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Matthew Aaron Reilly, Samuel T Croarkin, Nicholas Pennza; In Vitro Models of Lens Stiffening. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3171.
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© ARVO (1962-2015); The Authors (2016-present)
While it is well known that the lens nucleus stiffens significantly with age, the molecular mechanism driving this stiffening remains unknown. This knowledge gap is largely due to the lack of relevant animal models or in vitro models of lens aging. In this study, we explore a variety of in vitro models which are intended to simulate specific aspects of biochemical aging while measuring aggregation and mechanical changes in lens protein solutions. The time course of these changes was compared with age-related changes in human lens samples to determine which models most accurately reproduce age-related changes.
Porcine and human donor lenses were homogenized and fractionated using an ultracentrifuge. Porcine samples were tested at 37°C with and without UV exposure, 37°C with and without hydrogen peroxide, and 50°C. Human samples were tested at 37°C without other stresses. Additional porcine lenses were submerged in formalin or microwaved for various time period prior to homogenization and fractionation. Particle size and shear modulus of homogenate and soluble fractions were respectively measured using dynamic light scattering and dynamic shear rheometry.
All models were able to reproduce time-dependent aggregation and orders-of-magnitude increases in shear modulus. Moreover, the ultimate shear modulus achieved by these solutions approaches that of the intact shear modulus of the old human lens. The extent of these changes were similar to those found in human lenses with age.
Each in vitro model was able to stiffen the lens following crystallin aggregation in a dose-dependent manner. The age-dose equivalency will be modeled to determine the thermodynamic driving forces of these changes in vivo.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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