Transduction of various mammalian bone marrow-derived mesenchymal stem cells by baculovirus

The use of stem cells will lead to novel treatments for a wide range of diseases due to their properties of self-renewing, pluripotent, and undifferentiated state, and the stem cells are usually genetically modified for cell and gene therapy. If the baculovirus, as a new gene vector, can be effectively transduced into various mammalian bone marrow-derived mesenchymal stem cells (BMSCs) in vitro, it will be a better gene vector to genetically modify the stem cells. The aim of the present study is to investigate the transduction efficiency of recombinant baculovirus (BacV-CMV-EGFP), which expressed a reporter gene encoding enhanced green fluorescent protein (EGFP) under a cytomegalovirus immediate early (CMV-IE) promoter, into various mammalian BMSCs. The BMSCs of mouse, rat, porcine, rhesus, and human were cultured primarily in vitro. After more than three passages, the mammalian BMSCs were seeded into dishes and cultured in a humidified incubator at 37 oC with 5% CO2. When the cells reached about 80% confluence, the complete medium was removed by aspiration. The cells were transduced with recombinant baculovirus at a multiplicity of infection (MOI) of 200 vector genomes/cell with 500 μL PBS at 25 oC for 4 h. At the end of baculovirus transduction, cells were washed and incubated with 2 mL complete medium, and baculovirus-transduced mammalian BMSCs were cultured in a humidified incubator for 2 d. Then, the inverted fluorescent microscope was used to observe GFP expressions in different mammalian BMSCs, and flow cytometry was used to detect the transduction efficiency of baculovirus in various mammalian BMSCs. After more than three passages, the BMSCs of mouse, rat, porcine, rhesus, and human showed a homogeneous spindle-shaped morphology. Compared with the BMSCs of mouse, rat and porcine, the inverted fluorescent microscope observations showed that there were more BMSCs expressing GFP and greater mean fluorescence intensity in rhesus and human transduced with baculovirus. The baculovirus could efficiently transduce into the BMSCs of mouse, rat, porcine, rhesus and human, and the transduction efficiency was (20.21±3.02)%, (22.51±4.48)%, (39.13± 5.79)%, (71.16±5.36)% and (70.67±3.74)%, respectively. In conclusion, baculovirus displays different transduction efficiency into various mammalian BMSCs. Due to the high transduction efficiency for primate and human BMSCs, baculovirus is possibly a more suitable gene vector to genetically modify BMSCs of human and primates.