alignment-visible-light-optical-coherence-tomography-fibergrams-with

Alignment of Visible-Light Optical Coherence Tomography Fibergrams with Confocal Images of the Same Mouse Retina

In recent years, in vivo retinal imaging, which provides non-invasive, real-time, and longitudinal information about biological systems and processes, has ...

University of Virginia

The purpose of this study was to examine the protein profile differences between capillary and Schirmer strip tear fluid samples.

Comparison of Capillary and Schirmer Strip Tear Fluid Sampling Methods Using SWATH-MS Proteomics Approach.

A leading cause of blindness worldwide, glaucoma is often caused by elevated intraocular pressure (IOP) due to impaired aqueous humor outflow from the anterior chamber through Schlemm's canal (SC) and the trabecular meshwork. Despite the large clinical burden, glaucoma research and drug development are hindered by a limited selection of preclinical models that accurately recapitulate human disease. Here, we propose that  conditional knockout mice may provide one such model. Angiopoietin/TEK (ANGPT/TEK) signaling is crucial for SC formation and integrity in mice and humans, and mice lacking TEK or its ligand ANGPT1 develop a hypomorphic SC insufficient for normal aqueous humor outflow.

Angiopoietin-1 Knockout Mice as a Genetic Model of Open-Angle Glaucoma.

C5a is a crucial terminal effector of the C cascade, mostly involved in pain and neuroinflammatory conditions. DF3016A is a novel potent and selective C5a receptor (C5aR) inhibitor that crosses the blood-brain barrier (BBB) and may have pharmacological properties. We have previously demonstrated a protective effect of DF3016A on injured primary cortical neurons by oxygen-glucose deprivation-reoxygenation (OGD/R) model to mimic the neuroinflammatory process. Here, we investigated the molecular pathway and factors involved in the neuroprotection previously reported. Our findings show that DF3016A protects against the neuroinflammatory insult by activating brain-derived neurotrophic factor (BDNF) transcription pathway, which involves methyl CpG-binding protein 2 (MeCP2) and microRNA-132 (miR-132) regulatory factors, both required in nociceptive signaling and neuroinflammation. Further in vivo investigations will confirm the functionality of the DF3016A molecule as a therapeutic resource in neuroinflammation and pain injuries.

DF3016A induces increased BDNF transcription in ischemic neuroinflammation injury.

To develop a practical technique for visualizing and quantifying retinal ganglion cell (RGC) axon bundles .

Visible-Light Optical Coherence Tomography Fibergraphy for Quantitative Imaging of Retinal Ganglion Cell Axon Bundles.

Low bioavailability of topically applied drugs remains a significant challenge for long-term glaucoma therapy. To enhance drug delivery efficiency, we developed dendrimer gel particles that collectively exhibit structural benefits of dendrimer, hydrogel, and particles, using the inverse emulsion method coupled with the highly efficient aza-Michael addition reaction (IEaMA). This hierarchical approach would maximize the utility of the structural features of existing ocular drug delivery systems. We have tested the delivery efficiency and efficacy of two first-line antiglaucoma drugs, brimonidine tartrate (BT) and timolol maleate (TM), which were loaded into dendrimer gel particles of various sizes, i.e., nDHP (nano-in-nano dendrimer hydrogel particles, ~200 nm), μDHP3 (3 μm), and μDHP10 (9 μm). We found that nDHP was superior to μDHP3 and μDHP10 in terms of cytocompatibility, degradability, drug release kinetics, and corneal permeability. The nDHPs increased drug corneal permeability by 17-fold compared to plain drug solution and enabled zero-order prolonged drug release kinetics. The nDHP-based formulation demonstrated pronounced IOP-lowering effects in both single-dose test and 7-day chronic daily dosing test in both Brown Norway rats and glaucoma mice. Taken together, we have developed nano-in-nano dendrimer gel particles for precise dosing and enabling sustained and synergistic efficacy of antiglaucoma drugs, which could be clinically impactful for improving glaucoma treatment.

Nano-in-Nano Dendrimer Gel Particles for Efficient Topical Delivery of Antiglaucoma Drugs into the Eye.

The growth of the mouse eye and retina after birth is a dynamic, highly regulated process. In this study, we applied visible-light optical coherence tomography (vis-OCT), a non-invasive imaging technique, to examine developing retinal layer structures after eye-opening. We introduced a resampled circumpapillary B-scan averaging technique to improve the inter-layer contrast, enabling retinal layer thickness measurements as early as postnatal day 13 (P13) - right after eye-opening. We confirmed vis-OCT measurements using ex vivo confocal microscopy of retinal sections at different ages. Our results demonstrate that vis-OCT can visualize the developmental murine retinal layer structure in vivo, which offers us new opportunities to better characterize the pathological alterations in mouse models of developmental eye diseases.

In vivo imaging of the inner retinal layer structure in mice after eye-opening using visible-light optical coherence tomography.

