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L Del Priore, Y Sheng, E Johnson, O Ishida, AS B Edge, D Jacoby, TH Tezel, HJ Kaplan; Triple Immune Suppression Increases the Long-term Survival of Fetal Pig Retinal Pigment Epithelium(RPE) Xenografts . Invest. Ophthalmol. Vis. Sci. 2002;43(13):923.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To determine the effects of triple drug immune suppression on survival of fetal pig RPE xenografts after transplantation into the albino rabbit subretinal space. Methods:Primary RPE were harvested from late second trimester fetal pigs by using 6.25 U/ml of Dispase and embedding the RPE in a thin slice of 25% gelatin/300 mM sucrose at 4oC. Sheets were triturated and injected as micro aggregates (approximately 40,000 RPE) into the subretinal space of 24 albino rabbits without RPE debridement. Half the rabbits were maintained on oral triple systemic immune suppression with prednisone, azathioprine and cyclosporine; the other half received no immune suppression. Rabbits were sacrificed at 4, 8 or 12 weeks. The number of surviving RPE was estimated by staining some sections through the transplant site with: (1) in situ hybridization using a DNA probe (PRE) against a porcine-specific repetitive chromosomal marker and (2) RAM-11 antibody against rabbit macrophages Results:Numerous pigmented cells were visible in the subretinal space at all time points, but the majority of pigment-containing cells were RAM-11 positive and PRE-negative. The number of PRE-positive cells after surgery in the immune suppressed group (4193 ± 2461, 1184 ± 1502, 541 ± 324 at 4, 8 and 12 weeks, respectively) was greater than in immune competent controls (292 ± 506, 193 ± 173, 111 ± 96 at 4, 8 and 12 weeks), but the difference was only statistically significant at 4 weeks due to small n and large variation. There was a time-dependent decrease in PRE-positive cells that was more pronounced in immune suppressed animals. Pigmented monolayers were composed mainly of PRE-negative cells with rare PRE-positive cells. Conclusion:Systemic immune suppression increases the survival of porcine RPE xenografts transplanted into the albino rabbit subretinal space. There is poor correlation between pigment and PRE nuclear markers ≷ 4 weeks after transplantation, indicating that many of the pigment-containing cells are of host origin.
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