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Abstract
Clinical gene therapy has been increasingly successful owing both to an enhanced molecular understanding of human disease and to progressively improving gene delivery technologies. Among these technologies, delivery vectors based on adeno-associated viruses (AAVs) have emerged as safe and effective and, in one recent case, have led to regulatory approval. Although shortcomings in viral vector properties will render extension of such successes to many other human diseases challenging, new approaches to engineer and improve AAV vectors and their genetic cargo are increasingly helping to overcome these barriers.
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Affiliation(s)
- Melissa A. Kotterman
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California, USA
| | - David V. Schaffer
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California, USA
- Department of Bioengineering, University of California, Berkeley, California, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
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52
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Prolonged expression of an anti-HIV-1 gp120 minibody to the female rhesus macaque lower genital tract by AAV gene transfer. Gene Ther 2014; 21:802-10. [PMID: 24965083 PMCID: PMC5530589 DOI: 10.1038/gt.2014.56] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 03/13/2014] [Accepted: 04/10/2014] [Indexed: 02/07/2023]
Abstract
Topical microbicides are a leading strategy for prevention of HIV mucosal infection to women, however, numerous pharmacokinetic limitations associated with coitally-related dosing strategy have contributed to their limited success. Here we test the hypothesis that adeno-associated virus (AAV) mediated delivery of the b12 human anti-HIV-1 gp120 minibody gene to the lower genital tract of female rhesus macaques (Rh) can provide prolonged expression of b12 minibodies in the cervical-vaginal secretions. Gene transfer studies demonstrated that, of various GFP-expressing AAV serotypes, AAV-6 most efficiently transduced freshly immortalized and primary genital epithelial cells (PGECs) of female Rh in vitro. In addition, AAV-6-b12 minibody transduction of Rh PGECs led to inhibition of SHIV162p4 transmigration and virus infectivity in vitro. AAV-6-GFP could also successfully transduce vaginal epithelial cells of Rh when applied intra-vaginally, including p63+ epithelial stem cells. Moreover, intra-vaginal application of AAV-6-b12 to female Rh resulted in prolonged minibody detection in their vaginal secretions throughout the 79 day study period. These data provide proof-of-principle that AAV-6-mediated delivery of anti-HIV broadly neutralizing antibody (BnAb) genes to the lower genital tract of female Rh results in persistent minibody detection for several months. This strategy offers promise that an anti-HIV-1 genetic microbicide strategy may be possible in which topical application of AAV vector, with periodic reapplication as needed, may provide sustained local BnAb expression and protection.
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53
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Kim E, Lee S, Hong S, Jin G, Kim M, Park KI, Lee H, Jang JH. Sticky "delivering-from" strategies using viral vectors for efficient human neural stem cell infection by bioinspired catecholamines. ACS APPLIED MATERIALS & INTERFACES 2014; 6:8288-8294. [PMID: 24827581 DOI: 10.1021/am5011095] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Controlled release of biosuprastructures, such as viruses, from surfaces has been a challenging task in providing efficient ex vivo gene delivery. Conventional controlled viral release approaches have demonstrated low viral immobilization and burst release, inhibiting delivery efficiency. Here, a highly powerful substrate-mediated viral delivery system was designed by combining two key components that have demonstrated great potential in the fields of gene therapy and surface chemistry, respectively: adeno-associated viral (AAV) vectors and adhesive catecholamine surfaces. The introduction of a nanoscale thin coating of catecholamines, poly(norepinephrine) (pNE) or poly(dopamine) (pDA) to provide AAV adhesion followed by human neural stem cell (hNSC) culture on sticky solid surfaces exhibited unprecedented results: approximately 90% loading vs 25% (AAV_bare surface), no burst release, sustained release at constant rates, approximately 70% infection vs 20% (AAV_bare surface), and rapid internalization. Importantly, the sticky catecholamine-mediated AAV delivery system successfully induced a physiological response from hNSCs, cellular proliferation by a single-shot of AAV encoding fibroblast growth factor-2 (FGF-2), which is typically achieved by multiple treatments with expensive FGF-2 proteins. By combining the adhesive material-independent surface functionalization characters of pNE and pDA, this new sticky "delivering-from" gene delivery platform will make a significant contribution to numerous fields, including tissue engineering, gene therapy, and stem cell therapy.
