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Margaret Dellett, Eoin Brown, Jasenka Guduric-Fuchs, Reinhold Medina, David A Simpson; Use of endothelial colony forming cell vesicles to modulate retinal angiogenesis. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3658.
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© ARVO (1962-2015); The Authors (2016-present)
Impaired blood flow to the retina resulting in hypoxia and neovascularisation is a feature of many ocular diseases, including diabetic retinopathy and AMD. The current gold standard of treatment is anti-VEGF therapy. However, mounting concerns surrounding chronic inhibition of VEGF mean that an alternative therapeutic strategy based upon prevention of the initial impaired blood flow would be preferable. A subtype of endothelial progenitor cells (EPCs), termed endothelial colony forming cells (ECFCs), provide an attractive approach to promote revascularisation of the ischaemic retina. Their paracrine activity may be mediated by microRNA-containing extracellular vesicles (EVs). The aim of this study is to harness the EVs released from ECFCs to promote vascular regeneration.
ECFCs were isolated from umbilical cords using established protocols. EVs were isolated from conditioned cell culture medium by ultracentrifugation and characterised by electron microscopy and flow cytometry. MicroRNA content was measured by deep sequencing. EVs from ECFCs were delivered to human retinal microvascular endothelial cells in culture at various concentrations and their migratory potential assessed. EVs were labelled with CellTracker™ CM-DiI and delivered by intravitreal injection to mice at P13 in a model of oxygen-induced retinopathy. A range of vascular cell markers were used to identify recipient cells. The effects of manipulating ECFC EV microRNA content were analysed in cell culture.
The EVs released by ECFCs ranged in size from 50-2000nm and was positive for CD9 and CD63. Specific microRNAs were enriched in EVs, including miR-451.The EVs were taken up by retinal endothelial cells in culture and increased their migratory potential. Following intravitreal injection, labelled EVs can be detected in the retina for >7 days and predominantly target perivascular cells. Co-localisation studies suggest that these may be macrophage/microglia. Intravitreal injection of EVs in the OIR model showed a trend towards decreased retinal avascular area.
EVs derived from ECFCs can be delivered successfully to the retina where they become localised around vessels. They therefore have the potential to modulate revascularisation and reduce pathologic angiogenesis. Modifying the miRNA content of EVs can alter their functional effects. EVs could form the basis of a cell-free therapy to reduce retinal ischaemia.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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