Serum starvation improves transient transfection efficiency in differentiating embryonic stem cells

Transcriptomic analysis of the innate immune response to in vitro transfection of plasmid DNA

The innate immune response to cytosolic DNA is intended to protect the host from viral infections, but it can also inhibit the delivery and expression of therapeutic transgenes in gene and cell therapies. The goal of this work was to use mRNA sequencing to identify genes that may influence transfection efficiency in four different cell types (PC-3, Jurkat, HEK-293T, and primary T cells). The highest transfection efficiency was observed in HEK-293T cells, which upregulated only 142 genes with no known antiviral functions after transfection with lipofectamine. Lipofection upregulated 1,057 cytokine-stimulated genes (CSGs) in PC-3 cells, which exhibited a significantly lower transfection efficiency. However, when PC-3 cells were transfected in serum-containing media or electroporated, the observed transfection efficiencies were significantly higher while the expression levels of cytokines and CSGs decreased. In contrast, lipofection of Jurkat and primary T cells only upregulated a few genes, but several of the antiviral CSGs that were absent in HEK-293T cells and upregulated in PC-3 cells were observed to be constitutively expressed in T cells, which may explain the relatively low Lipofection efficiencies observed with T cells (8%-21% GFP⁺). Indeed, overexpression of one CSG (IFI16) significantly decreased transfection efficiency in HEK-293T cells.

Evaluating the Potential of Marine Invertebrate and Insect Protein Hydrolysates to Reduce Fetal Bovine Serum in Cell Culture Media for Cultivated Fish Production

The use of fetal bovine serum (FBS) and the price of cell culture media are the key constraints for developing serum-free cost-effective media. This study aims to replace or reduce the typical 10% serum application in fish cell culture media by applying protein hydrolysates from insects and marine invertebrate species for the growth of Zebrafish embryonic stem cells (ESC) as the model organism. Protein hydrolysates were produced from black soldier flies (BSF), crickets, oysters, mussels, and lugworms with a high protein content, suitable functional properties, and adequate amino-acid composition, with the degree of hydrolysis from 18.24 to 33.52%. Protein hydrolysates at low concentrations from 0.001 to 0.1 mg/mL in combination with 1 and 2.5% serums significantly increased cell growth compared to the control groups (5 and 10% serums) (p < 0.05). All protein hydrolysates with concentrations of 1 and 10 mg/mL were found to be toxic to cells and significantly reduced cell growth and performance (p < 0.05). However, except for crickets, all the hydrolysates were able to restore or significantly increase cell growth and viability with 50% less serum at concentrations of 0.001, 0.01, and 0.1 mg/mL. Although cell growth was enhanced at lower concentrations of protein hydrolysates, the cell morphology was altered due to the lack of serum. The lactate dehydrogenase (LDH) activity results indicated that BSF and lugworm hydrolysates did not alter the cell membrane. In addition, light and fluorescence imaging revealed that the cell morphological features were comparable to those of the 10% serum control group. Overall, lugworm and BSF hydrolysates reduced the serum by up to 90% while preserving excellent cell health.

Augmenting recombinant antibody production in HEK293E cells: Optimising transfection and culture parameters

Background

Optimising recombinant antibody production is important for cost-effective therapeutics and diagnostics. With impact on commercialisation, higher productivity beyond laboratory scales is highly sought, where efficient production can also accelerate antibody characterisations and investigations.

Methods

Investigating HEK293E cells for mammalian antibody production, various transfection and culture parameters were systematically analysed for antibody light chain production before evaluating them for whole antibody production. Transfection parameters investigated include seeding cell density, the concentration of the transfection reagent and DNA, complexation time, temperature, and volume, as well as culture parameters such as medium replacement, serum deprivation, use of cell maintenance antibiotic, incubation temperature, medium volume, post-transfection harvest day and common nutrient supplements.

Results

Using 2 mL adherent HEK293E cell culture transfections with 25 kDa linear Polyethylenimine in the most optimised parameters, we demonstrated a ~ 2-fold production increase for light chain alone and for whole antibody production reaching 536 and 49 μg respectively in a cost-effective manner. With the addition of peptone, κ light chain increased by ~ 4-fold to 1032 μg while whole antibody increased to a lesser extent by ~ 2.5-fold to 51 μg, with benefits potentially for antibodies limited by their light chains in production.