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Affiliation(s)
- Eunmi Kim
- Department of Chemical and Biomolecular Engineering, Yonsei University , 50 Yonsei-Ro, Seoul 120-749, Korea
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54
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Ojala DS, Amara DP, Schaffer DV. Adeno-associated virus vectors and neurological gene therapy. Neuroscientist 2014; 21:84-98. [PMID: 24557878 DOI: 10.1177/1073858414521870] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Gene therapy has strong potential for treating a variety of genetic disorders, as demonstrated in recent clinical trials. There is unfortunately no scarcity of disease targets, and the grand challenge in this field has instead been the development of safe and efficient gene delivery platforms. To date, approximately two thirds of the 1800 gene therapy clinical trials completed worldwide have used viral vectors. Among these, adeno-associated virus (AAV) has emerged as particularly promising because of its impressive safety profile and efficiency in transducing a wide range of cell types. Gene delivery to the CNS involves both considerable promise and unique challenges, and better AAV vectors are thus needed to translate CNS gene therapy approaches to the clinic. This review discusses strategies for vector design, potential routes of administration, immune responses, and clinical applications of AAV in the CNS.
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Affiliation(s)
- David S Ojala
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, USA
| | - Dominic P Amara
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - David V Schaffer
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, USA Department of Bioengineering, University of California, Berkeley, CA, USA The Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA
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55
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Lee S, Cho S, Kim M, Jin G, Jeong U, Jang JH. Highly moldable electrospun clay-like fluffy nanofibers for three-dimensional scaffolds. ACS APPLIED MATERIALS & INTERFACES 2014; 6:1082-1091. [PMID: 24393142 DOI: 10.1021/am404627r] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The development of three-dimensional polymeric systems capable of mimicking the extracellular matrix is critical for advancing tissue engineering. To achieve these objectives, three-dimensional fibrous scaffolds with "clay"-like properties were successfully developed by coaxially electrospinning polystyrene (PS) and poly(ε-caprolactone) (PCL) and selective leaching. As PS is known to be nonbiodegradable and vulnerable to mechanical stress, PS layers present at the outer surface were removed using a "selective leaching" process. The fibrous PCL scaffolds that remained after the leaching step exhibited highly advantageous characteristics as a tissue engineering scaffold, including moldability (i.e., clay-like), flexibility, and three-dimensional structure (i.e., cotton-like). More so, the "clay-like" PCL fibrous scaffolds could be shaped into any desired form, and the microenvironment within the clay scaffolds was highly favorable for cell expansion both in vitro and in vivo. These "electrospun-clay" scaffolds overcome the current limitations of conventional electrospun, sheet-like scaffolds, which are structurally inflexible. Therefore, this work extends the scope of electrospun fibrous scaffolds toward a variety of tissue engineering applications.
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Affiliation(s)
- Slgirim Lee
- Department of Chemical and Biomolecular Engineering, Yonsei University , 134 Shinchon-dong, Seoul, Korea
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56
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Bartel MA, Schaffer DV. Enhanced gene targeting of adult and pluripotent stem cells using evolved adeno-associated virus. Methods Mol Biol 2014; 1114:169-79. [PMID: 24557903 DOI: 10.1007/978-1-62703-761-7_11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Efficient approaches for the precise genetic engineering of stem cells can enhance both basic and applied stem cell research. Adeno-associated virus (AAV) vectors have demonstrated high-efficiency gene delivery and gene targeting to numerous cell types, and AAV vectors developed specifically for gene delivery to stem cells have further increased gene targeting frequency compared to plasmid construct techniques. This chapter details the production and purification techniques necessary to generate adeno-associated viral vectors for use in high-efficiency gene targeting of adult or pluripotent stem cell applications. Culture conditions used to achieve high gene targeting frequencies in rat neural stem cells and human pluripotent stem cells are also described.
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Affiliation(s)
- Melissa A Bartel
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, USA
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57
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Ho ML, Adler BA, Torre ML, Silberg JJ, Suh J. SCHEMA computational design of virus capsid chimeras: calibrating how genome packaging, protection, and transduction correlate with calculated structural disruption. ACS Synth Biol 2013; 2:724-33. [PMID: 23899192 DOI: 10.1021/sb400076r] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Adeno-associated virus (AAV) recombination can result in chimeric capsid protein subunits whose ability to assemble into an oligomeric capsid, package a genome, and transduce cells depends on the inheritance of sequence from different AAV parents. To develop quantitative design principles for guiding site-directed recombination of AAV capsids, we have examined how capsid structural perturbations predicted by the SCHEMA algorithm correlate with experimental measurements of disruption in seventeen chimeric capsid proteins. In our small chimera population, created by recombining AAV serotypes 2 and 4, we found that protection of viral genomes and cellular transduction were inversely related to calculated disruption of the capsid structure. Interestingly, however, we did not observe a correlation between genome packaging and calculated structural disruption; a majority of the chimeric capsid proteins formed at least partially assembled capsids and more than half packaged genomes, including those with the highest SCHEMA disruption. These results suggest that the sequence space accessed by recombination of divergent AAV serotypes is rich in capsid chimeras that assemble into 60-mer capsids and package viral genomes. Overall, the SCHEMA algorithm may be useful for delineating quantitative design principles to guide the creation of libraries enriched in genome-protecting virus nanoparticles that can effectively transduce cells. Such improvements to the virus design process may help advance not only gene therapy applications but also other bionanotechnologies dependent upon the development of viruses with new sequences and functions.
