Strategies to enhance transductional efficiency of adenoviral-based gene transfer to primary human fibroblasts and keratinocytes as a platform in dermal wounds

Therapeutic delivery of nucleic acids for skin wound healing

Though wound care has advanced, treating chronic wounds remains a challenge and there are many clinical issues that must be addressed. Gene therapy is a recent approach to treating chronic wounds that remains in its developmental stage. The limited reports available describe the therapeutic applications of various forms of nucleic acid delivery for treating chronic wounds, including DNA, mRNA, siRNA, miRNA and so on. Though these bioactive molecules represent great therapeutic potential, sustaining their bioactivity in the wound bed is a challenge. To overcome this hurdle, delivery systems are also being widely investigated. In this review, nucleic acid-based therapy and its delivery for treating chronic wounds is discussed in detail.

Adenovirus-mediated specific tumor tagging facilitates CAR-T therapy against antigen-mismatched solid tumors

Chimeric antigen receptor T (CAR-T) therapy faces at least two major obstacles in solid tumors, including to find specific antigen among the heterogeneous tumor mass and to overcome the inhibitory microenvironment. Developing novel strategies to overcome these difficulties has been the burning issue in immunotherapy. Here we came up with the concept of tagging cancer cells by tumor-targeting adenoviruses (Ad). We constructed recombinant Ads expressing CD19 tag driven by tumor-specific promoters, which could label antigenically different tumors for single anti-CD19 CAR-T recognition. One Ad, namely AdC68-TMC-tCD19 could mediate universal tag expression and functional immunological synapse formation between CAR-T and cancer cells. In premixed mice model, all tagged mice survived after CAR-T infusion and tumor volume were inhibited by 91.78%. Furthermore, we combined the tumor tagging ability with oncolysis and generated the replicative AdC68-Sur-E1A-TMC-tCD19. Oncolytic tagging system could diminish established tumors in vivo and prolong mice survival significantly. Therefore, we suggest the universal oncolytic Ad-tagging system in combination with single target CAR-T cells could be a powerful complement in immunotherapy against antigenically mismatched solid tumors.

Enhanced Delivery of Oncolytic Adenovirus by Neural Stem Cells for Treatment of Metastatic Ovarian Cancer

Oncolytic virotherapy is a promising approach for treating recurrent and/or drug-resistant ovarian cancer. However, its successful application in the clinic has been hampered by rapid immune-mediated clearance or neutralization of the virus, which reduces viral access to tumor foci. To overcome this barrier, patient-derived mesenchymal stem cells have been used to deliver virus to tumors, but variability associated with autologous cell isolations prevents this approach from being broadly clinically applicable. Here, we demonstrate the ability of an allogeneic, clonal neural stem cell (NSC) line (HB1.F3.CD21) to protect oncolytic viral cargo from neutralizing antibodies within patient ascites fluid and to deliver it to tumors within preclinical peritoneal ovarian metastases models. The viral payload used is a conditionally replication-competent adenovirus driven by the survivin promoter (CRAd-S-pk7). Because the protein survivin is highly expressed in ovarian cancer, but not in normal differentiated cells, viral replication should occur selectively in ovarian tumor cells. We found this viral agent was effective against cisplatin-resistant ovarian tumors and could be used as an adjunct treatment with cisplatin to decrease tumor burden without increasing toxicity. Collectively, our data suggest NSC-delivered CRAd-S-pk7 virotherapy holds promise for improving clinical outcome, reducing toxicities, and improving quality of life for patients with advanced ovarian cancer.

