Parallel assessment of globin lentiviral transfer in induced pluripotent stem cells and adult hematopoietic stem cells derived from the same transplanted β-thalassemia patient

Abstract

A patient with b E /b 0 -thalassemia major was converted to transfusion-independence 4.5 years ago by lentiviral gene transfer in hematopoietic stem cells while showing a myeloid-biased cell clone. Induced pluripotent stem cells (iPSCs) are a potential alternative source of hematopoietic stem cells. If fetal to adult globin class, switching does not occur in vivo in iPSC-derived erythroid cells, b-globin gene transfer would be unnecessary. To investigate both vector integration skewing and the potential use of iPSCs for the treatment of thalassemia, we derived iPSCs from the thalassemia gene therapy patient and compared iPSCderived hematopoietic cells to their natural isogenic somatic counterparts. In NSG immunodeficient mice, embryonic to fetal and a partial fetal to adult globin class switching were observed, indicating that the gene transfer is likely necessary for iPSC-based therapy of the bhemoglobinopathies. Lentivector integration occurred in regions of low and high genotoxicity. Surprisingly, common integration sites (CIS) were identified across those iPSCs and cells retrieved from isogenic and nonisogenic gene therapy patients with b-thalassemia and adrenoleukodystrophy, respectively. This suggests that CIS observed in the absence of overt tumorigenesis result from nonrandom lentiviral integration rather than oncogenic in vivo selection. These findings bring the use of iPSCs closer to practicality and further clarify our interpretation of genome-wide lentivector integration.

Induced pluripotent stem cells in hematology: current and future applications

“…To date, only one adult with transfusion-dependent β E /β 0 -thalassemia major was transplanted with globin LV-transduced autologous CD34 + cells. This patient (who is still transfusion independent at 4.5 years of follow-up 25 ) showed a semidominant myeloid-biased cell clone bearing a globin lentivirus within the HMGA2 gene. The clonal dominance that accompanies therapeutic efficacy may be coincidental and stochastic or result from a hitherto benign cell expansion caused by dysregulation of the HMGA2 gene in stem/progenitor cells.…”

Differentiation and Application of Induced Pluripotent Stem Cell–Derived Vascular Smooth Muscle Cells

“…50,81 Moreover, a nonviral method of reprogramming peripheral blood mononuclear cells for iPSC generation reduces the tumorigenesis risk associated with using lentivirus-based iPSCs for in vivo studies. 82,83 Alternative tissue-engineered vessel studies have included the use of bilayered collagen scaffolds for iPSC-VSMC seeding. 84 Nakayama et al 84 showed that iPSC-derived VSMCs orientate themselves circumferentially along collagen nanofibrils when they are aligned, mimicking the behavior of primary VSMCs.…”

Cell signaling pathways involved in drug-mediated fetal hemoglobin induction: Strategies to treat sickle cell disease

“…The addition of a normal b-globin gene has been used to cure a few b-thalassemia patients; 154 work continues to extend this approach to sickle cell patients. To identify repressors of g-globin expression, human genetic and developmental murine studies established TR2/TR4, BCL11A, and KLF1 as potential targets for gene therapy.…”