{
  "abstract": "Background Robust humanized mouse models are critical for evaluating human hematopoietic stem cell (HSC) biology, immune system development, and therapeutic efficacy. The NCG strain provides a superior platform for human HSC engraftment due to severe immunodeficiency. To further enhance human immune system reconstitution, we engineered a next generation strain NCG-hIL6-mTSLP-mFlt3-KO by: 1. knocking in human IL6 (hIL6) to support human myeloid cell survival and inflammation, 2. transgenic (Tg) expression of mouse TSLP (mTSLP) to enhance human T and B cell development and lymphoid organogenesis, and 3. knock-out (KO) mouse Flt3 (mFlt3) to eliminate cytokine competition for FLT3 ligand (FLT3L) and promote the expansion of FLT3-expressing human dendritic cells (DCs) and natural killer (NK) cells.Methods Human CD34+ HSC was transplanted into NCG and NCG-hIL6-mTSLP-mFlt3-KO mice. Human immune cell reconstitution was longitudinally monitored in the peripheral blood of mice by flow cytometry (up to 24 weeks post-transplantation). Human immunoglobulin (IgG and IgM) levels were quantified by ELISA. Selected cohorts of HSC-NCG-hIL6-mTSLP-mFlt3-KO mice received repeated intraperitoneal injections of recombinant human FLT3L protein at 18 weeks post-transplantation. Lymphoid tissue development was assessed histologically.Results HSC-NCG-hIL6-mTSLP-mFlt3-KO mice exhibited improved engraftment and reconstitution of human immune cells compared to HSC-NCG controls. Flow cytometry revealed significantly higher levels of human T cells, NK cells, plasmacytoid DCs (pDCs), and conventional DCs (cDCs) in peripheral blood at multiple time points. Furthermore, functional human B cell maturation was confirmed by elevated serum levels of human IgG and IgM. Histopathological analysis revealed advanced development of various lymph nodes, which are key sites for antigen presentation and the initiation of adaptive immunity. Administration of exogenous human FLT3L further amplified reconstitution levels of human NK cells, pDCs, and cDCs, validating the model’s responsiveness to human cytokine signaling.Conclusions The NCG-hIL6-mTSLP-mFlt3-KO mouse model offers a powerful platform for human HSC engraftment and development of a functional, multi-lineage human immune system, including lymphoid (T, B), myeloid (DC subsets), and NK cells. Together with enhanced lymphoid organ development, this model is positioned to be a valuable tool for translational immunology and preclinical evaluation of immunotherapies.",
  "authors": [
    {
      "affiliations": [
        "GePharmatech Co. Ltd., Nanjing, China"
      ],
      "name": "Jun Xing"
    },
    {
      "affiliations": [
        "GePharmatech Co. Ltd., Nanjing, China"
      ],
      "name": "Jianming Xu"
    },
    {
      "affiliations": [
        "GePharmatech Co. Ltd., Nanjing, China"
      ],
      "name": "Shiying Guo"
    },
    {
      "affiliations": [
        "GePharmatech Co. Ltd., Nanjing, China"
      ],
      "name": "Hongyan Sun"
    },
    {
      "affiliations": [
        "GePharmatech Co. Ltd., Nanjing, China"
      ],
      "name": "Xiang Gao"
    }
  ],
  "title": "769 Enhanced human immune system engraftment in a novel triple-engineered NCG-hIL6-mTSLP-mFlt3-KO mouse model",
  "uid": "8d6d9e51-46a9-54ad-9836-539aede99544"
}