Viscoelastic Properties of Vitreous Body: Role of Hyaluronic Acid

Abstract

Abstract: : Purpose: To study effect of sex and species on the rheological behaviour of animal vitreous bodies with the aim of analysing the influence of the vitreous composition, in particular Hyaluronic acid (HA) concentration, molecular weight (MW) and MW distribution, on the rheological properties. Methods: The rheological properties of vitreous bodies were evaluated on a Bohlin VOR Rheometer (Bohlin Reologi A B, Lund, Sweden) at controlled temperatures of 37°C and/or 25°C. The small–amplitude oscillatory shear experiments were performed to measure the unsteady response of the samples, and hence, their linear viscoelastic properties. The HA samples were extracted from animals’ vitreous bodies using P. Bishop method. The viscosimetric average MW and the average concentration of HA extracted samples were indirectly measured using agarose gel electrophoresis and densitometric scan. Results: Results showed that the vitreous behaved as a solid–like material and its rheological behaviour was typical of a weak gel. Its rheological properties, are quantitatively species dependent, while the sex, except for the goat, does not have influence on the them. The biochemical and rheological analysis showed that the overall mechanical behaviour of the vitreous body is not directly related to Hyaluronic acid network alone. Conclusions: solutions of Hyaluronic acid having molecular weight and concentration comparable to the ones found in the vitreous body behave as viscous lquid. Therefore the overall mechanical behaviour of vitreous body can not be ascribed to Hyaluronic acid alone but most probably to the interaction between Hyaluronic acid and collagen network.

Keywords: vitreous