CR1 INSERM, Group Leader “Therapeutic genome editing” Genethon, Evry, FRANCE

Monday 1 July 2019 | 12:00 noon

Ex vivo editing of HSC for erythroid- specific expression of therapeutic proteins

Host: A. Muro

Genome editing can correct the underlying disease-causing mutation of virtually any genetic disease; however, insufficient expression from the endogenous promoters and the need of countless mutation– specific editing strategies represent major obstacles.
Here, we developed an alternative platform for erythroid-specific expression of proteins via ex vivo targeted integration (CRISPR/Cas9) of therapeutic transgenes in hematopoietic stem/progenitor cells (HSPC). Specifically, by inserting transgenes under the control of the endogenous α or β-globin promoter, we aim to redirect a fraction of the striking globin synthesis capacity of erythroid cells (~7.2gr/day) for therapeutic protein expression without interfering with physiological erythropoiesis. The combination of robust transcription and the abundance of transgene-expressing cells should maximize protein production, reducing the number of integration events required to reach therapeutic levels. We showed the feasibility of the approach using a GFP reporter transgene and its therapeutic potential by expressing coagulation factors and lysosomal enzymes. Lack of cellular toxicity and CRISPR off-targets support the safety of this approach.
Overall, we established a safe and novel ex vivo nuclease-based platform to achieve robust erythroid- specific expression of proteins for different therapeutic applications, such as hemophilia and inherited metabolic disorders.