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Kevin J. McHugh, Carrie Spencer, Patricia A. D'Amore, Sarah L. Tao, Magali Saint-Geniez; A porous poly(-caprolactone) tissue engineering scaffold for RPE Transplantation. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3641.
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Transplantation of retinal pigment epithelium (RPE) is a promising approach for the treatment of retinal diseases including dry age-related macular degeneration (AMD). Past replacement strategies using RPE cell suspensions or sheets have failed largely due to poor adhesion or lack of organization on a Bruch’s Membrane (BrM) that is aged or itself diseased. In this study, we developed and tested a thin film, porous poly(ε-caprolactone) (PCL) scaffold to act as a biomimetic BrM substitute for RPE culture and potential implantation into the sub-retinal space.
A nanopatterned mold was created using a combined process of photolithography and reactive ion etching. Porous PCL scaffolds were then produced from the mold by spin-assisted templating and mounted on transwell inserts. Fetal human RPE cells (fhRPE) were maintained at confluence on the scaffolds for up to 8 weeks and compared to non-porous PCL and porous polyester (PET) transwells (Costar) using transepithelial resistance, gene expression, phagocytic capacity, and immunohistochemistry.
fhRPE transepithelial resistance significantly increased on porous PCL compared to PET transwells beginning at 5 days and persisting through the end of the 8 week experiment. Cells on porous PCL also displayed significant upregulation of key RPE proteins including a 6.45-fold increase in RPE65 and 2.19-fold increase in CRALBP compared to the PET control at 4 weeks. Alternately, cells on non-porous PCL fail to show a significant change in major RPE markers compared to the control. fhRPE cultured on porous PCL and PET displayed similar levels of binding and phagocytosis of fluorescently-labeled photoreceptor outer segments after four weeks of culture. In addition, the greatest degree of pigmentation was observed in cells on the porous PCL followed by non-porous PCL, and finally PET.
Both material and porosity are important factors in RPE maturation and function in vitro. Our porous PCL thin film scaffold exploits both characteristics to promote the development of a mature RPE monolayer as evaluated by gene expression profile, organization, and polarization while allowing transport across the membrane.
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