Fig. 2. Cloaked mESCs escape immune rejection and survive long term in various immunocompetent and MHC-mismatched recipient strains.
a, Uncloaked FS B6 mESCs were injected subcutaneously into isogeneic (B6) or allogeneic (FVB, C3H, BALB/c or CD-1) recipients and followed for 15 days with BLI. One representative mouse is shown for each condition, but 10–20 were transplanted and followed for each condition. b, Klg-1 mESCs injected into FVB recipients; BLI showed the presence of donor cells 17 days after injection in one representative mouse. c, Assay to test rejection or long-term acceptance of cloaked FS mESCs. Rejected cells are cleared and no teratoma forms; acceptance results in formation and expansion of the teratoma. The growth of teratomas is halted by activation of the FS system with GCV to ablate dividing cells and allow for testing of long-term persistence/survival of injected allogeneic cells. d, Growth and survival curves of untreated and GCV-stabilized teratomas derived from uncloaked FS and Klg-1 FS B6 mESCs in 3 representative isogeneic and allogeneic (FVB, C3H, BALB/c and CD-1) recipients. Teratoma-growth curves in 3–4 recipients are shown per group. Pictures of representative teratomas (red arrows) shown on the right were taken at the endpoint. Red ‘x’ indicates recipients were euthanized. e, Percent of isogeneic and allogeneic recipients that formed long-term and GCV-stabilized teratomas from uncloaked FS and Klg-1 FS mESCs. Horizontal bar shows the total number of recipients that formed teratomas divided by the total number of mice injected. Observation period ranged from 2 to 9 months depending on euthanasia date. No instances of Klg-1 teratoma clearance occurred in any recipient once formed and stabilized. Data for all recipients including observation period are shown in Supplementary Table 1.