Conclusions

Our optimised findings show promise for a more efficient and convenient antibody production method through transfection and culture optimisations that can be incorporated to scale up processes and with potential transferability to other mammalian-based recombinant protein production using HEK293E cells.

Statement of Significance

Recombinant antibody production is crucial for antibody research and development. Systematically investigating transfection and culture parameters such as PEI/DNA concentrations, complexation time, volume, and temperature, supplements, etc., we demonstrated a ~ 4-fold light chain alone production increase to 1032 μg and a 2.5-fold whole antibody production increase to 51 μg from 2 mL transfections.

Boosting transfection efficiency: A systematic study using layer-by-layer based gene delivery platform

Nowadays, the nanoparticle-based delivery approach is becoming more and more attractive in gene therapy due to its low toxicity and immunogenicity, sufficient packaging capacity, targeting, and straightforward, low-cost, large-scale good manufacturing practice (GMP) production. A number of research works focusing on multilayer structures have explored different factors and parameters that can affect the delivery efficiency of pDNA. However, there are no systematic studies on the performance of these structures for enhanced gene delivery regarding the gene loading methods, the use of additional organic components and cell/particle incubation conditions. Here, we conducted a detailed analysis of different parameters such as (i) strategy for loading pDNA into carriers, (ii) incorporating both pDNA and organic additives within one carrier and (iii) variation of cell/particle incubation conditions, to evaluate their influence on the efficiency of pDNA delivery with multilayer structures consisting of inorganic cores and polymer layers. Our results reveal that an appropriate combination of all these parameters leads to the development of optimized protocols for high transfection efficiency, compared to the non-optimized process (> 70% vs. < 7%), and shows a good safety profile. In conclusion, we provide the proof-of-principle that these multilayer structures with the developed parameters are a promising non-viral platform for an efficient delivery of nucleic acids.

Transfection types, methods and strategies: a technical review

Transfection is a modern and powerful method used to insert foreign nucleic acids into eukaryotic cells. The ability to modify host cells' genetic content enables the broad application of this process in studying normal cellular processes, disease molecular mechanism and gene therapeutic effect. In this review, we summarized and compared the findings from various reported literature on the characteristics, strengths, and limitations of various transfection methods, type of transfected nucleic acids, transfection controls and approaches to assess transfection efficiency. With the vast choices of approaches available, we hope that this review will help researchers, especially those new to the field, in their decision making over the transfection protocol or strategy appropriate for their experimental aims.

Development of Silica-Based Biodegradable Submicrometric Carriers and Investigating Their Characteristics as in Vitro Delivery Vehicles

Nanostructured silica (SiO2)-based materials are attractive carriers for the delivery of bioactive compounds into cells. In this study, we developed hollow submicrometric particles composed of SiO2 capsules that were separately loaded with various bioactive molecules such as dextran, proteins, and nucleic acids. The structural characterization of the reported carriers was conducted using transmission and scanning electron microscopies (TEM/SEM), confocal laser scanning microscopy (CLSM), and dynamic light scattering (DLS). Moreover, the interaction of the developed carriers with cell lines was studied using standard viability, proliferation, and uptake assays. The submicrometric SiO2-based capsules loaded with DNA plasmid encoding green fluorescence proteins (GFP) were used to transfect cell lines. The obtained results were compared with studies made with similar capsules composed of polymers and show that SiO2-based capsules provide better transfection rates on the costs of higher toxicity.

One-Step Formation of Chondrocytes through Direct Reprogramming via Polysaccharide-Based Gene Delivery

An innovative strategy for the generation of chondrocytes was thoroughly studied in this paper. Polyetherimide-modified polysaccharides of Porphyra yezoensis (pmPPY) served as a nonviral gene vector and delivered Sox9 plasmid to directly reprogram mouse embryonic fibroblasts into chondrocytes. The gene transfer efficiency was evaluated through ELISA, RT-PCR, and Western blot. The induced chondrocytes were identified through toluidine blue, Safranin O, and the immunostaining. The expression level of collagen II was finally evaluated through western blot. The pSox9/pmPPY nanoparticles (1:50) showed lower cytotoxicity as well as greater gene transfection efficiency than Lipofectamine 2000 and polyetherimide (PEI) (p<0.05). The results of toluidine blue, Safranin O, and the immunostaining of collagen II further showed that the normal MEFs were successfully reprogrammed into chondrocytes. These findings indicate that pmPPY could be a promising gene vector for the generation of chondrocytes via single-gene delivery strategy, which might provide abundant chondrocytes for cartilage repair.

