Lipid Nanoparticles

RNA therapeutics are rapidly emerging as a key therapeutic modality. However, a major challenge for broader application remains their specific delivery to target tissues and cells, particularly beyond the liver. While small RNA therapeutics, such as siRNAs or LNAs, can be chemically modified to achieve sufficient stability and tissue uptake, larger molecules, including circRNAs and modRNAs, require specialized formulations that not only protect them from degradation but also enhance cellular uptake.

The clinically most advanced nanocarriers for RNA delivery are lipid nanoparticles (LNPs), with billions of doses administered during the SARS-CoV-2 pandemic, demonstrating their effectiveness and safety. Classic LNPs are composed of four key components: (1) Ionisable lipid, (2) Phospholipid, (3) Cholesterol, (4) Polyethylene glycol (PEG)-conjugated lipid. To assemble these particles, the four lipids are dissolved in an organic solvent and combined with RNA, which is dissolved in a slightly acidic aqueous buffer. In collaboration with the Fraunhofer Institute for Toxicology and Experimental Medicine (ITEM), we employ microfluidic mixing strategies to produce LNP-based RNA therapeutics at micro- to millilitre scale.

Beyond production, we conduct comprehensive LNP characterization to assess hydrodynamic diameter and size distribution, charge, and encapsulation efficiency using techniques such as dynamic light scattering (DLS) and fluorescence-based RNA quantification. We also perform functional investigations to evaluate RNA release, intracellular uptake, and gene expression efficiency in combination with in vitro and in vivo toxicity assessments, to ensure the safety and efficacy of our formulations. These evaluations are critical for optimizing LNP formulations and advancing RNA therapeutics toward clinical applications.

Key references:

Juchem M, Cushman S, Lu D, Chatterjee S, Bär C, Thum T. (2024) Encapsulating In Vitro Transcribed circRNA into Lipid Nanoparticles Via Microfluidic Mixing. Methods Mol Biol. 2765:247-260. https://doi.org/0.1007/978-1-0716-3678-7_14