Ex vivo editing of human hematopoietic stem cells for erythroid expression of therapeutic proteins

Mario Amendola

INSERM researcher, Head of the "genome editing" group, UMR_S951, Evry, FR.

Targeted genome editing has a great therapeutic potential to treat disorders that require protein replacement therapy. To develop a platform independent of specific patient mutations, therapeutic transgenes can be inserted in a safe and highly transcribed locus to maximize protein expression. Therefore, we developed an ex vivo editing approach to achieve efficient gene targeting in human hematopoietic stem/progenitor cells (HSPCs) and robust expression of clinically relevant proteins by the erythroid lineage. Using CRISPR-Cas9, we integrated different transgenes under the transcriptional control of the endogenous α-globin promoter, recapitulating its high and erythroid-specific expression. Erythroblasts derived from targeted HSPCs secrete different therapeutic proteins, which retain enzymatic activity and cross-correct patients’ cells. Moreover, modified HSPCs maintain long-term repopulation and multilineage differentiation potential in transplanted mice. Finally, additional optimization of therapeutic transgene, CRISPR-Cas9 tools and donor DNA delivery further improve efficiency and safety of the approach.