A Pre-Formulation Study for Delivering Nucleic Acids as a Possible Gene Therapy Approach for Spinocerebellar Ataxia Disorders

Liposomes are lipid bilayer vesicles that are highly biocompatible, able to interact with the cell membrane, and able to release their cargo easily. The improvement of the physicochemical properties of liposomes, such as surface charge, lipid composition, and functionalization, makes these vesicles eligible delivery nanosystems for the gene therapy of many pathological conditions. In the present study, pre-formulation analysis was conducted to develop liposomes that facilitate the delivery of nucleic acids to neuronal cells, with the aim of future delivery of a CRISPR/Cas9 system designed to silence genes responsible for autosomal dominant neurodegenerative disorders. To this aim, different nucleic acid cargo models, including λ phage DNA, plasmid DNA, and mRNA encoding GFP, were considered. Liposomes with varying lipid compositions were produced using the ethanol injection method and analyzed for their dimensional stability and ability to interact with DNA. The selected formulations were tested in vitro using a neuroblastoma cell line (SH-SY5Y) to evaluate their potential toxicity and the ability to transfect cells with a DNA encoding the green fluorescent protein (pCMV-GFP). Among all formulations, the one containing phosphatidylcholine, phosphatidylethanolamine, pegylated 1,2-distearoyl-sn-glycero-3- phosphethanolamine, cholesterol, and dioctadecyl-dimethyl ammonium chloride (in the molar ratio 1:2:4:2:2) demonstrated the highest efficiency in mRNA delivery. Although this study was designed with the goal of ultimately enabling the delivery of a CRISPR/Cas9 system for treating autosomal dominant neurodegenerative disorders such as polyglutamine spinocerebellar ataxias (SCAs), CRISPR/Cas9 components were not delivered in the present work, and their application remains the objective of future investigations.