Solid tissues can be manipulated ex vivo and used as vehicles for gene therapy

Gene Therapy for Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a devastating clinical syndrome that leads to acute respiratory failure and accounts for over 70,000 deaths per year in the United States alone, even prior to the COVID-19 pandemic. While its molecular details have been teased apart and its pathophysiology largely established over the past 30 years, relatively few pharmacological advances in treatment have been made based on this knowledge. Indeed, mortality remains very close to what it was 30 years ago. As an alternative to traditional pharmacological approaches, gene therapy offers a highly controlled and targeted strategy to treat the disease at the molecular level. Although there is no single gene or combination of genes responsible for ARDS, there are a number of genes that can be targeted for upregulation or downregulation that could alleviate many of the symptoms and address the underlying mechanisms of this syndrome. This review will focus on the pathophysiology of ARDS and how gene therapy has been used for prevention and treatment. Strategies for gene delivery to the lung, such as barriers encountered during gene transfer, specific classes of genes that have been targeted, and the outcomes of these approaches on ARDS pathogenesis and resolution will be discussed.

Angiogenic potential of mesenchymal stem cells derived from patients with diabetes seeded on decellularized micro fragments

Mesenchymal stem cells (MSCs) are a potential source of angiogenic factors which may promote wound healing in poorly vascularized diabetic foot ulcers. We demonstrate that MSCs of patients with diabetic foot ulcers seeded on decellularized micro-fragments transcribe and secrete angiogenic factors in amounts comparable to MSCs derived from healthy individuals.

Sustained secretion of anti-tumor necrosis factor α monoclonal antibody from ex vivo genetically engineered dermal tissue demonstrates therapeutic activity in mouse model of rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a symmetric inflammatory polyarthritis associated with high concentrations of pro-inflammatory, cytokines including tumor necrosis factor (TNF)-α. Adalimumab is a monoclonal antibody (mAb) that binds TNF-α, and is widely used to treat RA. Despite its proven clinical efficacy, adalimumab and other therapeutic mAbs have disadvantages, including the requirement for repeated bolus injections and the appearance of treatment limiting anti-drug antibodies. To address these issues, we have developed an innovative ex vivo gene therapy approach, termed transduced autologous restorative gene therapy (TARGT), to produce and secrete adalimumab for the treatment of RA.

METHODS

Helper-dependent (HD) adenovirus vector containing adalimumab light and heavy chain coding sequences was used to transduce microdermal tissues and cells of human and mouse origin ex vivo, rendering sustained secretion of active adalimumab. The genetically engineered tissues were subsequently implanted in a mouse model of RA.

RESULTS

Transduced human microdermal tissues implanted in SCID mice demonstrated 49 days of secretion of active adalimumab in the blood, at levels of tens of microgram per milliliter. In addition, transduced autologous dermal cells were implanted in the RA mouse model and demonstrated statistically significant amelioration in RA symptoms compared to naïve cell implantation and were similar to recombinant adalimumab bolus injections.

CONCLUSIONS

The results of the present study report microdermal tissues engineered to secrete active adalimumab as a proof of concept for sustained secretion of antibody from the novel ex vivo gene therapy TARGT platform. This technology may now be applied to a range of antibodies for the therapy of other diseases.

Targeting the gastrointestinal tract with viral vectors: state of the art and possible applications in research and therapy

While there is a large body of preclinical data on the use of viral vectors in gene transfer, relatively little is known about viral gene transfer in the gastrointestinal tract. Viral vector technology is especially underused in the field of neurogastroenterology when compared to brain research. This review provides an overview of the studies employing viral vectors-in particular retroviruses, adenoviruses and adeno-associated viruses-to transduce different cell types in the intestine. Early work mainly focused on mucosal transduction, but had limited success due to the harsh luminal conditions in the gastrointestinal tract and the high turnover rate of enterocytes. More recently, several studies have successfully employed viral gene transfer to target the enteric nervous system and its progenitors. Although several hurdles still need to be overcome, in particular on how to augment transduction efficiency and specific cell targeting, viral vector technology holds strong potential not only as a valid research tool in fundamental gastroenterological research but also as a therapeutic agent in translational (bio)medical research.

