Efficient and effective transfection reagents are essential for protein expression in eukaryotic cells. Recent years have seen a rapid expansion in the number and type of transfection reagents available from different manufacturers. Invitrogen have taken the unusual step of releasing the PLUS™ Reagent. Rather than being a stand-alone transfection reagent, PLUS™ Reagent is designed as an additive to boost the efficiency of existing transfection reagents.
According to Invitrogen, this reagent enhances cationic lipid-mediated DNA transfection by aiding in the stage in transfection where DNA is complexed to the lipids. PLUS™ is designed for transfection of DNA and RNAi (not siRNA) and can be used with a range of Invitrogen transfection reagents including Lipofectamine™ LTX LINK TO LTX REVIEW, Lipofectamine, Lipofectin™ Cellfectin™ and Oligofectamine™ Reagents. No mention is made of using this enhancer with cationic lipid reagents from other manufacturers.
The protocol for use is simple. In a normal transfection, the DNA is diluted in media before the addition of the transfection reagent (this may vary slightly with different reagents). The DNA and reagent are incubated to allow complexes to form, before being added to adherent or suspension cells. Only a minor modification in the protocol is required: a small amount (0.5 µl for one well of a 24-well plate) of the PLUS™ reagent is added to the DNA before the transfection reagent and then the transfection is carried out as normal. There should be no effect on the toxicity of the transfection mix and no change in media is mentioned as necessary. However, each cell line may react differently.
We have trialed this product in our laboratory with a number of cell lines. We used Lipofectamine™ LTX reagent and common cell lines such as VERO and BHK-21 in OPTI-MEM® I Reduced Serum medium. A slight increase in transfection efficiency was seen with these cell lines; however, not enough of an increase to warrant the extra steps in the protocol and expense of the additional reagent. The product insert states that the efficiency of enhancement is dependent on the cell line. It is possible that hard-to-transfect cell lines would benefit form using the PLUS™ reagent, if you already have an established protocol using the reagents mentioned. However, if you are experiencing trouble with your transfections it may pay to change the type of reagent completely rather than add an enhancer.
Research Scholar
School of Molecular and Microbial Sciences
The University of Queensland