1
|
Fischer MD, Hickey DG, Singh MS, MacLaren RE. Evaluation of an Optimized Injection System for Retinal Gene Therapy in Human Patients. Hum Gene Ther Methods 2017; 27:150-8. [PMID: 27480111 DOI: 10.1089/hgtb.2016.086] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Many retinal gene therapy clinical trials require subretinal injections of small volumes of adeno-associated viral (AAV) vector solutions in patients with retinal dystrophies, using equipment not specifically designed for this purpose. We therefore evaluated an optimized injection system in order to identify variables that might influence the rate of injection and final dose of vector delivered. An optimized injection system was assembled with a 41G polytetrafluoroethylene tip for retinal gene therapy. Flow rate was recorded at relevant infusion pressures (2-22 psi [14-152 kPa]), different target pressures (0.02-30 mm Hg [0.003-4 kPa]) and temperatures (18°C vs. 36°C) using a semiautomated Accurus(®) Surgical System. Retention of AAV2/8 and AAV2/8(Y733F) vector was quantified after simulating loading/injection with or without 0.001% Pluronic(®) F-68 (PF-68). The optimized injection system provided a linear flow rate (μl/s)-to-infusion pressure (psi) relationship (y = 0.62x; r(2) = 0.99), independent of temperature and pressure changes relevant for intraocular surgery (18-36°C, 0.02-30 mm Hg). Differences in length of 41G polytetrafluoroethylene tips caused significant variation in flow rate (p < 0.001). Use of PF-68 significantly (p < 0.001) reduced loss of vector genomes in the injection system by 55% (AAV2/8) and 52% (AAV2/8(Y733F)). A customized subretinal injection system assembled using equipment currently available in the operating room can deliver a controlled volume of vector at a fixed rate across a range of possible clinical parameters encountered in vitreoretinal surgery. The inclusion of 0.001% PF-68 had a significant effect on the final dose of vector genomes delivered. The described technique is currently used successfully in a clinical trial.
Collapse
Affiliation(s)
- M Dominik Fischer
- 1 Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford , Oxford, United Kingdom.,2 Oxford Eye Hospital, Oxford University Hospitals NHS Trust , Oxford, United Kingdom.,3 University Eye Hospital , Centre for Ophthalmology, Tübingen, Germany
| | - Doron G Hickey
- 1 Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford , Oxford, United Kingdom
| | - Mandeep S Singh
- 1 Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford , Oxford, United Kingdom.,2 Oxford Eye Hospital, Oxford University Hospitals NHS Trust , Oxford, United Kingdom.,4 Moorfields Eye Hospital NHS Foundation Trust , Oxford, United Kingdom
| | - Robert E MacLaren
- 1 Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford , Oxford, United Kingdom.,2 Oxford Eye Hospital, Oxford University Hospitals NHS Trust , Oxford, United Kingdom.,4 Moorfields Eye Hospital NHS Foundation Trust , Oxford, United Kingdom
| |
Collapse
|
2
|
Fischer MD. On Retinal Gene Therapy. Ophthalmologica 2016; 236:1-7. [PMID: 27119148 DOI: 10.1159/000445782] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 03/18/2016] [Indexed: 11/19/2022]
Abstract
Mutations in a large number of genes cause retinal degeneration and blindness with no cure currently available. Retinal gene therapy has evolved over the last decades to become a promising new treatment paradigm for these rare disorders. This article reflects on the ideas and concepts arising from basic science towards the translation of retinal gene therapy into the clinical realm. It describes the advances and present thinking on the efficacy of current clinical trials and discusses potential roadblocks and solutions for the future of retinal gene therapy.
Collapse
Affiliation(s)
- M Dominik Fischer
- University Eye Hospital, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| |
Collapse
|
3
|
Tropism-modified AAV vectors overcome barriers to successful cutaneous therapy. Mol Ther 2014; 22:929-39. [PMID: 24468915 DOI: 10.1038/mt.2014.14] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 01/11/2014] [Indexed: 12/11/2022] Open
Abstract
Autologous human keratinocytes (HK) forming sheet grafts are approved as skin substitutes. Genetic engineering of HK represents a promising technique to improve engraftment and survival of transplants. Although efficacious in keratinocyte-directed gene transfer, retro-/lentiviral vectors may raise safety concerns when applied in regenerative medicine. We therefore optimized adeno-associated viral (AAV) vectors of the serotype 2, characterized by an excellent safety profile, but lacking natural tropism for HK, through capsid engineering. Peptides, selected by AAV peptide display, engaged novel receptors that increased cell entry efficiency by up to 2,500-fold. The novel targeting vectors transduced HK with high efficiency and a remarkable specificity even in mixed cultures of HK and feeder cells. Moreover, differentiated keratinocytes in organotypic airlifted three-dimensional cultures were transduced following topical vector application. By exploiting comparative gene analysis we further succeeded in identifying αvβ8 integrin as a target receptor thus solving a major challenge of directed evolution approaches and describing a promising candidate receptor for cutaneous gene therapy.
Collapse
|