Stable engraftment and expression of human α-globin protein in primary, secondary, and tertiary transplanted mice. (A) The VCN was measured via ddPCR analysis of genomic DNA (gDNA) from AG-KO^ALS20αI mice. gDNA for the first 2 time points was isolated from the peripheral blood, whereas gDNA from the final time point was isolated from the BM. Each point represents a single mouse. (B) Cation-exchange HPLC analysis of RBC lysate collected from primary, secondary, and tertiary transplanted AG-KO^ALS20αI mice. This analysis indicated that ALS20αI transduced long-term HSC, and its expression is stable over time.