Abstract: PURPOSE: To investigate the influence of lyophilization on the biological activity of recombinant lentiviral vectors of bone morphogenetic protein 2(BMP-2). METHODS: Recombinant lenti-BMP-2 was constructed. lenti-BMP-2 was transfected with rat bone marrow stromal cells (BMSCs) by multiplicity infection (MOI) of 10, 25, 50, 100, 200. The infection efficiency was observed by X-gal staining. Under suitable conditions, the lenti-BMP-2 and 10% trehalose ratio of lyophilized protective agent was mixed into the lyophilization form. Before and after lyophilization, the effect of lenti-BMP-2 on the proliferation of BMSCs was evaluated by MTS assay. The expression of BMP-2 protein in the cells of lyophilized lenti-BMP-2 was detected by ELISA method. The expression of Runx-2, OCN, Col1 and OPN in BMSCs was detected by real-time PCR after transfection of lyophilized lenti-BMP-2. SPSS13.0 software package was used for statistical analysis. RESULTS: X-gal staining showed an MOI of 100 pfu/cell, and stable transfection efficiency. Before and after lyophilization, no significant change was observed in regard to the effect of lyophilized lenti-BMP-2 on BMSCs proliferation (P>0.05). ELISA method showed that BMSCs transfected by lyophilized lenti-BMP-2 could express BMP-2 protein continuously and stably at a high level. Before and after lyophilization, the result of real-time PCR showed that no significant difference in the expression of OPN,Col1,OCN and Runx-2 in BMSCs (P>0.05). CONCLUSIONS: Lyophilized lenti-BMP-2 with trehalose can maintain high activity for a long time as an effective and reliable storage method.

Key words: Bone morphogenetic protein 2, Lentiviral vector, Lyophilization, Biological activities