Effects of the Surface Charge of Stem Cell Membranes and DNA/Polyethyleneimine Nanocomplexes on Gene Transfection Efficiency

In this work, we examined the effects of the surface charge of stem cell membranes and DNA/polyethyleneimine (PEI) nanocomplexes on gene transfection efficiency, because PEI was one of the most reliable and efficient carriers, and rat bone marrow mesenchymal stem cells (rBMSCs) and rat muscle-derived stem cells (rMDSCs) were one of the readily accessible and plentiful sources of stem cells. Thus, we compared the efficiency of DNA transfection in rBMSCs and rMDSCs using the PEI as a gene carrier. Transfection efficiency was evaluated on the basis of electrostatic interaction between negatively charged stem cell membranes and positively charged DNA/PEI nanocomplexes. DNA was fully complexed with PEI at negative-to-positive (NIP) charge ratios greater than 2, as confirmed by gel electrophoresis and fluorescence measurements. DNA and PEI formed spherical nanocomplexes ranging in diameter from 150 nm to 500 nm. The positive surface charge of DNA/PEI nanocomplexes increased with an increasing N/P charge ratio, as measured using dynamic light scattering and a single-walled carbon nanotube-based field-effect transistor device. rBMSCs and rMDSCs both carried a negative surface charge, with rBMSCs being more negatively charged. The transfection efficiency of rMDSCs measured using DNA/PEI nanocomplexes was very low (1%-5%) at most of the N/P charge ratios tested, whereas better efficiencies were observed with rBMSCs (1%-17%). Nanocomplexes with high NIP charge ratios were cytotoxic to both rBMSCs and rMDSCs. Collectively, the results indicate that rBMSCs were more effectively transfected with DNA/PEI nanocomplexes than were rMDSCs, reflecting the higher negative charge of rBMSC membranes that facilitate the interaction with positively charged DNA/PEI nanocomplexes.