Influence of cell physiological state on gene delivery to T lymphocytes by chimeric adenovirus Ad5F35

The dynamics of chemoattractant receptors redistribution in the electrotaxis of 3T3 fibroblasts

BACKGROUND

Electrotaxis, the directed cell movement in direct current electric field (dcEF), is crucial for wound healing and development. We recently proposed a biphasic electrotaxis mechanism, where an initial rapid response is driven by ionic mechanisms, while redistribution of membrane components come into play during prolonged exposure to dcEF.

METHODS

To verify this hypothesis, we studied the redistribution dynamics of EGFR, PDGFRα/β, and TGFβR1 in dcEF. For this purpose, we utilized cells transfected with plasmids encoding fluorescently tagged receptors, which were exposed to dcEF in a custom-designed electrotactic chamber. Fluorescent images were captured using wide-field or TIRF microscopy, enabling precise quantitative analysis of receptor redistribution. Additionally, the functional significance of these selected receptors in electrotaxis was evaluated by silencing their expression using an siRNA library.

RESULTS

Although EGFR moved immediately to cathode after dcEF application, maximum distribution asymmetry was reached after 30-40 min. This process was more efficient at higher dcEF intensities, specifically, asymmetry was greater at 3 V/cm compared to 1 V/cm, consistent with the biphasic mechanism observed only under the stronger dcEF. Additionally, redistribution was more effective under alkaline conditions and near the cell base, but decreased when glass was coated with poly-L-lysine, indicating electroosmosis as a key factor. Importantly, EGFR redistribution did not correlate with the rapid reaction of 3T3 cells to dcEF reversal, which occurred within 1-2 min, when receptor orientation was not yet reversed. PDGFRα exhibited similar but less marked cathodal redistribution, while PDGFRβ and TGFβR1 did not redistribute. siRNA knockdown experiments confirmed the importance of EGFR and ErbB4 in the electrotaxis. EGFR's role was largely ligand-independent, and it had a significant impact on the response of 3T3 cells to dcEF during the first hour of the experiment, but was not involved in the fastest response, which was Kir-dependent.

CONCLUSIONS

Our study suggests that EGFR redistribution may play a role in the early stages and partially contribute to the long-term electrotaxis of 3T3 fibroblasts. However, this mechanism alone does not fully explain rapid responses to dcEF orientation changes indicating a more complex, multimodal mechanism of electrotaxis in these cells.

Designing molecules: directing stem cell differentiation

Stem cells have been widely applied in regenerative and therapeutic medicine for their unique regenerative properties. Although much research has shown their potential, it remains tricky in directing stem cell differentiation. The advancement of genetic and therapeutic technologies, however, has facilitated this issue through development of design molecules. These molecules are designed to overcome the drawbacks previously faced, such as unexpected differentiation outcomes and insufficient migration of endogenous or exogenous MSCs. Here, we introduced aptamer, bacteriophage, and biological vectors as design molecules and described their characteristics. The methods of designing/developing discussed include various Systematic Evolution of Ligands by Exponential Enrichment (SELEX) procedures, in silico approaches, and non-SELEX methods for aptamers, and genetic engineering methods such as homologous recombination, Bacteriophage Recombineering of Electroporated DNA (BRED), Bacteriophage Recombineering with Infectious Particles (BRIP), and genome rebooting for bacteriophage. For biological vectors, methods such as alternate splicing, multiple promoters, internal ribosomal entry site, CRISPR-Cas9 system and Cre recombinase mediated recombination were used to design viral vectors, while non-viral vectors like exosomes are generated through parental cell-based direct engineering. Besides that, we also discussed the pros and cons, and applications of each design molecule in directing stem cell differentiation to illustrate their great potential in stem cells research. Finally, we highlighted some safety and efficacy concerns to be considered for future studies.

Efficient Editing of an Adenoviral Vector Genome with CRISPR/Cas9

Immunotherapy based on genetic modification of T cells has played an important role in the treatment of tumors and viral infections. Moreover, adenoviral vectors engineered with improved safety due to their inability to integrate into the host genome have been key in the clinical application of T cell therapy. However, the commonly used adenoviral vector Ad5 exhibits low efficiency of infection of human T cells and the details of the intracellular trafficking pathway of adenoviral vectors in human primary T cells remains unclear. Resolution of these issues will depend on successful modification of the adenoviral vector. To this end, here we describe the successful establishment of a simple and efficient method for editing adenoviral vectors in vitro using the CRISPR-Cas9 gene editing system to target the adenoviral fiber gene.

