35†Review on endothelial cell loss of corneal transplants and possible correlations.

The Tissue Bank of the Upper Austrian Red Cross in Linz, Austria, is a multi-tissue bank, processing corneal transplants (for PKP, for DMEK, pre-cut DMEK), homografts (aortic valve, pulmonary valve, pulmonal patch), amnion grafts (frozen or cryopreserved), autologous tissues and cells (ovarian tissue, cranial bone, PBSC) as well as investigational medicinal products and ATMPs (Aposec, APN401).This presentation sums up retrospective data of the endothelial cell count of corneae at the time of first evaluation and at the time of reevaluation before transplantation as well as the cell count of pre-cut DMEK before transplantation.Regarding corneal grafts it is advisable to review the data of the previous years to find potential factors influencing the cell count of corneal tissue. Certain factors as donor age or duration of time between death of the donor until the cornea is cultivated might have an impact on endothelial cell loss.719 corneal transplants were included in this data comparison (PKPs, Corneae for DMEK and pre-cut DMEK), which were evaluated between January 2017 and March 2021. The average donor age was 66 years (22 to 88yrs). The average time until enucleation was 18 hours after death (3 to 44h). The mean duration of cultivating the cornea until reevaluation before transplantation was 15 days (7 to 29d).The average cell count at time of first evaluation was 2723 c/mm² (1550 to 3950c/mm²), at the time of reevaluation before transplantation 2613c/mm² (1650 to 3325c/mm²) and of the pre-cut DMEK transplants 2550c/mm² (2000 to 3233c/mm²).The results show an average cell loss of 6% from time of first evaluation compared to the time of reevaluation before transplantation and an average cell loss of 9% for pre-cut DMEK in comparison to the cell count at first evaluation. Dividing the donors in age groups of 10 years shows no noticeable difference in the results as the cell count at first evaluation compared to reevaluation shows cell loss between 4,9% and 8,8% with no tendency of increasing cell loss regarding donor age. The same seems to be the case regarding duration of cultivation until reevaluation.The aim of the data review was to determine the cell loss of corneal transplants and attempt to identify possible factors having an impact on endothelial cell loss of cultivated corneae. In conclusion the data comparison shows that donor age and time of cultivation seem to have no impact on cell loss.

Human amniotic membrane as newly identified source of amniotic fluid pulmonary surfactant.

Pulmonary surfactant (PS) reduces surface tension at the air-liquid interface in the alveolar epithelium of the lung, which is required for breathing and for the pulmonary maturity of the developing foetus. However, the origin of PS had never been thoroughly investigated, although it was assumed to be secreted from the foetal developing lung. Human amniotic membrane (hAM), particularly its epithelial cell layer, composes the amniotic sac enclosing the amniotic fluid. In this study, we therefore aimed to investigate a potential contribution of the cellular components of the hAM to pulmonary surfactant found in amniotic fluid. We identified that cells within the native membrane contain lamellar bodies and express all four surfactant proteins as well as ABCA3. Lipidomic profiling by nanoESI - MS/MS revealed the presence of the essential lipid species as found in PS. Also, the biophysical activity of conditioned cell culture supernatant obtained from hAM was tested with captive bubble surfactometry. hAM supernatant showed the ability to reduce surface tension, similar to human PS obtained from bronchoalveolar lavage. This means that hAM produces the essential PS-associated components and can therefore contribute as second potential source of PS in amniotic fluid aside from the foetal lung.

Different metabolic activity in placental and reflected regions of the human amniotic membrane.

Cells of the human amniotic membrane (hAM) have stem cell characteristics with low immunogenicity and anti-inflammatory properties. While hAM is an excellent source for tissue engineering, so far, its sub-regions have not been taken into account. We show that placental and reflected hAM differ distinctly in morphology and functional activity, as the placental region has significantly higher mitochondrial activity, however significantly less reactive oxygen species. Since mitochondria may participate in processes such as cell rescue, we speculate that amniotic sub-regions may have different potential for tissue regeneration, which may be crucial for clinical applications.