Co-Treatment of Erythroid Cells from β-Thalassemia Patients with CRISPR-Cas9-Based β39-Globin Gene Editing and Induction of Fetal Hemoglobin

Gene editing (GE) is an efficient strategy for correcting genetic mutations in monogenic hereditary diseases, including β-thalassemia. We have elsewhere reported that CRISPR-Cas9-based gene editing can be employed for the efficient correction of the β39-thalassemia mutation. On the other hand, robust evidence demonstrates that the increased production of fetal hemoglobin (HbF) can be beneficial for patients with β-thalassemia. The aim of our study was to verify whether the de novo production of adult hemoglobin (HbA) using CRISPR-Cas9 gene editing can be combined with HbF induction protocols. The gene editing of the β39-globin mutation was obtained using a CRISPR-Cas9-based experimental strategy; the correction of the gene sequence and the transcription of the corrected gene were analyzed by allele-specific droplet digital PCR and RT-qPCR, respectively; the relative content of HbA and HbF was studied by high-performance liquid chromatography (HPLC) and Western blotting. For HbF induction, the repurposed drug rapamycin was used. The data obtained conclusively demonstrate that the maximal production of HbA and HbF is obtained in GE-corrected, rapamycin-induced erythroid progenitors isolated from β39-thalassemia patients. In conclusion, GE and HbF induction might be used in combination in order to achieve the de novo production of HbA together with an increase in induced HbF.