Njected intravenously into irradiated NOG mice. About 4 months after cell transplantation, 0?00 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. doi:10.1371/journal.pone.0050448.gIn Vivo Tool for Assessing Hematotoxicity in HumanFigure 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 Lin2 gate. (B) Numbers of Lin2hCD382hCD34+ 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?). Each point represents the mean 6 SD of each group. * p,0.05 and ** p,0.01 represent significant differences compared with untreated mice, as determined by t tests. doi:10.1371/journal.pone.0050448.gsusceptibility to benzene than human cells [20,21], the administration of 10 mg/kg-b.w. benzene to Mo-NOG mice was not performed.Title Loaded From File cytometry data. Data from several samples in which the number of leukocytes exceeding 2 standard deviations of the group mean was detected were not used for analysis.Cell Preparation from the Peripheral Blood and Hematopoietic OrgansAfter benzene administration for 2 weeks, samples from the bone marrow, spleen, thymus, and peripheral blood were harvested from each mouse. Bone marrow cells were collected as described above. The spleen and thymus were crushed between 2 glass slides. Peripheral blood was aspirated from the postcava under anticoagulation treatment. Erythrocytes that could have interfered with further evaluation were lysed using VersaLyse (Beckman Coulter, Fullerton, CA). Collected cells were suspended in phosphate buffered saline supplemented with 4 mM EDTA and 0.5 BSA. Mice in which edema was observed in the thymus at the time of dissection were not used for subsequent analysis. We did not observe detectable differences in the appearance 1655472 of abnormalities or the amount of benzene administered.Colony-forming AssayBone marrow cells (16105) collected from Hu-NOG mice were plated in methylcellulose-based medium (MethoCult H4034, StemCell Technologies, Vancouver, Canada). After 13 days of cultivation at 37uC in a humidified atmosphere containing 5 CO2, the numbers of colony-forming unit-granulocyte/erythroid/ macrophage/megakaryocytes (CFU-GEMMs) were enumerated using Title Loaded From File visible light microscopy.Results Benzene Toxicity in Human Hematopoietic Stem/ progenitor Cells from Hu-NOG MiceAbout 4 months after cell transplantation, daily oral administration of 0?00 mg/kg-b.w. benzene was performed in Hu-NOG mice for 2 weeks (Fig. 1). We carried out flow cytometric enumerations of Lin2hCD382hCD34+ cells contained in the bone marrow of Hu-NOG mice (Fig. 2A), which were highly enriched in the population of human hematopoietic stem/progenitor cells. The number of Lin2hCD382hCD34+ cells in the bone marrow of Hu-NOG mice decreased depending on the amount of benzene administered (Fig. 2B). Compared with the number of Lin2hCD382hCD34+ cells in the bone marrow of untreated Hu-NOG mice, the numbers of Lin2hCD382hCD34+ cells decreased significantly following administration of greater than 30 mg/kg-b.w./day benzene (2.46104, 2.06104, 9.36103, 1.06103, and 4.76102 cells/tissue were present a.Njected intravenously into irradiated NOG mice. About 4 months after cell transplantation, 0?00 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. doi:10.1371/journal.pone.0050448.gIn Vivo Tool for Assessing Hematotoxicity in HumanFigure 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 Lin2 gate. (B) Numbers of Lin2hCD382hCD34+ 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?). Each point represents the mean 6 SD of each group. * p,0.05 and ** p,0.01 represent significant differences compared with untreated mice, as determined by t tests. doi:10.1371/journal.pone.0050448.gsusceptibility to benzene than human cells [20,21], the administration of 10 mg/kg-b.w. benzene to Mo-NOG mice was not performed.cytometry data. Data from several samples in which the number of leukocytes exceeding 2 standard deviations of the group mean was detected were not used for analysis.Cell Preparation from the Peripheral Blood and Hematopoietic OrgansAfter benzene administration for 2 weeks, samples from the bone marrow, spleen, thymus, and peripheral blood were harvested from each mouse. Bone marrow cells were collected as described above. The spleen and thymus were crushed between 2 glass slides. Peripheral blood was aspirated from the postcava under anticoagulation treatment. Erythrocytes that could have interfered with further evaluation were lysed using VersaLyse (Beckman Coulter, Fullerton, CA). Collected cells were suspended in phosphate buffered saline supplemented with 4 mM EDTA and 0.5 BSA. Mice in which edema was observed in the thymus at the time of dissection were not used for subsequent analysis. We did not observe detectable differences in the appearance 1655472 of abnormalities or the amount of benzene administered.Colony-forming AssayBone marrow cells (16105) collected from Hu-NOG mice were plated in methylcellulose-based medium (MethoCult H4034, StemCell Technologies, Vancouver, Canada). After 13 days of cultivation at 37uC in a humidified atmosphere containing 5 CO2, the numbers of colony-forming unit-granulocyte/erythroid/ macrophage/megakaryocytes (CFU-GEMMs) were enumerated using visible light microscopy.Results Benzene Toxicity in Human Hematopoietic Stem/ progenitor Cells from Hu-NOG MiceAbout 4 months after cell transplantation, daily oral administration of 0?00 mg/kg-b.w. benzene was performed in Hu-NOG mice for 2 weeks (Fig. 1). We carried out flow cytometric enumerations of Lin2hCD382hCD34+ cells contained in the bone marrow of Hu-NOG mice (Fig. 2A), which were highly enriched in the population of human hematopoietic stem/progenitor cells. The number of Lin2hCD382hCD34+ cells in the bone marrow of Hu-NOG mice decreased depending on the amount of benzene administered (Fig. 2B). Compared with the number of Lin2hCD382hCD34+ cells in the bone marrow of untreated Hu-NOG mice, the numbers of Lin2hCD382hCD34+ cells decreased significantly following administration of greater than 30 mg/kg-b.w./day benzene (2.46104, 2.06104, 9.36103, 1.06103, and 4.76102 cells/tissue were present a.