Optimization and physicochemical characterization of a cationic lipid-phosphatidylcholine mixed emulsion formulated as a highly efficient vehicle that facilitates adenoviral gene transfer

Abstract

Cationic lipid-based nanoparticles enhance viral gene transfer by forming electrostatic complexes with adenoviral vectors. We recently demonstrated the superior complexation capabilities of 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) emulsion compared with a liposomal counterpart but the cytotoxicity of DOTAP emulsions remained a challenge. The present study is aimed at formulating an emulsion capable of acting as a highly effective viral gene transfer vehicle with reduced cytotoxicity and to physicochemically characterize the structures of virus-emulsion complexes in comparison with virus–liposome complexes when the only difference between emulsions and liposomes was the presence or absence of inner oil core. The emulsion formulation was performed by 1) reducing the content of DOTAP while increasing the content of zwitterionic lipid 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and 2) optimizing the oil content. The complexation capability of formulated DOTAP:DMPC mixed emulsions was similar to those of emulsions containing DOTAP alone while displaying significantly lower cytotoxicity. The complexation capabilities of the DOTAP:DMPC mixed emulsion were serum-compatible and were monitored in a variety of cell types, whereas its liposomal counterpart was totally ineffective. Characterization by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and dynamic light scattering studies indicated that the optimized emulsions spontaneously surrounded the virus particles to generate emulsions that encapsulated the viral particles, whereas viral particles merely attached to the surfaces of the counterpart liposomes to form multiviral aggregates. Overall, these studies demonstrated that optimized DOTAP:DMPC mixed emulsions are potentially useful for adenoviral gene delivery due to less cytotoxicity and the unique ability to encapsulate the viral particle, highlighting the importance of nanoparticle formulation.

Polymersomes as Stable Nanocarriers for a Highly Immunogenic and Durable SARS-CoV-2 Spike Protein Subunit Vaccine

“…DOTAP-based nanoparticles are generally cytotoxic owing to the cationic nature of the lipid. 38 Although, we had only 30 mM of DOTAP in our polymersomes, we wanted to investigate potential toxicity issues with our vaccine formulation. We incubated the human embryonic kidney 293T (HEK293T) cell line, frequently used for cytoxicity assessment, 39 , 40 with ACM-S1S2 and ACM-CpG individually or in combination and determined cell viability using the MTT assay ( Figure 1 k).…”

Multivesicular Liposomes for the Sustained Release of Angiotensin I-Converting Enzyme (ACE) Inhibitory Peptides from Peanuts: Design, Characterization, and In Vitro Evaluation

“…Some dosage forms have been introduced, such as liposomes [11], nanoliposomes [12], nanoparticle suspension [13], oral microemulsion [14,15], and solid dispersions. However, these showed some shortcomings, such as poor long-term stability [16], small drug loading [17], and unobvious release effect.…”

Complex Size and Surface Charge Determine Nucleic Acid Transfer by Fusogenic Liposomes

“…While concentrations of 25% and lower massively impair fusogeneity, concentrations above 50% continuously result in high fusion efficiencies of 75% and more. Furthermore, cell culture experiments indicate that the transfer of such high concentrations of positively charged lipids by fusion does not induce cytotoxic effects [33] as typically found for other systems [60]. As described by Chernomordik and Kozlov, membrane fusion intermediate states require membrane leaflets with slightly negative curvatures.…”