Purpose The number of endothelial grafts precut by eye banks increases. Their shelf life is limited to a few days. We previously demonstrated the superiority of an active storage machine (ASM) over organ culture (passive) for whole corneas. Aims: To measure the endothelial viability of pre-dissected DMEK after 3 and 10 days of storage in our ASM in a preclinical study.
Methods Pairs of human corneas were included. The endothelial cell density (ECD in cells/mm2), thickness and transparency of corneas were measured before graft preparation. Descemet’s membrane (DM) was peeled using the no-touch technique leaving the graft attached to the center of the cornea (on approx. 1mm2). After randomization, one cornea was kept in organ culture (OC) and the other in the ASM (21 mmHg, 2.6 µL/min) in the same medium (CorneaMax, Eurobio). The final viable ECD was determined using the triple staining with Hoechst-Ethidium-Calcein-AM. In addition, the expression of CD166 and NCAM (lateral membranes), ZO-1 (apical junctions), Na+/K+ ATPase (endothelial pump function) and COX-IV (mitochondrial content) was studied by immunostaining to characterize endothelial cells after the storage.
Results Initial ECDs were comparable: 2185±232 cells/mm2 in the ASM versus 2276±328 in OC for the 3-day period and 2680±416 cells/mm2 in the ASM versus 2644±420 in OC for the 10-day period. The DMs did not fold back in either BR or OC. The viable ECD did not differ significantly between the ASM and OC for either storage period: 2378±501 (ASM) versus 2342±503 (OC) for the 3-day period (n=8 pairs and p=0.624) and 2482±288 (ASM) versus 2579±315 (OC) for the 10-day period (n=5 pairs and p=0.176). Corneas were more transparent and thinner in the ASM than in OC after 3 days (916±86 versus 1193±136µm, p=0.0001) and 10 days (957±128 versus 1220±105µm, p=0.0625). The functional and structural markers studied were expressed in both groups after 3 and 10 days, some better preserved in the ASM.
Conclusion The storage of precut DMEKs is possible in ASM and OC for at least 10 days. Interestingly, a pre-dissected endothelium continues to partially exert its pump function into the ASM. In practice, this could allow the stroma to be used for DALK without further deswelling. In addition to improving the storage of whole grafts, the ASM allows the storage of precut DMEKs for up to 10 days with excellent endothelial survival.
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