Fig. 6.

Townes mouse HSPCs edited at HBG1 engraft efficiently but fail to recapitulate human hereditary persistence of fetal hemoglobin (HPFH). (A) Experimental strategy. Lin⁻ HSPCs from Townes mice were transfected with Cas9+gRNA RNP targeting the human HBG1 promoter or Cas9 only, then transplanted into irradiated C57Bl/6 hosts. (B) Kaplan–Meier curves showing survival of recipients after transplantation of edited or control HSPCs. (C) Engraftment of donor HSPCs, as determined by the fraction of circulating CD45.2⁺ mononuclear cells in recipient mice. (D) Percentage of HBG1 promoter indels in blood mononuclear cells after transplantation. (E) HbF immunostaining cells (F-cells) determined by flow cytometry. (F) Percentage of HbF protein in red blood cell lysates, determined by ion-exchange high-performance liquid chromatography. Graphs in C-F show data as mean±s.e.m. of three independent transplantation experiments, n=13 HBG-edited and n=9 Cas9 control mice. **P<0.01, ***P<0.001, ****P<0.0001, by unpaired, two-tailed Student's t-test. (G) %RBC HbF protein versus %peripheral blood mononuclear cell indels in recipient mice transplanted with HBG1-edited Townes HSPCs (teal circles) or HBG-edited human CD34⁺ cells from SCD patients (orange circles). Orange data points are adapted from Métais et al. (2019) with permission.