production-humanized-mouse-via-thymic-renal-capsule-grafting-cd34

Production of Humanized Mouse via Thymic Renal Capsule Grafting, CD34<sup>+</sup> Cells Injection, and Cytokine Delivery

Animal models provide a vital translation between in vitro and in vivo biomedical research. Humanized mouse models provide a bridge in the representation ...

Anti-PD-1 therapy is used as a front-line treatment for many cancers, but mechanistic insight into this therapy resistance is still lacking. Here we generate a humanized (Hu)-mouse melanoma model by injecting fetal liver-derived CD34 cells and implanting autologous thymus in immune-deficient NOD-scid IL2Rγ (NSG) mice. Reconstituted Hu-mice are challenged with HLA-matched melanomas and treated with anti-PD-1, which results in restricted tumor growth but not complete regression. Tumor RNA-seq, multiplexed imaging and immunohistology staining show high expression of chemokines, as well as recruitment of FOXP3 Treg and mast cells, in selective tumor regions. Reduced HLA-class I expression and CD8/Granz B T cells homeostasis are observed in tumor regions where FOXP3 Treg and mast cells co-localize, with such features associated with resistance to anti-PD-1 treatment. Combining anti-PD-1 with sunitinib or imatinib results in the depletion of mast cells and complete regression of tumors. Our results thus implicate mast cell depletion for improving the efficacy of anti-PD-1 therapy.

Robin Choi

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