AIM: To obtain high level expression of recombinant human truncated osteoprotegerin (TOPG) with higher bioactivity in CHO-DHFR~-cells. METHODS: The recombinant vector pcDNA3.1/DHFR-TOPG was constructed and transfected into CHO-DHFR~- Cells by the directions of LipofectAMINE~(TM)2000 for stable expression. The stable expression cell strains were screened by selective medium IMDM with 50 mL/L FCS, then serially passed in methotraxate (MTX) for gene amplification. The expression were analyzed by ELISA and RT-PCR. At last, the bioactivity analysis was performed in vitro. RESULTS: The expression level of recombinant truncated human OPG was up to 6 mg/L·72 h, and it had significant suppression effect on the formation of OLC(P<0.05). CONCLUSION: Recombinant truncated human OPG has high expression and bioactivity. The results make it possible for further studying and clinical implying of OPG.

Objective To clarify the effects of Xinfukang containing-serum on stromal cell-derived factor-1α (SDF-1α) translation and protein secretion of bone marrow stem cells (BMSCs).Methods BMSCs were isolated and amplified using bone marrow culture method,and were identified by flow cytometry.mRNA and protein secretion of SDF-1α were detected by quantitative PCR (q-PCR) and enzyme linked immunosorbent assay (ELISA),respectively.Results The expression of SDF-1α mRNA were significantly increased after 72 h in drug-containing serum,and SDF-1α mRNA in the experimental group was approximately 200 times as that in the control group (P＜0.05).Secretion of SDF-1 α in the experimental group (277.561 1 ± 15.651 8) pg/ml was nearly doubled compared with that in the control group (153.107 1±14.765 1) pg/ml (P＜0.05).Conclusions BMSCs from whole bone marrow adherent culture have high purity,and drug-containing serum can promote BMSCs to express SDF-1 α mRNA and secretion of SDF-1 α.