Agrin nonredundant role at the hematopoietic niche. (A) Total bone marrow cells from either control or Musk-L;Agrn^−/− P5, CD45.2 mice were transplanted into lethally irradiated CD45.1 recipients in competition with BM cells from CD45.1/45.2 adult mice, at a 1:1 ratio. Donor repopulating units (RU_D) in the PB of recipient mice 9 and 16 weeks after transfer are shown (left). Data are from 3 independent experiments (ctrl, n = 8; Musk-L;Agrn^−/−, n = 6). Right: mean numbers relative to controls of the LSK population in the bone marrow of P5 Musk-L;Agrn^−/− mice or of mice transplanted as described and analyzed 16 weeks after transfer (CD45.1⁻Lin⁻IL7R⁻c-Kit⁺Sca-1⁺ gate; ctrl n = 8, Musk-L;Agrn^−/−, n = 6; *P < .05). (B) Pie charts (right) represent average percentages of CD150⁺CD41/48⁻, CD34⁺ CD135⁻, and CD34⁺CD135⁺ subsets within the LSK population (ctrl, n = 8; Musk-L;Agrn^−/−, n = 6). Annexin V analysis (left) on CD34⁺CD135⁻ LSK cells of donor origin (ctrl, n = 8; Musk-L;Agrn^−/−, n = 6; differences are not statistically significant). In all panels, error bars represent SEM.