Segmental Mechanobiology of Normal and Glaucomatous Human Trabecular Meshwork Cells

Glaucoma is a leading
cause of irreversible blindness
worldwide,
with elevated intraocular pressure (IOP) serving as the major risk
factor for disease onset and progression. IOP is largely determined
by aqueous humor outflow resistance in the conventional pathway, where
interactions between trabecular meshwork (TM) cells and the surrounding
extracellular matrix (ECM) are pivotal. In this study, we examined
the segmental mechanobiology of normal and glaucomatous human TM cells
isolated from high-flow (HF) and low-flow (LF) regions of the outflow
pathway of normal and primary open-angle glaucoma (both male and female).
Cells were seeded on type I collagen gels with fibrillar elastic moduli
of 4.7 kPa and 27.7 kPa to approximate the ECM conditions
of normal and glaucomatous eyes, respectively. We employed 3D traction
force microscopy to quantify time-dependent contractile forces in
the cells as well as curl, divergence, orientation, and tensile strain
in the collagen fibers within 12 h postseeding. We also analyzed the
organization of actin, microtubule, and intermediate filaments in
normal and glaucomatous TM cells from both HF and LF regions. Multivariable
mixed-effects models showed that, after accounting for fibrillar stiffness,
time, normal/glaucoma status, and sex, HF cells generated ∼1.6-fold
higher mean traction (window averaged, ∼5–6 cells) and
∼1.4-fold higher tensile strain than LF cells and induced ∼1.5-fold
greater collagen curl (p < 0.001 for all), whereas
divergence and glaucoma versus normal difference were not significant
in this data set. Stiffer gels increased the collagen fibril preferred
orientation angle (HF > LF), and glaucomatous LF cells showed persistently
disorganized actin and microtubules with little change in intermediate
filaments. These findings emphasize the importance of segmental cell–ECM
interactions in modulating cell–ECM interaction.