DNA/PEI nano-particles for gene delivery of rat bone marrow stem cells

The objective of this study was to deliver the DNA/PEI nano-particles into rat bone marrow stem cells (rBMSCs). The formation of nano-particles from DNA and PEI was performed by the adding of the PEI solution to the DNA solution. Gel retardation assay showed the optimal N/P charge ratio where PEI completely binds DNA. The particle size of DNA/PEI complexes measured by dynamic light scattering (DLS) showed diameters of about 200–400 nm. These results indicated that DNA was sufficiently condensed by PEI to give DNA/PEI nano-particles and the optimal packing was achieved at N/P charge ratio of 4. From AFM image, PEI completely condensed DNA into round-shaped. The diameters of the DNA/PEI nano-particles observed by AFM were in good agreement with the results of the DLS. rBMSCs viability in the presence of DNA/PEI nano-particles was evaluated by means of the MTT assay. The DNA/PEI nano-particles were transfected into rBMSCs. After gene transfection, enhanced green fluorescence protein (EGFP) was monitored by flow cytometry. Naked DNA showed no EGFP expression, whereas delivery of DNA/PEI nano-particles to rBMSCs showed EGFP expression and resulted in 2–10% transfection.