Development of a novel in vivo corneal fibrosis model in the dog

Abstract

The aim of this study was to develop a novel in vivo corneal model of fibrosis in dogs utilizing alkali burn and determine the ability of suberanilohydroxamic acid (SAHA) to inhibit corneal fibrosis using this large animal model. To accomplish this, we used seven research Beagle dogs. An axial corneal alkali burn in dogs was created using 1 N NaOH topically. Six dogs were randomly and equally assigned into 2 groups: A) vehicle (DMSO, 2 μL/mL); B) anti-fibrotic treatment (50 μM SAHA). The degree of corneal opacity, ocular health, and anti-fibrotic effects of SAHA were determined utilizing the Fantes grading scale, modified McDonald-Shadduck (mMS) scoring system, optical coherence tomography (OCT), corneal histopathology, immunohistochemistry (IHC), and transmission electron microscopy (TEM). The used alkali burn dose to produce corneal fibrosis was well tolerated as no significant difference in mMS scores between control and treatment groups (p=0.89) were detected. The corneas of alkali burned dogs showed significantly greater levels of α-smooth muscle actin, the fibrotic marker, than the controls (p=0.018). Total corneal thickness of all dogs post-burn was significantly greater than baseline OCT images irrespective of treatment (p=0.004); TEM showed that alkali burned corneas had significantly greater minimum and maximum interfibrillar distances than the controls (p=0.026, p=0.018). The tested topical corneal alkali burn dose generated significant opacity and fibrosis in dog corneas without damaging the limbus as evidenced by histopathology, IHC, TEM, and OCT findings, and represents a viable large animal corneal fibrosis in vivo model. Additional in vivo SAHA dosing studies with larger sample size are warranted.

Kinetics of Fluorescein in Tear Film After Eye Drop Instillation in Beagle Dogs: Does Size Really Matter?

“…The present study supports the use of a single eyedrop in dogs, whether used therapeutically in canine patients with ocular disease or experimentally in canine models of translational research (25,26). A second drop achieved higher tear film concentrations immediately after topical administration (t = 0 min), a finding that is partly explained by a lower dilution effect for two drops (1.9-fold) than one drop (2.9-fold) from the tear fluid present on the canine ocular surface (∼65 µl) (17).…”

Establishment of in vitro model of corneal scar pathophysiology

“…The most interesting revelation of the immunofluorescence analysis was the expression of α‐SMA; the most important fibrotic marker of wound healing event that regulates differentiation of activated keratocytes to myofibroblasts (Jester et al, ). The emergence of α‐SMA positive cells as soon as day 3 was an indicator of an early fibrotic response which extended uptill day 14 with an increase in the number of α‐SMA positive cells depicting phenotypically stable myofibroblasts, similar to earlier reports of in vivo and in vitro studies on fibrotic response and scar formation (Gronkiewicz et al, ; Janin‐Manificat et al, ; Jester et al, ; Karamichos et al, ; Wilson et al, ). The increased expression of the fibrotic genes including the myofibroblastic marker α‐SMA in our in vitro CS model could be related to the exogenous addition of IL‐6 since IL‐6 has been reported to act through JAK 1 activated ERK1/2 pathway for the induction of α‐SMA expression in vivo (Gallucci, Lee, & Tomasek, ).…”

Development of semi-automatic procedure for detection and tracking of fiducial markers for orofacial kinematics during natural feeding

“…LoG output is processed with morphological h-maxima operation to suppress local maxima whose height is lower than a threshold. LoG is more robust to image contrast and intensity variations compared to raw intensity values and detects prominent dark blobs (markers) while limiting spurious detections as in [8], [9]. …”