Hypoxia modulates the development of a corneal stromal matrix model. (May 2018)

• Record Type: Journal Article
• Authors: Lee, Albert; Karamichos, Dimitrios; Onochie, Obianamma E.; Hutcheon, Audrey E.K.; Rich, Celeste B.; Zieske, James D.; Trinkaus-Randall, Vickery
• Is Part Of: Experimental eye research. Volume 170(2018)
• Page Start: 127
• Page End: 137
• Publication Date: 2018-05
• Subjects: Extracellular matrix -- Cornea -- Corneal organ culture -- Confocal fluorescence microscopy -- Stroma; F-actin filamentous actin -- Sulf1 sulfatase 1 -- LOX1 lysyl oxidase -- SMA smooth muscle actin -- TGF-beta1 transforming growth factor beta 1 -- GAG glycosaminoglycan -- DMEM Dulbecco's modified Eagles medium -- EMEM Eagle's minimum essential medium -- TEM transmission electron microscopy -- PCR polymerase chain reaction; Ophthalmology -- Periodicals; Eye -- Periodicals; Œil -- Périodiques; Ophthalmology; Periodicals; Electronic journals; 612.8405
• DOI: 10.1016/j.exer.2018.02.021
• Languages: English
• ISSNs: 0014-4835

Abstract

Abstract: Deposition of matrix proteins during development and repair is critical to the transparency of the cornea. While many cells respond to a hypoxic state that can occur in a tumor, the cornea is exposed to hypoxia during development prior to eyelid opening and during the diurnal sleep cycle where oxygen levels can drop from 21% to 8%. In this study, we used 2 three-dimensional (3-D) models to examine how stromal cells respond to periods of acute hypoxic states. The first model, a stromal construct model, is a 3-D stroma-like construct that consists of human corneal fibroblasts (HCFs) stimulated by a stable form of ascorbate for 1, 2, and 4 weeks to self-assemble their own extracellular matrix. The second model, a corneal organ culture model, is a corneal wound-healing model, which consists of wounded adult rat corneas that were removed and placed in culture to heal. Both models were exposed to either normoxic or hypoxic conditions for varying time periods, and the expression and/or localization of matrix proteins was assessed. No significant changes were detected in Type V collagen, which is associated with Type I collagen fibrils; however, significant changes were detected in the expression of both the small leucine-rich repeating proteoglycans and the larger heparan sulfate proteoglycan, perlecan. Also, hypoxia decreased both the number of Cuprolinic blue-positive glycosaminoglycan chains along collagen fibrils and Sulfatase 1, which modulates the effect of heparan sulfate by removing the 6-O-sulfate groups. In the stromal construct model, alterations were seen in fibronectin, similar to those that occur in development and after injury. These changes in fibronectin after injury were accompanied by changes in proteoglycans. Together these findings indicate that acute hypoxic changes alter the physiology of the cornea, and these models will allow us to manipulate the conditions in the extracellular environment in order to study corneal development and trauma. Highlights: The stromal construct response to hypoxia was similar to that observed in development. Changes in proteoglycan and fibronectin with hypoxia mirrored changes in development. Type III collagen synthesis was decreased with hypoxic exposure. Decoration of collagen fibrils with sulfated glycosaminoglycans decreased in response to hypoxia.