Calculating Traction Forces in Normal and Glaucomatous Trabecular Meshwork Cells in an Active 3D Fluid-Structure Interaction Culture Setting

Abstract

Purpose : Research has demonstrated a significant increase in matrix stiffness within the trabecular meshwork (TM) tissue in primary open angle glaucoma (POAG). This increased stiffness not only affects the functionality of TM cells but also alters the adhesion forces between these cells and the extracellular matrix (ECM). This change also plays a substantial role in modulating the resistance to aqueous outflow, a key factor in the pathophysiology of POAG. This study developed an advanced 3D in vitro model that accurately mimics the anatomical and biomechanical characteristics of the conventional aqueous outflow pathway, derived from serial block-face scanning electron microscopy images.

Methods : Our model was 3D printed from collagen-coated polyacrylamide gel with elastic moduli of 1.5 and 21.7 kPa. This model facilitates the detailed estimation of 3D, depth-dependent dynamic traction forces, along with tensile and shear strains in both normal and glaucomatous (NTM & GTM) cells within a fluid-structure interaction (FSI) environment (Fig. 1). The study involved two experimental conditions: a control setup observing the intrinsic contractile forces in TM cells over 20 hours without flow, and a dynamic setup incorporating FSI to analyze the effect of fluid dynamics on cellular traction forces.

Results : Our findings indicated that active FSI markedly increases traction forces (1.83-fold in NTM & 2.24-fold in GTM cells) and shear strains (1.81-fold in NTM & 2.41-fold in GTM cells) compare to 3D culture model with no active FSI (Fig. 2). This effect was more pronounced on stiffer substrates. The active flow introduced additional mechanical stimuli, enhancing the dynamic interaction between the cells and their environment. This led to increased traction forces under flow conditions as compared to the no-flow scenarios, where such dynamic interactions were absent. These findings underscore the critical role of environmental dynamics in modulating cellular biomechanics, particularly in the context of GTM cells. Larger traction forces were consistently observed in GTM cells compared to NTM cells.

Conclusions : Developed 3D culture model significantly advances our comprehension of human TM cell biomechanics and the stiffening of ECM in glaucoma. It also highlights the crucial role of FSI in these processes, demonstrating its impact on TM cell responses and ECM dynamics.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.