Polyethylenimine-mediated transfection of human monocytes with the IFN-gamma gene: an approach for cancer adoptive immunotherapy

Optimized Recombinant Production of Secreted Proteins Using Human Embryonic Kidney (HEK293) Cells Grown in Suspension

Recombinant proteins are an essential milestone for a plethora of different applications ranging from pharmaceutical to clinical, and mammalian cell lines are among the currently preferred systems to obtain large amounts of proteins of interest due to their high level of post-translational modification and manageable large-scale production. In this regard, human embryonic kidney 293 (HEK293) cells constitute one of the main standard lab-scale mammalian hosts for recombinant protein production since these cells are relatively easy to handle, scale-up, and transfect. Here, we present a detailed protocol for the cost-effective, reproducible, and scalable implementation of HEK293 cell cultures in suspension (suitable for commercially available HEK293 cells, HEK293-F) for high-quantity recombinant production of secreted soluble multi-domain proteins. In addition, the protocol is optimized for a Monday-to-Friday maintenance schedule, thus simplifying and streamlining the work of operators responsible for cell culture maintenance. Graphic abstract: Schematic overview of the workflow described in this protocol.

An update on the therapeutic role of alkylglycerols

Scandinavian folk medicine used shark liver oil for the treatment of cancers and other ailments based on the rarity of tumors in sharks and their ability to resist infections. Shark liver oil is a source of alkylglycerols which have been studied as anti-cancer agents in several clinical trials. Moreover, alkylglycerols have been investigated for the treatment of radiation induced side effects and for their ability to boost the immune system. Several experimental studies have shown the ability of alkylglycerols to open the blood brain barrier to facilitate the access of therapeutic drugs to the central nervous system. This review covers the most important studies of alkylglycerols in both animals and humans.

Influence of murine hepatitis induced by D-(+)-galactosamine hydrochloride and lipopolysaccharide on gene expression of polyethylenimine/plasmid DNA polyplex

We investigated the influence of murine hepatitis induced by D-(+)-galactosamine and lipopolysaccharide (D-GalN/LPS) on polyethylenimine (PEI)-mediated plasmid DNA (pDNA) delivery. pDNA encoding firefly luciferase was used as the model reporter gene. PEI was used as the non-viral vector because of its high gene expression and low toxicity. The activities of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in mice indicated the highest peaks at 12 h after D-GalN/LPS injection, then the activities of serum ALT and AST rapidly decreased. We determined luciferase activity in various organs of D-GalN/LPS-treated mice and control mice after an intravenous administration of PEI/pDNA complexes. High transgene expression was observed in the liver, spleen, and lung of both mice. Compared to the control mice, a significant increase of transgene expression was observed in the liver of D-GalN/LPS-treated mice after D-GalN/LPS injection. The transgene expression in the spleen and lung decreased at 6 and 12 h after D-GalN/LPS injection. In conclusion, we found that murine hepatitis induced by D-GalN/LPS injection can influence PEI-mediated pDNA delivery and its influence was different from that induced by CCl(4) injection which was reported previously. These results demonstrated the necessity of considering the timing and dose of gene therapy according to the disease and its stage.

Pharmacological immunomodulation enhances peripheral nerve regeneration

To assess the effect of N-Acetylmuramyl-L-Alanyl-D-Isoglutamine MDP topically administrated on the regenerating peripheral neurons, twelve male C57BL/6J adult mice were equally distributed into three groups. Four mice underwent unilateral sciatic nerve transection and polyethylene tubulization, with a 4mm gap between the proximal and distal nerve stumps and were implanted with collagen + PBS (COL). Other four animals underwent the same surgical procedure but received collagen + MDP (COL/MDP) inside the prosthesis. Four animals were not operated and served as control group (NOR). After 4 weeks, the regenerated nerve cables were processed for total myelinated axon counting and myelinated fiber diameter measurement. The L5 dorsal root ganglion (DRG) was also removed and sectioned for sensory neurons counting and measurement. The results revealed significant difference (p<0.05) in axonal counting among the groups NOR (4,355±32), COL (1,869±289) and COL/MDP (2,430±223). There was a significant reduction in the axonal diameter in the operated groups (COL=3.38µm±1.16 and COL/MDP=3.54µm±1.16) compared to NOR (6.19µm±2.45). No difference was found in the number of DRG neurons between the experimental groups (COL=564±51; COL/MDP=514±56), which presented fewer sensory neurons compared to NOR (1,097±142). Data obtained indicate that locally applied MDP stimulates peripheral nerve regeneration in mice.

