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Gade S, Glover K, Mishra D, Sharma S, Guy O, Donnelly RF, Vora LK, Thakur RRS. Hollow microneedles for ocular drug delivery. J Control Release 2024; 371:43-66. [PMID: 38735395 DOI: 10.1016/j.jconrel.2024.05.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 05/03/2024] [Accepted: 05/07/2024] [Indexed: 05/14/2024]
Abstract
Microneedles (MNs) are micron-sized needles, typically <2 mm in length, arranged either as an array or as single needle. These MNs offer a minimally invasive approach to ocular drug delivery due to their micron size (reducing tissue damage compared to that of hypodermic needles) and overcoming significant barriers in drug administration. While various types of MNs have been extensively researched, significant progress has been made in the use of hollow MNs (HMNs) for ocular drug delivery, specifically through suprachoroidal injections. The suprachoroidal space, situated between the sclera and choroid, has been targeted using optical coherence tomography-guided injections of HMNs for the treatment of uveitis. Unlike other MNs, HMNs can deliver larger volumes of formulations to the eye. This review primarily focuses on the use of HMNs in ocular drug delivery and explores their ocular anatomy and the distribution of formulations following potential HMN administration routes. Additionally, this review focuses on the influence of formulation characteristics (e.g., solution viscosity, particle size), HMN properties (e.g., bore or lumen diameter, MN length), and routes of administration (e.g., periocular transscleral, suprachoroidal, intravitreal) on the ocular distribution of drugs. Overall, this paper highlights the distinctive properties of HMNs, which make them a promising technology for improving drug delivery efficiency, precision, and patient outcomes in the treatment of ocular diseases.
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Affiliation(s)
- Shilpkala Gade
- School of Pharmacy, Queen's University Belfast, Medical Biology Centre, Belfast, UK
| | - Katie Glover
- School of Pharmacy, Queen's University Belfast, Medical Biology Centre, Belfast, UK
| | - Deepakkumar Mishra
- School of Pharmacy, Queen's University Belfast, Medical Biology Centre, Belfast, UK
| | - Sanjiv Sharma
- College of Engineering, Swansea University, Swansea, UK; Pharmacology and Therapeutics, University of Liverpool, UK
| | - Owen Guy
- Department of Chemistry, School of Engineering and Applied Sciences, Faculty of Science and Engineering, Swansea University, Swansea SA2 8PP, UK
| | - Ryan F Donnelly
- School of Pharmacy, Queen's University Belfast, Medical Biology Centre, Belfast, UK
| | - Lalitkumar K Vora
- School of Pharmacy, Queen's University Belfast, Medical Biology Centre, Belfast, UK.
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L'Abbate D, Prescott K, Geraghty B, Kearns VR, Steel DHW. Biomechanical considerations for optimising subretinal injections. Surv Ophthalmol 2024:S0039-6257(24)00053-5. [PMID: 38797394 DOI: 10.1016/j.survophthal.2024.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 05/16/2024] [Accepted: 05/20/2024] [Indexed: 05/29/2024]
Abstract
Subretinal injection is the preferred delivery technique for various novel ocular therapies and is widely used because of its precision and efficient delivery of gene and cell therapies; however, choosing an injection point and defining delivery parameters to target a specified retinal location and area is an inexact science. We provide an overview of the key factors that play important roles during subretinal injections to refine the technique, enhance patient outcomes, and minimise risks. We describe the role of anatomical and physical variables that affect subretinal bleb propagation and shape and their impact on retinal integrity. We highlight the risks associated with subretinal injections and consider strategies to mitigate reflux and retinal trauma. Finally, we explore the emerging field of robotic assistance in improving intraocular manouvrability and precision to facilitate the injection procedure.
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Affiliation(s)
- Dario L'Abbate
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| | - Kia Prescott
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| | - Brendan Geraghty
- Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| | - Victoria R Kearns
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK.
| | - David H W Steel
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK; Sunderland Eye Infirmary, Sunderland, UK; Bioscience Institute, Newcastle University, Newcastle Upon Tyne, UK
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Boyd RF, Petersen-Jones SM. Techniques for subretinal injections in animals. Vet Ophthalmol 2024. [PMID: 38700998 DOI: 10.1111/vop.13219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 04/03/2024] [Accepted: 04/05/2024] [Indexed: 05/05/2024]
Abstract
Subretinal injections are not commonly performed during clinical treatment of animals but are frequently used in laboratory animal models to assess therapeutic efficacy and safety of gene and cell therapy products. Veterinary ophthalmologists are often employed to perform the injections in the laboratory animal setting, due to knowledge of comparative ocular anatomy between species and familiarity with operating on non-human eyes. Understanding the different approaches used for subretinal injection in each species and potential complications that may be encountered is vital to achieving successful and reproducible results. This manuscript provides a summary of different approaches to subretinal injections in the most common animal model species, along with information from published literature and experience of the authors to educate novice or experienced surgeons tasked with performing these injections for the first time.
