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Haven Roberts, Michael Lucio De Ieso, Daniel W Stamer; Differential Responses of Human Juxtacanalicular and Trabecular Meshwork Beam Cells to Mechanical Stretch. Invest. Ophthalmol. Vis. Sci. 2021;62(8):552.
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© ARVO (1962-2015); The Authors (2016-present)
The contractility status of the trabecular meshwork (TM) plays a major role in the regulation of aqueous humor outflow resistance. However, the TM contains two morphologically different cell types, the endothelial-like cells that cover the beams and plates of the inner TM and the myofibroblast-like cells that reside in the Juxtacanalicular region. The purpose of this study was to determine the contractile responses of TM cell cultures having endothelial versus myofibroblast appearance.
TM cells from healthy and glaucomatous donors were isolated and categorized as predominately “beam” or “JCT” cultures based on morphology at confluence. Each strain was plated at confluence into wells of Collagen Type IV flex plates and cultured in 10% FBS for 3 days. Media was changed to 1% FBS 1 hour before stretch began. Plates were then stretched using the FlexCell FX5K Tension Stretch machine at 20% stretch (1 hertz) for 24 hours. Cell lysates were collected and subjected to SDS-PAGE, followed by western blotting for total and phosphorylated myosin light chain (MLC), a surrogate measure for cell contractility. Quantitative analysis of MLC expression was achieved using Image Lab software.
JCT strains (n=3) responded to stretch with a 40% ± 24% decrease in pMLC levels. Conversely, the mixed morphology (n=1) and beam (n=1) TM cell strains showed a 39% and 30% increase in pMLC, respectively under the same conditions. Notably, the glaucomatous TM strain, characterized as a primarily beam morphology, showed a 10% decrease in pMLC. Furthermore, we noted a pattern of morphological change from beam to JCT as cell culture passages increased.
Contractile responses to mechanical stress are opposite between beam TM and JCT cell strains, likely reflecting their different roles in conventional outflow homeostasis. Interestingly, a beam cell strain isolated from a glaucomatous donor eye behaved more like a JCT cell strain.
This is a 2021 ARVO Annual Meeting abstract.
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