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In-vitro methods to decrease MHC class II-positive cells in retinal pigment epithelium cell grafts
V Enzmann1, M Stadler, P Wiedemann
1Department of Ophthalmology, Faculty of Medicine, University of Leipzig, Germany. enzv@server3.medizin.uni-leipzig.de
Abstract:
Rejection of RPE transplants may be caused by expression of MHC class II molecules on the graft. We wanted to determine if passage level, hyperoxia, low temperature, or magnetic separation had an influence on this expression or on several other physiological parameters of bovine RPE cells. For this, bovine RPE cells were cultured under normal conditions for several passages (1-5) or were incubated with a high level of oxygen (75%) for 24 h or at low temperature (24 degrees C) for seven days. Magnetic beads coated with monoclonal antibody against MHC class II antigens were used to separate the positive cells from the total cell population. The number of MHC class II-positive RPE cells was not affected by increased passage, oxygen concentration, or low temperature. Using magnetic beads, approximately 7.5% of the cells were separated from the total RPE population as MHC class II-positive cells. Hyperoxia initially increased the number of RPE cells to 178% that of the untreated controls, but the subsequent MTT test showed a decrease in proliferation to 95% of control levels. Similarly, low temperature increased cell number of 110% that of controls, but prolonged proliferation decreased to 76% of the controls. None of the experimental conditions had a significant influence on the viability of the cells. Culture conditions can be modified to increase the yield of RPE cells, and MHC class II-positive RPE cells can be detected and selectively separated from the total cell population, both of which may prove to be useful for RPE cell transplantation.
Insights
Investigating bovine RPE cells, this study found that passage level, hyperoxia, and low temperature do not affect MHC class II expression. However, these conditions can alter RPE cell yield for transplantation.
Area of Science:
- Ophthalmology
- Cell Biology
- Immunology
Background:
- Rejection of retinal pigment epithelium (RPE) transplants can be linked to MHC class II molecule expression on the graft.
- Optimizing RPE cell culture conditions is crucial for successful transplantation outcomes.
Purpose of the Study:
- To investigate the influence of passage level, hyperoxia, and low temperature on MHC class II expression in bovine RPE cells.
- To assess the impact of these conditions on RPE cell proliferation and viability.
- To evaluate the efficacy of magnetic separation for isolating MHC class II-positive RPE cells.
Main Methods:
- Bovine RPE cells were cultured under varying conditions: normal passage (1-5), hyperoxia (75% O2 for 24h), and low temperature (24°C for 7 days).
- MHC class II expression was analyzed, and cell proliferation/viability were assessed using MTT assays.
- Magnetic beads with monoclonal antibodies were used for selective separation of MHC class II-positive RPE cells.
Main Results:
- Passage level, hyperoxia, and low temperature did not significantly alter the number of MHC class II-positive RPE cells.
- Hyperoxia and low temperature initially increased RPE cell numbers but subsequently decreased proliferation.
- Magnetic separation successfully isolated approximately 7.5% of MHC class II-positive RPE cells from the total population.
- Cell viability remained unaffected across all experimental conditions.
Conclusions:
- Culture conditions can be modified to enhance RPE cell yield for transplantation.
- MHC class II-positive RPE cells can be identified and selectively separated, potentially improving transplant efficacy.
- These findings offer strategies for optimizing RPE cell preparation for therapeutic applications.