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Affiliation(s)
- Ryan F Boyd
- Charles River Laboratories, Mattawan, Michigan, USA
| | - Simon M Petersen-Jones
- Department of Small Animal Clinical Sciences, Michigan State University, East Lansing, Michigan, USA
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Hartman RR, Kompella UB. Intravitreal, Subretinal, and Suprachoroidal Injections: Evolution of Microneedles for Drug Delivery. J Ocul Pharmacol Ther 2017; 34:141-153. [PMID: 29206556 PMCID: PMC5963636 DOI: 10.1089/jop.2017.0121] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 10/13/2017] [Indexed: 01/04/2023] Open
Abstract
Even though the very thought of an injection into the eye may be frightening, an estimated 6 million intravitreal (IVT) injections were made in the USA during 2016. With the introduction of new therapeutic agents, this number is expected to increase. In addition, drug products that are injectable in ocular compartments other than the vitreous humor are expected to enter the back of the eye market in the not so distant future. Besides the IVT route, some of the most actively investigated routes of invasive administration to the eye include periocular, subretinal, and suprachoroidal (SC) routes. While clinical efficacy is the driving force behind new injectable drug product development for the eye, safety is also being improved with time. In the case of IVT injections, the procedural guidelines have evolved over the years to improve patient comfort and reduce injection-related injury and infection. Similar advances are anticipated for other routes of administration of injectable products to the eye. In addition to procedural improvements, the design of needles, particularly those with smaller diameters, length, and controlled bevel angles are expected to improve overall safety and acceptance of injected ophthalmic drug products. A key development in this area is the introduction of microneedles of a length less than a millimeter that can target the SC space. In the future, needles with smaller diameters and lengths, potentially approaching nanodimensions, are expected to revolutionize ophthalmic disease management.
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Affiliation(s)
- Rachel R. Hartman
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Uday B. Kompella
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado
- Department of Ophthalmology, University of Colorado Anschutz Medical Campus, Aurora, Colorado
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Colorado
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Borlongan CV, Sanberg PR. Article Commentary: Neural Transplantation in the New Millenium. Cell Transplant 2017. [DOI: 10.3727/000000002783985558] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Affiliation(s)
- Cesario V. Borlongan
- Department of Neurology and Institute of Molecular Medicine and Genetics, Medical College of Georgia; Research and Affiliations Service Line, Veterans Administration Medical Center, Augusta, GA 30912-3200
| | - Paul R. Sanberg
- Center for Aging and Brain Repair, Department of Neurological Surgery and Neuroscience Program, University of South Florida College of Medicine, 12901 Bruce B. Downs Blvd., Tampa, FL 33612
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Bruewer AR, Mowat FM, Bartoe JT, Boye SL, Hauswirth WW, Petersen-Jones SM. Evaluation of lateral spread of transgene expression following subretinal AAV-mediated gene delivery in dogs. PLoS One 2013; 8:e60218. [PMID: 23560080 PMCID: PMC3616166 DOI: 10.1371/journal.pone.0060218] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 02/23/2013] [Indexed: 11/19/2022] Open
Abstract
Dog models with spontaneously occurring mutations in retinal dystrophy genes are an invaluable resource for preclinical development of retinal gene therapy. Adeno-associated virus (AAV) vectors have been most successful; to target the outer retina and RPE they are delivered by subretinal injection, causing a temporary retinal detachment with some potential for retinal morbidity. A recent reporter gene study using an AAV2/8 vector in dogs reported transgene expression beyond the boundary of the subretinal bleb. This could be a desirable feature which increases the area of retina treated while minimizing the retinal detachment and any associated morbidity. We performed a detailed study of the lateral spread of transgene expression beyond the subretinal injection site following subretinally delivered AAV vectors in normal dogs. Vectors expressed green fluorescent protein (GFP) using a small chicken beta-actin promoter. AAV2/2 (quadruple tyrosine to phenylalanine (Y-F) capsid mutant), self-complementary (sc) AAV2/8 (single Y-F capsid mutant) and a scAAV2/5 were used. We found that in all eyes GFP expression involved retina beyond the initial post-injection subretinal bleb boundary. In all eyes there was post-injection spread of the retinal detachment within the first 3 days post procedure and prior to retinal reattachment. In 11/16 eyes this accounted for the entire "lateral spread" of GFP expression while in 5/16 eyes a very slight extension of GFP expression beyond the final boundary of the subretinal bleb could be detected. All 3 AAV constructs induced GFP expression in the nerve fiber layer with spread to the optic nerve. Patients treated by subretinal injection should be monitored for possible expansion of the subretinal injection bleb prior to reattachment. Injections in the para-foveal region may expand to lead to a foveal detachment that may be undesirable. Cell-specific promoters may be required to limit spread of expressed transgene to the brain with these AAV serotypes.
