Influence of temporary hypothermia on corneal endothelial cell density during organ culture preservation

Abstract

Purpose: To evaluate temporary exposure to hypothermia for its effects on endothelial cell density of porcine corneas in dextran containing organ-culture medium, with regard to possible negative influences of low temperatures during the transport of corneal grafts.

Methods: Two groups of central discs from pig corneas (diameter 8 mm) were first organ-cultured (MEM with 6% dextran 500) for 24 hours at 32 degrees C. Twelve corneas were exposed to 4 degrees C in group 1 for 12 hours and to 21 degrees C in group 2 for 48 hours each. The paired corneal discs were not treated, and served as controls. After further organ culture of all corneas for 48 hours at 32 degrees C to allow regenerative processes, corneal endothelium was stained with alizarin red S and examined by light microscopy. The endothelial cell densities were determined manually on three central images.

Results: Exposure for 12 hours to 4 degrees C as well as for 48 hours to 21 degrees C induced an endothelial cell loss of 0.3% and 1.8% respectively. Statistical analysis showed no significant difference (p = 0.680) of the endothelial cell density between corneas exposed to 4 degrees C and the control corneas (4166 +/- 389 cells/mm(2) and 4177 +/- 407 cells/mm(2) respectively). Despite the minor cell loss, the difference of the endothelial cell density between corneas exposed to 21 degrees C and the control corneas (4085 +/- 260 cells/mm(2) and 4159 +/- 312 cells/mm(2) respectively) was statistically significant (p = 0.025).

Conclusions: Exposure of organ-cultured porcine corneas in dextran containing medium to 4 degrees C for 12 hours and 21 degrees C for 48 hours does not compromise the endothelial cell density of donor corneas in a clinically relevant manner. A storage of corneal grafts at temperatures down to 4 degrees C for 12 hours, as might be the case during transport from the cornea bank to the ocular surgeon, does not seem to damage the endothelial cell layer.