Targeted genome editing in blood and immune cells enable new therapeutic applications, especially for infectious diseases. We present a GMP-compliant protocol to manufacture CCR5-edited CD34+ hematopoietic stem and precursor cells (HSPCs) with the goal to cure patients suffering from chronic infection with human immunodeficiency virus type 1 (HIV1). We hypothesize that genetic disruption of the CCR5 gene, which encodes the major HIV1 co-receptor, in HSPCs will give rise to an HIV-resistant immune system after transplantation. We have developed engineered nucleases based on transcription activator-like effector nucleases (TALENs) targeting CCR5. Electroporation of CD4+ T-cells and CD34+ HSPCs with mRNAs encoding TALENs revealed disruption of up to 80% of CCR5 alleles in CD4+ T-cells and over 90% of alleles in HSPCs. The high gene editing frequencies in T-cells and HSPCs were confirmed by deep sequencing, and no cleavage activity above background levels were detected at the top 20 predicted off-target sites. CCR5-edited CD4+ cells preserved their proliferation capacity and their biological function. Importantly, these cells showed significantly reduced CCR5 expression and became resistant to infection with the R5-tropic HIV-1JR-FL virus. The CCR5-edited HSPCs maintained their proliferation potential and their capacity to differentiate into the various blood lineages in vitro and in vivo, and clonal analysis revealed bi-allelic CCR5 disruption in more than 75% of cells. In summary, our developed protocol enables highly efficient and GMP-compliant knockout of the CCR5 locus in clinically relevant cells, so forming the foundation for a planned phase I/II clinical study.


Gautron:Cellectis SA: Employment. Busser:Cellectis: Employment, Patents & Royalties: Cellectis. Smith:Cellectis. Inc: Employment, Patents & Royalties. Duchateau:Cellectis: Employment, Patents & Royalties: Cellectis. Cathomen:TRACR Hematology: Consultancy; Cellectis: Research Funding; Miltenyi Biotec: Research Funding. Cornu:Cellectis: Research Funding; Miltenyi Biotec: Research Funding.

Author notes


Asterisk with author names denotes non-ASH members.

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