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Affiliation(s)
- Michelle L. Ho
- Department
of Bioengineering and ‡Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005,
United States
| | - Benjamin A. Adler
- Department
of Bioengineering and ‡Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005,
United States
| | - Michael L. Torre
- Department
of Bioengineering and ‡Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005,
United States
| | - Jonathan J. Silberg
- Department
of Bioengineering and ‡Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005,
United States
| | - Junghae Suh
- Department
of Bioengineering and ‡Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005,
United States
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58
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Ramamoorthi K, Curtis D, Asuri P. Advances in homology directed genetic engineering of human pluripotent and adult stem cells. World J Stem Cells 2013; 5:98-105. [PMID: 24179598 PMCID: PMC3812527 DOI: 10.4252/wjsc.v5.i4.98] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 09/06/2013] [Accepted: 09/17/2013] [Indexed: 02/06/2023] Open
Abstract
The ability to introduce precise genomic modifications in human cells has profound implications for both basic and applied research in stem cells, ranging from identification of genes regulating stem cell self-renewal and multilineage differentiation to therapeutic gene correction and creation of in vitro models of human diseases. However, the overall efficiency of this process is challenged by several factors including inefficient gene delivery into stem cells and low rates of homology directed site-specific targeting. Recent studies report the development of novel techniques to improve gene targeting efficiencies in human stem cells; these methods include molecular engineering of viral vectors to efficiently deliver episomal genetic sequences that can participate in homology directed targeting, as well as the design of synthetic proteins that can introduce double-stranded breaks in DNA to initiate such recombination events. This review focuses on the potential of these new technologies to precisely alter the human stem cell genome and also highlights the possibilities offered by the combination of these complementary strategies.
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59
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Schmidt C, Bezuidenhout D, Zilla P, Davies NH. A slow-release fibrin matrix increases adeno-associated virus transduction of wound repair cells in vivo. J Biomater Appl 2013; 28:1408-18. [PMID: 24163331 DOI: 10.1177/0885328213510331] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Virus-mediated gene therapy is a promising strategy for numerous tissue engineering applications. Fibrin-based scaffolds have been previously used as vehicles for localised delivery of adenovirus to wound sites. However, their utility in the delivery of adeno-associated viruses to wound repair cells has not yet been determined. The influence of fibrin concentration on efficacy of delivery of AAV-2 to wound tissue was assessed in this study. Fibrin scaffolds containing recombinant AAV-2 encoding for β-galactosidase were polymerised in porous polyurethane discs and implanted subcutaneously in rats. A fibrin scaffold with a concentration of 50 mg/ml showed significantly elevated levels of β-galactosidase activity within explanted discs at 10 days compared to 10 mg/ml and 25 mg/ml fibrin. These findings inform efforts to optimise biodegradable scaffolds for the localised delivery of AAV in tissue engineering.
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Affiliation(s)
- Christian Schmidt
- 1Cardiovascular Research Unit, University of Cape Town, South Africa
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60
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Oh JS, Park M, Kim JS, Jang JH. Enhanced cellular transfection by ternary non-viral gene vectors coupled with adeno-associated virus-derived peptides. Macromol Biosci 2013; 14:121-30. [PMID: 23966357 DOI: 10.1002/mabi.201300296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 07/15/2013] [Indexed: 11/08/2022]
Abstract
The establishment of efficient and safe gene delivery systems is crucial for biomedical applications. To address this objective, novel, ternary hybrid gene vectors are designed with viral capsid peptides in non-viral gene carriers. The viral peptide, TQVGQKT, is coupled with a membrane active peptide, LK15. Which acts as a linker to tag peptide with plasmid DNA. Additionally, polyethylenimine (PEI) is employed to condense the complexes further, thereby forming ternary DNA/TQVGQKT-LK15/PEI complexes. The ternary complexes result in rapid internalization leading to significantly enhanced cellular transfection. The new moiety, TQVGQKT, as well as enhanced cellular transfection, will certainly provide crucial insights for the design of novel non-viral gene carriers with efficient and safe properties.
