The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform
Robert E Maclaren - One of the best experts on this subject based on the ideXlab platform.
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assessment of aav Dual Vector safety in the abca4 mouse model of stargardt disease
Translational Vision Science & Technology, 2020Co-Authors: Michelle E Mcclements, Alun R Barnard, Peter Charbel Issa, Robert E MaclarenAbstract:Purpose Adeno-associated viral (AAV) gene therapy treatment for Stargardt disease currently requires a Dual Vector approach owing to the size of the ATP-binding cassette transporter family member gene (ABCA4). The nature of the Dual Vector system creates the potential for adverse events. Here we have investigated an overlapping adeno-associated viral ABCA4 Dual Vector system for signs of toxicity in Abca4-/- mice as a prelude to Dual Vector first in human clinical trials. Methods Abca4-/- mice received a subretinal injection of a 1:1 5':3' Dual Vector mix; 5' Vector only; 3 ' Vector only; a GFP reporter Vector; or diluent only (sham). All Vectors were adeno-associated virus-8 Y733F. Mice were subsequently assessed for signs of toxicity as measured by loss in retinal structure by optical coherence tomography and retinal function by electroretinography up to 6 months after injection. Results Subretinal delivery of the Dual Vector system and its comprising parts induced no structural or functional changes relative to paired uninjected eyes beyond those observed in the sham control cohort. Histologic changes were limited to the superior retina where the injection was performed. Electroretinography analysis confirmed the Dual Vector system inferred no functional changes beyond those observed in the sham control cohort. Conclusions An optimized overlapping Dual Vector system for the treatment of Stargardt disease shows no additional signs of toxicity beyond those observed from a sham injection. Translational Relevance This presentation of safety of a Dual Vector system for the treatment of Stargardt disease encourages its future use in clinical trial.
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an aav Dual Vector strategy ameliorates the stargardt phenotype in adult abca4 mice
Human Gene Therapy, 2019Co-Authors: Michelle E Mcclements, Alun R Barnard, Mandeep S Singh, Charbel P Issa, Zhichun Jiang, Roxana A Radu, Robert E MaclarenAbstract:The recent approval in the United States of the first adeno-associated viral (AAV) Vector for the treatment of an inherited retinal degeneration validates this approach for the treatment of many ot...
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adeno associated virus aav Dual Vector strategies for gene therapy encoding large transgenes
Yale Journal of Biology and Medicine, 2017Co-Authors: Michelle E Mcclements, Robert E MaclarenAbstract:The use of adeno-associated viral (AAV) Vectors for gene therapy treatments of inherited disorders has accelerated over the past decade with multiple clinical trials ongoing in varying tissue types and new ones initiating every year. These Vectors are exhibiting low-immunogenicity across the clinical trials in addition to showing evidence of efficacy, making it clear they are the current standard Vector for any potential gene therapy treatment. However, AAV Vectors do have a limitation in their packaging capacity, being capable of holding no more than ~5kb of DNA and in a therapeutic transgene scenario, this length of DNA would need to include genetic control elements in addition to the gene coding sequence (CDS) of interest. Given that numerous diseases are caused by mutations in genes with a CDS exceeding 3.5kb, this makes packaging into a single AAV capsid not possible for larger genes. Due to this problem, yet with the desire to use AAV Vectors, research groups have adapted the standard AAV gene therapy approach to enable delivery of such large genes to target cells using Dual AAV Vector systems. Here we review the AAV Dual Vector strategies currently employed and highlight the virtues and drawbacks of each method plus the likelihood of success with such approaches.
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a fragmented adeno associated viral Dual Vector strategy for treatment of diseases caused by mutations in large genes leads to expression of hybrid transcripts
Journal of Genetic Syndromes & Gene Therapy, 2016Co-Authors: Michelle E Mcclements, Peter Charbel Issa, Veronique Blouin, Robert E MaclarenAbstract:Objective Dual Vector AAV systems are being utilised to enable gene therapy for disorders in which the disease gene is too large to fit into a single capsid. Fragmented adeno-associated viral (fAAV) Vectors containing single inverted terminal repeat truncated transgenes have been considered as one such gene replacement strategy. Here we aim to add to the current understanding of the molecular mechanisms employed by fAAV Dual Vector systems. Methods Oversized (>8kb) transgene constructs containing ABCA4 coding sequence were packaged as truncated fragments <5kb in size into various AAV serotypes. In vitro transductions with these fAAV Vector preparations were conducted with mRNA and protein expression products assessed by way of RT-PCR, qPCR and western blot techniques. Results Transductions with fAAV Vector preparations yielded ABCA4 mRNA, but did not generate detectable levels of protein. Sequencing of the transcript population revealed the presence of full length ABCA4 CDS with additional hybrid ABCA4 variants, indicating truncated transgenes without regions of overlap were joining and forming stable hybrid transgenes. In contrast, an ABCA4 overlapping Dual Vector system (OV) with a defined complementary region generated only full length mRNA transcripts plus detectable ABCA4 protein. Conclusion Despite previous success shown with the fAAV approach, the lack of repeatability and identification of stable hybrid transcripts capable of protein production suggests there is more refinement required before considering this approach in a clinical setting.
