A method of mRNA production for use in 
transfection is provided, that involves 
in vitro transcription of PCR generated templates with specially designed primers, followed by polyA addition, to produce a construct containing 3′ and 5′ untranslated sequence (“UTR”), a 5′ cap and / or 
Internal Ribosome Entry Site (IRES), the 
gene to be expressed, and a polyA 
tail, typically 50-2000 bases in length. This 
RNA can efficiently transfect different kinds of cells. This approach results in increased efficiency (fidelity and productivity) of mRNA synthesis and is less 
time consuming because it does not require 
cloning, and also consequently eliminates the unwanted errors and effects related to 
RNA made on 
DNA templates obtained with 
cloning techniques. The results of 
transfection of RNAs demonstrate that 
RNA transfection can be very effective in cells that are exceedingly difficult to transfect efficiently with 
DNA constructs. Further, the levels of 
gene expression following 
mRNA transfection are consistent from 
cell to 
cell in an experiment and these levels can be controlled over a wide range simply by changing the amount of mRNA that is transfected, and without obvious cytotoxic effects due to the levels of RNA per se. Due to high efficiency the cells can be simultaneously transfected with multiple genetic constructs. The method can be used to deliver genes into cells not- or only poorly transfectable for 
DNA, 
in vitro and 
in vivo.