Tropism and transduction of oncolytic adenovirus 5 vectors in cancer therapy: Focus on fiber chimerism and mosaicism, hexon and pIX

The cellular internalization (infection of cells) of adenovirus 5 (Ad5) is mediated by the initial attachment of the globular knob domain of the capsid fiber protein to the cell surface coxsackievirus and adenovirus receptor (CAR), then followed by the interaction of the virus penton base proteins with cellular integrins. In tumors, there is a substantial intra- and intertumoral variability in CAR expression. The CAR-negative cells generally exhibit very low infectability. Since the fiber knob is a primary mediator of Ad5 binding to the cell surface, improved infectivity of Ad5-based vectors as oncolytic agents may be achieved via genetic modifications of this domain. The strategies to modify or broaden tropism and increase transduction efficiency of Ad5-based vectors include: 1) an incorporation of a targeting peptide into the fiber knob domain (the HI loop and/or C-terminus); 2) fiber knob serotype switching, or pseudotyping, by constructing chimeric fibers consisting of the knob domain derived from an alternate serotype (e.g., Ad5/3 or Ad5/35 chimeras), which binds to receptor(s) other than CAR (e.g., desmoglein 2/DSG2 and/or CD46); 3) "fiber complex mosaicism", an approach of combining serotype chimerism with peptide ligand(s) incorporation (e.g., Ad5/3-RGD); 4) "dual fiber mosaicism" by expressing two separate fibers with distinct receptor-binding capabilities on the same viral particle (e.g., Ad5-5/3 or Ad5-5/σ1); 5) fiber xenotyping by replacing the knob and shaft domains of wild-type Ad5 fiber protein with fibritin trimerization domain of T4 bacteriophage or σ1 attachment protein of reovirus. Other genetic approaches to increase the CAR-independent transduction efficiency include insertion of a targeting peptide into the hypervariable region of the capsid protein hexon or fusion to the C-terminus of pIX. Finally, we consider a yet unsolved molecular mechanism of liver targeting by Ad5-based vectors (CAR-, integrin-, fiber shaft KKTK motif-, and hepatic heparan sulfate glycosaminoglycans-independent, but fiber-, hexon- and blood factor X-dependent).

Adaptation of vectors and drug-inducible systems for controlled expression of transgenes in the tumor microenvironment

Biological therapies based on recombinant proteins such as antibodies or cytokines are continuously improving the repertoire of treatments against cancer. However, safety and efficacy of this approach is often limited by inappropriate biodistribution and pharmacokinetics of the proteins when they are administered systemically. Local administration of gene therapy vectors encoding these proteins would be a feasible alternative if they could mediate long-term and controlled expression of the transgene after a single intratumoral administration. We describe a new vector platform specially designed for this purpose. Different combinations of transactivators and promoters were evaluated to obtain a fully humanized inducible system responsive to the well-characterized drug mifepristone. The optimal transactivator conformation was based on DNA binding domains from the chimeric protein ZFHD1 fused to the progesterone receptor ligand binding domain and the NFkb p65 activation domain. The expression of this hybrid transactivator under the control of the elongation factor 1α (EF1α) or the chimeric CAG promoters ensured functionality of the system in a variety of cancer types. Expression cassettes with luciferase as a reporter gene were incorporated into High-Capacity adenoviral vectors (HC-Ad) for in vivo evaluation. Systemic administration of the vectors into C57BL/6 mice revealed that the vector based on the EF1α promoter (HCA-EF-ZP) allows tight control of transgene expression and remains stable for at least two months, whereas the CAG promoter suffers a progressive inactivation. Using an orthotopic pancreatic cancer model in syngeneic C57BL/6 mice we show that the local administration of HCA-EF-ZP achieves better tumor/liver ratio of luciferase production than the intravenous route. However, regional spread of the vector led to substantial transgene expression in peritoneal organs. We reduced this leakage through genetic modification of the vector capsid to display RGD and poly-lysine motifs in the fiber knob. Safety and antitumor effect of this gene therapy platform was demonstrated using interleukin-12 as a therapeutic gene. In conclusion, we have developed a new tool that allows local, sustained and controlled production of therapeutic proteins in tumors.

Hepatocyte growth factor-expressing adenovirus upregulates matrix metalloproteinase-1 expression in keloid fibroblasts

BACKGROUND

Keloids are marked by an overabundance of extracellular matrix. The antifibrotic effect of hepatocyte growth factor (HGF) is achieved by increasing the expression of matrix metalloproteinases (MMPs) that drive extracellular matrix catabolism. As such, we cultivated an RGD-modified HGF-expressing adenovirus (dE1-RGD/lacZ/HGF) for introduction into keloid fibroblasts (KFs), looking at the subsequent impact on MMP-1 expression.

