title: Salt ions and related parameters affect PEI-DNA particle size and transfection efficiency in Chinese hamster ovary cells.
abstract: Transfection efficiency is directly associated with the expression level and quantity of recombinant protein after the transient transfection of animal cells. The transfection process can be influenced by many still-unknown factors, so it is valuable to study the precise mechanism and explore these factors in gene delivery. Polyethylenimine (PEI) is considered to have high transfection efficiency and endosome-disrupting capacity. Here we aimed to investigate optimal conditions for transfection efficiency by setting different parameters, including salt ion concentration, DNA/PEI ratio, and incubation time. We examined the PEI-DNA particle size using a Malvern particle size analyzer and assessed the transfection efficiency using flow cytometry in Chinese hamster ovary-S cells. Salt ions, higher amounts of PEI tended to improve the aggregation of PEI-DNA particles and the particle size of PEI-DNA complexes and the transfection efficiency were increased. Besides, the particle size was also found to benefit from longer incubation time. However, the transfection efficiency increased to maximum of 68.92 % at an incubation time of 10 min, but decreased significantly thereafter to 23.71 %, when incubating for 120 min (P < 0.05). Besides, PEI-DNA complexes formed in salt-free condition were unstable. Our results suggest DNA and PEI incubated in 300 mM NaCl at a ratio of 1:4 for 10 min could achieve the optimal transfection efficiency. Our results might provide guidance for the optimization of transfection efficiency and the industrial production of recombinant proteins.
authors.affiliation: School of Pharmacy, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Shanghai, 200240, People's Republic of China.
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Sang
authors.forename: Kui
authors.initials: K
authors.lastname: Xie
authors.forename: Yubin
authors.initials: Y
authors.lastname: Mu
authors.forename: Yun
authors.initials: Y
authors.lastname: Lei
authors.forename: Baohong
authors.initials: B
authors.lastname: Zhang
authors.forename: Sheng
authors.initials: S
authors.lastname: Xiong
authors.forename: Yantian
authors.initials: Y
authors.lastname: Chen
authors.forename: Nianmin
authors.initials: N
authors.lastname: Qi