Patient-Specific iPSC-Derived Endothelial Cells Provide Long-Term Phenotypic Correction of Hemophilia A

Summary: We generated patient-specific disease-free induced pluripotent stem cells (iPSCs) from peripheral blood CD34+ cells and differentiated them into functional endothelial cells (ECs) secreting factor VIII (FVIII) for gene and cell therapy approaches to cure hemophilia A (HA), an X-linked bleeding disorder caused by F8 mutations. iPSCs were transduced with a lentiviral vector carrying FVIII transgene driven by an endothelial-specific promoter (VEC) and differentiated into bona fide ECs using an optimized protocol. FVIII-expressing ECs were intraportally transplanted in monocrotaline-conditioned non-obese diabetic (NOD) severe combined immune-deficient (scid)-IL2rγ null HA mice generating a chimeric liver with functional human ECs. Transplanted cells engrafted and proliferated in the liver along sinusoids, in the long term showed stable therapeutic FVIII activity (6%). These results demonstrate that the hemophilic phenotype can be rescued by transplantation of ECs derived from HA FVIII-corrected iPSCs, confirming the feasibility of cell-reprogramming strategy in patient-derived cells as an approach for HA gene and cell therapy. : Follenzi and colleagues show that endothelial cells can be obtained starting from blood CD34+ cells of both healthy and hemophilic donors passing through iPSC generation. During the differentiation process the cells can be genetically modified by LV to express FVIII; corrected endothelial cells secrete FVIII in vitro and ameliorate the hemophilic phenotype in a mouse model of the disease. Keywords: hemophilia A, induced pluripotent stem cells (iPSCs), endothelial cells, cell and gene therapy, FVIII, chimeric vasculature, lentiviral vector