N. Nicosia

Arabinogalactan as active compound in the management of corneal wounds: In vitro toxicity and in vivo investigations on rabbits

Purpose: Aims of the present investigation were to prove that natural polysaccharide arabinogalactan (AG) is well tolerated after ocular administration and exerts a high restoring effect on corneal epithelium abrasions. Materials and Methods: AG interactions with corneal cells, as well as its effect on their proliferation, were evaluated employing rabbit corneal epithelial cell cultures. The effects due to the presence of benzalkonium chloride (BAK) were also studied on cell cultures, ex vivo on rabbit isolated corneas, evaluating the hydration level, and on the healing rate of experimental corneal wounds in rabbits. Furthermore, the healing process of corneal lesions treated with an experimental 5.0% AG solution was studied and compared with those obtained applying solutions of hyaluronic acid and tamarind seed polysaccharide, both chosen as a reference by virtue of their well-known adjuvant properties on corneal trophism; the study was carried out by light and transmission electron microscopy. Results: BAK showed toxic effects on corneal epithelium in all experiments. AG proved to stimulate the growth of the corneal epithelial cells by interacting at the level of the cell plasma membrane. The microscopy observations of the epithelial surface of AG-treated damaged corneas revealed a well-restored and histologically organized ultrastructure characterized by fully formed microvilli and glycocalyx; the healing process resulted faster with respect to spontaneously recovered untreated corneas. Conclusion: Our results suggest that AG can interact with corneal epithelial cells without any toxic side effect; moreover, it proved to stimulate cell proliferation, thus promoting tissue re-epithelialization and reorganization just 48 hr post-wounding.

Arabinogalactan: a new ophthalmic vehicle for dry eye protection and treatment of corneal lesions

Purpose: Dry eye syndrome and contact lens wearing may lead to desiccation of the corneal epithelium with abrasions and increased incidence of infectious diseases. Therefore, it is important a rapid regeneration when epithelium is compromised. Aim of the present investigation was to demonstrate that Arabinogalactan (AG), a natural polysaccharide from Larch tree, was well tolerated after ocular administration and exerted a corneal protective action. Methods: AG formulation was then subjected to specific investigations. Results: Rheological measurements highlighted a newtonian non-viscous behavior of AG aqueous dispersions at concentration up to 10% with η value of 1.6 mPas. The rheological evaluation of mucoadhesive properties showed strong interactions with mucin, property useful to retain the formulation on the eye surface. 5.0% AG dispersion exerted a significant increase in healing rate of experimental corneal wound in rabbits since 27 h after the first treatment. The corneal re-epithelization process produced a tissue stratification in the same features of native epithelium, restoring the normal multilayered architecture of the rabbit corneal epithelium. Finally, studies of cell proliferation on rabbit corneal epithelial cell culture were carried out. Solutions at AG concentrations from 5x10-3 to 1% enhanced the proliferation of the cells culture, showing cell viability values of 180% respect to the control after 48 hs exposure time. Conclusions: These findings suggest that AG may be a new potential artificial tear for the prevention and the treatment of corneal wounds in dry eye syndrome and in contact lens induced abrasions since it do not interfere with vision because of its non-viscous feature.