Efficient Hematopoietic Redifferentiation of Induced Pluripotent Stem Cells Derived from Primitive Murine Bone Marrow Cells
Heterogeneity among induced pluripotent stem cell (iPSC) lines with regard to their gene expression profile and differentiation potential has been described and at least partly linked to the tissue of origin. Here, we generated iPSCs from primitive [lineage negative (Linneg)] and nonadherent differentiated [lineage positive (Linpos)] bone marrow cells (BM-iPSC), and compared their differentiation potential to that of fibroblast-derived iPSCs (Fib-iPSC) and embryonic stem cells (ESC). In the undifferentiated state, individual iPSC clones but also ESCs proved remarkably similar when analyzed for alkaline phosphatase and SSEA-1 staining, endogenous expression of the pluripotency genes Nanog, Oct4, and Sox2, or global gene expression profiles. However, substantial differences between iPSC clones were observed after induction of differentiation, which became most obvious upon cytokine-mediated instruction toward the hematopoietic lineage. All 3 BM-iPSC lines derived from undifferentiated Linneg cells yielded high proportions of cells expressing the hematopoietic differentiation marker CD41 and in 2 of these lines high proportions of CD41+/CD45+ cells were detected. In contrast, little hematopoiesis-specific surface marker expression was detected in 4 Linpos BM-iPSC and 3 Fib-iPSC lines. These results were corroborated by functional studies demonstrating robust colony outgrowth from hematopoietic progenitors in 2 of the Linneg BM-iPSCs only. Thus, in conclusion, our data demonstrate efficient generation of iPSCs from primitive hematopoietic tissue as well as efficient hematopoietic redifferentiation for Linneg BM-iPSC lines, thereby supporting the notion of an epigenetic memory in iPSCs.