Systematic improvement of lentivirus transduction protocols by antibody fragments fused to VSV-G as envelope glycoprotein

Cell and gene therapy for kidney disease

Kidney disease is a leading cause of morbidity and mortality across the globe. Current interventions for kidney disease include dialysis and renal transplantation, which have limited efficacy or availability and are often associated with complications such as cardiovascular disease and immunosuppression. There is therefore a pressing need for novel therapies for kidney disease. Notably, as many as 30% of kidney disease cases are caused by monogenic disease and are thus potentially amenable to genetic medicine, such as cell and gene therapy. Systemic disease that affects the kidney, such as diabetes and hypertension, might also be targetable by cell and gene therapy. However, although there are now several approved gene and cell therapies for inherited diseases that affect other organs, none targets the kidney. Promising recent advances in cell and gene therapy have been made, including in the kidney research field, suggesting that this form of therapy might represent a potential solution for kidney disease in the future. In this Review, we describe the potential for cell and gene therapy in treating kidney disease, focusing on recent genetic studies, key advances and emerging technologies, and we describe several crucial considerations for renal genetic and cell therapies.

Hematopoietic-Stem-Cell-Targeted Gene-Addition and Gene-Editing Strategies for β-hemoglobinopathies

Sickle cell disease (SCD) is caused by a well-defined point mutation in the β-globin gene and therefore is an optimal target for hematopoietic stem cell (HSC) gene-addition/editing therapy. In HSC gene-addition therapy, a therapeutic β-globin gene is integrated into patient HSCs via lentiviral transduction, resulting in long-term phenotypic correction. State-of-the-art gene-editing technology has made it possible to repair the β-globin mutation in patient HSCs or target genetic loci associated with reactivation of endogenous γ-globin expression. With both approaches showing signs of therapeutic efficacy in patients, we discuss current genetic treatments, challenges, and technical advances in this field.

The Engineered MARCH8-Resistant Vesicular Stomatitis Virus Glycoprotein Enhances Lentiviral Vector Transduction

Lentiviral vectors are one of the most commonly used viral delivery systems for gene therapy. Vesicular stomatitis virus-G envelope glycoprotein (VSV G)-pseudotyped lentiviral vectors have been widely used in clinical studies for treatment of virus infections and genetic deficient diseases. However, the efficiency of lentiviral vector transduction has been long recognized as a limiting factor in clinical gene therapy application, especially in transducing hematopoietic stem cells. MARCH8 (membrane-associated RING-CH 8), an E3 ubiquitin ligase, has been reported to target and downregulate VSV G. Results in this study show that MARCH8 induces ubiquitination and lysosome degradation of VSV G, and knockout of MARCH8 in virus-producing cells increases lentiviral vector transduction by elevating the level of VSV G protein. We then engineered VSV G mutant that has the lysine residues in the cytoplasmic domain substituted for arginine, and showed that this G mutant resists degradation by MARCH8, and allows the enhancement of transduction efficiency of lentiviral vector particles than the parental VSV G protein. This engineered VSV G mutant thus further advances the lentiviral vector system as a powerful tool in gene therapy.

Concise review on optimized methods in production and transduction of lentiviral vectors in order to facilitate immunotherapy and gene therapy

Lentiviral vectors (LVs) have provided an efficient way to integrate our gene of interest into eukaryote cells. Human immunodeficiency virus (HIV)-derived LVs have been vastly studied to become an invaluable asset in gene delivery. This abled LVs to be used in both research laboratories and gene therapy. Pseudotyping HIV-1 based LVs, abled it to transduce different types of cells, especially hematopoietic stem cells. A wide range of tropism, plus to the ability to integrate genes into target cells, made LVs an armamentarium in gene therapy. The third and fourth generations of self-inactivating LVs are being used to achieve safe gene therapy. Not only advanced methods enabled the clinical-grade LV production on a large scale, but also considerably heightened transduction efficiency. One of which is microfluidic systems that revolutionized gene delivery approaches. Since gene therapy using LVs attracted lots of attention to itself, we provided a brief review of LV structure and life-cycle along with methods for improving both LV production and transduction. Also, we mentioned some of their utilization in immunotherapy and gene therapy.

Surface-Engineered Lentiviral Vectors for Selective Gene Transfer into Subtypes of Lymphocytes

Lymphocytes have always been among the prime targets in gene therapy, even more so since chimeric antigen receptor (CAR) T cells have reached the clinic. However, other gene therapeutic approaches hold great promise as well. The first part of this review provides an overview of current strategies in lymphocyte gene therapy. The second part highlights the importance of precise gene delivery into B and T cells as well as distinct subtypes of lymphocytes. This can be achieved with lentiviral vectors (LVs) pseudotyped with engineered glycoproteins recognizing lymphocyte surface markers as entry receptors. Different strategies for envelope glycoprotein engineering and selection of the targeting ligand are discussed. With a CD8-targeted LV that was recently used to achieve proof of principle for the in vivo reprogramming of CAR T cells, these vectors are becoming a key tool to genetically engineer lymphocytes directly in vivo.

