Ionic liquid-coated lipid nanoparticles increase siRNA uptake into CNS targets.

Lipidoid nanoparticles (LNPs) have transformed the field of drug delivery and are clinically used for the delivery of nucleic acids to liver and muscle targets. Post-intravenous administration, LNPs are naturally directed to the liver due to the adsorption of plasma proteins like apolipoprotein E. In the present work, we have re-engineered LNPs with ionic liquids (ILs) to reduce plasma protein adsorption and potentially increase the accumulation of LNPs in hard-to-deliver central nervous system (CNS) targets such as brain endothelial cells (BECs) and neurons. We have developed two approaches to re-engineer LNPs using a choline trans-2-hexenoate IL: first, we have optimized an IL-coating process using the standard LNP formulation and in the second approach, we have incorporated ILs into the LNPs by replacing the PEG-lipid component in the standard formulation using ILs. IL-coated as well as IL-incorporated LNPs were colloidally stable with morphologies similar to the standard LNPs. IL-coated LNPs showed superior uptake into mouse BECs and neurons and demonstrated reduced mouse plasma protein adsorption compared to the standard LNPs. Overall, our results (1) demonstrate the feasibility of re-engineering the clinically approved LNP platform with highly tunable biomaterials like ILs for the delivery of therapeutics to CNS targets like BECs and neurons and (2) suggest that the surface properties of LNPs play a critical role in altering their affinity to and uptake into hard-to-deliver cell types.

Lipid nanoparticle-mediated drug delivery to the brain.

Lipid nanoparticles (LNPs) have revolutionized the field of drug delivery through their applications in siRNA delivery to the liver (Onpattro) and their use in the Pfizer-BioNTech and Moderna COVID-19 mRNA vaccines. While LNPs have been extensively studied for the delivery of RNA drugs to muscle and liver targets, their potential to deliver drugs to challenging tissue targets such as the brain remains underexplored. Multiple brain disorders currently lack safe and effective therapies and therefore repurposing LNPs could potentially be a game changer for improving drug delivery to cellular targets both at and across the blood-brain barrier (BBB). In this review, we will discuss (1) the rationale and factors involved in optimizing LNPs for brain delivery, (2) ionic liquid-coated LNPs as a potential approach for increasing LNP accumulation in the brain tissue and (3) considerations, open questions and potential opportunities in the development of LNPs for delivery to the brain.

Lipidoid nanoparticles increase ATP uptake into hypoxic brain endothelial cells.

Lipidoid nanoparticles (LNPs) are clinically successful carriers for nucleic acid delivery to liver and muscle targets. The ability of LNPs to load and deliver small molecule drugs has not been reported yet. We propose that the delivery of adenosine triphosphate (ATP) to brain endothelial cells (BECs) lining the blood-brain barrier may increase cellular energetics of the injured BECs. We formulated and studied the physicochemical characteristics of ATP-loaded LNPs using the C12-200 ionizable cationic lipid and other helper lipids. Polyethylene glycol-dimyristoyl glycerol (PEG-DMG), one of the helper lipids, played a crucial role in maintaining colloidal stability of LNPs over time whereas the inclusion of both ATP and PEG-DMG maintained the colloidal stability of LNPs in the presence of serum proteins. ATP-LNPs formulated with PEG-DMG resulted in a 7.7- and 6.6- fold increased uptake of ATP into normoxic and hypoxic BECs, respectively. Altogether, our results demonstrate the potential of LNPs as a novel carrier for the delivery of small molecular mass actives to BECs-a CNS target.

Gellan gum-based in situ gelling ophthalmic nanosuspension of Posaconazole.

The formulation and delivery of highly hydrophobic drugs in an optimized dosage form is challenging to formulation scientists. Posaconazole has shown promising action in case studies against fungal keratitis. Biological macromolecules like gellan gum would aid in enhancing the availability of such drugs by increasing the contact time of the formulation. Herein, we propose a transmucosal ocular delivery system of Posaconazole by developing a gellan gum-based in situ gelling nanosuspension. The HPLC method for Posaconazole was developed and validated as per ICH guidelines. The nanosuspension was prepared by microfluidization and optimized by Quality by Design. The gellan gum concentration selected was 0.4% w/v based on the viscosity and mucoadhesion measurements. A greater zone of inhibition of ~ 15 mm was observed for the prepared nanosuspension as compared to ~ 11 mm for the marketed itraconazole nanosuspension. A potential irritancy score of 0.85, considered to be non-irritant, was observed for the developed nanosuspension. Higher drug release of ~ 35% was noted for the nanosuspension compared to about ~ 10% for the coarse suspension. Ex vivo corneal retention studies on excised goat cornea demonstrated ~ 70% drug retention in the tissue. Graphical abstract depicting the central hypothesis of the work.

Development of Lipidoid Nanoparticles for siRNA Delivery to Neural Cells.

Lipidoid nanoparticles (LNPs) are the delivery platform in Onpattro, the first FDA-approved siRNA drug. LNPs are also the carriers in the Pfizer-BioNTech and Moderna COVID-19 mRNA vaccines. While these applications have demonstrated that LNPs effectively deliver nucleic acids to hepatic and muscle cells, it is unclear if LNPs could be used for delivery of siRNA to neural cells, which are notoriously challenging delivery targets. Therefore, the purpose of this study was to determine if LNPs could efficiently deliver siRNA to neurons. Because of their potential delivery utility in either applications for the central nervous system and the peripheral nervous system, we used both cortical neurons and sensory neurons. We prepared siRNA-LNPs using C12-200, a benchmark ionizable cationic lipidoid along with helper lipids. We demonstrated using dynamic light scattering that the inclusion of both siRNA and PEG-lipid provided a stabilizing effect to the LNP particle diameters and polydispersity indices by minimizing aggregation. We found that siRNA-LNPs were safely tolerated by primary dorsal root ganglion neurons. Flow cytometry analysis revealed that Cy5 siRNA delivered via LNPs into rat primary cortical neurons showed uptake levels similar to Lipofectamine RNAiMAX-the gold standard commercial transfection agent. However, LNPs demonstrated a superior safety profile, whereas the Lipofectamine-mediated uptake was concomitant with significant toxicity. Fluorescence microscopy demonstrated a time-dependent increase in the uptake of LNP-delivered Cy5 siRNA in a human cortical neuron cell line. Overall, our results suggest that LNPs are a viable platform that can be optimized for delivery of therapeutic siRNAs to neural cells.