Lipid-based siRNA Nanodelivery Systems: A Learning Process for Improving Transfer from Concepts to Clinical Applications.

BACKGROUND: The molecular mechanism of silencing genes using small interference RNA is as particular and innovative phenomenon as the proposed delivery systems to release them. Recent advances in RNAi have resulted in the development of multiple siRNA candidates that are currently being evaluated in preclinical / clinical instances. SNALP®, Atuplex® and Rondel® technologies stand out; they are mainly based on polymers, cyclodextrins or lipids. METHOD: The objective of this work is to review the main features that Gene Therapy Medicinal Product under current clinical evaluation present from a pharmaceutical technology point of view; it tries to bring up theoretical concepts that give scientific support to the interpretation of data obtained during pharmaceutical development process. It is basically focused on improving the translation from bench/theoretical concepts to bedside of non viral vectors carrying siRNA. RESULTS: The extensive presence of lipid-based nanoparticle non-viral systems in clinical stages is due to the advantages of their formulations. These include: safety, low immunogenicity, high degree of material properties control, function tuning and ability to impact pharmacokinetics and in vivo biodistribution. This work presents a pharmaceutical approach so as to improve the potential of success in siRNA delivery using liposomal systems. CONCLUSION: Formulation design should be increasingly addressed with industrial criteria; it should be based on quality by design and on the estimation of critical attributes that affect product performance, and supported by a range of characterization techniques and appropriate analytical methods.

Formulation Strategies, Characterization, and In Vitro Evaluation of Lecithin-Based Nanoparticles for siRNA Delivery.

The aim of the present work was to take advantage of lecithin's biocompatibility along with its physicochemical properties for the preparation of lecithin-based nanocarriers for small interfering RNA (siRNA) delivery. Water lecithin dispersions were prepared in different conditions, loaded with siRNA at different N/P ratios, and evaluated for loading capacity. The most appropriate ones were then assayed for cytotoxicity and characterized in terms of particle size distribution, zeta potential, and morphology. Results demonstrated that formulations prepared at pH 5.0 and 7.0 were able to load siRNA at broad N/P ratios, and cellular uptake assays showed an efficient delivery of oligos in MCF-7 human breast cancer cells; fluorescent-labeled dsRNA mainly located next to its target, near the nucleus of the cells. No signs of toxicity were observed for broad compositions of lecithin. The physicochemical characterization of the siRNA-loaded dispersions exhibited particles of nanometric sizes and pH-dependant shapes, which make them suitable for ex vivo and in vivo further evaluation.