Reprogramming of human hematopoietic progenitor and peripheral blood mononuclear cells. (a) HPCs and PBMCs were cultured in a serum-free medium and transduced with lentiviral vectors expressing four stemness factors at an MOI of 5. Representative phase-contrast images of HPCs before transduction (left panel) and 7 days after infection (left panel) are shown. Representative HPC-derived (left panel) and PBMC-derived (right panel) colonies with characteristic morphologies of reprogrammed cells are shown. (b) HPC and PBMC-derived iPSC clones were further characterized through immunocytochemistry analysis by using a panel of antibodies against pluripotency-associated markers. All clones stained positive for the markers, including SSEA-4, TRA-1-60, OCT4, and NANOG.