Abstract
Purpose: :
To investigate strategies to manipulate expression of major– and minor–antigens of mice cornea prior to keratoplasty. Riboflavin/UV–irradiation represents a clinically proven method to stiffen pathologic corneal tissue in keratoconus patients. This method also enables to reduce antigen presenting cells in the corneal stroma by inducing apoptosis, as proven in this project. Future aim is to use this technique in order to prevent or reduce immunological reactions and graft rejection after keratoplasty.
Methods: :
After removal of the epithelium, the central corneas of mice eyes were irradiated over an area of 2×2mm2 with a UVA diode under riboflavin treatment in vivo and in vitro. Enucleated mice eyes were treated with different concentrations of riboflavin and using different irradiation times, followed by a cultivating step of the excised corneas for 1, 2 or 3 d at 37 °C. 7 µm paraffin sections were cut and stained with Hematoxylin–Eosin. In a second cohort with 42 mice, one eye of each anaesthetised mouse was exposed to UVA .3 d later, the mice were killed and the excised corneas were embedded, cut and stained as described before.
Results: :
Most of the corneal component cells in the stroma undergo apoptosis, if irradiation doses of 1.2mW/cm2 were used. Cell death increased from 1 to 3 d of cultivation. When the irradiation doses were increased over 1.2 mW/cm2 and especially over 2 mW/cm2, all cells of the stroma and additionally the corneal endothelial cells were destroyed. In corneas which were irradiated in vivo, cells of the central corneal stroma underwent apoptsis using higher irradiation doses (3 mW/cm2), but the endothelium survived.
Conclusions: :
Cell–free zone in the stroma was achieved on the mice cornea irradiated by UVA/Riboflavin in vivo and in vitro. It provides the possibility that this method could also be transferred to human donor corneas in organ culture. This technique may help to complete strategies around corneal transplantation to prevent corneal allograft rejection by removing antigen–presenting cells.
Keywords: cornea: stroma and keratocytes • apoptosis/cell death • cornea: basic science