Abstract
Abstract: :
Purpose: Triple immune suppression increases the survival of fetal pig RPE after transplantation into the albino rabbit subretinal space. We performed sequential fundus photography and fluoresecin angiography to determine if these techniques can detect differences in transplant behavior in immune competent and systemic triple immune suppressed animals receiving RPE xenografts. Methods: Primary RPE were harvested from late second trimester fetal pigs by using 6.25 U/ml of Dispase and embedding the RPE in 25% gelatin/300 mM sucrose at 4ºC. Sheets were triturated and transplanted as microaggregates into the subretinal space of 6 albino rabbits. 3 rabbits were maintained on triple immune suppression with prednisone, azathioprine and oral cyclosporine for 12 weeks while 3 rabbits were not suppressed. Fluorescein angiography was obtained at 2, 4, 8 and 12 weeks and sequential photographs and angiograms were overlayed using Adobe Photoshop, and the size and gray-scale brightness of the pigmented patch were measured using Image J. Results: Fundus photography revealed a heavily pigmented patch in the subretinal space immediately after surgery. The ratio of the size of the pigmented patch (12weeks/2weeks) in the immune suppressed group and in immune competent group was 95.06 8.97% and 87.46 7.97%, respectively, but this difference was not statistically significant (p=0.252, t-test). The change in gray scale value of the patch (12weeks/2weeks) in the immune suppressed group and in immune competent group were 102.72 0.90% and 120.91 7.50%, respectively (p=0.053, t-test). Fluorescein angiography demonstrated a blocking defect in the area of the pigmentation with no leakage or staining of the transplant site in either suppressed or immune competent animals. Conclusions: Despite significant differences in RPE survival after transplantation, sequential fundus photography and fluorescein angiography did not detect loss of transplanted RPE up to 12 weeks after surgery. Supported by Diacrin, Inc., Charlestown, MA, and unrestricted funds from RPB, Inc., NY, NY.
Keywords: 567 retinal pigment epithelium • 607 transplantation • 435 immunomodulation/immunoregulation