Rational design of transient gene expression process with lipoplexes for high-level therapeutic protein production in HEK293 cells

Increasing Transfection Efficiency of Lipoplexes by Modulating Complexation Solution for Transient Gene Expression

Transient gene expression is a suitable tool for the production of biopharmaceutical candidates in the early stage of development and provides a simple and rapid alternative to the generation of stable cell line. In this study, an efficient transient gene expression methodology using DC-Chol/DOPE cationic liposomes and pDNA in Chinese hamster ovary suspension cells was established through screening of diverse lipoplex formation conditions. We modulated properties of both the liposome formation and pDNA solution, together called complexation solutions. Protein expression and cellular cytotoxicity were evaluated following transfection over the cell cultivation period to select the optimal complexation solution. Changes in hydrodynamic size, polydispersity index, and ζ potential of the liposomes and lipoplexes were analyzed depending on the various pH ranges of the complexation solutions using dynamic light scattering. The transfer of lipoplexes to the cytosol and their conformation were traced using fluorescence analysis until the early period of transfection. As a result, up to 1785 mg/L and 191 mg/L of human Fc protein and immunoglobulin G (bevacizumab), respectively, were successfully produced using acidic liposome formation and alkaline pDNA solutions. We expect that this lipoplex formation in acidic and alkaline complexation solutions could be an effective methodology for a promising gene delivery strategy.

Progress of cationic gene delivery reagents for non-viral vector

Gene delivery systems play a vital role in gene therapy and recombinant protein production. The advantages of using gene delivery reagents for non-viral vector include the capacity to accommodate a large packaging load and their low or absent immunogenicity. Furthermore, they are easy to produce at a large scale and preserve. Gene delivery reagents for non-viral vector are commonly used for transfecting a variety of cells and tissues. It is mainly composed of liposomes and non-liposome cationic polymers. According to the different head structures used, the non-viral cationic transfection reagents include a quaternary ammonium salt, amine, amino acid or polypeptide, guanidine salt, and a heterocyclic ring. This article summarizes these approaches and developments of types and components of transfection reagents and optimization of gene delivery. The optimization of mammalian cell transient recombinant protein expression system and cationic reagents for clinical or clinical trials are also discussed.

Systematic study of liposomes composition towards efficient delivery of plasmid DNA as potential application of dermal fibroblasts targeting

The use of non-viral DNA vectors to topically treat skin diseases has demonstrated a high potential. However, vectors applied on the skin face extracellular barriers including the stratum corneum and intracellular barriers such as the endosomal escape and the nuclear targeting of the plasmid DNA. The aim of this study was to develop a formulation suitable for dermal application and effective for delivering plasmid DNA into cells. Different formulations were prepared using different cationic lipids (DOTAP, DC-Chol, DOTMA) and co-lipids (DOPE, DSPE). Lipoplexes were produced by complexing liposomes with plasmid DNA at different pDNA/CL (w/w) ratios. Our results showed that appropriate pDNA/CL ratios allowing total complexation of plasmid DNA differed depending on the structure of the lipid used. The transfection rates showed that (i) higher rates were obtained with DOTMA lipoplexes, (ii) DC-Chol lipoplexes provided a transfection twice as important as DOTAP lipoplexes and (iii) when DSPE was added, the cytotoxicity decreased while transfection rates were similar. We found that formulations composed of DC-Chol:DOPE:DSPE or DOTMA:DOPE were appropriate to complex plasmid DNA and to transfect human primary dermal fibroblasts with efficacy and limited cytotoxicity. Therefore, these formulations are highly promising in the context of gene therapy to treat skin diseases.