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Affiliation(s)
- Ji-Seon Oh
- Department of Chemical and Biomolecular Engineering, Yonsei University, 120-749, Seoul, Korea
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61
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Kim JS, Kim E, Oh JS, Jang JH. Integration of Adeno-Associated Virus-Derived Peptides into Nonviral Vectors to Synergistically Enhance Cellular Transfection. Biomacromolecules 2013; 14:2136-45. [DOI: 10.1021/bm4005854] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Jung-Suk Kim
- Department of Chemical
and Biomolecular
Engineering, Yonsei University, Seoul, Korea, 120-749
| | - Eunmi Kim
- Department of Chemical
and Biomolecular
Engineering, Yonsei University, Seoul, Korea, 120-749
| | - Ji-Seon Oh
- Department of Chemical
and Biomolecular
Engineering, Yonsei University, Seoul, Korea, 120-749
| | - Jae-Hyung Jang
- Department of Chemical
and Biomolecular
Engineering, Yonsei University, Seoul, Korea, 120-749
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62
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Liu Y, Fang Y, Zhou Y, Zandi E, Lee CL, Joo KI, Wang P. Site-specific modification of adeno-associated viruses via a genetically engineered aldehyde tag. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2013; 9:421-9. [PMID: 23038676 DOI: 10.1002/smll.201201661] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Indexed: 05/26/2023]
Abstract
As a consequence of their well-defined nanostructure and intrinsic bioactive functionality, virus-based nanoparticles have shown promise for mediating gene delivery. Adeno-associated virus (AAV) nanoparticles, which possess an excellent safety profile and therapeutic potential, hold potential for use in human gene therapy. However, because of their native tropisms, the applicability of AAV nanoparticles is often limited to restricted ranges of cells or tissues. Thus, retargeting AAV particles to the desired cell populations has continued to be a major research focus in many gene therapy applications. In this study, a general strategy is reported for nanoparticle targeting. This involves the site-specific modification of AAV type 2 (AAV2) by genetically incorporating a short peptide, in this case an aldehyde tag, in the viral capsid. Such a tag can be exploited for site-specific attachment of targeting molecules and allows for further introduction of targeting antibodies or ligands. It is shown that this modification neither affects the level of infectious viral titer nor intracellular trafficking properties. Furthermore, the site-specific conjugation of targeting antibodies could significantly enhance viral transduction to those target cells that have otherwise exhibited very low permissiveness to AAV2 infection. This method also allows the functional incorporation of RGD peptides onto AAV2 for enhanced delivery with implications for cancer gene therapy.
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Affiliation(s)
- Yarong Liu
- Department of Chemical Engineering and Material Science, University of Southern California, Los Angeles, CA 90089, USA
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63
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Yang L, Xiao X. Creation of a cardiotropic adeno-associated virus: the story of viral directed evolution. Virol J 2013; 10:50. [PMID: 23394344 PMCID: PMC3574030 DOI: 10.1186/1743-422x-10-50] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 01/16/2013] [Indexed: 12/13/2022] Open
Abstract
Adeno-associated virus (AAV) is an important vector system for human gene therapy. Although use of AAV serotypes can result in efficient myocardial gene transfer, improvements in the transduction efficiency and specificity are still required. As a method for artificial modification and selection of gene function, directed evolution has been used for diverse applications in genetic engineering of enzymes and proteins. Since 2000, pioneering work has been performed on directed evolution of viral vectors. We further attempted to evolve the AAV using DNA shuffling and in vivo biopanning in a mouse model. An AAVM41 mutant was characterized, which was found to have improved transduction efficiency and specificity in myocardium, an attribute unknown for any natural AAV serotypes. This review focuses on the development of AAV vector for cardiac gene transfer, the history of directed evolution of viral vectors, and our creation of a cardiotropic AAV, which might have implications for the future design and application of viral vectors.
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Affiliation(s)
- Lin Yang
- Wuhan Institute of Virology, Chinese Academy of Sciences, 44 Xiaohongshan, Wuhan 430071, Hubei, China.