METHODS

KFs infected with either test virus as experimental group (dE1-RGD/lacZ/HGF) or its counterpart (dE1-RGD/lacZ) as control group were examined for HGF protein expression using an enzyme-linked immunosorbent assay (ELISA). Collagen (types I and III) and MMP-1 mRNA levels were also determined by reverse transcriptase-polymerase chain reaction, and ELISA was used to monitor MMP-1 protein expression.

RESULTS

In KFs harboring the test virus, high levels of HGF were induced at a multiplicity of infection ratio of 50 (3260.6 ± 162.7 pg/ml) after 72 hours of incubation. Furthermore, reverse transcriptase-polymerase chain reaction and ELISA confirmed that MMP-1 mRNA and protein expression rose significantly in KFs after transduction by the test virus (P < 0.05). However, mRNA levels of collagen were unaffected by the experimental group.

CONCLUSION

These results suggest that an HGF-expressing adenovirus may be therapeutic for keloids by increasing MMP-1 expression.

Coxsackie and adenovirus receptor is a critical regulator for the survival and growth of oral squamous carcinoma cells

Coxsackie and adenovirus receptor (CAR) is essential for adenovirus infection to target cells, and its constitutive expression in various cancerous and normal tissues has been reported. Recently, the biological role of CAR in human cancers of several different origins has been investigated with respect to tumor progression, metastasis and tumorigenesis. However, its biological function in tumor cells remains controversial. Here we report the critical role of CAR in growth regulation of oral squamous cell carcinomas (SCCs) in vitro and in vivo via the specific interaction with Rho-associated protein kinase (ROCK). Loss of endogenous CAR expression by knockdown using specific small interfering RNA (siRNA) against CAR facilitates growth suppression of SCC cells due to cell dissociation, followed by apoptosis. The consequent morphological reaction was reminiscent of anoikis, rather than epithelial-mesenchymal transition, and the dissociation of oral SCC cells was triggered not by lack of contact with extracellular matrix, but by loss of cell-to-cell contact caused by abnormal translocation of E-cadherin from surface membrane to cytoplasm. Immunoprecipitation assays of the CAR-transfected oral SCC cell line, HSC-2, with or without ROCK inhibitor (Y-27632) revealed that CAR directly associates with ROCKI and ROCKII, which results in inhibition of ROCK activity and contributes to maintenance of cell-to-cell adhesion for their growth and survival. Based on these findings, in vivo behavior of CAR-downregulated HSC-2 cells from siRNA knockdown was compared with that of normally CAR-expressing cells in intraperitoneally xenografted mouse models. The mice engrafted with CAR siRNA-pretreated HSC-2 cells showed poor formation of metastatic foci in contrast to those implanted with the control siRNA-pretreated cells. Thus, CAR substantially has an impact on growth and survival of oral SCC cells as a negative regulator of ROCK in vitro and in vivo.

Adenovirus i-leader truncation bioselected against cancer-associated fibroblasts to overcome tumor stromal barriers

Tumor-associated stromal cells constitute a major hurdle in the antitumor efficacy with oncolytic adenoviruses. To overcome this biological barrier, an in vitro bioselection of a mutagenized AdwtRGD stock in human cancer-associated fibroblasts (CAFs) was performed. Several rounds of harvest at early cytopathic effect (CPE) followed by plaque isolation led us to identify one mutant with large plaque phenotype, enhanced release in CAFs and enhanced cytotoxicity in CAF and several tumor cell lines. Whole genome sequencing and functional mapping identified the truncation of the last 17 amino acids in C-terminal end of the i-leader protein as the mutation responsible for this phenotype. Similar mutations have been previously isolated in two independent bioselection processes in tumor cell lines. Importantly, our results establish the enhanced antitumor activity in vivo of the i-leader C-terminal truncated mutants, especially in a desmotic fibroblast-embedded lung carcinoma model in mice. These results indicate that the i-leader truncation represents a promising trait to improve virotherapy with oncolytic adenoviruses.