In vitro and ex vivo vanadium antitumor activity in (TGF-β)-induced EMT. Synergistic activity with carboplatin and correlation with tumor metastasis in cancer patients

Epithelial to mesenchymal transition (EMT) plays a key role in tumor progression and metastasis as a crucial event for cancer cells to trigger the metastatic niche. Transforming growth factor-β (TGF-β) has been shown to play an important role as an EMT inducer in various stages of carcinogenesis. Previous reports had shown that antitumor vanadium inhibits the metastatic potential of tumor cells by reducing MMP-2 expression and inducing ROS-dependent apoptosis. However, the role of vanadium in (TGF-β)-induced EMT remains unclear. In the present study, we report for the first time on the inhibitory effects of vanadium on (TGF-β)-mediated EMT followed by down-regulation of ex vivo cancer stem cell markers. The results demonstrate blockage of (TGF-β)-mediated EMT by vanadium and reduction in the mitochondrial potential of tumor cells linked to EMT and cancer metabolism. Furthermore, combination of vanadium and carboplatin (a) resulted in synergistic antitumor activity in ex vivo cell cultures, and (b) prompted G0/G1 cell cycle arrest and sensitization of tumor cells to carboplatin-induced apoptosis. Overall, the findings highlight the multifaceted antitumor action of vanadium and its synergistic antitumor efficacy with current chemotherapy drugs, knowledge that could be valuable for targeting cancer cell metabolism and cancer stem cell-mediated metastasis in aggressive chemoresistant tumors.

MiR-205 and miR-218 expression is associated with carboplatin chemoresistance and regulation of apoptosis via Mcl-1 and Survivin in lung cancer cells

Lung cancer chemoresistance is the most frequent barrier in lung cancer therapy. Recent studies have indicated that microRNAs play a significant role in this mechanism and can function as either tumor suppressor or tumor promoters. However the effect of miRNA in lung cancer chemoresistance is poorly understood. Therefore, in the present study we investigated the role of two distinct miR members, the miR-205 and the tumor suppressor miR-218 in the proliferation, invasion and induction of apoptosis in lung cancer cells after carboplatin treatment. The results showed that miR-205 overexpression in A549 and H1975 lung cancer cells is concurrent with the down regulation of miR-218 and in linked with carboplatin sensitivity and chemoresistance. Interestingly, ectopic miR-218 overexpression reduced cell proliferation, invasion and migration of lung cancer cells, whereas miR-205 rescued the suppressive effect of miR-218 by altering the expression levels of the pro-apoptotic proteins PARP, Caspase 3, Bax and upregulating the anti-apoptotic markers Mcl-1 and Survivin. Taken together our findings imply that the miRNAs miR-205 and miR-218 play a key role in the development of lung cancer acquired chemoresistance and the tumor suppressor role of miR-218 in inhibiting lung cancer cell tumorigenesis and overcoming platinum chemoresistance is significant for future cancer therapeutic approaches.

Biopump: Autologous skin-derived micro-organ genetically engineered to provide sustained continuous secretion of therapeutic proteins

A novel approach for sustained production of therapeutic proteins is described, using genetic modification of intact autologous micro-organ tissue explants from the subject's own skin. The skin-derived micro-organ can be maintained viable ex vivo for extended periods and is transduced with a transgene encoding a desired therapeutic protein, resulting in protein-secreting micro-organ (biopump (BP)). The daily protein production from each BP is quantified, enabling drug dosing by subcutaneous implantation of the requisite number of BPs into the patient to provide continuous production to the circulation of a known amount of the therapeutic protein. Each implanted BP remains localized and is accessible, to enable removal or ablation if needed. Examples from preclinical and clinical studies are presented, including use of associated virus vector 1 and helper-dependent adenoviral vectors producing BPs to provide long-term sustained secretion of recombinant interferon-α and erythropoietin.

Modeling of human cytomegalovirus maternal-fetal transmission in a novel decidual organ culture

Human cytomegalovirus (HCMV) is the leading cause of congenital infection, associated with severe birth defects and intrauterine growth retardation. The mechanism of HCMV transmission via the maternal-fetal interface is largely unknown, and there are no animal models for HCMV. The initial stages of infection are believed to occur in the maternal decidua. Here we employed a novel decidual organ culture, using both clinically derived and laboratory-derived viral strains, for the ex vivo modeling of HCMV transmission in the maternal-fetal interface. Viral spread in the tissue was demonstrated by the progression of infected-cell foci, with a 1.3- to 2-log increase in HCMV DNA and RNA levels between days 2 and 9 postinfection, the expression of immediate-early and late proteins, the appearance of typical histopathological features of natural infection, and dose-dependent inhibition of infection by ganciclovir and acyclovir. HCMV infected a wide range of cells in the decidua, including invasive cytotrophoblasts, macrophages, and endothelial, decidual, and dendritic cells. Cell-to-cell viral spread was revealed by focal extension of infected-cell clusters, inability to recover infectious extracellular virus, and high relative proportions (88 to 93%) of cell-associated viral DNA. Intriguingly, neutralizing HCMV hyperimmune globulins exhibited inhibitory activity against viral spread in the decidua even when added at 24 h postinfection-providing a mechanistic basis for their clinical use in prenatal prevention. The ex vivo-infected decidual cultures offer unique insight into patterns of viral tropism and spread, defining initial stages of congenital HCMV transmission, and can facilitate evaluation of the effects of new antiviral interventions within the maternal-fetal interface milieu.