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64
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Rahman SH, Bobis-Wozowicz S, Chatterjee D, Gellhaus K, Pars K, Heilbronn R, Jacobs R, Cathomen T. The nontoxic cell cycle modulator indirubin augments transduction of adeno-associated viral vectors and zinc-finger nuclease-mediated gene targeting. Hum Gene Ther 2013; 24:67-77. [PMID: 23072634 PMCID: PMC3555098 DOI: 10.1089/hum.2012.168] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 10/08/2012] [Indexed: 01/28/2023] Open
Abstract
Parameters that regulate or affect the cell cycle or the DNA repair choice between non-homologous end-joining and homology-directed repair (HDR) are excellent targets to enhance therapeutic gene targeting. Here, we have evaluated the impact of five cell-cycle modulating drugs on targeted genome engineering mediated by DNA double-strand break (DSB)-inducing nucleases, such as zinc-finger nucleases (ZFNs). For a side-by-side comparison, we have established four reporter cell lines by integrating a mutated EGFP gene into either three transformed human cell lines or primary umbilical cord-derived mesenchymal stromal cells (UC-MSCs). After treatment with different cytostatic drugs, cells were transduced with adeno-associated virus (AAV) vectors that encode a nuclease or a repair donor to rescue EGFP expression through DSB-induced HDR. We show that transient cell-cycle arrest increased AAV transduction and AAV-mediated HDR up to six-fold in human cell lines and ten-fold in UC-MSCs, respectively. Targeted gene correction was observed in up to 34% of transduced cells. Both the absolute and the relative gene-targeting frequencies were dependent on the cell type, the cytostatic drug, the vector dose, and the nuclease. Treatment of cells with the cyclin-dependent kinase inhibitor indirubin-3'-monoxime was especially promising as this compound combined high stimulatory effects with minimal cytotoxicity. In conclusion, indirubin-3'-monoxime significantly improved AAV transduction and the efficiency of AAV/ZFN-mediated gene targeting and may thus represent a promising compound to enhance DSB-mediated genome engineering in human stem cells, such as UC-MSCs, which hold great promise for future clinical applications.
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Affiliation(s)
- Shamim H Rahman
- Laboratory of Cell and Gene Therapy, Center for Chronic Immunodeficiency, University Medical Center Freiburg, 79108 Freiburg, Germany.
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65
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Gregoire S, Kwon I. A revisited folding reporter for quantitative assay of protein misfolding and aggregation in mammalian cells. Biotechnol J 2012; 7:1297-307. [PMID: 22623352 DOI: 10.1002/biot.201200103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 04/15/2012] [Accepted: 05/21/2012] [Indexed: 01/12/2023]
Abstract
Protein misfolding and aggregation play important roles in many physiological processes. These include pathological protein aggregation in neurodegenerative diseases and biopharmaceutical protein aggregation during production in mammalian cells. To develop a simple non-invasive assay for protein misfolding and aggregation in mammalian cells, the folding reporter green fluorescent protein (GFP) system, originally developed for bacterial cells, was evaluated. As a folding reporter, GFP was fused to the C-terminus of a panel of human copper/zinc superoxide dismutase (SOD1) mutants with varying misfolding/aggregation propensities. Flow cytometric analysis of transfected HEK293T and NSC-34 cells revealed that the mean fluorescence intensities of the cells expressing GFP fusion of SOD1 variants exhibited an inverse correlation with the misfolding/aggregation propensities of the four SOD1 variants. Our results support the hypothesis that the extent of misfolding/aggregation of a target protein in mammalian cells can be quantitatively estimated by measuring the mean fluorescence intensity of the cells expressing GFP fusion. The assay method developed herein will facilitate the understanding of aggregation process of SOD1 variants and the identification of aggregation inhibitors. The method also has great promise for misfolding/aggregation studies of other proteins in mammalian cells.