Selective transduction of mature DC in human skin and lymph nodes by CD80/CD86-targeted fiber-modified adenovirus-5/3

In vivo targeting of dendritic cells (DC) represents an attractive alternative to currently apply ex vivo DC-based genetic tumor vaccination protocols. Finding the optimal vector for in vivo targeting of DC is important for such strategies. We, therefore, tested a panel of subgroup C/B chimeric and fiber-modified adenoviruses (Ads) for their relative capacity to transduce human DC. We made use of in vitro generated Langerhans cells, and of ex vivo human skin and melanoma-draining lymph node derived DC. Of the tested viruses the C/B-chimeric adenovirus serotype 5 (Ad5)/3 virus most efficiently transduced in vitro generated Langerhans cells. In addition, Ad5/3 preferentially targeted mature myeloid DC from human skin and draining lymph node and transduced them at significantly higher frequencies than Ad5. In addition, Ad5/3 was more specific for mature human skin-derived CD1a+ CD83+ DC than the previously reported DC-transducing C/B-chimeric vector Ad5/35, infecting less bystander cells. It was previously reported that Ad5/3 transduced human monocyte-derived DC by binding to the B7 molecules CD80 and CD86. High-efficiency transduction of mature skin-derived DC was similarly shown to be mediated through binding to CD80/CD86 and not to interfere with subsequent T-cell priming. We conclude that Ad5/3, in combination with DC-activating adjuvants, represents a promising therapeutic tool for the in vivo transduction of mature DC, and may be less likely to induce unwanted side effects such as immune tolerance through the infection of nonprofessional antigen-presenting cells.

The noninvasive, quantitative, in vivo assessment of adenoviral-mediated gene delivery in skin wound biomaterials

Because there are few reports using gene delivery in clinically-approved synthetic matrices, we examined the feasibility of using a noninvasive imaging system to study the kinetics of luciferase gene expression when delivered in an adenoviral vector. Using a mouse model of full thickness injury, we quantified the kinetics of gene expression, determined the optimal dose of particle delivery, and established the temporal importance of drug delivery in obtaining optimal gene expression. Specifically, we found that the ideal time to deliver adenovirus to a graft is during the early phase of graft wound closure (days 0-3 post-operatively) for a peak of gene expression to occur 7 days after delivery. Under these conditions, there is a saturating dose of 6 x 10(8) adenoviral particles per graft. In light of these findings, we examined whether the efficacy of delivery could be increased by modulating the composition of the grafts. When a collagen gene-activated matrix (GAM) containing basic fibroblast growth factor (FGF2) was compared to matrix alone, a significant increase in gene expression is observed when identical amounts of vector are delivered (p<0.05). Taken together, these results show how a noninvasive and quantitative assessment of gene expression can be used to optimize gene delivery and that the composition of matrices can dramatically influence gene expression in the wound bed.

A novel A33 promoter-based conditionally replicative adenovirus suppresses tumor growth and eradicates hepatic metastases in human colon cancer models

PURPOSE

A33 antigen is a membrane-bound protein expressed in intestinal epithelium that is overexpressed in 95% of primary and metastatic colorectal carcinomas but is absent in most epithelial tissues and tumor types. We hypothesized that A33 promoter might be useful in the design of a conditionally replicative adenovirus for the treatment of colorectal cancer (CRC).

EXPERIMENTAL DESIGN

We cloned an A33 promoter fragment (A33Pr) that extends from -105 to +307 bp. Using luciferase activity as a reporter gene, we showed that A33Pr was active in CRC cell lines. We next constructed a conditionally replicative adenovirus named AV22EL where E1A was placed under the control of A33Pr. The tumor-specific oncolytic effect of AV22EL was investigated both in vitro and in vivo.

RESULTS

AV22EL induced specific in vitro lysis of human CRC cell lines that expressed A33 and have negligible lytic capacity on cells that lacked or had minimal A33 expression, including normal human colonic cells. In vivo, a marked reduction of tumor growth and increased long-term survival rates were observed in nude mice xenografted with s.c. CRC tumors. Combination with 5-fluorouracil induced an additive effect in vitro with no toxic effects in vivo. Remarkably, AV22EL completely eliminated established hepatic metastases in >90% of mice and restored hepatic function according to biochemical parameters. Its systemic administration induced E1A expression only in the hepatic metastasis but not in normal organs.