Restrictions that control herpes simplex virus type 1 infection in mouse brain ex vivo

Elucidating the cellular and molecular factors governing herpes simplex virus type 1 (HSV-1) neurotropism is a prerequisite for understanding HSV-1 encephalitis and for targeting HSV-1-derived vectors for gene transfer to the brain. Earlier we had described an ex vivo system of mouse brain slices and demonstrated a selective and unique infection pattern, mostly around the ventricles. Here, we examined tissue factors controlling HSV-1 infection of brain slices. We demonstrated that heparan sulphate, while an important factor, does not determine the infection pattern. Hyaluronic acid, but not collagen, appears to enhance HSV-1 brain infection. To investigate whether tissue distribution of viral receptors determines the infection pattern, we examined transcription of herpes virus entry mediator and nectin-1 receptor genes in infected and uninfected brain regions. Both the infected and the uninfected regions express the receptors. We also explored the influence of intra-cellular factors. HSV-1 does not preferentially infect proliferating cells in the brain slices, despite its predilection to the ventricular zones. To delineate the step at which the HSV-1 infection cascade is restricted, mRNA was isolated following tissue infection, and transcription of the immediate-early and late viral genes was evaluated. The results indicated that HSV-1 genes are not expressed in regions that do not express a viral reporter gene. Therefore, we conclude that tissue resistance to infection is associated with a block at or prior to the immediate-early mRNA synthesis. Taken together, using the ex vivo system of organotypic culture we describe here extra-cellular and intra-cellular restriction levels of HSV-1 brain infection.

Organ-specific scaffolds for in vitro expansion, differentiation, and organization of primary lung cells

In light of the increasing need for differentiated primary cells for cell therapy and the rapid dedifferentiation occurring during standard in vitro cultivation techniques, there is an urgent need for developing three-dimensional in vitro systems in which expanded cells display in vivo-like differentiated phenotypes. It is becoming clear that the natural microenvironment provides the optimal conditions for achieving this aim. To this end, we prepared natural decellularized scaffolds of microscopic dimensions that would allow appropriate diffusion of gases and nutrients to all seeded cells. Scaffolds from either the lung or the liver were analyzed for their ability to support growth and differentiation of progenitor alveolar cells and hepatocytes. We observed that progenitor alveolar cells that have been expanded on plastic culture and thus dedifferentiated grew within the lung-derived scaffolds into highly organized structures and regained differentiation markers classical for type I and type II alveolar cells. The cells generated proper alveolar structures, and only 15%-30% of them secreted surfactant proteins in a localized manner for extended periods. Vice versa, liver-derived scaffolds supported the differentiation state of primary hepatocytes. We further demonstrate that the natural scaffolds are organ specific, that is, only cells derived from the same organ become properly differentiated. A proteomic analysis shows significant different composition of lung and liver scaffolds, for example, decorin, thrombospondin 1, vimentin, and various laminin isoforms are especially enriched in the lung. Altogether, our data demonstrate that complex interactions between the seeded cells and a highly organized, organ-specific stroma are required for proper localized cell differentiation. Thus, our novel in vitro culture system can be used for ex vivo differentiation and organization of expanded primary cells.

Polyhydroxylated fatty alcohols derived from avocado suppress inflammatory response and provide non-sunscreen protection against UV-induced damage in skin cells

Exposing skin to ultraviolet (UV) radiation contributes to photoaging and to the development of skin cancer by DNA lesions and triggering inflammatory and other harmful cellular cascades. The present study tested the ability of unique lipid molecules, polyhydroxylated fatty alcohols (PFA), extracted from avocado, to reduce UVB-induced damage and inflammation in skin. Introducing PFA to keratinocytes prior to their exposure to UVB exerted a protective effect, increasing cell viability, decreasing the secretion of IL-6 and PGE(2), and enhancing DNA repair. In human skin explants, treating with PFA reduced significantly UV-induced cellular damage. These results support the idea that PFA can play an important role as a photo-protective agent in UV-induced skin damage.