Influence of disease stage on polyethylenimine-mediated plasmid DNA delivery in murine hepatitis

In order to determine the influence of hepatic disease-stage on polyethylenimine-mediated gene delivery, we investigated branched and linear polyethylenimine (B-PEI, L-PEI)-mediated plasmid DNA delivery with time in murine hepatitis induced by a subcutaneous injection of tetrachloro carbon (CCl(4)). Plasmid DNA (pDNA) encoding firefly luciferase was used as the model reporter gene. We determined luciferase activity in various organs of CCl(4)-treated mice and control mice after an intravenous administration of B-PEI and L-PEI/pDNA complexes. Both B-PEI and L-PEI/pDNA complexes showed significantly lower gene expression in the liver, spleen, and lung at the stage of severe hepatitis (18 h after CCl(4) injection), whereas the complexes induced gene expression in the liver at the liver regeneration stage (48 h after CCl(4) injection). Significant differences in gene expressions between CCl(4)-treated mice and control mice vanished in most organs at the hepatitis subsidence stage (168 h after CCl(4) injection), indicating that the influence of hepatitis induced by CCl(4) was reversible with PEI-mediated gene delivery. Our findings demonstrated that murine hepatitis induced by CCl(4) could influence polyethylenimine-mediated plasmid DNA delivery according to the disease stage. These results indicate the necessity of considering the timing and dose of gene therapy according to the disease stage.

Acetylation of poly(ADP-ribose) polymerase-1 by p300/CREB-binding protein regulates coactivation of NF-kappaB-dependent transcription

Poly(ADP-ribose) polymerase-1 (PARP-1) and nuclear factor kappaB (NF-kappaB) have both been demonstrated to play a pathophysiological role in a number of inflammatory disorders. We recently presented evidence that PARP-1 can act as a promoter-specific coactivator of NF-kappaB in vivo independent of its enzymatic activity. PARP-1 directly interacts with p300 and both subunits of NF-kappaB (p65 and p50) and synergistically coactivates NF-kappaB-dependent transcription. Here we show that PARP-1 is acetylated in vivo at specific lysine residues by p300/CREB-binding protein upon stimulation. Furthermore, acetylation of PARP-1 at these residues is required for the interaction of PARP-1 with p50 and synergistic coactivation of NF-kappaB by p300 and the Mediator complex in response to inflammatory stimuli. PARP-1 physically interacts with the Mediator. Interestingly, PARP-1 interacts in vivo with histone deacetylases (HDACs) 1-3 but not with HDACs 4-6 and might be deacetylated in vivo by HDACs 1-3. Thus, acetylation of PARP-1 by p300/CREB-binding protein plays an important regulatory role in NF-kappaB-dependent gene activation by enhancing its functional interaction with p300 and the Mediator complex.

Picolinic acid- or desferrioxamine-inducible autocrine activation of macrophages engineered to produce IFNγ: an approach for gene therapy

Macrophage (Mphi)-based vectors are highly mobile cellular shuttles designed to deliver therapeutic genes within the tissues. We engineered a mouse Mphi cell line to express the murine interferon-gamma (IFNgamma) under the control of an inducible promoter containing the hypoxia-responsive element, which can be triggered by hypoxia and other stimuli. We show that this Mphi vector can be induced to produce IFNgamma under normoxic conditions by stimulation with picolinic acid (PA), a catabolite of tryptophan, or desferrioxamine (DFX), an iron-chelating drug. The Mphi vector responds to IFNgamma with the induction of IRF-1 and of other IFNgamma-inducible genes, the expression of Ia antigens and induction of phagocytic activity. Inducible nitric oxygen synthase gene expression, nitric oxide production, as well as TNFalpha secretion were enhanced by PA or DFX as the sole stimuli. None of the above responses could be triggered individually by PA or DFX in control, normal Mphi, indicating that the Mphi vector overcame the need for costimulatory molecules derived from the immune system for its full activation. Furthermore, we demonstrate that extracellular iron can downregulate such response, thereby identifying an additional tool for the fine tuning of the Mphi vector response to stimulation.