CONCLUSIONS

These data show that AV22EL is a stringently regulated and potent oncolytic agent for the treatment of CRC.

Cutaneous gene delivery

Over the past decade, many approaches to transferring genes into the skin have been investigated. However, most such approaches have been specifically aimed against genodermatosis, and have not produced sufficient results. The goal of such research is to develop a method in which genes are transferred easily, efficiently and stably into keratinocytes, especially into keratinocyte stem cells, and in which the transgene expression persists without a reaction from the host immune response. Although accidental development of cancer has occurred in trials of gene therapy for X-linked severe combined immunodeficiency (X-SCID), resulting in slowing of the progress of this research, the lessons of these setbacks have been applied to further research. Moreover, combined with the techniques acquired from tissue engineering, recent developments in our knowledge about stem cells will lead to new treatments for genodermatoses. The present review summarizes the methods by which therapeutic genes can be transferred into keratinocytes, with discussion of how gene transfer efficiency can be improved, with particular emphasis on disruption of the skin barrier function. It concludes with discussion of the challenges and prospects of keratinocyte gene therapy, in terms of achieving efficient and long-lasting therapeutic effects.

Lysis of Dysplastic but not Normal Oral Keratinocytes and Tissue-Engineered Epithelia with Conditionally Replicating Adenoviruses

There is no effective medical treatment for oral precancer, and surgery to remove these lesions is imprecise because abnormal mucosa extends beyond the visible lesion. Development of vectors for tumor-selective viral replication has been a significant advance, and viral lysis is well suited to destruction of oral precancerous mucosa. To facilitate evaluation of new treatments, we engineered dysplastic oral epithelium using keratinocytes isolated from dysplastic lesions. We show that these model systems recapitulate the key characteristics of the clinical lesions closely, and that topical delivery of the conditionally replicating adenovirus (CRAd) dl922-947 can lyse tissue-engineered epithelia that show mild, moderate, or severe dysplasia, but normal oral epithelia are very resistant to this treatment. The lytic effect is determined by various factors, including the grade and proliferation index of the dysplastic epithelia. The presence of suprabasal cycling cells, expression of the coxsackie adenovirus receptor (CAR), the transcription cofactor p300, and other aberrations that affect the regulation of the cell cycle or apoptosis and promote viral replication may also be important. The ability of dl922-947 to destroy engineered oral dysplasia was significantly greater than that observed using wild-type adenovirus, d/1520, or viruses modified to bypass cell entry dependent on the presence of CAR. Evidence of infection in clinical dysplastic lesions was also shown ex vivo using tissue explants. We conclude that dl922-947 may provide an efficient molecular cytotoxic to dissolve oral dysplastic lesions.

AAV-Mediated Gene Transfer to Cardiac Cells in a Heterotopic Rat Heart Transplantation Model

INTRODUCTION

Adeno-associated virus (AAV) vectors offer the possibility to transfer genes to a wide range of organ and cell types. To determine the efficiency of AAV-mediated gene transfer to cardiac cells, vectors were administered to the heart under various conditions.

METHODS

In Sprague-Dawley rats, AAV vectors based on serotype 2 and coding for beta-galactosidase were injected via coronaries into hypothermic nonbeating and normothermic beating hearts before transplantation. In addition, vectors were injected intravenously or into the thigh muscle. After 28 days all animals were humanely killed and organs explanted for analysis.

RESULTS

Transgenic DNA was always detectable in the liver and the heart, irrespective of the application mode. However, transgenic mRNA could not be determined in the transplanted hearts. In contrast, direct injection into the thigh muscle resulted in transgenic mRNA production and marker gene expression. After systemic application, transgenic mRNA was detected in the liver but not in the heart.

CONCLUSION

The results of our study indicated that AAV-mediated gene transfer to cardiac cells is possible. However, it was impossible to detect transgenic mRNA or marker gene expression in the transplanted hearts after intracoronary perfusion or systemic injection.