Optimized Lentiviral Transduction Protocols by Use of a Poloxamer Enhancer, Spinoculation, and scFv-Antibody Fusions to VSV-G

Lentiviral vectors (LV) are widely used to successfully transduce cells for research and clinical applications. This optimized LV infection protocol includes a nontoxic poloxamer-based adjuvant combined with antibody-retargeted lentiviral particles. The novel poloxamer P338 demonstrates superior characteristics for enhancing lentiviral transduction over the best-in-class polybrene-assisted transduction. Poloxamer P338 exhibited dual benefits of low toxicity and high efficiency of lentiviral gene delivery into a range of different primary cell cultures. One of the major advantages of P338 is its availability in pharma grade and applicability as cell culture medium additive in clinical protocols. Lentiviral vectors pseudotyped with the vesicular stomatitis virus glycoprotein (VSV-G) can be produced to high titers and mediate high transduction efficiencies in vitro. For clinical applications the need for optimized transduction protocols, especially for transduction of primary T and stem cells, is high. The successful use of retronectin, the second lentivirus enhancer available as GMP material, requires the application of specific coating protocols not applicable in all processes, and results in the need of a relatively high multiplicity of infection (MOI) to achieve effective transduction efficiencies for hematopoietic cells (e.g., CD34+ hematopoietic stem cells). Cell specificity of lentiviral vectors was successfully increased by displaying different ratios of scFv-fused VSV-G glycoproteins on the viral envelope. The system has been validated with human CD30+ lymphoma cells, resulting in preferential gene delivery to CD30+ cells, which was increased fourfold in mixed cell cultures, by presenting scFv antibody fragments binding to respective surface markers. A combination of spinoculation and poloxamer-based chemical adjuvant increases the transduction of primary T-cells by greater than twofold. The combination of poloxamer-based and scFv-retargeted LVs increased transduction of CD30+ lymphoma cells more than tenfold, and has the potential to improve clinical protocols.

Surface modification via strain-promoted click reaction facilitates targeted lentiviral transduction

As a result of their ability to integrate into the genome of both dividing and non-dividing cells, lentiviruses have emerged as a promising vector for gene delivery. Targeted gene transduction of specific cells and tissues by lentiviral vectors has been a major goal, which has proven difficult to achieve. We report a novel targeting protocol that relies on the chemoselective attachment of cancer specific ligands to unnatural glycans on lentiviral surfaces. This strategy exhibits minimal perturbation on virus physiology and demonstrates remarkable flexibility. It allows for targeting but can be more broadly useful with applications such as vector purification and immunomodulation.

Surface-Engineered Viral Vectors for Selective and Cell Type-Specific Gene Delivery

Recent progress in gene transfer technology enables the delivery of genes precisely to the application-relevant cell type ex vivo on cultivated primary cells or in vivo on local or systemic administration. Gene vectors based on lentiviruses or adeno-associated viruses can be engineered such that they use a cell surface marker of choice for cell entry instead of their natural receptors. Binding to the surface marker is mediated by a targeting ligand displayed on the vector particle surface, which can be a peptide, single-chain antibody, or designed ankyrin repeat protein. Examples include vectors that deliver genes to specialized endothelial cells or lymphocytes, tumor cells, or particular cells of the nervous system with potential applications in gene function studies and molecular medicine.

A 3D-microtissue-based phenotypic screening of radiation resistant tumor cells with synchronized chemotherapeutic treatment

Background

Radiation resistance presents a challenge to the effective treatment of cancer. If therapeutic compounds were capable of resensitizing resistant tumours then a concurrent chemo-radiation treatment could be used to overcome radiation resistance.

Methods

We have developed a phenotypic assay to investigate the response of radiation resistant breast cancer cells grown in 3D-microtissue spheroids to combinations of radiation and established chemotherapeutic drugs. The effects were quantified by real time high content imaging of GFP detection area over 14 days. Ten established chemotherapeutic drugs were tested for their ability to enhance the effects of radiation.

Results

Of ten analysed chemotherapeutics, vinblastine was the most effective compound, with docetaxel and doxorubicine being less effective in combination with radiation. To investigate the response in a model closer to the in vivo situation we investigated the response of heterotypic 3D microtissues containing both fibroblasts and breast cancer cells. Drug treatment of these heterotypic 3D cultures confirmed treatment with radiation plus vinblastine to be additive in causing breast cancer growth inhibition. We have validated the screen by comparing radiation sensitizing effects of known chemotherapeutic agents. In both monotypic and heterotypic models the concurrent treatment of vinblastine and radiation proved more effective inhibitors of mammary cancer cell growth. The effective concentration range of both vinblastine and radiation are within the range used in treatment, suggesting the 3D model will offer a highly relevant screen for novel compounds.

Conclusions

For the first time comfortable 3D cell-based phenotypic assay is available, that allows high throughput screening of compounds with radiation therapy modulating capacity, opening the field to drug discovery.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1481-9) contains supplementary material, which is available to authorized users.

Versatile Viral Vector Strategies for Postscreening Target Validation and RNAi ON-Target Control

Our approach aims to optimize postscreening target validation strategies using viral vector-driven RNA interference (RNAi) cell models. The RNAiONE validation platform is an array of plasmid-based expression vectors that each drives tandem expression of the gene of interest (GOI) with one small hairpin RNA (shRNA) from a set of computed candidate sequences. The best-performing shRNA (>85% silencing efficiency) is then integrated in an inducible, all-in-one lentiviral vector to transduce pharmacologically relevant cell types that endogenously express the GOI. VariCHECK is used subsequently to combine the inducible knockdown with an equally inducible rescue of the GOI for ON-target phenotype verification. The complete RNAiONE-VariCHECK system relies on three key elements to ensure high predictability: (1) maximized silencing efficiencies by a focused shRNA validation process, (2) homogeneity of the RNAi cell pools by application of sophisticated viral vector technologies, and (3) exploiting the advantages of inducible expression systems. By using a reversible expression system, our strategy adds critical information to hot candidates from RNAi screens and avoids potential side effects that may be caused by other, irreversible genomic manipulation methods such as transcription activator-like effector nucleases (TALEN) or clustered regularly interspaced short palindromic repeats/Cas9 (CRISPR/Cas). This approach will add credibility to top-hit screening candidates and protect researchers from costly misinterpretations early in the preclinical drug development process.