title: Optimizing conditions for calcium phosphate mediated transient transfection.
abstract: BACKGROUND
  Calcium phosphate mediated transfection has been used for delivering DNA into mammalian cells in excess of 30 years due to its most low cost for introducing recombinant DNA into culture cells. However, multiple factors affecting the transfect efficiency are commonly recognized meanwhile for years, the low transfection efficiency of this approach on higher differentiated and non-tumor cells such as CHO and C2C12 limits its application on research.
  
  
  RESULTS
  In this paper, we systematically evaluated the possible factors affecting the transfection rate of this approach. Two categories, calcium phosphate-DNA co-precipitation and on-cell treatments were set for optimization of plasmid DNA transfection into CHO and C2C12 cell-lines. Throughout experimentation of these categories such as buffer system, transfection media and time, glycerol shocking and so on, we optimized the best procedure to obtain the highest efficiency ultimately. During calcium phosphate DNA-precipitation, the transfection buffer is critical condition optimized with HBS at pH 7.10 (P= 0.013 compared to HEPES in CHO). In the transfection step, FBS is a necessary component in transfection DMEM for high efficiency (P= 0.0005 compared to DMEM alone), and high concentration of co-precipitated particles applied to cultured cells in combination with intermittent vortexing is also crucial to preserve the efficiency. For 6-well culture plates, 800 µl of co-precipitated particles (11.25 µg/mL of cDNA) in 1 well is the optimal (P= 0.007 compared to 200 µl). For the highest transfection efficiency, the most important condition is glycerol in shock treatment (P= 0.002 compared to no shock treatment in CHO, andP= 0.008 compared to no shock treatment in C2C12) after a 6 h incubation (P= 0.004 compared to 16 h in CHO, andP= 0.039 compared to 16 h in C2C12) on cultured cells.
  
  
  CONCLUSIONS
  Calcium phosphate mediated transfection is the most low-cost approach to introduce recombinant DNA into culture cells. However, the utility of this procedure is limited in highly-differentiated cells. Here we describe the specific HBS-buffered saline, PH, glycerol shock, vortex strength, transfection medium, and particle concentrations conditions necessary to optimize this transfection method in highly differentiated cells.
authors.affiliation: College of Life Science, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Guo
authors.affiliation: College of Life Science, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Liyang
authors.initials: L
authors.lastname: Wang
authors.affiliation: College of Life Science, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Ronghua
authors.initials: R
authors.lastname: Yang
authors.affiliation: College of Life Science, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Feng
authors.affiliation: College of Life Science, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Zhongguang
authors.initials: Z
authors.lastname: Li
authors.affiliation: College of Life Science, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhou
authors.affiliation: 2nd Hospital, Lanzhou University, Lanzhou, China.
authors.forename: Zhilong
authors.initials: Z
authors.lastname: Dong
authors.affiliation: College of Life Science, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: George
authors.initials: G
authors.lastname: Ghartey-Kwansah
authors.affiliation: Medical Scientist Training Program, Duke University Medical Center, USA.
authors.forename: MengMeng
authors.initials: M
authors.lastname: Xu
authors.affiliation: School of Pharmacology, Kyoto University, Japan.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Nishi
authors.affiliation: College of Chemistry and Materials, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: School of Medicine, Johns Hopkins University, USA.
authors.forename: Williams
authors.initials: W
authors.lastname: Isaacs
authors.affiliation: School of Medicine, Ohio State University, USA.
authors.forename: Jianjie
authors.initials: J
authors.lastname: Ma
authors.affiliation: College of Life Science, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Xuehong
authors.initials: X
authors.lastname: Xu
keywords: C2C12, mouse myoblast cells; CHO, Chinese hamster ovary cells; Calcium phosphate transfection; Co-precipitation; FBS, fetal bovine serum; IntDen, integrated density; PEG, polyethylene glycol; Pen-Strep, penicillinstreptomycin; Transfection efficiency