Chemoprevention of colorectal cancer by targeting APC-deficient cells for apoptosis

Cancer chemoprevention uses natural, synthetic, or biological substances to reverse, suppress, or prevent either the initial phase of carcinogenesis or the progression of neoplastic cells to cancer. It holds promise for overcoming problems associated with the treatment of late-stage cancers. However, the broad application of chemoprevention is compromised at present by limited effectiveness and potential toxicity. To overcome these challenges, here we developed a new chemoprevention approach that specifically targets premalignant tumour cells for apoptosis. We show that a deficiency in the adenomatous polyposis coli (APC) gene and subsequent activation of beta-catenin lead to the repression of cellular caspase-8 inhibitor c-FLIP (also known as CFLAR) expression through activation of c-Myc, and that all-trans-retinyl acetate (RAc) independently upregulates tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) death receptors and suppresses decoy receptors. Thus, the combination of TRAIL and RAc induces apoptosis in APC-deficient premalignant cells without affecting normal cells in vitro. In addition, we show that short-term and non-continuous TRAIL and RAc treatment induce apoptosis specifically in intestinal polyps, strongly inhibit tumour growth, and prolong survival in multiple intestinal neoplasms C57BL/6J-Apc(Min)/J (Apc(Min)) mice. With our approach, we further demonstrate that TRAIL and RAc induce significant cell death in human colon polyps, providing a potentially selective approach for colorectal cancer chemoprevention by targeting APC-deficient cells for apoptosis.

Herpes simplex virus type 1 preferentially targets human colon carcinoma: role of extracellular matrix

Viral therapy of cancer (viral oncolysis) is dependent on selective destruction of the tumor tissue compared with healthy tissues. Several factors, including receptor expression, extracellular components, and intracellular mechanisms, may influence viral oncolysis. In the present work, we studied the potential oncolytic activity of herpes simplex virus type 1 (HSV-1), using an organ culture system derived from colon carcinoma and healthy colon tissues of mouse and human origin. HSV-1 infected normal colons ex vivo at a very low efficiency, in contrast to high-efficiency infection of colon carcinoma tissue. In contrast, adenoviral and lentiviral vectors infected both tissues equally well. To investigate the mechanisms underlying the preferential affinity of HSV-1 for the carcinoma tissue, intracellular and extracellular factors were investigated. Two extracellular components, collagen and mucin molecules, were found to restrict HSV-1 infectivity in the healthy colon. The mucin layer of the healthy colon binds to HSV-1 and thereby blocks viral interaction with the epithelial cells of the tissue. In contrast, colon carcinomas express small amounts of collagen and mucin molecules and are thus permissive to HSV-1 infection. In agreement with the ex vivo system, HSV-1 injected into a mouse colon carcinoma in vivo significantly reduced the volume of the tumor. In conclusion, we describe a novel mechanism of viral selectivity for malignant tissues that is based on variance of the extracellular matrix between tumor and healthy tissues. These insights may facilitate new approaches to the application of HSV-1 as an oncolytic virus.

Nonviral gene delivery: what we know and what is next

Gene delivery using nonviral approaches has been extensively studied as a basic tool for intracellular gene transfer and gene therapy. In the past, the primary focus has been on application of physical, chemical, and biological principles to development of a safe and efficient method that delivers a transgene into target cells for appropriate expression. This review summarizes the current status of the most commonly used nonviral methods, with an emphasis on their mechanism of action for gene delivery, and their advantages and limitations for gene therapy applications. The technical aspects of each delivery system are also reviewed, with a focus on how to achieve optimal delivery efficiency. A brief discussion of future development and further improvement of the current systems is intended to stimulate new ideas and encourage rapid advancement in this new and promising field.

Neurotropism of herpes simplex virus type 1 in brain organ cultures

The mechanism of herpes simplex virus type 1 (HSV-1) penetration into the brain and its predilection to infect certain neuronal regions is unknown. In order to study HSV-1 neurotropism, an ex vivo system of mice organotypic brain slices was established and the tissue was infected with HSV-1 vectors. Neonate tissues showed restricted infection confined to leptomeningeal, periventricular and cortical brain regions. The hippocampus was the primary parenchymatous structure that was also infected. Infection was localized to early progenitor and ependymal cells. Increasing viral inoculum increased the intensity and enlarged the infected territory, but the distinctive pattern of infection was maintained and differed from that observed with adenovirus and Vaccinia virus. Neonate brain tissues were much more permissive for HSV-1 infection than adult mouse brain tissues. Taken together, these results indicate a complex interaction of HSV-1 with different brain-cell types and provide a useful vehicle to elucidate the mechanisms of viral neurotropism.