Transcription from the tartrate-resistant acid phosphatase promoter is negatively regulated by the Myc oncoprotein

TRAP, a characteristic marker of osteoclast differentiation, is an enzyme that plays an active role in the process of bone resorption. Despite the importance of TRAP in osteoclast biology, the components involved in the transcriptional regulation of this gene are largely unknown. This study investigated the regulation of TRAP transcription by the Myc oncoprotein in three different cell types. A series of nested TRAP promoter deletion constructs were cotransfected into P388D1 murine macrophages and C3H10T1/2 murine embryonic fibroblasts along with a backbone plasmid control or expression plasmids containing v-Myc, c-Myc, or an inactive v-Myc protein construct (delta84/NLS). Both v-Myc and c-Myc negatively regulated transcription from the TRAP promoter in P388D1 and C3H10T1/2 cells, 90% and 50%, respective to cell type and amount of endogenous Myc protein, and delta84/NLS had no effect. The functional Myc-responsive element(s) within the TRAP promoter was localized to a region between -436 and +1 bp, which contains two putative Myc-inhibitory binding sites coincident with an initiator element (Inr) at -116 bp and -18 bp. Conversely, in the HD-11EM chicken v-Myc transformed preosteoclast cell line, the full-length TRAP promoter transcription was increased when endogenous v-Myc levels were decreased in response to pretreatment of these cells with 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3]. This report provides the first evidence of the specific regulation of TRAP at the transcriptional level by Myc, a transcription factor that is normally expressed at relatively high levels in preosteoclasts and other myelomonocytic cells and suggests that Myc plays an active role in suppressing the transcription of a mature osteoclast selective gene.

Efficient gene delivery via non-covalent complexes of folic acid and polyethylenimine

Polyethylenimine (PEI) is a cationic polymer capable of delivering DNA molecules into cultured mammalian cells as charge complexes. The application of PEI polyplexes in gene therapy, however, is hampered by the sensitivity of its transfection activity to the presence of serum. We found that folic acid, in a variety of cell lines, significantly enhanced PEI-mediated transfection activity in the presence of serum, whether the folic acid was added during or after PEI/DNA polyplex formation. The increase in activity could not be produced with other anionic compounds such as cholic acid, citric acid, EDTA, or glutamic acid. This novel formulation provides a reliable, low-cost, and highly efficient method for delivery of genes and may have applications in gene therapy.

Prolonged organ retention and safety of plasmid DNA administered in polyethylenimine complexes

Polyethylenimine (PEI) has been studied as an efficient nonviral gene transfer vector. Here, we report the biodistribution fates and safety of plasmid DNA intravenously administered in PEI complexes. Using pCMVbeta as a model gene, the biodistribution of plasmid DNA was measured by quantitative polymerase chain reaction. A deletion mutant of pCMVbeta was used as an internal standard. After intravenous administration of PEI/DNA complexes, the serum levels of DNA rapidly declined for up to 15 min. However, after this point, the serum levels of DNA diminished slowly. At 15 min after dose, PEI/DNA complexes showed 33-fold higher distribution of DNA in the lung than did naked DNA. At 24 h, all the organs tested showed much higher levels of plasmid DNA in PEI/DNA complexes, with distribution in the liver and lung being three orders of magnitude higher than naked DNA. The mRNA expression of DNA was observed in various organs of PEI/DNA-treated mice at 12 days after dose. Once a week dosing of PEI/DNA complexes over 3 consecutive weeks did not alter the histology of the organs. However, twice a week dosing over 3 weeks induced a sign of inflammation in the liver. These results indicate that PEI enhances the delivery and retention of plasmid DNA in the organs, especially the liver, but that safe delivery requires proper dosing intervals.

