Optimization of a Dissolvable Lipid Nanoparticle Microneedle Formulation for mRNA Delivery Using Design of Experiments.

Microneedles (MNs) are an emerging strategy to realize the transdermal delivery of lipid nanoparticles (LNPs) in a minimally invasive manner. Via development, the LNP's physicochemical properties, such as size and charge, and the MN's composition and fabrication procedure, must be optimized. Currently, the optimization is done through trial and error, which is heavily influenced by personal experience and preference of researchers. This study utilizes Design of Experiments (DoE) for optimizing parameters in LNP-MN fabrication to gain independence from personal experience and preference. As a proof of concept, we develop an LNP-MN device to deliver mRNA encoding green fluorescent protein (GFP). Flow cytometric analysis reveals that freshly prepared LNP-MNs achieve a transfection efficiency of 43.3% in mesenchymal stem cells, compared with 8.51% for the lipofectamine control. The LNP-MN group also provides more homogeneous transfection (99.4% GFP positive cells), while the number is only 31.0% in the lipofectamine group. mRNA-LNP-MN maintains a transfection efficiency of 22.7% after 42 days of storage at room temperature. Finally, luciferase mRNA is successfully transfected into mice by the mRNA-LNP-MN delivery system.