久米 晃啓

The development of genome-editing technology could lead to breakthrough gene therapy. Genome editing has made it possible to easily knock out or modify a target gene, while current gene therapy using a virus vector or plasmid hampering modification with respect to gene replacement therapies. Clinical development using these genome-editing tools is progressing rapidly. However, it is also becoming clear that there is a possibility of unintended gene sequence modification or deletion, or the insertion of undesired genes, or the selection of cells with abnormalities in the cancer suppressor gene p53; these unwanted actions are not possible with current gene therapy. The Science Board of the Pharmaceuticals and Medical Devices Agency of Japan has compiled a report on the expected aspects of such genome-editing technology and the risks associated with it. This article summarizes the history of that discussion and compares the key concepts with information provided by other regulatory authorities.

Idiopathic pulmonary fibrosis (IPF) is a fibroproliferative disorder with limited therapeutic options. An aberrant wound healing process in response to repetitive lung injury has been suggested for its pathogenesis, and a number of cytokines including transforming growth factor β1 play pivotal roles in the induction and progression of fibrosis. Thus, the regulation of these pro-inflammatory conditions may reduce the progression of IPF and ameliorate its symptoms in patients. Interleukin-10 (IL-10), a pleiotropic cytokine, exerts anti-inflammatory and anti-fibrotic effects in numerous biological settings. In the present study, we investigated the preventive effects of IL-10 on bleomycin-induced pulmonary fibrosis in mice with the continuous expression of this cytokine via an adeno-associated virus serotype 6 vector. Mice were administered the adeno-associated virus serotype 6 vector encoding mouse IL-10 by intratracheal injection, and osmotic minipumps containing bleomycin were subcutaneously implanted seven days later. Lung histology and the expression levels of pro-inflammatory cytokines and fibrogenic cytokines were then analyzed. In mice exhibiting persistent IL-10 expression on day 35, the number of infiltrated inflammatory cells and the development of fibrosis in lung tissues were significantly reduced. Increases in transforming growth factor β1 and decreases in IFN-γ were also suppressed in treated animals, with changes in these cytokines playing important roles in the pathogenesis of pulmonary fibrosis. Furthermore, IL-10 significantly improved survival in bleomycin-induced mice. Our results provide insights into the potential benefit of the anti-fibrotic effects of IL-10 as a novel therapeutic approach for IPF.

An efficient adeno-associated virus (AAV) vector was constructed for the treatment of respiratory diseases. AAV serotypes, promoters and routes of administration potentially influencing the efficiency of gene transfer to airway cells were examined in the present study. Among the nine AAV serotypes (AAV1-9) screened in vitro and four serotypes (AAV1, 2, 6, 9) evaluated in vivo, AAV6 showed the strongest transgene expression. As for promoters, the cytomegalovirus (CMV) early enhancer/chicken beta-actin (CAG) promoter resulted in more robust transduction than the CMV promoter. Regarding delivery routes, intratracheal administration resulted in strong transgene expression in the lung, whereas the intravenous and intranasal administration routes yielded negligible expression. The combination of the AAV6 capsid and CAG promoter resulted in sustained expression, and the intratracheally administered AAV6-CAG vector transduced bronchial cells and pericytes in the lung. These results suggest that AAV6-CAG vectors are more promising than the previously preferred AAV2 vectors for airway transduction, particularly when administered into the trachea. The present study offers an optimized strategy for AAV-mediated gene therapy for lung diseases, such as cystic fibrosis and pulmonary fibrosis.

Engineered T-cell therapy using a CD19-specific chimeric antigen receptor ( CD19-CAR) is a promising strategy for the treatment of advanced B-cell malignancies. Gene transfer of CARs to T-cells has widely relied on retroviral vectors, but transposon-based gene transfer has recently emerged as a suitable nonviral method to mediate stable transgene expression. The advantages of transposon vectors compared with viral vectors include their simplicity and cost-effectiveness. We used the Tol2 transposon system to stably transfer CD19-CAR into human T-cells. Normal human peripheral blood lymphocytes were co-nucleofected with the Tol2 transposon donor plasmid carrying CD19-CAR and the transposase expression plasmid and were selectively propagated on NIH3T3 cells expressing human CD19. Expanded CD3+ T-cells with stable and high-level transgene expression (similar to 95%) produced interferon. gamma upon stimulation with CD19 and specifically lysed Raji cells, a CD19(+) human B-cell lymphoma cell line. Adoptive transfer of these T-cells suppressed tumor progression in Raji tumor-bearing Rag2(-/-)gamma c(-/-) immunodeficient mice compared with control mice. These results demonstrate that the Tol2 transposon system could be used to express CD19-CAR in genetically engineered T-cells for the treatment of refractory B-cell malignancies.