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single residue aav capsid mutation improves transduction of photoreceptors in the abca4 mouse and bipolar cells in the rd1 mouse and human retina ex vivo
Gene Therapy, 2016Co-Authors: S R De Silva, Alun R Barnard, Mandeep S Singh, Charbel P Issa, Daniel M Lipinski, Alona O Barneacramer, Nathan J Walker, Mark W Hankins, Robert E MaclarenAbstract:Gene therapy using adeno-associated viral (AAV) Vectors for the treatment of retinal degenerations has shown safety and efficacy in clinical trials. However, very high levels of Vector expression may be necessary for the treatment of conditions such as Stargardt disease where a Dual Vector approach is potentially needed, or in optogenetic strategies for end-stage degeneration in order to achieve maximal light sensitivity. In this study, we assessed two Vectors with single capsid mutations, rAAV2/2(Y444F) and rAAV2/8(Y733F) in their ability to transduce retina in the Abca4-/- and rd1 mouse models of retinal degeneration. We noted significantly increased photoreceptor transduction using rAAV2/8(Y733F) in the Abca4-/- mouse, in contrast to previous work where Vectors tested in this model have shown low levels of photoreceptor transduction. Bipolar cell transduction was achieved following subretinal delivery of both Vectors in the rd1 mouse, and via intravitreal delivery of rAAV2/2(Y444F). The successful use of rAAV2/8(Y733F) to target bipolar cells was further validated on human tissue using an ex vivo culture system of retinal explants. Capsid mutant AAV Vectors transduce human retinal cells and may be particularly suited to treat retinal degenerations in which high levels of transgene expression are required.
Charbel P Issa - One of the best experts on this subject based on the ideXlab platform.
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an aav Dual Vector strategy ameliorates the stargardt phenotype in adult abca4 mice
Human Gene Therapy, 2019Co-Authors: Michelle E Mcclements, Alun R Barnard, Mandeep S Singh, Charbel P Issa, Zhichun Jiang, Roxana A Radu, Robert E MaclarenAbstract:The recent approval in the United States of the first adeno-associated viral (AAV) Vector for the treatment of an inherited retinal degeneration validates this approach for the treatment of many ot...
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single residue aav capsid mutation improves transduction of photoreceptors in the abca4 mouse and bipolar cells in the rd1 mouse and human retina ex vivo
Gene Therapy, 2016Co-Authors: S R De Silva, Alun R Barnard, Mandeep S Singh, Charbel P Issa, Daniel M Lipinski, Alona O Barneacramer, Nathan J Walker, Mark W Hankins, Robert E MaclarenAbstract:Gene therapy using adeno-associated viral (AAV) Vectors for the treatment of retinal degenerations has shown safety and efficacy in clinical trials. However, very high levels of Vector expression may be necessary for the treatment of conditions such as Stargardt disease where a Dual Vector approach is potentially needed, or in optogenetic strategies for end-stage degeneration in order to achieve maximal light sensitivity. In this study, we assessed two Vectors with single capsid mutations, rAAV2/2(Y444F) and rAAV2/8(Y733F) in their ability to transduce retina in the Abca4-/- and rd1 mouse models of retinal degeneration. We noted significantly increased photoreceptor transduction using rAAV2/8(Y733F) in the Abca4-/- mouse, in contrast to previous work where Vectors tested in this model have shown low levels of photoreceptor transduction. Bipolar cell transduction was achieved following subretinal delivery of both Vectors in the rd1 mouse, and via intravitreal delivery of rAAV2/2(Y444F). The successful use of rAAV2/8(Y733F) to target bipolar cells was further validated on human tissue using an ex vivo culture system of retinal explants. Capsid mutant AAV Vectors transduce human retinal cells and may be particularly suited to treat retinal degenerations in which high levels of transgene expression are required.