Retinal ganglion cells (RGCs) exhibit compartmentalized organization, receiving synaptic inputs through their dendrites and transmitting visual information from the retina to the brain through the optic nerve. Little is known about the structure of RGC axon bundles extending from individual RGC somas to the optic nerve head (ONH) and how they respond to disease insults. We recently introduced visible-light optical coherence tomography fibergraphy (vis-OCTF), a technique for directly visualizing and analyzing mouse RGC axon bundles  In this study, we validated vis-OCTF's ability to quantify RGC axon bundles with an increased number of RGCs using mice deficient in BCL2-associated X protein (BAX). Next, we performed optic nerve crush (ONC) injury on wild-type (WT) mice and showed that the changes in RGC axon bundle width and thickness were location-dependent. Our work demonstrates the potential of vis-OCTF to longitudinally quantify and track RGC damage at single axon bundle level in optic neuropathies. Nearly all clinical and preclinical studies measure the retinal nerve fiber (RNFL) thickness as the sole indicator of retinal ganglion cell (RGC) damage without investigating RGC axon bundles directly. We demonstrated visible-light optical coherence tomography fibergraphy (vis-OCTF) to directly quantify global and regional RGC axon bundle organizations  as a new biomarker for RGC health. We validated  vis-OCTF measures using both confocal microscopy of the immunostained flat-mounted retina and numerical simulations. Vis-OCTF for monitoring RGC axon bundle organization has the potential to bring new insight into RGC damage in optic neuropathies.

Global and Regional Damages in Retinal Ganglion Cell Axon Bundles Monitored Non-Invasively by Visible-Light Optical Coherence Tomography Fibergraphy.

Aniridia is a panocular condition characterized by impaired eye development and vision, which is mainly due to the haploinsufficiency of the paired-box-6 (PAX6) gene. Like what is seen in aniridia patients, Pax6-deficient mice Pax6 exhibit a varied degree of ocular damage and impaired vision. Our previous studies showed that these phenotypes were partially rescued by PD0325901, a mitogen-activated protein kinase kinase (MEK or MAP2K) inhibitor. In this study, we assessed the long-term efficacy of PD0325901 treatment in retinal health and visual behavior. At about one year after the postnatal treatment with PD0325901, Pax6 mice showed robust improvements in retina size and visual acuity, and the elevated intraocular pressure (IOP) was also alleviated, compared to age-matched mice treated with vehicles only. Moreover, the Pax6 eyes showed disorganized retinal ganglion cell (RGC) axon bundles and retinal layers, which we termed as hotspots. We found that the PD treatment reduced the number and size of hotspots in the Pax6 retinas. Taken together, our results suggest that PD0325901 may serve as an efficacious intervention in protecting retina and visual function in aniridia-afflicted subjects.

Long-term retinal protection by MEK inhibition in Pax6 haploinsufficiency mice.

We developed a new analytic tool based on visible-light optical coherence tomography fibergraphy (vis-OCTF) to longitudinally track individual axon bundle transformation as a new in vivo biomarker for retinal ganglion cell (RGC) damage.

Longitudinal Analysis of Retinal Ganglion Cell Damage at Individual Axon Bundle Level in Mice Using Visible-Light Optical Coherence Tomography Fibergraphy.

Article	Year
Comparison of Capillary and Schirmer Strip Tear Fluid Sampling Methods Using SWATH-MS Proteomics Approach. Translational vision science & technology\| PubMed ID: 32714642	2020
Angiopoietin-1 Knockout Mice as a Genetic Model of Open-Angle Glaucoma. Translational vision science & technology\| PubMed ID: 32818103	2020
DF3016A induces increased BDNF transcription in ischemic neuroinflammation injury. Brain research\| PubMed ID: 32898508	2020
Visible-Light Optical Coherence Tomography Fibergraphy for Quantitative Imaging of Retinal Ganglion Cell Axon Bundles. Translational vision science & technology\| PubMed ID: 33110707	2020
Nano-in-Nano Dendrimer Gel Particles for Efficient Topical Delivery of Antiglaucoma Drugs into the Eye. Chemical engineering journal (Lausanne, Switzerland : 1996)\| PubMed ID: 34121919	2021
In vivo imaging of the inner retinal layer structure in mice after eye-opening using visible-light optical coherence tomography. Experimental eye research\| PubMed ID: 34492282	2021
Global and Regional Damages in Retinal Ganglion Cell Axon Bundles Monitored Non-Invasively by Visible-Light Optical Coherence Tomography Fibergraphy. The Journal of neuroscience : the official journal of the Society for Neuroscience\| PubMed ID: 34702745	2021
Long-term retinal protection by MEK inhibition in Pax6 haploinsufficiency mice. Experimental eye research\| PubMed ID: 35245513	2022
Longitudinal Analysis of Retinal Ganglion Cell Damage at Individual Axon Bundle Level in Mice Using Visible-Light Optical Coherence Tomography Fibergraphy. Translational vision science & technology\| PubMed ID: 37163286	2023

Marta Grannonico

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