Distribution and Co-localization of endosome markers in cells

Clathrin mediated endocytosis is one pathway for internalization of extracellular nano materials into cells [1, 2]. In this pathway, proteins attached to receptors and the internalized materials are encapsulated in clathrin coated membrane vesicles that subsequently fuse with or transform into intracellular compartments (early and late endosomes) as their contents are being directed to the lysosomes for degradation. The following proteins are commonly used to mark the pathway at various stages: Rab5 (early endosome), Rab7 (late endosome), and LAMP-1 (lysosome). In this work, we studied the distribution and co-localization of these marker proteins in two cell lines (C2C12 and A549) to determine whether these markers are unique for specific endosome types or whether they can co-exist with other markers. We estimate the densities and sizes of the endosomes containing the three markers, as well as the number of marker antibodies attached to each endosome. We determine that the markers are not unique to one endosome type but that the extent of co-localization is different for the two cell types. In fact, we find endosomes that contain all three markers simultaneously. Our results suggest that the use of these proteins as specific markers for specific endosome types should be reevaluated. This was the first successful use of triple image cross correlation spectroscopy to qualitatively and quantitatively study the extent of interaction among three different species in cells and also the first experimental study of three-way interactions of clathrin mediated endocytic markers.

Gene Therapy Leaves a Vicious Cycle

The human genetic code encrypted in thousands of genes holds the secret for synthesis of proteins that drive all biological processes necessary for normal life and death. Though the genetic ciphering remains unchanged through generations, some genes get disrupted, deleted and or mutated, manifesting diseases, and or disorders. Current treatment options—chemotherapy, protein therapy, radiotherapy, and surgery available for no more than 500 diseases—neither cure nor prevent genetic errors but often cause many side effects. However, gene therapy, colloquially called “living drug,” provides a one-time treatment option by rewriting or fixing errors in the natural genetic ciphering. Since gene therapy is predominantly a viral vector-based medicine, it has met with a fair bit of skepticism from both the science fraternity and patients. Now, thanks to advancements in gene editing and recombinant viral vector development, the interest of clinicians and pharmaceutical industries has been rekindled. With the advent of more than 12 different gene therapy drugs for curing cancer, blindness, immune, and neuronal disorders, this emerging experimental medicine has yet again come in the limelight. The present review article delves into the popular viral vectors used in gene therapy, advances, challenges, and perspectives.

Plasma from some cancer patients inhibits adenoviral Ad5f35 vector transduction of dendritic cells

BACKGROUND

Pooled AB serum is often used as a media supplement for cell culture but it has the potential to transmit infectious diseases. To avoid this risk, we used autologous plasma as a media supplement for manufacturing dendritic cells (DCs) for cancer immunotherapy. We noticed inconsistencies in the DCs and investigated their nature and cause.

METHODS

Adenovirus human epidural growth factor receptor 2 (adHER2/neu) DCs for 21 patients were manufactured from autologous peripheral blood monocytes that were treated with granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4 for 3 days, transduced with Ad5f35HER2ECTM and then treated with lipopolysaccharide and interferon (IFN)-γ for 1 day. The cells were cultured in RPMI-1640 supplemented with either 10% heat inactivated autologous or AB plasma.

RESULTS

Twenty-eight adHER2/neu DCs were manufactured for 21 patients using autologous plasma and 68 were manufactured for 20 of those patients using AB plasma. The expression of human epidural growth factor receptor 2 (HER2/neu) was less for DCs manufactured with autologous plasma (70.3 ± 33.3% versus 86.1 ± 22.8%; P <0.01). Manufacturing adHER2/neu DCs using monocytes from three healthy subjects and plasma from one patient with low HER2/neu expression (18%) resulted in low HER2/neu expression by all three DCs (13%, 16% and 23%). Analysis of the levels of 1322 proteins in eight plasma samples associated with low HER2/neu expression and in 12 associated with high HER2/neu expression revealed that the levels of 14 predicted HER2/neu transduction efficiency.

CONCLUSION

The manufacture of adHER2/neu DC using autologous plasma as a media supplement resulted in inconsistent HER2/neu expression. It is likely that variability in the levels of multiple proteins in autologous plasma contributed to low HER2/neu expression.

Blood Coagulation Factor X Exerts Differential Effects on Adenovirus Entry into Human Lymphocytes

It has been proposed that blood coagulation factors, principally factor X (FX), enhance the uptake of human adenovirus type 5 (Ad5) into cultured epithelial cells by bridging the viral hexon capsid protein and cell-surface heparan sulphate proteoglycans (HSPGs). We studied the effects of FX on Ad transduction of lymphoid cell lines (NK92MI, a natural killer cell line; Daudi, a B-cell line and Jurkat, a T-cell line) as well as primary peripheral blood lymphocytes (PBL) and HeLa epithelial cells using either replication-deficient Ad5, or a derivative in which the Ad5 fiber was replaced with that of another Ad type, Ad35, termed Ad5F35. PBL and NK92MI were resistant to Ad5 transduction. Transduction of Jurkat and Daudi cells by Ad5 was reduced by FX but without discernible effects on cell-surface Ad5 binding. FX reduced virus binding and transduction of all lymphoid cell lines by Ad5F35, as well as transduction of the T- and Natural Killer (NK)-cell populations of PBL. Flow cytometry analysis showed that all lymphoid cell lines were negative for HSPG components, in contrast to HeLa cells. FX reduced transduction of an HSPG-negative mutant Chinese hamster ovary cell line (CHOpgsA745) by Ad5 and Ad5F35, with Ad5F35 binding also being reduced by FX. These results point to fiber-dependent differences (Ad5 versus Ad35 fiber) in Ad binding to and transduction of human lymphoid and epithelial cells in the presence of FX.