Dextran appears helpful in corneal cryopreservation

Each layer of the cornea is capable of regaining its structural integrity after cryopreservation in media containing dextran, a study in human corneas determined. The study authors noted, however, that because of variability in endothelial cell loss the technique must be refined before it can be applied clinically.

Markus Halberstadt, of the Inselspital in Bern, Switzerland, and colleagues in Germany cryopreserved 28 human corneas in minimum essential medium containing 10% dextran with a molecular weight of 500,000 as an extracellular cryoprotectant. Once thawed, the tissue was cultured to determine latent cell damage. Confocal microscopy was used to examine each corneal layer in six specimens after 6, 24 and 48 hours of organ culturing.

Endothelial cell density decreased to 1,300 cells/mm2 from a pre-freezing count of 1,940 cells/mm2. Two of the corneas had a completely necrotic endothelium. All corneal layers in each of the six specimens maintained structural integrity 48 hours after organ culturing.

The study is published in the December issue of Investigative Ophthalmology & Visual Science.