Galanin and its receptors, GALR1 and GALR2, are known tumor suppressors and potential therapeutic targets in head and neck squamous cell carcinoma (HNSCC). Previously, we demonstrated that, in GALR1-expressing HNSCC cells, the addition of galanin suppressed tumor proliferation via upregulation of ERK1/2 and cyclin-dependent kinase inhibitors, whereas, in GALR2-expressing cells, the addition of galanin not only suppressed proliferation, but also induced apoptosis. In this study, we first transduced HEp-2 and KB cell lines using a recombinant adeno-associated virus (rAAV)-green fluorescent protein (GFP) vector and confirmed a high GFP expression rate (>90%) in both cell lines at the standard vector dose. Next, we demonstrated that GALR2 expression in the presence of galanin suppressed cell viability to 40-60% after 72h in both cell lines. Additionally, the annexin V-positive rate and sub-G0/G1 phase population were significantly elevated in HEp-2 cells (mock vs GALR2: 12.3 vs 25.0% (P < 0.01) and 9.1 vs 32.0% (P < 0.05), respectively) after 48h. These changes were also observed in KB cells, although to a lesser extent. Furthermore, in HEp-2 cells, GALR2-mediated apoptosis was caspase-independent, involving downregulation of ERK1/2, followed by induction of the pro-apoptotic Bcl-2 protein, Bim. These results illustrate that transient GALR2 expression in the presence of galanin induces apoptosis via diverse pathways and serves as a platform for suicide gene therapy against HNSCC.

Galanin and its receptors, GALR1 and GALR2, are known tumor suppressors and potential therapeutic targets in head and neck squamous cell carcinoma (HNSCC). Previously, we demonstrated that, in GALR1-expressing HNSCC cells, the addition of galanin suppressed tumor proliferation via upregulation of ERK1/2 and cyclin-dependent kinase inhibitors, whereas, in GALR2-expressing cells, the addition of galanin not only suppressed proliferation, but also induced apoptosis. In this study, we first transduced HEp-2 and KB cell lines using a recombinant adeno-associated virus (rAAV)-green fluorescent protein (GFP) vector and confirmed a high GFP expression rate (&gt 90%) in both cell lines at the standard vector dose. Next, we demonstrated that GALR2 expression in the presence of galanin suppressed cell viability to 40-60% after 72 h in both cell lines. Additionally, the annexin V-positive rate and sub-G0/G1 phase population were significantly elevated in HEp-2 cells (mock vs GALR2: 12.3 vs 25.0% (P &lt 0.01) and 9.1 vs 32.0% (P &lt 0.05), respectively) after 48 h. These changes were also observed in KB cells, although to a lesser extent. Furthermore, in HEp-2 cells, GALR2-mediated apoptosis was caspase-independent, involving downregulation of ERK1/2, followed by induction of the pro-apoptotic Bcl-2 protein, Bim. These results illustrate that transient GALR2 expression in the presence of galanin induces apoptosis via diverse pathways and serves as a platform for suicide gene therapy against HNSCC. © 2013 The Authors.

Cytosolic isocitrate dehydrogenase 1 (IDH1) with an R132H mutation in brain tumors loses its enzymatic activity for catalyzing isocitrate to alpha-ketoglutarate (alpha-KG) and acquires new activity whereby it converts alpha-KG to 2-hydroxyglutarate. The IDH1 mutation induces down-regulation of tricarboxylic acid cycle intermediates and up-regulation of lipid metabolism. Sterol regulatory element-binding proteins (SREBPs) regulate not only the synthesis of cholesterol and fatty acids but also acyclin-dependent kinase inhibitor p21 that halts the cell cycle at G1. Here we show that SREBPs were up-regulated in U87 human glioblastoma cells transfected with an IDH1(R132H)-expression plasmid. Small interfering ribonucleic acid (siRNA) for SREBP1 specifically decreased p21 messenger RNA (mRNA) levels independent of the p53 pathway. In IDH1(R132H)-expressing U87 cells, phosphorylation of Retinoblastoma (Rb) protein also decreased. We propose that metabolic changes induced by the IDH1 mutation enhance p21 expression via SREBP1 and inhibit phosphorylation of Rb, which slows progression of the cell cycle and may be associated with non-aggressive features of gliomas with an IDH1 mutation.

