Purpose For decades, human corneas are prepared and stored in specialized tissue banks prior to transplantation. Especially in Europe, storage takes place in ‘organ culture’, the storage in cell culture medium at approximately physiological temperature. Traditionally, a serum-containing medium is used for this purpose. However, the use of fetal calf serum has considerable disadvantages: there is a risk of disease transmission, availability may not always be guaranteed in the necessary quality, there are considerable differences from batch to batch, which is associated with batch testing required in each case, and last but not least, the extraction of serum from unborn calves is an ethical issue.

Methods In recent years, several studies have focused on the improvement of organ culture conditions for donor corneas, including different serum-free media and alternative deswelling substances. Meanwhile, media are on the market which seem to be equivalent to serum-supplemented MEM. Nevertheless, serum-free medium has not yet found its way into routine organ culture of corneas.

Results Our own preliminary studies have shown that despite the promising approaches, no satisfactory overall result could be achieved. Since only maintenance metabolism is required for storage of corneas until transplantation, in principle cultivation in the conventionally used medium seems possible without addition of serum at all. Corneas stored in this way had comparably endothelial cell density (ECD) to their counterpart stored in serum-supplemented medium. However, during the final evaluation after deswelling, the ECD dropped drastically.

Engelmann et al. started research on the use of serum-free culture medium (SFM) for a long time and comparable or even superior ECD and viability could be demonstrated. So far, however, it has not been possible to define a deswelling medium adapted to these conditions.

Also, a serum-free storage medium developed by Eurobio (CorneaSyn) could not completely convince, because although ECD of the examined corneas remained constant, the morphology of the cells changed.

Conclusion Since it is essential to intensify efforts towards a serum-free system it is planned to test serum substitutes and, if possible, also to replace the de-swelling additive dextran with a less harmful alternative to guarantee the quality of cornea grafts in the future.