Aims A study was undertaken to determine and compare the F-actin staining patterns in the cells of the lamina cribrosa (LC) of normal, dexamethasone (DEX)-treated and glaucomatous dissected tissue and cell cultures.
Methods About 30 dissected donor eyes and nine cell lines provided the human specimens; 25 eyes and 20 primary cell cultures provided the bovine material. Appropriate samples were exposed to 1×10−7 M DEX for up to 14 days. LC tissue and cells were stained with Phalloidin-Alexa 488 to identify F-actin, and all samples were examined by confocal or epifluorescent microscopy.
Results Both in the LC tissue and LC cell cultures the dominant actin arrangement was bundles of stress fibres. However, cross-linked actin networks (CLANs) were identified in the tissue and in culture. These were markedly increased by steroid treatment and were particularly large and abundant in cultures from glaucoma donors. CLANs were not associated with optic nerve head astrocytes.
Conclusions The presence of abundant stress fibres in situ and in vitro highlights the biomechanical contribution of LC cells. However, the identification of CLANs in these cells shows that they are not exclusive to the trabecular meshwork, the only other place they have been found, and may have a role in glaucoma pathology.
- Lamina cribrosa
- trabecular meshwork
- optic nerve
- intraocular pressure
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Funding The authors would like to acknowledge the generous support provided by Mid Cheshire Hospitals NHS Trust, The Guide Dogs for the Blind, Fight for Sight, Research into Ageing, the Foundation for Prevention of Blindness and an Unrestricted Grant from Alcon, Fort Worth.
Competing interests None.
Ethics approval The eyes were collected and fixed at Alcon Fort Worth, Texas before being sent to the University of Liverpool. Patient autopsy donations conformed to review board protocols and were obtained with prior consent for use in research studies. Acquisition of these eyes was in strict adherence with the Declaration of Helsinki.
Provenance and peer review Not commissioned; externally peer reviewed.