Stable, multilineage chimerism in humanized mice after in utero transplantation of human cord blood CD34⁺cells. (A) Experimental design for in utero transplantation timing and measurements of blood chimerism levels. Arrows indicate time points for peripheral blood chimerism checks. (B) Representative gating strategy of peripheral blood to detect human CD45⁺ cells. (C) Percentage of human CD45⁺ cells in peripheral blood over time (n = 25, *P < .05, **P < .01 by Student t test comparing chimerism levels each week to the initial 4-week level). (D) Representative gating strategy for lineage-specific chimerism, FoxP3⁺ cells, and confirmation of the presence of CD34⁺ cells within the bone marrow. Chimeric mice demonstrated different relative proportions of granulocytes, monocytes, B cells, and T cells. (E) Compiled lineage data in 10 individual mice with evidence of CD34⁺ cells in the bone marrow (n = 10). CB, cord blood; SSC-A, side scatter.