Dear Editor, Visual rehabilitation achieved with peripheral RPE autografts in exudative AMD is only modest. Moreover, complication rates using the popular RPE-choroid patch technique remain relatively high.Tissue-engineered transplants might improve the outcome of RPE transplantation. A culturing step could place cells on a substrate prior to transplantation, thereby optimizing delivery and long-term function [1]. This would require sufficient cellular plasticity (i.e., response to environmental stimuli) to achieve a well-differentiated, functional graft. While culture plasticity was confirmed for fetal cells or RPE cell lines [2,3], only sparse information is available for aged RPE [4].We studied the influence of culture conditions on select differentiation characteristics in long-term primary RPE cultures from ten human donors above age 55, and compared them to a 23-year-old and two fetal donors (20 and 21 weeks of gestation respectively). The main outcome measures at 6 weeks post-confluence (PC) were morphology and transepithelial resistance (TER), an electrophysiological method for assessing tight junctions build-up.Eyes were preserved within 6 hours of death. Adult primary RPE cultures (aRPE) were initiated from: (1) mechanically scraped RPE, or (2) collagenase pretreated (1 mg/ml for 40 minutes, CLS