Lelyte, Inesa 
ORCID: 0000-0002-9014-3165
(2024).
Targeting diabetic vascular complications using a novel rat model for diabetic retinopathy.
University of Birmingham.
Ph.D.
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Lelyte2024PhD.pdf
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Abstract
ABSTRACT
Aims
Diabetic retinopathy (DR) is a prevalent microvascular complication of diabetes, emerging as a primary cause of vision impairment and blindness in the working-age population. Many mechanisms of DR remain incompletely understood, and existing treatments are limited. Animal models serve as an invaluable tool for advancing our knowledge of DR and identifying novel interventions for this sight-threatening disease. However, current animal models fall short of reflecting the entire spectrum of DR. The aim of this PhD research project is to develop a novel rat animal model that replicates the pathophysiology of both proliferative and non-proliferative DR. The current gold standard streptozotocin (STZ)-induced DR animal model was also assessed.
Methods
A systematic literature review was performed to outline both structural and functional readouts in the rodent STZ-induced DR animal model. A follow-up experimental study was undertaken in the STZ-induced Brown Norway (BN) rats to characterize changes in the ocular structure and functional activity following injection. In the pursuit of developing a novel preclinical model relevant to DR, the feasibility of cumate-inducible lentiviral (LV) vectors mediating vascular endothelial grow factor (VEGF-A) expression was evaluated in retinal pigment epithelial cells (ARPE-19), and the tolerability of cumate was tested in Wistar rat eyes after intravitreal delivery. Finally, intravitreally injected adeno-associated virus (AAV) vectors encoding Vegf-a were investigated in BN rats, and the efficacy of aflibercept (Eylea®) as a therapeutic intervention was assessed within this model.
Results
Systematic literature review highlighted electroretinography (ERG) as the most consistent functional redout in rodent STZ-induced DR, revealing high risk of bias in selected studies. A detailed examination of STZ-induced BN rats revealed consistent morphological changes and visual deficits post-injection, though it primarily mirrored only the early stages of DR. Cumate-inducible LV expression of VEGF-A in ARPE-19 cells led to enhanced cell proliferation, viability, permeability, and migration in tube-like structures. However, the observed retinal toxicity following intravitreal injection of cumate in Wistar rat eyes made the use of cumate-inducible LV impractical for further in vivo DR studies. Intravitreal injection of AAV vectors mediating human VEGF-A expression resulted in DR-like vascular pathology in Brown Norway rat retinas, along with reduced retinal activity, and heightened immune cell reactivity. The administration of aflibercept effectively ameliorated these effects, thereby confirming the translational applicability of this newly established model.
Conclusion
The findings described in this thesis explore the prevalent STZ-induced DR animal model and successfully culminate in the development of a novel rat model replicating the main pathophysiological features of DR. The newly established easy-to-use AAV-induced rat model recapitulates several DR-related phenotypes and serves as an attractive tool to gain valuable insights into the underlying molecular mechanisms of DR pathologies and for testing novel therapeutic strategies.
| Type of Work: | Thesis (Doctorates > Ph.D.) | |||||||||
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| Award Type: | Doctorates > Ph.D. | |||||||||
| Supervisor(s): |
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| Licence: | All rights reserved | |||||||||
| College/Faculty: | Colleges (former) > College of Medical & Dental Sciences | |||||||||
| School or Department: | Institute of Inflammation and Ageing | |||||||||
| Funders: | Other | |||||||||
| Other Funders: | This research was funded, in part, by the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Actions, grant agreement—No. 813440 (ORBITAL—Ocular Research by Integrated Training and Learning). | |||||||||
| Subjects: | Q Science > QH Natural history > QH301 Biology Q Science > QR Microbiology R Medicine > RE Ophthalmology R Medicine > RM Therapeutics. Pharmacology |
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| URI: | http://etheses.bham.ac.uk/id/eprint/15475 |
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