Lymph node metastasis is the most important prognostic factor of endometrial cancer. However, effective therapy has not been established against lymph node metastasis. In this study, we explored the efficacy of gene therapy targeting lymph node metastasis of endometrial cancer by suppressing the action of vascular endothelial growth factor (VEGF)-C through soluble VEGF receptor-3 (sVEGFR-3) expression. For this purpose, we first conducted a model experiment by introducing sVEGFR-3 cDNA into an endometrial cancer cell line HEC1A and established HEC1A/sVEGFR-3 cell line with high sVEGFR-3 expression. The conditioned medium of HEC1A/sVEGFR-3 cells inhibited lymphatic endothelial cell growth in vitro, and sVEGFR-3 expression in HEC1A cells suppressed in vivo lymph node and lung metastases without inhibiting the growth of a subcutaneously inoculated tumor. To validate the therapeutic efficacy, adeno-associated virus vectors encoding sVEGFR-3 were injected into the skeletal muscle of mice with lymph node metastasis. Lymph node and lung metastases of HEC1A cells were completely suppressed by the muscle-mediated expression of sVEG-FR-3 using adeno-associated virus vectors. These results suggest the possibility of gene therapy against lymph node and lung metastases of endometrial cancer by using muscle-mediated expression of sVEGFR-3.

Adoptive T-cell therapy with CD19-specific chimeric antigen receptors (CARs) is promising for treatment of advanced B-cell malignancies. Tumor targeting of CAR-modified T-cells is likely to contribute therapeutic potency; therefore we examined the relationship between the ability of CD19-specific CAR (CD19-CAR)-transduced T-cells to accumulate at CD19(+) tumor lesions, and their ability to provide antitumor effects in xenograft mouse models. Normal human peripheral blood lymphocytes, activated with immobilized RetroNectin and anti-CD3 antibodies, were transduced with retroviral vectors that encode CD19-CAR. Expanded CD19-CAR T-cells with a high transgene expression level of about 75% produced IL-2 and IFN-gamma in response to CD19, and lysed both Raji and Daudi CD19(+) human B-cell lymphoma cell lines. Furthermore, these cells efficiently accumulated at Raji tumor lesions where they suppressed tumor progression and prolonged survival in tumor-bearing Rag2(-/-)gamma c(-/-) immunodeficient mice compared to control cohorts. These results show that the ability of CD19-CAR T-cells to home in on tumor lesions is pivotal for their anti-tumor effects in our xenograft models, and therefore may enhance the efficacy of adoptive T-cell therapy for refractory B-cell lymphoma. (C) 2013 Elsevier Inc. All rights reserved.

Varying degrees of metabolic abnormalities mediated by chronic inflammation are implicated in the chronic glomerular injuries associated with obesity. Interleukin (IL)-10, a pleiotropic cytokine, exerts anti-inflammatory effects in numerous biological settings. In the present study, we explored the biological benefits of adeno-associated virus (AAV) vector-mediated sustained IL-10 expression against the pathological renal characteristics observed in Zucker fatty rats (ZFRs). We injected an AAV vector, encoding rat IL-10 or enhanced green fluorescent protein (GFP) into male ZFRs at 5 weeks of age. Subsequently, the renal pathophysiological changes were analyzed. Persistent IL-10 expression significantly reduced the urinary protein excretion of ZFRs compared with GFP expression (47.1 +/- 11.6 mg per mg.creatinine versus 88.8 +/- 30.0 mg per mg.creatinine, P<0.01). The serum levels of IL-10 negatively correlated with the urinary protein in AAV-treated rats (r = -0.78, P<0.01). Renal hypertrophy, increased widths in the glomerular basement membrane, and the lack of uniformity and regularity of the foot process of the visceral glomerular epithelial cells of ZFRs were significantly blunted by IL-10 expression. IL-10 also abrogated the downregulation of glomerular nephrin observed in ZFRs treated with the GFP vector. Our findings provide insights into the potential benefit of the anti-inflammatory effects of IL-10 on the overall management of glomerulopathy induced by the metabolic disorders associated with obesity. Gene Therapy (2012) 19, 476-482; doi:10.1038/gt.2011.183; published online 24 November 2011

