There is a growing demand for new innovative technologies for use in “hard-to-transfect” cells such as primary cells and stem cells. Transfection tools are used routinely by 51% of life scientist surveyed. This market segment was valued at $1 billion in 2011 and is predicted to grow to $1.9B by 2016. The objective of this study is the commercial development of lipid nanoparticle (LNP) reagents for the delivery of nucleic acids to turn off or turn on target genes in “hard-to-transfect” primary and stem cells in vitro and in vivo. Specifically, the project will build on compelling preliminary data to accelerate the development of innovative products for the transfection of neurons, erythroid progenitor cells, hematopoietic cells and stem cells. The validation of LNP reagents as tools to manipulate gene function in these “difficult-to-transfect” cells will provide the basis for a suite of commercial reagent kits to address a substantial market need, as these cells are increasingly adopted by scientists to study normal and disease biology.