Fucosylated Tregs prevent xenogenic GVHD. (A) Longer in vivo persistence of fucosylated Tregs. Equal numbers (10⁷ cells) of eGFP-FFLuc transduced fucosylated or untreated Tregs were injected in the NSG mice on day −1, followed by 10⁷ PBMCs on day 0. Whole-animal luciferase imaging was performed on days −1, 0, 3, 4, 5, 7, and 10¹⁶. Continued persistence of fucosylated Tregs was demonstrated as compared with untreated Tregs. (B) On the quantification of the bioluminescence, significantly higher signal was seen on day 10 (P = .04). (C) A higher frequency of circulating PBMCs (CD45⁺HLA-A2^pos) was seen on day 31 in the untreated Tregs cohort compared with the fucosylated Treg recipient. Fucosylated (FT) Treg cells prevent xenogeneic GVHD. Sublethally irradiated NSG mice received Treg cells or FT-Treg cells at a cell dose of 1 × 10⁶ on day −1, followed by tail vein injection of PBMCs at a cell dose of 1 × 10⁷ on day 0. Mice were monitored every other day for weight, GVHD score, and survival. Ten mice in each group from 3 different experiments were analyzed. (D). Weight. Fucosylated Treg recipients were able to maintain weight compared with Treg recipients and PBMC-only mice (P = .03). (E) Improved GVHD score was observed in the fucosylated Treg recipients (P = .009). (F) Significant improvement in overall survival was seen in fucosylated Treg recipients compared with untreated Tregs at 1 × 10⁶ cell dose (P < .0001).