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Affiliation(s)
- Simpson Gregoire
- Department of Chemical Engineering, University of Virginia, Charlottesville, VA 22904, USA
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66
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Kim E, Song IT, Lee S, Kim JS, Lee H, Jang JH. Drawing Sticky Adeno-Associated Viruses on Surfaces for Spatially Patterned Gene Expression. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201201495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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67
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Kim E, Song IT, Lee S, Kim JS, Lee H, Jang JH. Drawing Sticky Adeno-Associated Viruses on Surfaces for Spatially Patterned Gene Expression. Angew Chem Int Ed Engl 2012; 51:5598-601. [DOI: 10.1002/anie.201201495] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Indexed: 11/12/2022]
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68
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Asokan A, Schaffer DV, Jude Samulski R. The AAV vector toolkit: poised at the clinical crossroads. Mol Ther 2012; 20:699-708. [PMID: 22273577 PMCID: PMC3321598 DOI: 10.1038/mt.2011.287] [Citation(s) in RCA: 332] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 12/02/2011] [Indexed: 12/14/2022] Open
Abstract
The discovery of naturally occurring adeno-associated virus (AAV) isolates in different animal species and the generation of engineered AAV strains using molecular genetics tools have yielded a versatile AAV vector toolkit. Promising results in preclinical animal models of human disease spurred the much awaited transition toward clinical application, and early successes in phase I/II clinical trials for a broad spectrum of genetic diseases have recently been reported. As the gene therapy community forges ahead with cautious optimism, both preclinical and clinical studies using first generation AAV vectors have highlighted potential challenges. These include cross-species variation in vector tissue tropism and gene transfer efficiency, pre-existing humoral immunity to AAV capsids and vector dose-dependent toxicity in patients. A battery of second generation AAV vectors, engineered through rational and combinatorial approaches to address the aforementioned concerns, are now available. This review will provide an overview of preclinical studies with the ever-expanding AAV vector portfolio in large animal models and an update on new lead AAV vector candidates poised for clinical translation.
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Affiliation(s)
- Aravind Asokan
- Gene Therapy Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - David V Schaffer
- Department of Chemical Engineering, University of California, Berkeley, California, USA
- The Helen Wills Neuroscience Institute, University of California, Berkeley, California, USA
| | - R Jude Samulski
- Gene Therapy Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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69
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Abstract
Gene therapy vectors based on adeno-associated virus (AAV) are currently in clinical trials for numerous disease targets, such as muscular dystrophy, hemophilia, Parkinson's disease, Leber's congenital amaurosis and macular degeneration. Despite its considerable promise and emerging clinical success, several challenges impede the broader implementation of AAV gene therapy, including the prevalence of neutralizing antibodies in the human population, low transduction of a number of therapeutically relevant cell and tissue types, an inability to overcome physical and cellular barriers in vivo and a relatively limited carrying capacity. These challenges arise as the demands we place on AAV vectors are often different from or even at odds with the properties nature bestowed on their parent viruses. Viral-directed evolution-the iterative generation of large, diverse libraries of viral mutants and selection for variants with specific properties of interest-offers an approach to address these problems. Here we outline progress in creating novel classes of AAV variant libraries and highlight the successful isolation of variants with novel and advantageous in vitro and in vivo gene delivery properties.
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70
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Transduction of E13 murine neural precursor cells by non-immunogenic recombinant adeno-associated viruses induces major changes in neuronal phenotype. Neuroscience 2012; 210:82-98. [PMID: 22406416 DOI: 10.1016/j.neuroscience.2012.02.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 02/03/2012] [Accepted: 02/06/2012] [Indexed: 11/21/2022]
Abstract
Neural precursor cells (NPCs) provide a cellular model to compare transduction efficiency and toxicity for a series of recombinant adeno-associated viruses (rAAVs). Results led to the choice of rAAV9 as a preferred candidate to transduce NPCs for in vivo transplantation. Importantly, transduction promoted a neuronal phenotype characterized by neurofilament M (NFM) with a concomitant decrease in the embryonic marker, nestin, without significant change in glial fibrillary acidic protein (GFAP). In marked contrast to recent studies for induced pluripotent stem cells (iPSCs), exposure to rAAVs is non-immunogenic and these do not result in genetic abnormalities, thus bolstering the earlier use of NPCs such as those isolated from E13 murine cells for clinical applications. Mechanisms of cellular interactions were explored by treatment with genistein, a pan-specific inhibitor of protein receptor tyrosine kinases (PRTKs) that blocked the transduction and differentiation, thus implying a central role for this pathway for inducing infectivity along with observed phenotypic changes and as a method for drug design. Implantation of transduced NPCs into adult mouse hippocampus survived up to 28 days producing a time line for targeting or migration to dentate gyrus and CA3-1 compatible with future clinical applications. Furthermore, a majority showed commitment to highly differentiated neuronal phenotypes. Lack of toxicity and immune response of rAAVs plus ability for expansion of NPCs in vitro auger well for their isolation and suggest potential therapeutic applications in repair or replacement of diseased neurons in neurodegeneration.
