Abstract
Purpose :
The retina resides in a well-regulated biomechanical environment, and several ophthalmological pathologies, such as retinal detachment and glaucoma, involve disruptions in the mechanical forces at work. However, the mechanisms through which the damaging actions are carried out are still poorly understood. The aim of this study was to develop a method of stretching retinal tissue in vitro with high precision and reproducibility in order to facilitate further research in retinal biomechanics. A secondary goal was to employ the developed methodology to determine the importance of lateral tension as a factor for retinal survival in vitro.
Methods :
Adult porcine retinal segments were placed in culturing wells with elastic EPTFE membranes. The explants were then inserted into a modified version of MCB1, a biomechanical stimulation unit from CellScale© that converts axial motion into radial stretch via a system comprised of an actuator, gooseneck and a deformable scaffold. Attached to the scaffold through eight separate anchoring pins in a circular pattern, retinas were kept at a constant degree of stretch - 0% (n=12), 4% (n=9), 6% (n=8), 8% (n=8), 10% (n=8), 12% (n=8), 16% (n=8), and cultured for five days. Specimens were subsequently fixed, cryosectioned and stained with NeuN, an immunohistochemical marker for ganglion and amacrine cells, as well as with hematoxylin and eosin.
Results :
At five days, unstretched specimens displayed widespread pyknosis and a near-total degradation of laminar architecture. In comparison, stretched retinas exhibited preservation of the inner nuclear layer as well as a relatively intact retinal structure. In addition, retinas kept at a stretch of 4%, 8% and 16% revealed a significantly improved survival of cells with ganglion cell morphology compared to unstretched controls.
Conclusions :
The retina is clearly a biomechanically active organ, and it’s role as such merits further research to better understand retinal pathologies where mechanical disturbances are important etiological factors. We believe the methodology here developed may provide a useful tool for research in retinal biomechanics as it enables reproducible, precise and quantifiable stretching of the retina in vitro.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.