Gene Editing as an Alternative to Retroviral Vectors for Wiskott-Aldrich syndrome Gene therapy

Abstract

One of the safest and most efficient treatments for monogenic diseases affecting the hematopoietic system is gene therapy using lentiviral vectors (LVs) and gammaretroviral vectors (GVs). However, although latest generation LVs and GVs are highly efficient and safe, both are retroviral vectors which integrate randomly in transcriptional active sites. This uncontrollable integration generates risk of insertional mutagenesis, which can produce undesirable effects on the modified cells. Gene editing has been proposed as a safer alternative, whose objective is the restoration of the endogenous levels of the wild type gene or the ectopic insertion of a therapeutic gene in the mutated locus or in a safe locus (safe harbor). The most potent gene editing strategies are based on the use of specific nucleases that produce double strand brakes (DSBs) in a specific site in the genome. Non homologous end joining (NHEJ) or homologous recombination (HR) repair of these DSBs allow editing the genome in different ways with a final objective: restore de normal function of the mutated gene. Our final aim was to develop a gene edition tool for efficient genetic rescue of human hematopoietic stem cells (hHSCs) from Wiskott-Aldrich syndrome (WAS) patients.