Maturation defects of erythroblasts derived from MT iPSCs. (A) The pellets (left) and iron staining (right) of erythroblasts derived from WT1-iPSC2 and MT1-iPSC3. The arrow indicates a ring sideroblast. CD235a⁺ cells were sorted on day 34 by FACS. Magnification of the objective lens: ×100. Bars represent 10 μm. (B) May Grunwald-Giemsa staining of erythroblasts derived from WT1-iPSC2 (top) and MT1-iPSC4 (bottom). CD235a⁺ cells were sorted on day 34 by FACS. Magnification of the objective lens: ×100. Bars represent 25 μm. (C) Percentages of polychromatic megaloblasts (Poly-M), polychromatic erythroblasts (Poly-E), and orthochromatic erythroblasts (Ortho-E) from 3 WT and 4 MT iPSC lines. (D) The pellets (top) and photomicrographs (bottom) of o-dianisidine–stained erythroblasts derived from WT1-iPSC3 and MT1-iPSC3 (bottom). CD235a⁺ cells were sorted on day 34 by FACS. Magnification of the objective lens: ×10. Bars represent, 200 μm. (E) The expression levels of HBB, HBG, and HO1 genes in erythroblasts derived from 1 control iPSC line, 3 WT iPSC lines, and 4 MT iPSC lines. Each line was tested in 3 independent experiments. Expression levels were normalized to the level of GAPDH. (F) The expression levels of HBB, HBG, and HO1 genes in WT1-iPSC1– and MT1–iPSC2-derived erythroblasts treated with DMSO or ALA relative to the expression levels of nontreated erythroblasts derived from a control iPSC line. Each line was tested in 3 independent experiments. Expression levels were normalized to the level of GAPDH. All data are presented as the mean ± standard error of the mean. P-values were calculated by using the unpaired, 2-tailed Student t test. **P < .01; ***P < .001; ****P < .0001; N.S., not significant. DMSO, dimethyl sulfoxide.