Abstract
Purpose: :
To evaluate optimal conditions for corneal cryopreservation with extracellular cryoprotectants, we previously used tissue from rabbits and pigs. Subsequently, the technique of cryopreservation had been applied for human corneas. In the present study we retrospectively assessed which animal model is most comparable to the freeze–thaw induced endothelial cell loss in human corneas.
Methods: :
We used eye balls from humans (n=36), rabbits (n= 20) and pigs (n=20). The human corneas were unsuitable for transplantation. The animals had been sacrificed for other purposes. Corneoscleral discs were cryopreserved in MEM with 20% hydroxyethylstarch (HES) or 10% dextran and stored at –196° Celsius in liquid nitrogen. The tissue was thawed at 37° Celsius and stored in organ culture medium (MEM with 10% FCS) for 24 hours at 37° Celsius. Endothelial cell density was determined before cryopreservation and after organ culture.
Results: :
Except for three human corneas all endothelial revealed a confluent monolayer after thawing and subsequent organ culture. One–way analysis of variance displayed significant differences between the groups. After thawing rabbit corneas frozen in the presence of 20% HES (p= 0.036) and 10% dextran (p= 0.024) displayed significantly higher endothelial cell losses than human ones. Comparison between human and porcine corneas never reached significance. Human (22.5 ± 7.8%) and porcine (22.4 ± 3.8%) corneas displayed the lowest endothelial cell losses in the presence of 10% dextran.
Conclusions: :
The results show that experimental knowledge obtained from the rabbit or pig model can be successfully applied to human tissue. Porcine corneas may be more comparable to human tissue.
Keywords: cornea: endothelium • cornea: storage • cornea: basic science