Nonirradiated NOD,B6.SCID Il2rγ-/- Kit(W41/W41) (NBSGW) mice support multilineage engraftment of human hematopoietic cells

Abstract

In this study, we demonstrate a newly derived mouse model that supports engraftment of human hematopoietic stem cells (HSCs) in the absence of irradiation. We cross the NOD.Cg-Prkdc(scid)Il2rg(tm1Wjl)/SzJ (NSG) strain with the C57BL/6J-Kit(W-41J)/J (C57BL/6.Kit(W41)) strain and engraft, without irradiation, the resulting NBSGW strain with human cord blood CD34+ cells. At 12-weeks postengraftment in NBSGW mice, we observe human cell chimerism in marrow (97% ± 0.4%), peripheral blood (61% ± 2%), and spleen (94% ± 2%) at levels observed with irradiation in NSG mice. We also detected a significant number of glycophorin-A-positive expressing cells in the developing NBSGW marrow. Further, the observed levels of human hematopoietic chimerism mimic those reported for both irradiated NSG and NSG-transgenic strains. This mouse model permits HSC engraftment while avoiding the complicating hematopoietic, gastrointestinal, and neurological side effects associated with irradiation and allows investigators without access to radiation to pursue engraftment studies with human HSCs.

Figure 1

Nonirradiated NOD,B6.Prkdc^scidIl2rg^tm1Wjl/SzJKit^W41/W41 (NBSGW) Mice Are Similar to Their irNSG Counterparts and Exhibit High Levels of Human Chimerism in the Absence of Irradiation (A) An NBSGW mouse. (B) Experimental design of nonirradiation comparisons. (C) Representative flow cytometry plots of non-irNSG and NBSGW mice 12-weeks postengraftment and analysis of mouse and human CD45. (D and E) Biweekly monitoring of the human chimerism in the peripheral blood of non-irNSG and of NBSGW mice. Error is represented by SD (n = 3 and n = 5, ^∗p < 0.01, ^∗∗p < 0.05). (F) Experimental design of irNSG versus nonirradiated NBSGW. (G) Monthly monitoring comparison of the human chimerism in peripheral blood of irNSG and of nonirradiated NBSGW strains. Error is represented by SD, n = 3, comparison only, not significant.

Figure 2

Xenotransplanted Nonirradiated NBSGW Mice Exhibit Increased Humanization in the Marrow and Are Conducive to Serial Transplantation (A) The percentage of observed human CD45+ leukocytes in the bone marrow of non-irNSG (white) and NBSGW (gray) mice at 12-weeks postengraftment. (B) Representative mouse CD45 versus human CD45 12-week flow cytometry plot comparison between non-irNSG and NBSGW mice. (C) The observed percentages of human CD34+ cells in the human CD45+ fraction of the mouse marrow (NSG, white; NBSGW, gray). (D) Representative flow cytometry analysis plot comparison between non-irNSG and NBSGW mice. (E) The observed percentages of human CD33+ cells observed in the human CD45+ fraction of the mouse marrow (NSG, white; NBSGW, gray). (F) The observed percentage of human GlyA+ cells observed in the mouse marrow (NSG, white; NBSGW, gray). (G) Representative flow cytometry analysis plot comparison between non-irNSG and NBSGW mice. (H) Experimental design of nonirradiation NBSGW serial transplantation. (I) Representative flow cytometry analysis of CD34 enriched Lin−CD34+CD38−CD90+CD45RA− cells isolated from the NBSGW marrow at 16 weeks. (J) Observed human chimerism at both 6 and 12 weeks in secondary NBSGW recipients. (Error is represented by SD, ^∗p < 0.01).

Figure 3

Human Chimerism, Lineage Development and Gross Pathology Observed in Lymphoid Organs of Non-irNSG (White) and NBSGW (Gray) Mice at 12-Weeks Postengraftment (A) The percentage of human CD45+ splenocytes (non-irNSG [white] and NBSGW [gray]). (B and C) The percentage of human (B) CD19+ cells and (C) CD19+IgM+ cells observed in the human CD45+ fraction. (D) The ratio of spleen:mouse weight in basal state (unengrafted, n = 4) and two xenograft experiments (C57BL/6J; dark gray, experiment 1, n = 5; experiment 2, n = 3). Error is represented by SD (^∗p < 0.01). (E) Representative photomicrographs of sectioned spleens of non-irNSG and NBSGW mice at 12-weeks postengraftment (based on flow cytometry data). Spleens were stained with anti-human CD45 (splenocyte), anti-human CD19 (B cell), anti-human CD11b (myeloid), and anti-human CD1a (dendritic) and were counterstained with hematoxylin (blue; the black scale bar is 20 μm). (F) Photomicrographs of hematoxylin (blue) and eosin (red) stained spleens from nonirradiated, nonengrafted mouse strains (left), and nonirradiated humanized mice at 12 weeks (right; white scale bar represents 400 μm). (G) Representative photomicrographs of sectioned thymus from non-irradiated NBSGW mice at 12-weeks postengraftment; anti-human MHCII (top), anti-human CD3 (middle), and hematoxylin (blue) and eosin (red) stained (bottom; white scale bar represents 400 μm; black scale bar represents 20 μm).