Neuraminidase treatment of donor BM leads to impaired engraftment of BCR-ABL1⁺leukemia-initiating cells. (A) Kaplan-Meier curve for survival of Balb/c recipients of BCR-ABL1–transduced BM incubated without NA (0 NA, solid line, n = 5), treated with NA at 6.25 (dotted line, n = 6) or 12.5 (dashed line, n = 6) mU/mL, or with heat-inactivated (HI) NA (dotted-dashed line, n = 5) prior to transplantation into WT recipients. All recipients died of CML-like leukemia. (B) NA treatment leads to decreased engraftment of BCR-ABL1–induced CML-like leukemia. Southern blot of genomic DNA from BM of recipients of BCR-ABL1–transduced BM incubated without NA (lanes 2-6), with 6.25 mU/mL NA (lanes 7-10), with 12.5 mU/mL NA (lanes 11-16), or with heat-inactivated NA (lanes 16-19). *Background band. (C) NA treatment selectively reduces leukemic stem cell engraftment. (Left) Ratio of mRFP⁺ to GFP⁺ BM myeloid (Mac-1⁺) cells from recipients of NA-treated BM transduced with BCR-ABL1 retrovirus, assessed at the time of morbidity or death. (Right) mRFP⁺ to GFP⁺ ratio of BM myeloid cells from recipients of BM transduced with parental retrovirus, assessed at 65 days after transplantation. The reduction in the mRFP⁺:GFP⁺ ratio at 12.5 mU/mL NA was significant for recipients of BCR-ABL1–expressing cells (P = .0063, Student t test) but not for normal HSCs.