My colleagues and I have run the transfection well by using PolyJet in vitro DNA transfection reagent with an advanced protocol provided by SignaGen Laboratories.
Alternatively, You may try the transfection by electroporation. It can be used with most cell types, yields a high frequency of both stable transformation and transient gene expression.
We did not employ the PolyJet reagent in primary cell setting. In our hard-to transfect cell line, the transfection efficiency with general protocol is ~1% GFP positive cell 48 hr post transfection. When we used the advanced protocol, the transfection efficiency is~25% GFP positive cells. So it may increase more than 20 times compared to general protocol.