Abstract 38: PBMC donor selection affects engraftment rates and onset of graft versus host disease in humanized NCG mice for use in cancer studies

Abstract Preclinical studies examining tumor biology and immunity are limited by differences between the mouse and human immune systems. Humanized mouse models offer a unique tool to assess the anti-tumor response by recapitulating aspects of human tumor biology. Humanized mice are created by injecting either human CD34+ hematopoietic stem cells or peripheral blood mononuclear cells (PBMCs) into an immunodeficient mouse strain. Here we utilized a PBMC humanized NCG mouse model to investigate human T-cell mediated anti-tumor response (>95% CD3+ T-cells by day 21). The challenges encountered with this model include the onset of graft versus host disease (GvHD) and donor variability leading to donor specific engraftment rates. Consistency is required with humanized PBMC models to ensure their use as an appropriate research model. Therefore, we examined the relationship between donor selection and engraftment rates as well as the onset of GvHD. Inter-donor variability was assessed by collecting PBMCs from multiple healthy donors. Intra-donor consistency was assessed by collecting PBMCs from the same donors at subsequent collections and comparing to initial human immune cell profiling by flow cytometry. NCG mice were injected with 1 × 107 PBMCs from individual donors. Animals were weighed three times a week to monitor for changes in body weight and general health status. Peripheral blood was collected at day 9, 21 and 42 for flow cytometry screening of human immune cell engraftment (hCD45+, hCD3+, hCD4+ and hCD8+) at the initial collection. Human PBMCs isolated from additional collections from the same donors were also injected into NCG mice and flow cytometry was performed on the new cell lots at day 21. Donors were grouped into categories based on engraftment rates, which were donor dependent. Donor variability is an important aspect to consider when humanizing mice with human PBMCs. PBMC humanized models are important for the study of pre-clinical therapeutics, but donor engraftment rates must be considered when engrafting the mice to create a consistently humanized mouse. Citation Format: Steven Bronson, Jenny Rowe, Christoph Eberle, Stephen Festin. PBMC donor selection affects engraftment rates and onset of graft versus host disease in humanized NCG mice for use in cancer studies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 38.