Stable and polyclonal gene modification in the PB and BM of Z13264. (A) CD34⁺ HSPCs from 3 pigtail macaques were enriched with immunomagnetic beads, CD34 subsets (CD90⁺CD45RA^–, CD90^-CD45RA^–, and CD90^–CD45RA⁺) FACS-purified, transduced, and cotransplanted after myeloablative conditioning with total body irradiation (TBI). (B) Animals were followed up for ∼50 months collecting PB and BM. Bulk WBCs were collected as indicated with red symbols, whereas blood lineages (T cells: CD3⁺; B cells: CD20⁺; natural killer cells: CD16⁺; monocytes: CD14⁺; and granulocytes: CD11b⁺CD14^-) were FACS-purified, as indicated with black symbols. Z15086 was euthanized because of multiple re-occurring cytomegalovirus (CMV) infections. (C) Expression of fluorochromes in PB WBCs, PB lineages, and BM HSPCs longitudinally tracked via flow cytometry. (D) Longitudinal flow-cytometric quantification of HSPC subsets in the BM. (E-F) Colony-forming cell potential of unmodified (mCh^– ) and gene-modified (mCh⁺) (E) CD34⁺ as well as (F) CD34⁺CD90⁺ HSPCs. Unmodified and gene-modified subsets were sort-purified into colony-forming cell assays, assays incubated for 10 to 14 days, and myeloid, erythroid, and as well as erythro-myeloid colonies quantified. (G-H) Polyclonal engraftment in the (G) PB and (H) BM. BFU-E, Burst forming unit–erythrocyte; CFU-G, granulocyte colony; CFU-GM, granulocyte-monocyte/macrophage colony; CFU-M, monocyte/macrophage colony; CFU-MIX, erythro-myeloid colony; GFP, Green fluorescent protein; mCer, monomeric Cerulean; mCh, monomeric Cherry.