Somatic transcriptome priming gates lineage specific differentiation potential of human induced pluripotent stem cell states

Human induced pluripotent stem cells (hiPSCs) provide an invaluable source for regenerative medicine; but are limited by proficient lineage specific differentiation. Here we reveal that hiPSCs derived from dermal skin fibroblasts (Fib) vs. human cord blood (CB) cells exhibit equivalent and indistinguishable pluripotent properties, but harbor important propensities for neural and hematopoietic lineage differentiation, independent of reprogramming factors used. Genes associated with germ layer specification were identical in both Fib or CB derived iPSCs; whereas patterns of lineage specific marks emerge upon differentiation induction of hiPSCs that were correlated to the cell type of origin used to create hiPSCs. Functionally, CB-iPSCs predominantly differentiate into hematopoietic cells and even adopt definitive hematopoiesis as evidenced by adult β-globin positive red blood cell development whereas Fib-iPSCs possess enhanced neural capacity. These clear differentiation propensities come at the expense of other lineages and cannot be overcome with additional external stimuli for alternative cell fates. Moreover, these differences in developmental potential are encoded within cultures of CB vs. Fib derived hiPSCs that can be used to predict differentiation propensity. To examine molecular properties of human iPSCs derived from different somatic sources, we generated iPSCs from CD34+CD45+ umbilical cord blood cells (CB) and compared to iPSCs from human adult dermal fibroblasts (Fib). All hiPSC lines were derived by transduction with Oct4, Sox2, Nanog and Lin28 (OSNL) or Oct4, Sox2, c-Myc and Klf4 expressing lentiviral vectors (OSMK). Human dermal fibroblasts (ScienCell) or human cord blood cells were obtained from healthy donors (two independent fibroblasts donors and three cord blood samples). Informed consent was obtained from all sample donors in accordance with Research Ethics Board-approved protocols at McMaster University and the London Health Sciences Centre. CD34+ cord blood cells, used for hCB-iPSCs generation, were isolated by immunomagnetic separation. Transduced cells were maintained on irradiated feeder MEFs in DMEM/F12 (Gibco) supplemented with 20% Knockout Serum Replacement (Gibco), 100 mM b-mercaptoethanol, 100 mM nonessential amino acid (Gibco), 1 mM L-glutamine (Gibco), and 10 ng/ml bFGF. After iPSC generation cells were maintained in MEF conditioned medium + 8ng/ml.