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Affiliation(s)
- Ashlee R. Bruewer
- Department of Small Animal Clinical Sciences, Michigan State University, East Lansing, Michigan, United States of America
| | - Freya M. Mowat
- Department of Small Animal Clinical Sciences, Michigan State University, East Lansing, Michigan, United States of America
| | - Joshua T. Bartoe
- Department of Small Animal Clinical Sciences, Michigan State University, East Lansing, Michigan, United States of America
| | - Sanford L. Boye
- Department of Ophthalmology, University of Florida College of Medicine, Gainesville, Florida, United States of America
| | - William W. Hauswirth
- Department of Ophthalmology, University of Florida College of Medicine, Gainesville, Florida, United States of America
| | - Simon M. Petersen-Jones
- Department of Small Animal Clinical Sciences, Michigan State University, East Lansing, Michigan, United States of America
- * E-mail:
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da Cruz L, Chen FK, Ahmado A, Greenwood J, Coffey P. RPE transplantation and its role in retinal disease. Prog Retin Eye Res 2007; 26:598-635. [PMID: 17920328 DOI: 10.1016/j.preteyeres.2007.07.001] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Retinal pigment epithelial (RPE) transplantation aims to restore the subretinal anatomy and re-establish the critical interaction between the RPE and the photoreceptor, which is fundamental to sight. The field has developed over the past 20 years with advances coming from a large body of animal work and more recently a considerable number of human trials. Enormous progress has been made with the potential for at least partial restoration of visual function in both animal and human clinical work. Diseases that have been treated with RPE transplantation demonstrating partial reversal of vision loss include primary RPE dystrophies such as the merTK dystrophy in the Royal College of Surgeons (RCS) rat and in humans, photoreceptor dystrophies as well as complex retinal diseases such as atrophic and neovascular age-related macular degeneration (AMD). Unfortunately, in the human trials the visual recovery has been limited at best and full visual recovery has not been demonstrated. Autologous full-thickness transplants have been used most commonly and effectively in human disease but the search for a cell source to replace autologous RPE such as embryonic stem cells, marrow-derived stem cells, umbilical cord-derived cells as well as immortalised cell lines continues. The combination of cell transplantation with other modalities of treatment such as gene transfer remains an exciting future prospect. RPE transplantation has already been shown to be capable of restoring the subretinal anatomy and improving photoreceptor function in a variety of retinal diseases. In the near future, refinements of current techniques are likely to allow RPE transplantation to enter the mainstream of retinal therapy at a time when the treatment of previously blinding retinal diseases is finally becoming a reality.
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Affiliation(s)
- Lyndon da Cruz
- Division of Cellular Therapy, Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK.
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Komáromy AM, Varner SE, de Juan E, Acland GM, Aguirre GD. Application of a new subretinal injection device in the dog. Cell Transplant 2007; 15:511-9. [PMID: 17121162 DOI: 10.3727/000000006783981701] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The use of a new subretinal injection device (RetinaJect Subretinal Cannula, SurModics, Inc., Eden Prairie, MN) to access the subretinal space in the canine model was evaluated. Subretinal injections were performed in 33 mongrel dogs between 2 and 52 months of age (median = 9 months). In 5 normal dogs the injection of 150 microl saline or India ink occurred by using a conventional subretinal injection device (CSID) with a 30-gauge anterior chamber irrigating cannula. The sclera had to be surgically exposed and penetrated before the subretinal injection with the CSID could occur. After removing the CSID, the conjunctiva over the sclerotomy site had to be closed. In a second group of 28 dogs [16 normals, 10 RPE65 mutants, and 2 with progressive rod cone degeneration (prcd)], the 25-gauge needle of the RetinaJect was used to penetrate the conjunctiva and the sclera. Once the tip of the needle was close to the retinal surface, a 39-gauge polyimide cannula was extended and brought into apposition with the retina for the subsequent subretinal injection of 150 microl saline, India ink, or adeno-associated virus (AAV). No closure of the conjunctiva was required. The animals were clinically monitored between 1 and 59 weeks after surgery. From this second group 25 eyes were harvested for routine histological analysis either immediately after surgery or after a clinical observation time of between 1 and 40 weeks. Both devices provided equally successful access to the subretinal space. The main advantage of the RetinaJect was that no surgical dissection was required; this led to a shorter procedure time and milder postoperative conjunctival swelling. In summary, the use of the RetinaJect can be recommended as an alternative to the CSID for subretinal injections in dogs.
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Affiliation(s)
- András M Komáromy
- Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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