Improved Hematopoietic Differentiation Efficiency of Gene-Corrected Beta-Thalassemia Induced Pluripotent Stem Cells by CRISPR/Cas9 System

The generation of beta-thalassemia (beta-Thal) patient-specific induced pluripotent stem cells (iPSCs), subsequent homologous recombination-based gene correction of disease-causing mutations/deletions in the beta-globin gene (HBB), and their derived hematopoietic stem cell (HSC) transplantation offers an ideal therapeutic solution for treating this disease. However, the hematopoietic differentiation efficiency of gene-corrected beta-Thal iPSCs has not been well evaluated in the previous studies. In this study, we used the latest gene-editing tool, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9), to correct beta-Thal iPSCs; gene-corrected cells exhibit normal karyotypes and full pluripotency as human embryonic stem cells (hESCs) showed no off-targeting effects. Then, we evaluated the differentiation efficiency of the gene-corrected beta-Thal iPSCs. We found that during hematopoietic differentiation, gene-corrected beta-Thal iPSCs showed an increased embryoid body ratio and various hematopoietic progenitor cell percentages. More importantly, the gene-corrected beta-Thal iPSC lines restored HBB expression and reduced reactive oxygen species production compared with the uncorrected group. Our study suggested that hematopoietic differentiation efficiency of beta-Thal iPSCs was greatly improved once corrected by the CRISPR/Cas9 system, and the information gained from our study would greatly promote the clinical application of beta-Thal iPSC-derived HSCs in transplantation.