Decreased Substrate Stiffness Prevents Epithelial-to-Mesenchymal Transition in Lens Cells

• Chloe Mirack, Biological Sciences, University of Delaware

• Justin Parreno, Biological Sciences, Biomedical Engineering, University of Delaware

Cataracts are a prominent issue that affect the ability of light to effectively pass through the lens and produce a clear image. Cataract surgery is an approach taken where the lens of the eye is replaced with an artificial intraocular lens (IOL). In cataract surgery, the capsule that surrounds the native lens is left behind to provide support for the new IOL. As a result, remnant lens epithelial cells (LECs) that remain on the lens capsule undergo epithelial-to-mesenchymal transition (EMT). In this process, LECs migrate to the posterior regions of the lens and dedifferentiate into myofibroblasts. Myofibroblasts produce contractile molecules and excessive extracellular matrix resulting in recurrent blockage of light and the development of posterior capsule opacification (PCO), also known as secondary cataracts. The lens capsule is known to stiffen following cataract surgery, however, the effect of stiffness on lens EMT is not completely known. Here, we test the hypothesis that soft substrates will reduce the acquisition of the myofibroblast phenotype. To test this hypothesis, we seeded immortalized lens epithelial cells (imLECs) onto 50 kPa and 0.5 kPa polyacrylamide gels to simulate the stiffening of the lens capsule following surgery. The imLECs that were seeded onto the stiffer substrates expressed higher levels of the myofibroblast proteins (alpha-smooth-muscle-actin, transgelin, fibronectin) than those seeded onto the softer gels. We also evaluated the motility of the cells on these different substrate stiffnesses. ImLECs seeded onto 50 kPa and 0.5 kPa gels were placed under the cytosmart camera for a 2-day time period. Cells were manually tracked on both gels and showed that softer substrates suppresses migration of the cells. Our results support our hypothesis that softer substrates will repress EMT, resulting in a decrease of the myofibroblast phenotype.