The number of keratoplasties in Germany has increased from 2001 to 2016. Since 2014, posterior lamellar keratoplasties have surpassed PKPs. There was a constant increase of DMEKs, with a 12-fold higher number compared to DSAEKs in 2016. The shorter recovery time after DMEK seems to contribute to the trend toward earlier operative intervention in corneal endothelial diseases.

ABSTRACT.Purpose: To investigate the ability of mesenchymal stem cells (MSC) to transdifferentiate to corneal epithelial cells in experimental limbal stem cell deficiency in rabbits. Methods: Total limbal stem cell deficiency was produced in 21 right eyes of 21 New Zealand rabbits; 6 eyes served as controls (group 1, G1). After removal of the conjunctival overgrowth, five eyes received amniotic membrane transplantation (AMT; G2). In four eyes, autologous limbal stem cell transplantation from the healthy eye was performed with AMT (G3). In another six eyes, enriched autologous MSC were injected under the amniotic membrane (AM) (G4). Within 280 days, corneoscleral discs were analysed for goblet cells, cytokeratin (CK) 3 ⁄ 12, connexin 43, b 1 -integrin, CK 19, a-enolase, p63 and ATP-binding cassette transporter subtype G-2 (ABCG-2) distribution patterns. Results: Cultivated MSC were positive for CK 3 ⁄ 12 and a-enolase, but negative for ABCG-2, p63 and connexin 43. On rabbit corneas, CK 3 ⁄ 12 was expressed in all corneal regions in all groups, but with significantly different intensities. Among all other parameters, expression levels of ABCG-2, b 1 -integrin and connexin 43 were significantly different between the transplanted groups and the control group. After a mean follow-up time of 172 (47-280) days, goblet cells were rarely present in the central cornea (G1-4). Conclusion: CK 3 ⁄ 12 is not highly specific for differentiated corneal epithelium. Further, goblet cells are not a reliable marker for conjunctivalization in rabbits. Expression of ABCG-2, b 1 -integrin and connexin 43 after mesenchymal stem cell transplantation may indicate their ability to maintain their stem cell character or to transdifferentiate to epithelial progenitor cells.

ZusammenfassungDie Sektion Gewebetransplantation und Biotechnologie legt ihren 9. Jahresbericht seit Bestehen vor. Zwar ist die Anzahl der eingeworbenen Hornhäute auf 10 840 angestiegen, von denen 7168 transplantiert wurden. Jedoch wurden weiterhin 1340 Transplantate aus dem Ausland importiert, und es warteten mehr als 3300 Patienten am Jahresende auf ein Hornhauttransplantat. Der Transplantatengpass ist somit noch nicht beseitigt.

In our heterogenous study group, HLA matching did not show a significant advantage compared to random graft assignment. The rejection rate in our sample was lower than expected. Therefore no definite conclusions can be drawn as to whether HLA matching is beneficial in corneal transplantation.