Generation of CCR5-defective CD34 cells from ZFN-driven stop codon-integrated mesenchymal stem cell clones

Homozygous 32-bp deletion of the chemokine receptor 5 gene (CCR5) is associated with resistance to human immunodeficiency virus (HIV) infection, while heterozygosity delays HIV progression. Bone marrow transplantation (BMT) from a 32/32 donor has been shown to cure an HIV-infected patient. However, the rarity of this mutation and the safety risks associated with current BMT protocols are the major obstacles to this treatment. Zinc finger nuclease (ZFN) targeting is a powerful method for achieving genomic disruption at specific DNA sites of interest.

Taking advantage of the self-renewal and plasticity properties of stem cells, in this study, we successfully generated isogenic and six-cell clones of bone marrow-derived mesenchymal stem cells that carry the stop codon of the CCR5 gene by using a ZFN-mediated homology-directed repair technique. These cells were expandable for more than 5 passages, and thus show potential to serve as an individual's cell factory. When Oct4 was overexpressed, the mutated cells robustly converted to CD34+ progenitor cells.

We here reported the novel approach on generation of patients own CD34 cells from high fidelity ZFN-mediated HDR MSC clones. We believe that our approach will be beneficial in future HIV treatment.