Title : The humanized mice transplanted with edited CCR5Δ32 hematopoietic stem cells are resistant to HIV infection
Abstract:
The acquired immune deficiency syndrome (AIDS) remains to be an incurable fatal infectious disease, while several documented cases demonstrated that the patients with AIDS achieved clinically defined viral clearance following transplantation of hematopoietic stem cells with homozygous CCR5Δ32 from either bone marrow or umbilical cord blood. Unfortunately, the homozygous CCR5Δ32 genotype is found only 1% among European populations. Asian and other populations predominantly carry the wild-type CCR5 alleles. This genetic landscape underscores the urgent need for generating allogeneic homozygous CCR5Δ32 hematopoietic stem cells via gene editing. In this study, the authors engineered a CRISPR/Cas9 RNP complex incorporating in vitro-synthesized Chimera guide RNA and single-stranded homology-directed repair (HDR) templates. This complex was electroporated into human cord blood hematopoietic stem cells (CB-HSCs) using anionic polymer poly-γ-glutamic acid (PGA) as a nano-carrier. The edited CB-HSCs exhibited up to 85% efficiency of CCR5Δ32 and the loss of protein level of CCR5 is up to 92%. Upon transplantation into the immunodeficient mice, these edited CB-HSCs successfully reconstituted the hematopoietic system in mice, yielding 85%~90% CCR5Δ32 genotype in immune cells and a 94% reduction in CCR5 protein expression. Critically, the mice transplanted with edited cells are resistant to HIV infection, comparing with its wild-type CCR5 parental mice. These results raise the potential of using CRISPR/Cas9 to produce a broader resource of CCR5△32/△32 hematopoietic stem cells, which are probably curative for the patients with AIDS.
