The thesis focuses on the in vivo and in vitro behavior of corneal endothelial cells before and after endothelial keratoplasty. The first part of the project concentrates on the ECD decrease after... Show moreThe thesis focuses on the in vivo and in vitro behavior of corneal endothelial cells before and after endothelial keratoplasty. The first part of the project concentrates on the ECD decrease after DMEK and DMEK graft viability prior to transplantation. The second part focusses on regenerative strategies for the treatment of FECD by developing and applying in vitro cell migration assays. In vitro cell migration from DMEK grafts of various sizes and shapes are investigated in a 3D cell culture system aiming to identify critical parameters for the successful clinical application of corneal endothelial therapies. Show less
Corneal diseases are among the leading causes of reversible blindness worldwide. When conservative treatment options fail, many eyes can be treated with corneal transplantation. Historically, full... Show moreCorneal diseases are among the leading causes of reversible blindness worldwide. When conservative treatment options fail, many eyes can be treated with corneal transplantation. Historically, full thickness corneal transplantation, in which all corneal layers are replaced, has been the mainstay of care in the treatment of corneal endothelial disorders. In the past two decades, however, there has been a trend towards the selective, less invasive replacement of only the diseased, rather than all corneal layers. These partial thickness corneal transplantations are known as lamellar keratoplasties. Lamellar keratoplasty has significantly improved the clinical outcomes, such as visual acuity, after transplantation. Since its introduction in 1998, lamellar keratoplasty has evolved from Deep lamellar endothelial keratoplasty to Descemet membrane endothelial keratoplasty (DMEK). Globally, however, there is only one donor cornea available for 70 people in need. This shortage inspired further refinement of conventional DMEK and led to the development of adapted DMEK-techniques, which may increase the availability of endothelial donor grafts. This thesis focuses on donor tissue preparation for DMEK and evaluates the feasibility and clinical outcomes of DMEK, DMET, Hemi-DMEK and Quarter-DMEK in the management of corneal endothelial disorders. Show less
Quarter-Descemet membrane endothelial keratoplasty (Quarter-DMEK) has been introduced as a modification of the standard DMEK technique to increase the pool of endothelial grafts. In this study, we... Show moreQuarter-Descemet membrane endothelial keratoplasty (Quarter-DMEK) has been introduced as a modification of the standard DMEK technique to increase the pool of endothelial grafts. In this study, we evaluated in vitro changes in endothelial cell distribution, viability and morphology of Quarter-DMEK grafts when stored in organ-culture medium. Quarter-DMEK grafts were prepared from 5 corneas and stored in organ-culture medium for 4, 7 and 11 days. Endothelial cell re-distribution was investigated by light microscopy, cell viability by a Calcein-AM assay, and expression of endothelial and non-endothelial markers by immunohistochemistry. Three standard DMEK-grafts were used as controls. After preparation, all Quarter-DMEK grafts showed a band with no viable endothelial cells along the radial cut graft edges [average width 190 (+/- 20) mu m]. Endothelial cell density in the central graft area decreased by 12%, 23% and 26% after 4, 7, and 11 days of storage, respectively. At the same time, empty bands along the cut edges were re-populated and some cells migrated to the stromal side of the Descemet membrane (DM). These cells showed an altered phenotype, as indicated by expression of migration marker CD73 and fibroblast marker alpha SMA. Majority of migration occurred within the first 4 days of storage. Our data suggest that endothelial cells on Quarter-DMEK grafts re-distribute during organ-culture storage to re-populate preparation-induced empty bands and after re-distribution, cells may show further migration to the stromal DM side during storage. Show less
Baydoun, L.; Bruinsma, M.; Santander-Garcia, D.; Ham, L.; Oellerich, S.; Melles, G.R.J. 2020
Purpose To assess whether combined analysis of specular microscopy and Scheimpflug imaging improves detection of an upcoming allograft rejection following Descemet membrane endothelial keratoplasty... Show morePurpose To assess whether combined analysis of specular microscopy and Scheimpflug imaging improves detection of an upcoming allograft rejection following Descemet membrane endothelial keratoplasty (DMEK).Methods Retrospective analysis of 22 eyes that had developed a clinical proven allograft rejection 28 (+/- 22) months (range: 4-84 months) after DMEK. Specular microscopy and Scheimpflug images routinely made after DMEK were retrospectively analysed for changes in endothelial cell morphology (e.g. nuclear activation), cell density (>10%) and pachymetry (>7%), and/or the presence of subclinical keratic precipitates. The same parameters were evaluated for 22 control eyes matched for age, gender and surgery indication.Results A total of 20/22 eyes (91%) showed detectable changes 0.25-75 months before allograft rejection became clinically manifest: 13/22 (59%) showed both specular microscopy and Scheimpflug imaging changes; 5/22 (23%) only had changes on Scheimpflug imaging; and 2/22 (9%) only had specular microscopy changes. In 18/22 (82%) and 14/22 (64%) eyes, subclinical keratic precipitates and endothelial cell morphology changes could be detected, respectively. A total of 11/22 (50%) eyes concurrently showed a >10% drop in endothelial cell density and 4/22 (18%) a >7% pachymetry increase. Of the control eyes, 7/22 (32%) showed changes with specular microscopy but not with Scheimpflug imaging.Conclusions Combined analysis of specular microscopy and Scheimpflug imaging may allow recognizing an upcoming allograft rejection in over 90% of eyes and up to 6 years before rejection becomes clinically manifest. Early recognition of eyes at risk may allow for targeted intensified steroid treatment to prevent endothelial cell damage associated with rejection. Show less
