OBJECTIVETo gain stable genetic modification of neural stem cells (NSC) that constitutively secrete brain-derived neurotropic factor (BDNF) and to explore the biological role on the survival and neurite outgrowth of cultured dorsal root ganglion (DRG) neurons.

METHODSBDNF gene fragment from human brain cDNA libraries was obtained by using PCR. With molecular cloning technique, the recombinant stem cell viral vector with report gene was constructed, which is that MSCV-BDNF-IRES(2)-EGFP vector could encode Polycistronic mRNA. Viral particle was packaged by PT67 cell line and infected neural stem cells (mouse clone: C17.2). After selection with cloning cylinder, the expression of BDNF was assessed by immunohistochemistry enzyme linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction (RT-PCR). The effects of stable gene-modified neural stem cells on embryonic mouse DRG neurons were evaluated in a dual-chambered cocultivation system at 3th, 10th day.

RESULTSRT-PCR analysis demonstrated expression of mRNA for human-BDNF. ELISA confirmed the presence of secreted BDNF 24 h after transfection and showed that the level of BDNF production by NSC-BDNF transfected C17.2 was at a rate of (14.6 +/- 0.8) ng x d(-1) x 10(-6) cells even after 3 months. With immunohistochemical analysis, compared with the control, the longer neurite outgrowth of cultured DRG cells and the more survival neurons were observed in NSC-BDNF transfected cells group.

CONCLUSIONSBDNF gene could be stably expressed in C17.2 cell line by MSCV, and the BDNF gene-modified NSC markedly enhances the survival and neurite outgrowth of cultured DRG neurons.