In vivo stable transduction of humanized liver tissue in chimeric mice via high-capacity adenovirus-lentivirus hybrid vector

The Effect of EPO Gene Overexpression on Proliferation and Migration of Mouse Bone Marrow-Derived Mesenchymal Stem Cells

The aim of this study is to investigate the effect of erythropoietin (EPO) gene overexpression on proliferation and migration of mouse bone marrow-derived mesenchymal stem cells (MSCs), and to determine the underlying signaling pathway. Mouse MSCs were cultured in vitro and EPO gene was transfected into the 6th generation of MSCs via lentivirus vector. The transfected cells were identified by flow cytometry and the EPO levels in supernatant were measured with ELISA. In addition, cell proliferation was assessed by CCK-8 assay and cell migration was evaluated by Transwell assay. The activation of Akt, ERK1/2, and p38MAPK signaling was detected by western blotting. The lentivirus vector containing EPO was successfully constructed and transfected into MSCs. No remarkable change was found in the cell surface markers after transfection while a significant increase of EPO level in supernatant was noticed in transfected MSCs compared to controls (P < 0.01). In addition, transfected MSCs showed a significantly enhanced proliferation (P < 0.01) as well as a notable increase in migration (P < 0.01) compared to controls. Furthermore, we also found that EPO modification enhanced the phosphorylation of PI3K/Akt and ERK signaling pathway, and suppressed the phosphorylation of p38MAPK without affecting the levels of total Akt, ERK1/2, and p38MAPK in MSCs. After transfection, MSCs secreted more EPO which enhanced the capability of proliferation and migration. Moreover, our results suggested that the enhanced proliferation and migration might be associated with activation of PI3K/Akt and ERK or inhibition of P38MAPK signaling pathway.

A Hybrid Adenoviral Vector System Achieves Efficient Long-Term Gene Expression in the Liver via piggyBac Transposition

Much research has gone into the development of hybrid gene delivery systems that combine the broad tropism and efficient transduction of adenoviral vectors with the ability to achieve stable expression of cargo genes. In addition to gene therapy applications, such a system has considerable advantages for studies of gene function in vivo, permitting fine-tuned genetic manipulation with higher throughput than can be achieved using standard transgenic and DNA targeting techniques. Existing strategies are limited, however, by low integration efficiencies, small cargo capacity, and/or a dependence on target cell division. The utility of this approach could be enhanced by a system that provides all of the following: (1) efficient delivery, (2) stable expression in a high percentage of target cells (whether mitotic or not), (3) large cargo capacity, (4) flexibility to use with a wide range of additional experimental conditions, and (5) simple experimental technique. Here we report the initial characterization of a hybrid system that meets these criteria by utilizing piggyBac (PB) transposition to achieve genomic integration from adenoviral vectors. We demonstrate stable expression of an adenovirus (Ad)-PB-delivered reporter gene in ∼20-40% of hepatocytes following standard tail vein injection. Its high efficiency and flexibility relative to existing hybrid adenoviral gene delivery approaches indicate a considerable potential utility of the Ad-PB system for therapeutic gene delivery and in vivo studies of gene function.

Efficient genome editing in hematopoietic stem cells with helper-dependent Ad5/35 vectors expressing site-specific endonucleases under microRNA regulation

Genome editing with site-specific endonucleases has implications for basic biomedical research as well as for gene therapy. We generated helper-dependent, capsid-modified adenovirus (HD-Ad5/35) vectors for zinc-finger nuclease (ZFN)– or transcription activator-like effector nuclease (TALEN)–mediated genome editing in human CD34+ hematopoietic stem cells (HSCs) from mobilized adult donors. The production of these vectors required that ZFN and TALEN expression in HD-Ad5/35 producer 293-Cre cells was suppressed. To do this, we developed a microRNA (miRNA)-based system for regulation of gene expression based on miRNA expression profiling of 293-Cre and CD34+ cells. Using miR-183-5p and miR-218-5p based regulation of transgene gene expression, we first produced an HD-Ad5/35 vector expressing a ZFN specific to the HIV coreceptor gene ccr5. We demonstrated that HD-Ad5/35.ZFNmiR vector conferred ccr5 knock out in primitive HSC (i.e., long-term culture initiating cells and NOD/SCID repopulating cells). The ccr5 gene disruption frequency achieved in engrafted HSCs found in the bone marrow of transplanted mice is clinically relevant for HIV therapy considering that these cells can give rise to multiple lineages, including all the lineages that represent targets and reservoirs for HIV. We produced a second HD-Ad5/35 vector expressing a TALEN targeting the DNase hypersensitivity region 2 (HS2) within the globin locus control region. This vector has potential for targeted gene correction in hemoglobinopathies. The miRNA regulated HD-Ad5/35 vector platform for expression of site-specific endonucleases has numerous advantages over currently used vectors as a tool for genome engineering of HSCs for therapeutic purposes.

Adenovirus-retrovirus hybrid vectors achieve highly enhanced tumor transduction and antitumor efficacy in vivo

Murine leukemia virus (MLV)-based replication-competent retrovirus (RCR) vectors have been shown to mediate efficient, selective, and persistent tumor transduction, thereby achieving significant therapeutic benefit in a wide variety of cancer models. To further augment the efficiency of this strategy, we have developed a delivery method employing a gutted adenovirus encoding an RCR vector (AdRCR); thus, tumor cells transduced with the adenoviral vector transiently become RCR vector producer cells in situ. As expected, high-titer AdRCR achieved significantly higher initial transduction levels in human cancer cells both in vitro and in vivo, as compared to the original RCR vector itself. Notably, even at equivalent initial transduction levels, more secondary RCR progeny were produced from AdRCR-transduced cells as compared to RCR-transduced cells, resulting in further acceleration of subsequent RCR replication kinetics. In pre-established tumor models in vivo, prodrug activator gene therapy with high-titer AdRCR could achieve enhanced efficacy compared to RCR alone, in a dose-dependent manner. Thus, AdRCR hybrid vectors offer the advantages of high production titers characteristic of adenovirus and secondary production of RCR in situ, which not only accelerates subsequent vector spread and progressive tumor transduction, but can also significantly enhance the therapeutic efficacy of RCR-mediated prodrug activator gene therapy.