, named G46T, showed 92% homology with mouse macrophage-derived monocyte chemotactic protein-3. The other 4 positives were unknown genes.　Conclusions　Titanium particles may alter the gene expression of rat osteoblasts.G46T gene may be related with periprosthetic osteolysis.