Increased Substrate Stiffness Elicits a Myofibroblastic Phenotype in Human Lamina Cribrosa Cells

Area of Science:

• Ophthalmology
• Biomaterials Science
• Cell Biology

Background:

• Alterations in the optic nerve head's (ONH) extracellular matrix (ECM) lead to lamina cribrosa (LC) fibrosis and compromise its mechanical integrity.
• Increased ECM stiffness is a known driver of myofibroblast activation and systemic fibrosis.

Purpose of the Study:

• To investigate the impact of substrate stiffness on profibrotic changes in primary human LC cells.
• To explore a potential molecular mechanism driving LC ECM remodeling in primary open-angle glaucoma (POAG).

Main Methods:

• Primary human LC cells from normal and POAG donors were cultured on substrates with 5 and 100 kPa stiffness.
• Cell morphology, actin cytoskeleton, focal adhesions, and α-smooth muscle actin (α-SMA) were assessed via immunofluorescence.
• Cell elastic modulus was measured using atomic force microscopy (AFM).

Main Results:

• Stiffer substrates significantly increased cell spread area, actin filament development, and focal adhesion formation in both normal and glaucoma LC cells.
• Glaucoma LC cells exhibited more pronounced changes in spreading and cytoskeleton organization compared to normal cells.
• Exposure to stiffer substrates induced a myofibroblast-like phenotype, evidenced by increased α-SMA and its colocalization with actin stress fibers.

Conclusions:

• A stiffer cellular microenvironment promotes myofibroblastic transformation in human LC cells.
• This mechanotransduction contributes to LC remodeling and fibrosis in glaucoma.
• Understanding these mechanical cues is crucial for developing glaucoma therapies targeting ECM remodeling.