Fig. 2: Transplantation of CMK6-derived ESC-RPE cells in a form of cell suspension without immunosuppressive drugs.

a Schema of the surgery for mESC (CMK6)-RPE cell suspension transplantation into the subretinal space of HM-20, −21 monkeys. If the transplanted cells survive, they should become a sheet-like graft. b HM-21 monkey transplanted with mESC-RPE cell suspension was evaluated by color picture (left), fluorescein angiography (middle), and OCT (right) at 1, 3, and 6 months after transplantation. At 6 months, many sheet-like grafted RPE cells were observed by OCT, without any signs of rejection. The left insert of the OCT is a navigation window that indicates the scanning position: OCT image was obtained by scanning along the red line; yellow dot (which is sometimes in a hidden mode) corresponds to the yellow line in the OCT image; when continuous scanning mode is used (usually when the grafted area is not clear), green and red lines indicate the series of scanning position, of which the red line indicates the layer of the OCT image shown; whether the shown OCT image is the vertical or horizontal red line-layer is indicated by the yellow dot (although the yellow dot is sometimes in a hidden mode). Dashed line circle: retinal bleb made for the injection, white arrows: mESC-RPE grafts. c H&E staining of HM-21 monkey 6 months after transplantation. Transplanted mESC-RPE cells were detected in the subretinal space of both eyes. There were no findings of inflammation. R: the right eye. L: the left eye. Arrows: mESC-RPE grafts. Scale bars: 50 μm. d IHC of the retinal section of HM-21 monkey. PKH (red) pre-labeling of the grafts was faint after 6 months of transplantation. CD3⁺ T cells (leftmost panel, green), CD20⁺ B cells (second left panel, green), and MHC-II⁺ cells (third left panel, green) were not detected. Infiltration of Iba1⁺ microglia/macrophages (rightmost panel, green) were detected around the grafted area. DAPI (blue) was used for counterstaining. INL inner nuclear layer, ONL outer nuclear layer, RPE retinal pigment epithelium. Scale bars: 20 μm.