Abstract 511: An assessment of pre-conditioning regimens for optimal hCD34+ hematopoietic stem cell humanization of NSGTMmice

Abstract

Humanized immune system (HIS) mice - immunocompromised Nod.Cg-Prkdcscid Il2rgtm1Wjl/SzJ animals in which the immune system has been humanized by the engraftment of CD34+ hematopoietic stem cells (HSC), peripheral blood mononuclear cells (PBMC), or other human cells/tissues - represent an important tool in pre-clinical oncology research. Here we investigated several pre-conditioning regimens (Busulfan pre-treatment or total body irradiation (TBI)) to determine which would yield maximum human leukocyte engraftment and lineage diversity. Animals were pre-treated either one or two doses of Busulfan (25 mg/kg) or varying doses of TBI (1.75, 2.0, or 2.5 Gy). One to two days later, animals received an adoptive transfer of native hCD34+ HSCs. Engraftment was monitored by flow cytometry assessment of peripheral blood four weeks after adoptive-transfer, and every four weeks thereafter through experiment termination at Week 16. Upon termination, spleen and bone-marrow were assessed for various leukocyte populations by flow cytometry. Animals undergoing pre-conditioning displayed increased human CD45+ cell engraftment at all timepoints as compared to animals without pre-conditioning, with animals treated with two doses of Busulfan demonstrating the greatest human CD45+ engraftment at all timepoints and reaching statistical significance at endpoint (vs no pre-conditioning; p<0.05). Diversity of leukocyte cell types (B cells, T cells, NK cells, and other hCD45+) in the bone-marrow was similar across pre-treatment paradigms, however for some lineages, representation in the bone-marrow was significantly altered between pre-conditioning type. The absolute number of T or B cells were increased in TBI and Busulfan treated groups, respectively, whereas NK cells as a percentage of singlets were increased in TBI treated groups. The diversity of leukocyte cell types in the spleen was likewise similar across groups, with B cells dominating. These data provide important insights into the utility of various pre-conditioning regimens for the humanization of NSG mice for pre-clinical oncology research, and demonstrate that the optimum pre-conditioning regimens should be selected based on treatment target. Citation Format: Caitlin S. Parello, Benjamin G. Cuiffo, Alexandria Kury, Kasey Reardon, Brett Van Dam, Sallyann Vu, Catarina Costa, Veronica Ritchie, Gavin Gagnon, Timothy Bateson, Samantha Rogers, Gregory D. Lyng, Stephen T. Sonis. An assessment of pre-conditioning regimens for optimal hCD34+ hematopoietic stem cell humanization of NSGTMmice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 511.