They recently released the AltoFect reagent for hard-to-transfect cell lines, and from preliminary studies my colleagues have shown me, it seems to work best for neuronal cultures when considering siRNA transfection. Here's the official page (https://altogen.com/product/altofect-transfection-reagent/), but they haven't yet listed studies using the reagent. I would bet it works for plasmids, but if you need in vivo look at some of the other reagents (like https://altogen.com/product/pancreas-in-vivo-transfection-kit/), scroll down the page, and you'll see a list of studies that used them. There you can get confirmation of plasmid capability.