Novel chitosan based nanoparticles as gene delivery systems to cancerous and noncancerous cells

The present study aimed to investigate in vitro DNA transfection efficiency of three novel chitosan derivatives: thiolated trimethyl chitosan (TMC-Cys), methylated 4-N,N dimethyl aminobenzyl N,O carboxymethyl chitosan(MABCC) and thiolated trimethyl aminobenzyl chitosan(MABC-Cys). After polymer synthesis and characterization, nanoparticles were prepared using these polymers and their size, zeta potential and DNA condensing ability were measured. After that, cytotoxicity and transfection efficiency of nanocomplexes were carried out in three different cells. The results showed that all polymers could condense DNA plasmid strongly from N/P 2 and nanocomplexes had eligible sizes and zeta potentials. Moreover, the nanocomplexes had negligible cytotoxicity and MABC-Cys was the most effective vehicle for gene delivery in HEK-293T cells. In the two other cell lines, SKOV-3 and MCF-7, TMC-Cys exhibited the highest transfection efficiency. This study indicated that chemical structure of these novel chitosan derivatives in the interaction with the cell type can lead to successful gene delivery.

Alterations in Cellular Processes Involving Vesicular Trafficking and Implications in Drug Delivery

Endocytosis and vesicular trafficking are cellular processes that regulate numerous functions required to sustain life. From a translational perspective, they offer avenues to improve the access of therapeutic drugs across cellular barriers that separate body compartments and into diseased cells. However, the fact that many factors have the potential to alter these routes, impacting our ability to effectively exploit them, is often overlooked. Altered vesicular transport may arise from the molecular defects underlying the pathological syndrome which we aim to treat, the activity of the drugs being used, or side effects derived from the drug carriers employed. In addition, most cellular models currently available do not properly reflect key physiological parameters of the biological environment in the body, hindering translational progress. This article offers a critical overview of these topics, discussing current achievements, limitations and future perspectives on the use of vesicular transport for drug delivery applications.

High-Efficient Transfection of Human Embryonic Stem Cells by Single-Cell Plating and Starvation

Nowadays, the low efficiency of small interfering RNA (siRNA) or plasmid DNA (pDNA) transfection is a critical issue in genetic manipulation of human embryonic stem (hES) cells. Development of an efficient transfection method for delivery of siRNAs and plasmids into hES cells becomes more and more imperative. In this study, we tried to modify the traditional transfection protocol by introducing two crucial processes, single-cell plating and starvation, to increase the transfection efficiency in hES cells. Furthermore, we comparatively examined the transfection efficiency of some commercially available siRNA or pDNA transfection reagents in hES cells. Our results showed that the new developed method markedly enhanced the transfection efficiency without influencing the proliferation and pluripotency of hES cells. Lipofectamine RNAiMAX exhibited much higher siRNA transfection efficiency than the other reagents, and FuGENE HD was identified as the best suitable reagent for efficient pDNA transfection of hES cells among the tested reagents.

Genetically-manipulated adult stem cells as therapeutic agents and gene delivery vehicle for wound repair and regeneration

Wound therapy remains a clinical challenge and much effort has been focused on the development of novel therapeutic approaches for wound management. New knowledge about the way in which signals control wound cellular and molecular behavior has promoted the topical application of multipotent stem cells and bioactive molecules to injured tissue, for skin regeneration with less scar formation. However, limited clinical success indicates that the effective delivery of polypeptides and therapeutic cells, with controlled releasing profile, is a major challenge which is yet to be overcome. Recently, a technique in which the genetically-manipulated stem cells were used both as the therapeutic agents and the vehicle for gene delivery for wound treatment - a method which serves to provide regenerative cells and bioactive genes within an optimal environment of regulatory molecular expression for wound sites - has emerged as a promising strategy for wound regenerative therapy. In this article, the roles of adult stem cells - as the therapeutics and the vehicles in these advanced biomimetic drug delivery systems for wound regeneration medicine - are scrutinized to indicate their mechanisms, characteristics, broad applicability and future lines of investigation.