A novel system to study adenovirus tropism to normal and malignant colon tissues

We describe here a new organ culture system for the evaluation of viral tropism to colon carcinomas and normal colon tissues. Organ cultures of mouse and human colon retained viability for several days and thus facilitated studies of viral tropism. Two adenoviral vectors (AD) were compared in the study: AD5, that utilizes the CAR receptor, demonstrated poor infectivity to both normal and carcinoma tissues, while a capsid-modified-AD, recognizing haparan-sulfate receptor, demonstrated efficient infectivity of both tissues. Immunohistochemistry analysis demonstrated different viral tropism; while AD5 infected only the colon epithelia, the capsid-modified-adeno infected both the epithelia and mesothelial layers. To investigate other determinants in the tissue that influence viral tropism, human cancer tissues were pretreated with collagenase and infected with the AD viruses. Increased infectivity and altered tropism were noted in the treated tumor tissue. Taken together, this ex vivo system indicated that receptor utilization and extracellular-matrix components influence AD viral tropism in solid tissues.

Induced dystrophin exon skipping in human muscle explants

Antisense oligonucleotide (AO) manipulation of pre-mRNA splicing of the dystrophin gene is showing promise in overcoming Duchenne muscular dystrophy (DMD)-causing mutations. To date, this approach has been limited to studies using animal models or cultured human muscle cells, and evidence that AOs can induce exon skipping in human muscle has yet to be shown. In this study, we used different AO analogues to induce exon skipping in muscle explants derived from normal and DMD human tissue. We propose that inducing exon skipping in human muscle explants is closer to in vivo conditions than cells in monolayer cultures, and may minimize the numbers of participants in Phase I clinical studies to demonstrate proof of principle of exon skipping in human muscle.

Relationship between retroviral vector membrane and vector stability

The present work studies the physico-chemical properties of retroviral vector membrane, in order to provide some explanation for the inactivation kinetics of these vectors and to devise new ways of improving transduction efficiency. For this purpose, vectors with an amphotropic envelope produced by TE Fly A7 cells at two culture temperatures (37 and 32 °C) were characterized by different techniques. Electron paramagnetic resonance (EPR) results showed that vectors produced at 32 °C are more rigid than those produced at 37 °C. Further characterization of vector membrane composition allowed us to conclude that the vector inactivation rate increases with elevated cholesterol to phospholipid ratio. Differential scanning calorimetry (DSC) showed that production temperature also affects the conformation of the membrane proteins. Transduction studies using HCT116 cells and tri-dimensional organ cultures of mouse skin showed that vectors produced at 37 °C have higher stability and thus higher transduction efficiency in gene therapy relevant cells as compared with vectors produced at 32 °C. Overall, vectors produced at 37 °C show an increased stability at temperatures below 4 °C. Since vector membrane physico-chemical properties are affected in response to changes in culture temperature, such changes, along with alterations in medium composition, can be used prospectively to improve the stability and the transduction efficiency of retroviral vectors for therapeutic purposes.

Skin-Derived Micro-Organs Induce Angiogenesis in Rabbits

We have recently reported an alternative cell therapy approach to induce angiogenesis. The approach is based on small organ fragments--micro-organs (MOs)--whose geometry allows preservation of the natural epithelial/mesenchymal interactions and ensures appropriate diffusion of nutrients and gases to all cells. We have shown that lung-derived MOs, when implanted into hosts, transcribe a wide spectrum array of angiogenic factors and can induce an angiogenic response that can rescue experimentally induced ischemic regions in mice. From a clinical perspective, skin-derived MOs are particularly appealing as they could readily be obtained from a skin biopsy taken from the same target patient. In the present work we have investigated the angiogenesis-inducing capacity of rabbit and human skin-derived micro-organs in vitro and in vivo. Rabbit skin MOs were implanted into homologous adult rabbits and human skin MOs were encapsulated and implanted into xenogenic mice. Skin-derived MOs, as lung-derived MOs, were found to secrete a whole array of angiogenic factors and to induce a powerful angiogenic response when implanted back into animals. We believe the approach presented suggests a novel, efficacious and simple approach for therapeutic angiogenesis.