Michelle E Mcclements - One of the best experts on this subject based on the ideXlab platform.
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assessment of aav Dual Vector safety in the abca4 mouse model of stargardt disease
Translational Vision Science & Technology, 2020Co-Authors: Michelle E Mcclements, Alun R Barnard, Peter Charbel Issa, Robert E MaclarenAbstract:Purpose Adeno-associated viral (AAV) gene therapy treatment for Stargardt disease currently requires a Dual Vector approach owing to the size of the ATP-binding cassette transporter family member gene (ABCA4). The nature of the Dual Vector system creates the potential for adverse events. Here we have investigated an overlapping adeno-associated viral ABCA4 Dual Vector system for signs of toxicity in Abca4-/- mice as a prelude to Dual Vector first in human clinical trials. Methods Abca4-/- mice received a subretinal injection of a 1:1 5':3' Dual Vector mix; 5' Vector only; 3 ' Vector only; a GFP reporter Vector; or diluent only (sham). All Vectors were adeno-associated virus-8 Y733F. Mice were subsequently assessed for signs of toxicity as measured by loss in retinal structure by optical coherence tomography and retinal function by electroretinography up to 6 months after injection. Results Subretinal delivery of the Dual Vector system and its comprising parts induced no structural or functional changes relative to paired uninjected eyes beyond those observed in the sham control cohort. Histologic changes were limited to the superior retina where the injection was performed. Electroretinography analysis confirmed the Dual Vector system inferred no functional changes beyond those observed in the sham control cohort. Conclusions An optimized overlapping Dual Vector system for the treatment of Stargardt disease shows no additional signs of toxicity beyond those observed from a sham injection. Translational Relevance This presentation of safety of a Dual Vector system for the treatment of Stargardt disease encourages its future use in clinical trial.
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an aav Dual Vector strategy ameliorates the stargardt phenotype in adult abca4 mice
Human Gene Therapy, 2019Co-Authors: Michelle E Mcclements, Alun R Barnard, Mandeep S Singh, Charbel P Issa, Zhichun Jiang, Roxana A Radu, Robert E MaclarenAbstract:The recent approval in the United States of the first adeno-associated viral (AAV) Vector for the treatment of an inherited retinal degeneration validates this approach for the treatment of many ot...
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adeno associated virus aav Dual Vector strategies for gene therapy encoding large transgenes
Yale Journal of Biology and Medicine, 2017Co-Authors: Michelle E Mcclements, Robert E MaclarenAbstract:The use of adeno-associated viral (AAV) Vectors for gene therapy treatments of inherited disorders has accelerated over the past decade with multiple clinical trials ongoing in varying tissue types and new ones initiating every year. These Vectors are exhibiting low-immunogenicity across the clinical trials in addition to showing evidence of efficacy, making it clear they are the current standard Vector for any potential gene therapy treatment. However, AAV Vectors do have a limitation in their packaging capacity, being capable of holding no more than ~5kb of DNA and in a therapeutic transgene scenario, this length of DNA would need to include genetic control elements in addition to the gene coding sequence (CDS) of interest. Given that numerous diseases are caused by mutations in genes with a CDS exceeding 3.5kb, this makes packaging into a single AAV capsid not possible for larger genes. Due to this problem, yet with the desire to use AAV Vectors, research groups have adapted the standard AAV gene therapy approach to enable delivery of such large genes to target cells using Dual AAV Vector systems. Here we review the AAV Dual Vector strategies currently employed and highlight the virtues and drawbacks of each method plus the likelihood of success with such approaches.
