Engraftment and in vivo proliferation advantage of gene-corrected mobilized CD34+ cells from Fanconi anemia patients

Abstract

Previous Fanconi anemia (FA) gene therapy studies have failed to demonstrate engraftment of gene-corrected hematopoietic stem and progenitor cells (HSPCs) from FA patients, either after autologous transplantation or infusion into immunodeficient mice.Inthisstudy,wedemonstratethatavalidatedshorttransductionprotocolofG-CSF plus plerixafor-mobilized CD341 cells from FA-A patients with a therapeutic FANCAlentiviral vector corrects the phenotype of in vitro cultured hematopoietic progenitor cells. Transplantation of transduced FA CD341 cells into immunodeficient mice resulted in reproducible engraftment of myeloid, lymphoid, and CD341 cells. Importantly, a marked increase in the proportion of phenotypically corrected, patient-derived hematopoietic cells was observed after transplantation with respect to the infused CD341 graft, indicating the proliferative advantage of corrected FA-A hematopoietic repopulating cells. Our data demonstrate for the first time that optimized protocols of hematopoietic stem cell collection from FA patients, followed by the short and clinically validated transductionofthesecellswithatherapeuticlentiviralvector,resultsinthegenerationof phenotypically corrected HSPCs capable of repopulating and developing proliferation advantage in immunodeficient mice. Our results suggest that clinical approaches for FA gene therapy similar to those used in this studywillfacilitatehematopoieticrepopulationinFApatientswithgenecorrectedHSPCs,openingnewprospectsforgenetherapy of FApatients