OBJECTIVETo construct a retroviral-mediated vector of FLT3 ligand (FL) and express it in human bone marrow stromal cells.

METHODSFL cDNA was inserted into the retroviral vector pLXIN by gene recombination technology. The recombinant plasmid pLFIN was transferred into retrovirus packaging cell line PA317 by lipofectamine, and the positive clones were selected by G418. The mRNA expression in human stromal cells and integration of genome DNA were assayed by reverse transcriptase-polymerase chain reaction (RT-PCR) and genomic DNA-PCR. The expression of FL protein and its biological activities in the culture were investigated by ELISA and mouse bone marrow CFU-GM assay.

RESULTSThe recombinant plasmid pLFIN was successfully constructed. In genome of these transfected target cells, Neo gene and FL gene were integrated, FL mRNA was transcripted and FL protein was expressed at 4.35 ng/ml/24 h. The specific activities of FL in the culture indicated that human bone marrow stromal cells transfected with FL could significantly express FL in vitro.

CONCLUSIONThe retroviral-mediated FL gene was expressed in bone marrow stromal cells and the biological activities of FL were detectable in the supernatant of the transfected cells. These results provide a basis for studies on hematopoietic regulation by gene transfected bone marrow stromal cells.