Figure 1.
After a 2-week quarantine and acclimatization period, human CD34+ cells or mouse Lin− bone marrow cells were injected intravenously into irradiated NOG mice. About 4 months after cell transplantation, 0–300 mg/kg-b.w. benzene was administered daily for 2 weeks. The assessment of benzene-induced hematotoxicity was performed using flow cytometric analysis and colony assays.
Figure 2.
Benzene toxicity in human hematopoietic stem/progenitor cells from Hu-NOG mice.
(A) Dot plot of a bone marrow sample from untreated Hu-NOG mice stained with hCD38 and hCD34 within the Lin− gate. (B) Numbers of Lin−hCD38−hCD34+ cells in the bone marrow of Hu-NOG mice after benzene administration (n = 7 or n = 8). (C) Numbers of colony-forming unit-granulocyte/erythroid/macrophage/megakaryocytes (CFU-GEMMs) arising from the bone marrow cells of Hu-NOG mice after benzene administration (n = 6–8). Each point represents the mean ± SD of each group. * p<0.05 and ** p<0.01 represent significant differences compared with untreated mice, as determined by t tests.
Figure 3.
Establishment of hematopoietic cell lineages in NOG mice.
Flow cytometric analysis of leukocytes in the peripheral blood and hematopoietic organs of untreated Hu-NOG (A) and Mo-NOG (B) mice. Rates of leukocyte chimerism in Hu-NOG mice were calculated as the percentage of hCD45+mCD45− cells in the total CD45+ cell population (the sum of human and mouse CD45+ cells). Data represent the mean ± standard deviation (SD; n = 7 or n = 8). Rates of leukocyte chimerism in Mo-NOG mice were calculated as the percentage of mCD45.2+mCD45.1− cells in the total CD45+ cell population (the sum of mCD45.1+ and mCD45.2+ cells). Data represent the mean ± SD (n = 6–8).
Figure 4.
Benzene toxicity in human leukocytes from Hu-NOG mice.
(A) Human leukocytes collected from the peripheral blood and hematopoietic organs of Hu-NOG mice. Upper panel: histogram of hCD45+mCD45− cells in Hu-NOG mice administered 0 (gray), 30 (red), or 300 mg (blue-lined) benzene/kg-b.w./day. Lower panel: numbers of hCD45+mCD45− cells in Hu-NOG mice. Each point represents the mean ± SD of each group (n = 7 or n = 8). * p<0.05 and ** p<0.01 represent significant differences compared with untreated mice, as determined by t tests. (B) Numbers of human myeloid and lymphoid cells in the bone marrow or peripheral blood of Hu-NOG mice. Human myeloid cells were identified as hCD45+mCD45−hCD33+ cells (open square). Human lymphoid cells were identified as hCD45+mCD45−hCD33− cells (solid square). Each point represents the mean of each group (n = 7 or n = 8). * p<0.05 and ** p<0.01 represent significant differences compared with untreated mice as determined by t tests. (C) The percentage of each T cell population in the thymus of Hu-NOG mice. The value was calculated based on the ratio of hCD45+mCD45−hCD33− cells. Individual types of T cells were determined by using combinations of anti-hCD4 and hCD8 antibodies. Values represent means (n = 7 or n = 8).
Figure 5.
Comparison of benzene toxicity in Hu-NOG and Mo-NOG mice.
(A) Ratios of donor cell-derived human or mouse leukocytes in Hu-NOG (Hu) and Mo-NOG (Mo) mice after benzene administration. Each ratio was calculated based on the mean number of leukocytes in untreated Hu-NOG or Mo-NOG mice. (B) Ratios of myeloid (upper) and lymphoid (lower) cells in the bone marrow and peripheral blood of Hu-NOG (Hu) and Mo-NOG (Mo) mice after benzene administration. Each ratio was calculated based on the mean number of myeloid and lymphoid cell in untreated Hu-NOG or Mo-NOG mice. Mouse myeloid cells in Mo-NOG mice were identified as mCD45.2+mCD45.1−mLy6C/6Ghi/mid. Mouse lymphoid cells in Mo-NOG mice were identified as mCD45.2+mCD45.1−mLy6C/6Glo/−. The box plot shows the maximum (top of the vertical line), 75th percentile (top of the box), median (middle line in the box), 25th percentile (bottom of the box), and minimum (bottom of vertical line) values of data (n = 6–8). * p<0.10 represents marginally significant differences between Hu-NOG and Mo-NOG mice, as determined by Mann-Whitney U tests. ** p<0.05 and *** p<0.01 represent significant differences.