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a fragmented adeno associated viral Dual Vector strategy for treatment of diseases caused by mutations in large genes leads to expression of hybrid transcripts
Journal of Genetic Syndromes & Gene Therapy, 2016Co-Authors: Michelle E Mcclements, Peter Charbel Issa, Veronique Blouin, Robert E MaclarenAbstract:Objective Dual Vector AAV systems are being utilised to enable gene therapy for disorders in which the disease gene is too large to fit into a single capsid. Fragmented adeno-associated viral (fAAV) Vectors containing single inverted terminal repeat truncated transgenes have been considered as one such gene replacement strategy. Here we aim to add to the current understanding of the molecular mechanisms employed by fAAV Dual Vector systems. Methods Oversized (>8kb) transgene constructs containing ABCA4 coding sequence were packaged as truncated fragments <5kb in size into various AAV serotypes. In vitro transductions with these fAAV Vector preparations were conducted with mRNA and protein expression products assessed by way of RT-PCR, qPCR and western blot techniques. Results Transductions with fAAV Vector preparations yielded ABCA4 mRNA, but did not generate detectable levels of protein. Sequencing of the transcript population revealed the presence of full length ABCA4 CDS with additional hybrid ABCA4 variants, indicating truncated transgenes without regions of overlap were joining and forming stable hybrid transgenes. In contrast, an ABCA4 overlapping Dual Vector system (OV) with a defined complementary region generated only full length mRNA transcripts plus detectable ABCA4 protein. Conclusion Despite previous success shown with the fAAV approach, the lack of repeatability and identification of stable hybrid transcripts capable of protein production suggests there is more refinement required before considering this approach in a clinical setting.
Mandeep S Singh - One of the best experts on this subject based on the ideXlab platform.
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an aav Dual Vector strategy ameliorates the stargardt phenotype in adult abca4 mice
Human Gene Therapy, 2019Co-Authors: Michelle E Mcclements, Alun R Barnard, Mandeep S Singh, Charbel P Issa, Zhichun Jiang, Roxana A Radu, Robert E MaclarenAbstract:The recent approval in the United States of the first adeno-associated viral (AAV) Vector for the treatment of an inherited retinal degeneration validates this approach for the treatment of many ot...
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single residue aav capsid mutation improves transduction of photoreceptors in the abca4 mouse and bipolar cells in the rd1 mouse and human retina ex vivo
Gene Therapy, 2016Co-Authors: S R De Silva, Alun R Barnard, Mandeep S Singh, Charbel P Issa, Daniel M Lipinski, Alona O Barneacramer, Nathan J Walker, Mark W Hankins, Robert E MaclarenAbstract:Gene therapy using adeno-associated viral (AAV) Vectors for the treatment of retinal degenerations has shown safety and efficacy in clinical trials. However, very high levels of Vector expression may be necessary for the treatment of conditions such as Stargardt disease where a Dual Vector approach is potentially needed, or in optogenetic strategies for end-stage degeneration in order to achieve maximal light sensitivity. In this study, we assessed two Vectors with single capsid mutations, rAAV2/2(Y444F) and rAAV2/8(Y733F) in their ability to transduce retina in the Abca4-/- and rd1 mouse models of retinal degeneration. We noted significantly increased photoreceptor transduction using rAAV2/8(Y733F) in the Abca4-/- mouse, in contrast to previous work where Vectors tested in this model have shown low levels of photoreceptor transduction. Bipolar cell transduction was achieved following subretinal delivery of both Vectors in the rd1 mouse, and via intravitreal delivery of rAAV2/2(Y444F). The successful use of rAAV2/8(Y733F) to target bipolar cells was further validated on human tissue using an ex vivo culture system of retinal explants. Capsid mutant AAV Vectors transduce human retinal cells and may be particularly suited to treat retinal degenerations in which high levels of transgene expression are required.
Hilmi H Hacisalihoglu - One of the best experts on this subject based on the ideXlab platform.
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on the determination of a developable spherical orthotomic ruled surface
Bulletin of Mathematical Sciences, 2015Co-Authors: Gokmen O Yildiz, Siddika O Karakus, Hilmi H HacisalihogluAbstract:In this paper, a method for determination of developable spherical orthotomic ruled surfaces is given by using Dual Vector calculus. We show that Dual Vectorial expression of a developable spherical orthotomic ruled surface can be obtained from coordinates and the first derivatives of the base curve. The paper concludes with an example related to this method.
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on the determination of a developable spherical orthotomic timelike ruled surface
Konuralp Journal of Mathematics, 2015Co-Authors: Gokmen O Yildiz, Siddika O Karakus, Hilmi H HacisalihogluAbstract:In this paper, a method for determination of developable spherical orthotomic ruled surfaces generated by a spacelike curve on Dual hyperbolic unit sphere is given by using Dual Vector calculus in R31 . We show that Dual Vectorial expression of a developable spherical orthotomic timelike ruled surface can be obtained from coordinates and the rst derivatives of the base curve. The paper concludes with an example related to this method.
