Gene correction for SCID-X1 in long-term hematopoietic stem cells
Pavel-Dinu, Mara; Wiebking, Volker; Dejene, Beruh T.; Srifa, Waracharee; Mantri, Sruthi; More... Nicolas, Carmencita E.; Lee, Ciaran; Bao, Gang; Kildebeck, Eric J.; Punjya, Niraj; Sindhu, Camille; Inlay, Matthew A.; Saxena, Nivedita; DeRavin, Suk See; Malech, Harry; Roncarolo, Maria Grazia; Weinberg, Kenneth I.; Porteus, Matthew H. Less...
Gene correction in human long-term hematopoietic stem cells (LT-HSCs) could be an effective therapy for monogenic diseases of the blood and immune system. Here we describe an approach for X-linked sSevere cCombined iImmunodeficiency (SCID-X1) using targeted integration of a cDNA into the endogenous start codon to functionally correct disease-causing mutations throughout the gene. Using a CRISPR-Cas9/AAV6 based strategy, we achieve up to 20% targeted integration frequencies in LT-HSCs. As measures of the lack of toxicity we observe no evidence of abnormal hematopoiesis following transplantation and no evidence of off-target mutations using a high-fidelity Cas9 as a ribonucleoprotein complex. We achieve high levels of targeting frequencies (median 45%) in CD34+ HSPCs from six SCID-X1 patients and demonstrate rescue of lymphopoietic defect in a patient derived HSPC population in vitro and in vivo. In sum, our study provides specificity, toxicity and efficacy data supportive of clinical development of genome editing to treat SCID-Xl.