Nonviral, cationic lipid-mediated delivery of mRNA

Appropriate gene delivery systems are essential for successful gene therapy in clinical medicine. Cationic lipid-mediated delivery is an alternative to viral vector-mediated gene delivery where transient gene expression is desirable. However, cationic lipid-mediated delivery of DNA to post-mitotic cells is often of low efficiency, due to the difficulty of DNA translocation to the nucleus. Rapid lipid-mediated delivery of RNA is preferable to nonviral DNA delivery in some clinical applications, because transit across the nuclear membrane is not necessary. Here we describe techniques for cationic lipid-mediated delivery of RNA encoding reporter genes in a variety of in vitro cell lines and in vivo. We describe optimized formulations and transfection procedures that we have previously assessed by flow cytometry. RNA transfection demonstrates increased efficiency relative to DNA transfection in nondividing cells. Delivery of mRNA results in onset of expression within 1 h after transfection and a peak in expression 5-7 h after transfection. These results are consistent with our in vivo delivery results, techniques for which are shown as well. Longer duration and the higher mean levels of expression per cell that are ultimately obtained following DNA delivery confirm a continuing role for DNA gene delivery in clinical applications that require long term transient gene expression. RNA delivery is suitable for short-term transient gene expression due to its rapid onset, short duration of expression, and greater efficiency, particularly in nondividing cells.