Table 2.

Targeting ratio as a function of method of delivery of vector DNA

Transfection method*	Transfection efficiency†	Random integration‡	Site-specific integration§	Gene targeting¶	Targeting ratio‖
Microinjection	ND	1.2  × 10−1	ND	8  × 10−3	1 :15
Electroporation	10% (30)	8.7  × 10−4	2.2  × 10−7	2.1  × 10−7	1 :2,400
Calcium phosphate	24% (155)	2.5  × 10−2	1.2  × 10−4	6.3  × 10−7	1 :40,000
Fugene-6	92% (22)	4.8  × 10−2	7.2  × 10−4	1.3  × 10−7	1 :370,000
LipofectAmine	98% (257)	2.2  × 10−1	1.5  × 10−3	6.2  × 10−7	1 :350,000

ND, not determined. 

^*Microinjection (G. N. Proctor, and J.H.W., unpublished work) used vector pAG-7 and cell line CHO-ATS-49tg (174). Mass delivery methods used vector pGS100, cell line RMP41 (175), and published protocols (175–178). 

^† Transfection efficiency was measured by FACS analysis of cells transfected with plasmid pEYFP-N1 (177). Counting gates were set to include 99% of cells treated in the absence of DNA. Percentages indicate the fraction of treated cells shifted across the counting gate after transfection; numbers in parentheses indicate the mean fluorescence intensity (arbitrary units) of the shifted population. 

^‡ Random integration was measured by selecting for GPT⁺ colonies after transfection of XhoI-linearized pGS100 (175). 

^§ FLP/FRT-mediated site-specific integration of pGS100 into the APRT gene in RMP41 cells was measured after cotransfection of circular pGS100 and pOG44, which expresses the FLP recombinase (175). 

^¶ Targeted HR was measured by selecting for APRT⁺ colonies after transfection of XhoI-linearized pGS100 (175). 

^‖ The targeting ratio is targeted recombinants to random integrants.