To prepare for an assay where several plasmids need to be transfected together, I am trying to optimize transfection into equine dermal fibroblasts with a constitutive GFP plasmid. I've tried lipofectamine 2000, TransIT LT1 & Turbofect but only got really low transfection efficiency. There are no other equine cell lines available unfortunately, so I have to use this one. Does anyone have a proven fibroblast transfection protocol they could share with me?