Phenylketonuria (PKU) is a common genetic disorder arising from a deficiency of phenylalanine hydroxylase. If left untreated, the accumulation of phenylalanine leads to brain damage and neuropsychological dysfunction. One of the abnormalities found in hyperphenylalaninemic patients and a mouse model of PKU is an aminergic deficit in the brain. We previously showed correction of hyperphenylalaninemia and concomitant behavioral recovery in PKU mice after liver-targeted gene transfer with a viral vector. Here, we addressed whether such a functional recovery was substantiated by an improved amine metabolism in the brain. After gene transfer, brain dopamine, norepinephrine, and serotonin levels in the PKU mice were significantly elevated to normal or near-normal levels, along with systemic improvement of phenylalanine catabolism. The results of biochemical analyses validated the efficacy of PKU gene therapy in the central nervous system. NeuroReport 23:30-34 (C) 2011 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.

Controlling lymph node metastasis is currently a key issue in cancer therapy. Lymph node metastasis is one of the most important prognostic factors in various types of cancers, including endometrial cancer. Vascular endothelial growth factor-C (VEGF-C) plays a crucial role in lymphangiogenesis, and is implicated to play an important role in lymph node metastasis. To evaluate the role of VEGF-C in lymph node metastasis, we developed an animal model by using an endometrial cancer cell line, HEC1A. This cell line is not invasive by nature and secretes moderate amounts of VEGF-C; intrauterine injection of HEC1A cells into Balb/c nude mice resulted in uterine cancer with lymph node metastasis after 8 weeks. To analyze the contribution of VEGF-C to lymph node metastasis, its corresponding gene was stably introduced into HEC1A cells (HEC1A/VEGF-C), which then produced more than 10 times the amount of VEGF-C. The number of lymph node metastases was significantly higher in HEC1A/VEGF-C cells than in HEC1A cells (3.2 vs 1.1 nodes/animal, respectively). Augmented lymphangiogenesis was observed within tumors when HEC1A/VEGF-C cells were inoculated. These results indicate that VEGF-C plays a critical role in lymph node metastasis, in addition to serving as a platform to test the efficacy of various therapeutic modalities against lymph node metastasis. (Cancer Sci 2011; 102: 22722277)

Although mesenchymal stem cells (MSCs) play pivotal supportive roles in hematopoiesis, how they interact with hematopoietic stem cells (HSCs) is not well understood. We investigated the interaction between HSCs and surrogate MSCs (C3H10T1/2 stromal cells), focusing on the molecular events induced by cell contact of these bipartite populations. C3H10T1/2 is a mesenchymal stromal cell line that can be induced to differentiate into preadipocytes (A54) and my oblasts (M1601). The stromal cell derivatives were cocultured with murine HSCs (Lineage-Sca1+), and gene expression profiles in stromal cells and HSCs were compared before and after the coculture. HSCs gave rise to cobblestone areas only on A54 cells, with nine fold more progenitors than on M1601 or undifferentiated C3H10T1/2 cells. Microarray-based screening and a quantitative reverse transcriptase directed-polymerase chain reaction showed that the levels of Notch ligands (Jagged1 and Deltalike 3) were increased in A54 cells upon interaction with HSCs. On the other hand, the expression of Notch1 and Hes1 was unregulated in the HSCs cocultured with A54 cells. A Tran swell assay revealed that the reciprocal up regulation was dependent on cell-to-cell contact. The result suggested that in the hematopoietic niche, HSCs help MSCs to produce Notch ligands, and in turn, MSCs help HSCs to express Notch receptor. Such a reciprocal up regulation would reinforce the downstream signaling to determine the fate of hematopoietic cell lineage. Clarification of the initiating events on cell contact should lead to the identification of specific molecular targets to facilitate HSC engraftment in transplantation therapy. © Journal of Stem Cells and Regenerative Medicine. All rights reserved.