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71
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Asuri P, Bartel MA, Vazin T, Jang JH, Wong TB, Schaffer DV. Directed evolution of adeno-associated virus for enhanced gene delivery and gene targeting in human pluripotent stem cells. Mol Ther 2012; 20:329-38. [PMID: 22108859 PMCID: PMC3277219 DOI: 10.1038/mt.2011.255] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 10/27/2011] [Indexed: 12/12/2022] Open
Abstract
Efficient approaches for the precise genetic engineering of human pluripotent stem cells (hPSCs) can enhance both basic and applied stem cell research. Adeno- associated virus (AAV) vectors are of particular interest for their capacity to mediate efficient gene delivery to and gene targeting in various cells. However, natural AAV serotypes offer only modest transduction of human embryonic and induced pluripotent stem cells (hESCs and hiPSCs), which limits their utility for efficiently manipulating the hPSC genome. Directed evolution is a powerful means to generate viral vectors with novel capabilities, and we have applied this approach to create a novel AAV variant with high gene delivery efficiencies (~50%) to hPSCs, which are importantly accompanied by a considerable increase in gene-targeting frequencies, up to 0.12%. While this level is likely sufficient for numerous applications, we also show that the gene-targeting efficiency mediated by an evolved AAV variant can be further enhanced (>1%) in the presence of targeted double- stranded breaks (DSBs) generated by the co-delivery of artificial zinc finger nucleases (ZFNs). Thus, this study demonstrates that under appropriate selective pressures, AAV vectors can be created to mediate efficient gene targeting in hPSCs, alone or in the presence of ZFN- mediated double-stranded DNA breaks.
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Affiliation(s)
- Prashanth Asuri
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720-1462, USA
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72
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Chun YS, Byun K, Lee B. Induced pluripotent stem cells and personalized medicine: current progress and future perspectives. Anat Cell Biol 2011; 44:245-55. [PMID: 22254153 PMCID: PMC3254878 DOI: 10.5115/acb.2011.44.4.245] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 12/16/2011] [Accepted: 12/21/2011] [Indexed: 01/26/2023] Open
Abstract
Generation of induced pluripotent stem cells (iPSCs) has revolutionized the field of regenerative medicine by providing researchers with a unique tool to derive disease-specific stem cells for study. iPSCs can self-renew and can differentiate into many cell types, offering a potentially unlimited source of cells for targeted differentiation into somatic effector cells. Hence, iPSCs are likely to be invaluable for therapeutic applications and disease-related research. In this review, we summarize the recent progress of iPSC generation that has been made with an emphasis on both basic and clinical applications including disease modeling, drug toxicity screening/drug discovery and cell replacement therapy.
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Affiliation(s)
- Yong Soon Chun
- Department of Surgery, Gachon University Gil Hospital, Incheon, Korea
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73
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Shah PS, Schaffer DV. Antiviral RNAi: translating science towards therapeutic success. Pharm Res 2011; 28:2966-82. [PMID: 21826573 PMCID: PMC5012899 DOI: 10.1007/s11095-011-0549-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Accepted: 07/25/2011] [Indexed: 01/07/2023]
Abstract
Viruses continuously evolve to contend with an ever-changing environment that involves transmission between hosts and sometimes species, immune responses, and in some cases therapeutic interventions. Given the high mutation rate of viruses relative to the timescales of host evolution and drug development, novel drug classes that are readily screened and translated to the clinic are needed. RNA interference (RNAi)-a natural mechanism for specific degradation of target RNAs that is conserved from plants to invertebrates and vertebrates-can potentially be harnessed to yield therapies with extensive specificity, ease of design, and broad application. In this review, we discuss basic mechanisms of action and therapeutic applications of RNAi, including design considerations and areas for future development in the field.
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Affiliation(s)
- Priya S. Shah
- Department of Chemical and Biolmolecular Engineering, University of California, Berkeley, California 94720 USA
| | - David V. Schaffer
- Department of Chemical and Biolmolecular Engineering, University of California, Berkeley, California 94720 USA
- Department of Bioengineering, University of California, Berkeley, California 94720 USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720 USA
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74
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Magnetically enhanced adeno-associated viral vector delivery for human neural stem cell infection. Biomaterials 2011; 32:8654-62. [DOI: 10.1016/j.biomaterials.2011.07.075] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 07/24/2011] [Indexed: 11/24/2022]
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75
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Lee S, Kim JS, Chu HS, Kim GW, Won JI, Jang JH. Electrospun nanofibrous scaffolds for controlled release of adeno-associated viral vectors. Acta Biomater 2011; 7:3868-76. [PMID: 21745607 DOI: 10.1016/j.actbio.2011.06.035] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 05/27/2011] [Accepted: 06/22/2011] [Indexed: 11/26/2022]
Abstract
The integration of viral gene delivery with key features of biomaterial scaffolds that modulate viral delivery in a controlled manner offers a promising strategy for numerous tissue engineering applications. In this study adeno-associated virus (AAV), which is widely utilized in human gene therapy as a gene carrier due to its safety and efficient gene delivery capability, was encapsulated within electrospun nanofibrous scaffolds composed of blended mixtures of elastin-like polypeptides (ELP) and poly (ε-caprolactone) (PCL) and was employed to transduce fibroblasts adherent on the scaffolds. Combinatorial interactions between ELP and PCL chains upon physical blending significantly altered the mechanical properties (i.e. wettability, elastic modulus, strain, etc.) of the ELP/PCL composites, thus providing key tools to mediate controlled release of AAV vectors and robust cellular transduction on the fibrous scaffolds. The ability of ELP/PCL composites to manipulate the controlled release of AAV-mediated gene delivery for subsequent high-efficiency cellular transduction will provide tremendous opportunities for a variety of tissue engineering applications.
