One week after transplantation, rats were killed, and the eyes were enucleated. After removal of the anterior segments, the eyecups were treated with papain/DNase solution (20 U/mL papain, 0.5 mM EDTA, 1 mM l-cysteine, 1000 U/mL DNase) for 30 minutes at 37°C followed by trituration. The cells were recovered by centrifugation at 300g for 5 minutes at room temperature (Worthington, Freehold, NJ). The cells showing green fluorescence (eGFP-BDNF) were collected by a cell-sorting system (FACS Vantage; Japan BD Biosciences, Ltd., Tokyo, Japan).