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Matthew Aaron Reilly, Gabriela Rice, Andre Cleaver, Luis Rodriguez; Thermal Induction of Murine Lens Stiffening. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5741. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies have correlated the loss of accommodation with age (presbyopia) with increasing lens stiffness, presumably due to protein modifications resulting in aggregation, cross-linking, and insolubility. It has been determined that heat can be used to artificially age lens proteins at an accelerated rate; however, it is not known whether or to what extent this approach recapitulates mechanical property changes in the lens.
Both lenses from 43 6-day-old mice were placed in silicone oil. One eye from each animal was then thermally stressed in an incubator for varying lengths of time (30 minutes to 15 hours) while the other rested for the same period of time at room temperature. Lenses were then evaluated using a parallel plate compression test. These data were then used to determine the resilience and stiffness of the lenses. A small number of lenses from adult mice (40 weeks) were tested fresh for comparison. All tissues were shared by other investigators performing unrelated experiments and were treated in accordance with the ARVO Statement for the Use of Animals in Ophthalmic and Visual Research.
Titration curves relating stiffness changes as a function of incubation time showed up to an eight-fold increase in lens stiffness. Lens sphericity also increased following incubation, possibly indicating a loss of water due to protein crystallization. Time-temperature superposition successfully predicted the changes in lens stiffness changes with time at various temperatures up to 55°C. Very young lenses incubated for up to 3 hours at 55°C did not achieve the same stiffness as fresh lenses from 40-week-old mice.
It is known that incubating lenses recapitulates some post-translational modifications. These results indicate that these modifications contribute significantly to lens stiffening and that stiffness measurements may be a suitable method for monitoring the kinetics of the biochemical reactions involved in presbyopigenesis. However, it does not fully recapitulate the aging process since fewer proteins are present in the lens and therefore the maximum achievable stiffness is somewhat lower than those of an adult mouse lens.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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