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76
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Hwang JH, Lee S, Kim E, Kim JS, Lee CH, Ahn IS, Jang JH. Heparin-coated superparamagnetic nanoparticle-mediated adeno-associated virus delivery for enhancing cellular transduction. Int J Pharm 2011; 421:397-404. [PMID: 22016032 DOI: 10.1016/j.ijpharm.2011.10.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 10/05/2011] [Accepted: 10/07/2011] [Indexed: 12/15/2022]
Abstract
Superparamagnetic iron oxide nanoparticles (SPIONs) have been exploited as an elegant vehicle to enhance gene delivery efficiencies in gene therapy applications. We developed a magnetically guided adeno-associated virus (AAV) delivery system for enhancing gene delivery to HEK293T and PC12 cell lines. Wild-type AAV2 and a novel AAV vector, AAVr3.45, which was directly evolved in a previous study to possess diverse cell tropisms, were used as gene carriers. Additionally, the affinity of each viral vector to heparin was employed as a moiety to immobilize virus onto heparin-coated SPIONs (HpNPs). Magnetically guided AAV delivery resulted fast and efficient cellular transduction. Importantly, a short exposure of virus to target cells under a magnetic field (<180min) yielded comparable transduction produced by the conventional gene-delivery protocol (i.e., 24h-incubation of virus with target cells prior to replacing with fresh medium). Additionally, magnetic guidance of AAV encoding nerve growth factor (NGF) produced sufficient functional NGF, leading to robust neurite elongation by PC12 as compared to direct NGF protein delivery or non-magnetic delivery. The successful establishment of a magnetically guided AAV delivery system, with the ability to efficiently and rapidly infect target cells, will provide a powerful platform for a variety of gene therapy applications.
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Affiliation(s)
- Jun-Ho Hwang
- Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul 120-749, Republic of Korea
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77
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Elastin-like polypeptide matrices for enhancing adeno-associated virus-mediated gene delivery to human neural stem cells. Gene Ther 2011; 19:329-37. [PMID: 21654823 DOI: 10.1038/gt.2011.84] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The successful development of efficient and safe gene delivery vectors continues to be a major obstacle to gene delivery in stem cells. In this study, we have developed an elastin-like polypeptide (ELP)-mediated adeno-associated virus (AAV) delivery system for transducing fibroblasts and human neural stem cells (hNSCs). AAVs have significant promise as therapeutic vectors because of their safety and potential for use in gene targeting in stem cell research. ELP has been recently employed as a biologically inspired 'smart' biomaterial that exhibits an inverse temperature phase transition, thereby demonstrating promise as a novel drug carrier. The ELP that was investigated in this study was composed of a repetitive penta-peptide with [Val-Pro-Gly-Val-Gly]. A novel AAV variant, AAV r3.45, which was previously engineered by directed evolution to enhance transduction in rat NSCs, was nonspecifically immobilized onto ELPs that were adsorbed beforehand on a tissue culture polystyrene surface (TCPS). The presence of different ELP quantities on the TCPS led to variations in surface morphology, roughness and wettability, which were ultimately key factors in the modulation of cellular transduction. Importantly, with substantially reduced viral quantities compared with bolus delivery, ELP-mediated AAV delivery significantly enhanced delivery efficiency in fibroblasts and hNSCs, which have great potential for use in tissue engineering applications and neurodegenerative disorder treatments, respectively. The enhancement of cellular transduction in stem cells, as well as the feasibility of ELPs for utilization in three-dimensional scaffolds, will contribute to the advancement of gene therapy for stem cell research and tissue regenerative medicine.
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