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Anita Chan, Sai Bo Bo Tun; Retinal effects of Intravitreal Neuroglobin (Ngb) Delivery study. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1106.
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© 2017 Association for Research in Vision and Ophthalmology.
To determine the retinal effects of intravitreal (IVT) delivery of exogenous Ngb protein by:i) Morphometric evaluation by photography, and histology on day 7 and day 30 post injectionii) Proteomic determination of retinal Ngb levels using ELISA on day 7 and day 30 post injection
All experiments were conducted in compliance with the ARVO Statement for the Use of Animals in Ophthalmic and Visual Research. Twenty-four rats were subjected to IVT Ngb injection (5ul of 10umol/l neuroglobin protein) on day 0 in the right eye (Ngb-IVT). The contralateral left eye was subjected to sham injection of balanced salt solution as control (Control). At day 7 and day 30 post injection, 12 rats were sacrificed respectively after fundus photography was performed. Twelves globes (6 Ngb-IVT) and (6 Control) were used for histology and immunohistochemistry and an the remaining 12 globes were used for enzyme-linked immunosorbent assays (ELISA) of Ngb levels in the retina.
No evidence of clinical inflammation (vitritis, vasculitis or retinitis) or endophthalmitis at day 7 and day 30 was detected (Fig1A &B). No statistical (p>0.05) or histological evidence of changes in retinal thickness in all retinal layers. Apoptosis detected with annexin was not seen (Fig 1C). ELISA analysis of Ngb protein in the retina on day 30 after a single intravitreal injection of Ngb showed more than 2-fold elevation of Ngb (p=0.57) in comparison to controls retinas without Ngb injection indicating that a single intravitreal dose could achieve almost significant levels of Ngb at 30 days post injection.
Neuroglobin is an endogenous retinal protein previously shown to be neuroprotective in retinal ischemia. We found that exogenous intravitreal injections of Ngb can be performed safely without inflammation or endopthalmitis and can achieve more than 2-fold Ngb elevation at day 30 post injection. Although further pharmacokinetic studies are required, this finding suggests a possible role for a single monthly IVT Ngb injection as neuroprotection therapy in retinal ischemia.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Figure 1A, B: The fundus and retina in eyes injected with NGB (NGB-IVT) show no evidence of inflammation in comparison to control eye on day 7 and day 30. Figure 1C: Annexin (apoptosis marker) showed no increase apoptosis (in presence of a working positive control, not shown) in NGB-IVT eyes in comparison to controls on day 7 and day 30.
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