Developing a human pluripotent stem cell model for hematopoiesis and blood disorders

Human induced pluripotent stem (iPS) cells derived from somatic cells hold promise to develop novel patient-specific cell therapies and research models for inherited and acquired diseases. We and others previously reprogrammed human adherent cells such as postnatal fibroblasts to iPS cells that resemble adherent human embryonic stem (hES) cells. It is also highly desirable to reprogram blood cells that are easily accessible and less exposed to environmental mutagens. More critically, the ability to reprogram blood cells is essential if one wishes to generate iPS cells containing somatic mutations that are restricted to the blood cells and found in acquired hematological disorders, such as myeloproliferative disorders (MPDs), in order to investigate their pathogenesis.;A second major hurdle for modeling blood diseases using pluripotent stem cells is the low differentiation efficiency of these cells to blood lineages especially hematopoietic progenitor cells. Most published methods involve either animal sourced feeder cells and/or fetal bovine serum (FBS) that are highly variable among batches. New methods not relying on serum are needed for better modeling human hematopoiesis and for producing clinically applicable cells.;Here I describe the derivation of iPS cells from postnatal human blood cells and the potential of these pluripotent cells for hematopoietic differentiation and disease modeling. Multiple human iPS cell lines were generated from previously frozen cord blood and adult CD34+ cells of healthy donors. The hematopoietic differentiation potential of these human iPS cells was examined by an improved method of embryoid body (EB) formation and differentiation under a feeder- and serum-free condition. Multiple iPS cell lines were also generated from peripheral blood CD34+ cells of two patients with myeloproliferative disorders (MPDs) who acquired the JAK2-V617F somatic mutation in their blood cells. The MPD-derived iPS cells containing the mutation appeared normal in phenotypes, karyotype and pluripotency. After directed hematopoietic differentiation, the MPD-iPS cell derived hematopoietic progenitor cells showed increased erythropoiesis and gene expression of specific genes, recapitulating features of the primary CD34+ cells of the corresponding patient from whom the iPS cells were derived. These iPS cells thus provide a renewable cell source and a prospective model for investigating MPD pathogenesis.