Heparanase overexpression alters hematopoietic development and leads to increased retention of stem cells in the BM. Cells were flushed from the BM of wildtype (WT) or hpa-Tg (Tg) mice. (A) The number of WBC, lymphocytes, monocytes, and neutrophils in 4 bones was assessed. Data are means plus or minus SE; n ≥ 10 mice. (B) Number of megakaryocytes in bone sections of WT or hpa-Tg mice, determined by counting of 9 random fields per bone section. Data are means plus or minus SE; n = 3 mice, 2 bone sections per mouse. (C) Representative figure showing hematoxylin and eosin staining of femoral bone in WT and hpa-Tg mice (original magnification ×10). Inset: original magnification ×40. Green arrowheads point at megakaryocytes. Micrographs were acquired by staining with H&E, viewed with a light microscope (Eclipse E800M) fitted with a 10×/Plan-Apoobjective, and photographed with a digital camera (DXm1200), and image acquisition software (ACT-1, v. 2.63, all from Nikon, Tokyo, Japan). Images were processed by Adobe Photoshop, v. 7.0 (San Jose, CA). (D) Number of primitive undifferentiated Sca-1⁺/c-Kit⁺/Lin⁻ cells in one femur of WT or hpa-Tg mice, as counted by flow cytometry. Data are means plus or minus SE; n = 7 mice. (E) A representative dot plot of Sca-1⁺/c-Kit⁺ (gated from Lin⁻ population) derived from the BM of WT or hpa-Tg mice (F) Survival of lethally irradiated C57/BL6 mice injected with the indicated number of BM cells from WT or hpa-Tg donors. (G) Number of progenitor cells in the peripheral blood and spleen of WT and hpa-Tg mice, determined by colony assay. Data are means plus or minus SE; n ≥ 4 mice (*P < .05).