Transfection of epithelial cells is enhanced by combined treatment with mannitol and polyethyleneglycol

BACKGROUND

Gene transfer efficiency drops significantly when polarized mammary epithelial cells are transfected instead of actively growing cells. However, fully differentiated cells are the targets for gene transfer in many in vivo applications. Therefore, a simple and effective method for the transfection of polarized mammary epithelial cells in confluent monolayers was developed.

METHODS

Reporter gene plasmids were complexed with polyethylenimine with an average molecular weight of 25 kDa (PEI 25), or other agents, to transfect confluent monolayers of ovine mammary epithelial cells (OMEC II) or human carcinoma cells (CaCo-2) in vitro. The improved technique included pretreatment of the cells with a hyperosmotic mannitol solution (7%) which caused a loosening of the tight contacts between the cells. Alternatively, the mannitol shock could be replaced by a short treatment with trypsin or EDTA. In addition to the pretreatment, 12.5% polyethyleneglycol with an average molecular weight of 8000 kDa (PEG 8000) was included in the transfection mixture containing the DNA complexes.

RESULTS

The combined application of mannitol and PEG resulted in a very reliable 5- to 30-fold increase in reporter gene expression in OMEC II and CaCo-2 cells, but not K562 cells (an example of another cell type). The improved technique can also be combined with other polymer-based transfection agents. The transfection rate was enhanced for confluent monolayer cells with fully developed epithelial polarity but also for subconfluent, growing epithelial cell cultures.

CONCLUSIONS

A novel transfection protocol for epithelial cells is presented. The combined treatment of cells with mannitol and polyethyleneglycol results in substantial enhancement of in vitro transfection of epithelial cell lines.

Receptor-mediated gene delivery to human peripheral blood mononuclear cells using anti-CD3 antibody coupled to polyethylenimine

Gene transfer to primary cells, especially to lymphoid cells, using a nonviral delivery system has been very challenging. In the present studies, we have used a cationic polymer, polyethylenimine (PEI) coupled to an anti-CD3 antibody for achieving receptor-mediated gene delivery to human peripheral blood mononuclear cells (PBMC). Naive, unstimulated PBMC did not express transfected genes, whereas the transgenes were expressed efficiently in PHA activated PBMC. Transiently expressed gene products were detected maximally at 24 and 48 h following transfection. Gene expression was detected until 96 h with a gradual diminution in the signal after 48 h. Receptor-mediated gene delivery was successfully used for freshly isolated, as well as previously frozen lymphocyte samples. The transfections performed using ligands other than anti-CD3 were not as efficient as anti-CD3-PEI. These results suggest that in addition to receptor-mediated endocytosis, signaling subsequent to engagement of the CD3 receptor with anti-CD3-PEI appears to be important for the efficacy of anti-CD3-PEI mediated gene delivery.

Chicken IFN-gamma monoclonal antibodies and their application in enzyme-linked immunosorbent assay

Twelve mabs against native or recombinant chicken IFN-gamma were produced and characterized by virus neutralization, ELISA, and Western blot assays. No data were obtained to suggest that the form of the immunogen (native versus recombinant) influenced the antigenic specificity of the mabs produced. While only two antibodies inhibited the in vitro virus neutralizing activity of IFN-gamma, other evidence indicated that the specificity of these mabs was indeed directed against IFN-gamma. By Western blot analysis, all antibodies identified a 17-kDa IFN-gamma polypeptide. Using a direct binding ELISA incorporating these mabs, a high correlation with IFN-gamma detected by in vitro virus neutralization was observed. The IFN-gamma ELISA was also capable of measuring cytokine levels in the sera of chickens orally infected with Eimeria maxima. At 8 and 10 days post-primary infection, significantly higher (p<0. 001) levels of serum IFN-gamma were detected in E. maxima infected chickens compared to uninfected controls. These results indicate that a mab-based direct binding ELISA is suitable to measure chicken IFN-gamma in a variety of formats.