Abstract
Purpose :
Accumulation of excess extracellular matrix (ECM) occurs in the trabecular meshwork (TM) of the eye in normal ageing processes and glaucoma. This can contribute to a fibrotic phenotype, increased aqueous humour outflow resistance, elevated intraocular pressure and disease progression. Structural changes of the ECM can lead to alterations in tissue biomechanics, mainly observed as altered tissue stiffness. Previous studies revealed that the stiffness of the human TM is increased in primary open angle glaucoma. The aim of this study was to determine the role of matrix rigidity on TM cell behaviours.
Methods :
Human TM cells were cultured on substrates with well-defined mechanical properties of 5 and 100 kPa to mimic the healthy or glaucomatous state, respectively. Subsequently, immunocytochemistry was used to assess the effects of substrate stiffness on TM cell spread and morphology. The proliferation rate of TM cells was measured by a 3, (4, 5-dimethyl-2-thiazolyl)-2, 5-diphenylate-2htetrazolium bromide (MTT) assay. The biophysical properties of TM cells in response to mechanical stimuli when grown on substrates of varied stiffness were analysed using atomic force microscopy (AFM).
Results :
Substrate stiffness significantly increased TM cell spread (p<0.001) and altered TM cell morphology. Immunostaining revealed that prominent stress fibres observed on stiff substrates were associated with formation of focal adhesion. Rac1 and Cdc42 immunostaining indicated a distinct stiffness-induced reorganisation of the actin cytoskeleton. Stiffer substrates also promoted increased TM cell proliferation (p<0.001). Moreover, increased substrate stiffness was found to alter the intrinsic TM cell stiffness profile (p < 0.001). Finally, Latrunculin-B promoted disruption of the actin stress fibre network on stiff substrates, where TM cell spread significantly decreased during drug treatment (p<0.001).
Conclusions :
Collectively, the data shown establishes the influence of substrate stiffness on TM cells and that stiffness might contribute to the fibrotic behaviours of TM cells in glaucoma.
This is a 2020 ARVO Annual Meeting abstract.