Viscoelastic properties' characterization of corneal stromal models using non‐contact surface acoustic wave optical coherence elastography (SAW‐OCE)

Abstract

Viscoelastic characterization of the tissue-engineered corneal stromal model is important for our understanding of the cell behaviors in the pathophysiologic altered corneal extracellular matrix (ECM). The effects of the interactions between stromal cells and different ECM characteristics on the viscoelastic properties during an 11-day culture period were explored. Collagen-based hydrogels seeded with keratocytes were used to replicate human corneal stroma. Keratocytes were seeded at 8 Â 10 3 cells per hydrogel and with collagen concentrations of 3, 5 and 7 mg/ml. Air-pulse-based surface acoustic wave optical coherence elastography (SAW-OCE) was employed to monitor the changes in the hydrogels' dimensions and viscoelasticity over the culture period. The results showed the elastic modulus increased by 111%, 56% and 6%, and viscosity increased by 357%, 210% and 25% in the 3, 5 and 7 mg/ml hydrogels, respectively. To explain the SAW-OCE results, scanning electron microscope was also performed. The results confirmed the increase in elastic modulus and viscosity of the hydrogels, respectively, arose from increased fiber density and force-dependent unbinding of bonds between collagen fibers. This study reveals the influence of cell-matrix interactions on the viscoelastic properties of corneal stromal models and can provide quantitative guidance for mechanobiological investigations which require collagen ECM with tuneable viscoelastic properties.

Effects of Excitation Angle on Air-Puff-Stimulated Surface Acoustic Wave-Based Optical Coherence Elastography (SAW-OCE)

“…Singh et al selected an incident angle of ~30 • for an air-pulse system that was applied to evaluate the changes in mechanical properties of the cornea after UV-induced collagen cross-linking (CXL) [22]. Zhang et al applied a 45 • angle to investigate the impact of corneal cell-matrix interactions on corneal stromal model viscoelasticity [40]. The normal of the sample surface (0 • ) was also employed in some research [12,[41][42][43][44] to investigate the excited angles of air-puff system application.…”