Artigo retina

Retina

Retinal Glial (Muller) Cells: Sensing and Responding ¨ to Tissue Stretch
Niclas Lindqvist,1 Qing Liu,1 Joachim Zajadacz,2 Kristian Franze,1,3 and Andreas Reichenbach1
PURPOSE. To test whether Muller glial cells sense, and respond ¨ to, mechanical tension in the retina. METHODS. A device was designed to stretch the retina at right angles to its surface, across retinal layers. Pieces of retina were mounted between two hollow tubes, and uniaxial force was applied to the tissue using a micrometer-stepping motor. Mul¨ ler cells were selectively stained with the fluorescent, calciumsensitive dye X-Rhod-1 and were monitored in real time during retinal stretch in vitro. Immunohistochemistry was used to study protein levels and activation of intracellular pathways in stretched retinas. RESULTS. Muller cells responded acutely with transient in¨ creases in fluorescence during stretch, indicative of increased intracellular calcium levels. All the Muller cells elongated uni¨ formly, and there was no apparent difference between retinal layers in resistance against mechanical deformation. After stretch, Muller cells showed fast activation of extracellular ¨ signal-regulated kinase (after 15 minutes), upregulation of transcription factor c-Fos (after 1 hour), and basic fibroblast growth factor (after 3 hours). No changes in intermediate filament protein expression were observed in Muller cells up to 3 hours ¨ after stretch. CONCLUSIONS. A novel technique was developed for real-time monitoring of Muller cells during retinal stretch, which al¨ lowed the identification of Muller cells as a mechanorespon¨ sive cell type. Mechanical stress triggers molecular responses in Muller cells that could prevent retinal damage. (Invest Oph¨ thalmol Vis Sci. 2010;51:1683–1690) DOI:10.1167/iovs.09-4159 he retina is a thin lamella on the inside of the eye that is responsible for photodetection. According to its ontogenetic origin from the distal part of the ocular vesicle, it is continuous with