Pathologic and molecular features of acute leukemias induced by genome editing of the MLL oncogene. (A) Plots show results of hematologic analyses performed on control (n = 7) and leukemic mice (n = 16), respectively. (B) Representative peripheral blood smears of control and leukemic mice are shown and summarized by calculating the percentage of blast cells (n = 16). Scale bars define 10 µm. (C) Spleen size and weight are shown for 1 representative control and leukemic mice (n = 17). (D) Hematoxylin-and-eosin–stained paraffin sections demonstrate disruption of organ architecture due to tumor infiltration compared with control mice. Scale bars define 100 µm. (E) PCR/RT-PCR was performed on gDNA and cDNA of leukemia cells to detect integration and expression of the MLL oncogenes and WT MLL gene. (F) Representative western blot analysis shows WT MLL^N and MLL-AF9 expression in control (CD34⁺ cells nucleofected with template alone) and explanted blast cells from xenotransplants induced by either retroviral transduction or under the expression of the endogenous promoter (MPAL, AML). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), loading control. Bottom, relative MLL-AF9 band intensities compared with WT MLL^N. (G) Representative qPCR analyses show elevated expression levels of MLL target genes compared with non-MLL leukemic cell lines or controls (human BM or BM CD10^+/−/CD19⁺) but similar to cell lines and patients with MLL translocations. Representative results from 8 independent experiments are shown. (H) Unsupervised hierarchical cluster analysis of 3 leukemic mice (ALL) and 70 MLL-rearranged ALL patients showing similar gene expression profiling in contrast to control samples. Each dot (A-C) represents a mouse; horizontal bars represent the mean. *P < .05 was considered statistically significant. Error bars indicate SEM. HGB, hemoglobin; PB, peripheral blood; PLT, platelet; WBC, white blood cell.