Background Classical phenylketonuria (PKU) arises from a deficiency of phenylalanine hydroxylase (PAH) that catalyses phenylalanine oxidation in the liver. Lack of PAH activity causes massive hyperphenylalaninemia and consequently severe brain damage. Preclinical studies showed that conventional adeno-associated virus (AAV) vectors could correct hyperphenylalaninemia in a mouse model of PKU, although limitations such as very large dose requirement and relative inefficiency in female animals were recognized. Method An AAV8-pseudotyped vector was constructed with a self-complementary AAV (scAAV) genome for efficient liver transduction and expression. Following vector injection to PKU mice, blood Phe was periodically measured by an enzymatic fluorometric assay. In vivo Phe oxidation was evaluated by a non-invasive breath test using [1-(13)C] Phe. Vector copy number in the host tissues was determined by quantitative polymerase chain reaction. Results A single injection of 1 x 10(11)-1 x 10(12) particles of the scAAV8 vector resulted in a reduction of blood Phe to normal or near-normal levels for more than 1 year in both genders. The treated animals showed normal level of in vivo Phe oxidation. The presence of > 1 copy of vector DNA per diploid genome in the liver was associated with normal blood Phe in the AAV-treated PKU mice. Conclusions Complete phenotypic correction of PKU mice was achieved by the scAAV8 vector for the longest duration reported to date. The vector overcame the female-specific disadvantage in AAV-mediated liver transduction; thus, it offers a promising platform of long-lasting gene therapy for PKU. Copyright (C) 2011 John Wiley & Sons, Ltd.

Gene therapy is considered as one of the innovative treatment modalities for diabetic retinopathy (DR). Since genuine animal models of DR are limited, only a few studies have reported the efficacy of gene therapy. For preclinical study of DR, spontaneously diabetic Torii (SDT) rat is a valuable model. Fortunately, we could evaluate the efficacy of adeno-associated virus (AAV)-mediated gene therapy in SDT rats and proved that sFlt-1 expression prevented DR progression. Because of a limited number of large-animal models of DR, it is uncertain whether gene therapy experiments using dogs or monkeys allow reliable conclusions. On the other hand, owing to the recent progress in AAV-mediated gene therapy for retinal diseases in monkeys and humans, gene therapy for DR using AAV vectors may become a reality in the near future. © Mizukami et al.

Gene transfer of dopamine-synthesizing enzymes into the striatal neurons has led to behavioral recovery in animal models of Parkinson's disease (PD). We evaluated the safety, tolerability, and potential efficacy of adenoassociated virus (AAV) vector-mediated gene delivery of aromatic l-amino acid decarboxylase (AADC) into the putamen of PD patients. Six PD patients were evaluated at baseline and at 6 months, using multiple measures, including the Unified Parkinson's Disease Rating Scale (UPDRS), motor state diaries, and positron emission tomography (PET) with 6-[(18)F] fluoro-l-m-tyrosine (FMT), a tracer for AADC. The short-duration response to levodopa was measured in three patients. The procedure was well tolerated. Six months after surgery, motor functions in the OFF-medication state improved an average of 46% based on the UPDRS scores, without apparent changes in the short-duration response to levodopa. PET revealed a 56% increase in FMT activity, which persisted up to 96 weeks. Our findings provide class IV evidence regarding the safety and efficacy of AADC gene therapy and warrant further evaluation in a randomized, controlled, phase 2 setting.

The CH-296 recombinant fragment of human fibronectin is essential for murine leukemia virus (MLV)-derived retroviral transduction of CD34(+) cells for the purpose of stem cell gene therapy. Although the major effect of CH-296 is colocalization of the MLV-derived retrovirus and target cells at specific adhesion domains of CH-296 mediated by integrins expressed on CD34(+) cells, the precise roles of the integrins are unclear. We examined the kinetics of integrin expression on CD34(+) cells during the course of MLV-derived retrovirus-mediated gene transduction with CH-296. Flow cytometry revealed that the levels of both very late activation protein (VLA)-4 and VLA-5 on CD34(+) cells freshly isolated from cord blood were insufficient for effective MLV-derived retroviral transduction. However, increases were achieved during culture for preinduction and MLV-derived retrovirus-mediated gene transduction in the presence of a cocktail of cytokines. In addition, we confirmed by using specific antibodies that inhibition of the cell adhesion mediated by the integrins significantly reduced transduction efficiency, indicating that integrin expression is indeed important for CH-296-based MLV-derived retroviral transduction. Only a few cytokines are capable of inducing integrin expression, and stem cell factor plus thrombopoietin was found to be the minimal combination that was sufficient for effective transduction of an MLV-derived retrovirus based on CH-296. Our findings should be useful for improving the culture conditions for CH-296-based MLV-derived retroviral transduction in stem cell gene therapy.