Efficient Reprogramming of Human Cord Blood CD34+ Cells Into Induced Pluripotent Stem Cells With OCT4 and SOX2 Alone

Abstract

The reprogramming of cord blood (CB) cells into induced pluripotent stem cells (iPSCs) has potential applications in regenerative medicine by converting CB banks into iPSC banks for allogeneic cell replacement therapy. Therefore, further investigation into novel approaches for efficient reprogramming is necessary. Here, we show that the lentiviral expression of OCT4 together with SOX2 (OS) driven by a strong spleen focus-forming virus (SFFV) promoter in a single vector can convert 2% of CB CD34(+) cells into iPSCs without additional reprogramming factors. Reprogramming efficiency was found to be critically dependent upon expression levels of OS. To generate transgene-free iPSCs, we developed an improved episomal vector with a woodchuck post-transcriptional regulatory element (Wpre) that increases transgene expression by 50%. With this vector, we successfully generated transgene-free iPSCs using OS alone. In conclusion, high-level expression of OS alone is sufficient for efficient reprogramming of CB CD34(+) cells into iPSCs. This report is the first to describe the generation of transgene-free iPSCs with the use of OCT4 and SOX2 alone. These findings have important implications for the clinical applications of iPSCs.

Modeling human osteosarcoma in mice through 3AB‐OS cancer stem cell xenografts

“…Pluripotency and immortality in CSCs depend on the expression of a group of genes (stemness genes) which form a self-organized core of transcription factors required for maintaining stem cell-like features [Chen and Daley, 2008;Meng et al, 2012]. In particular, four factors (Oct4, Sox2, Nanog, and Lin28) are sufficient to reprogram human somatic cells to pluripotent stem cells showing the essential characteristics of embryonic stem (ES) cells [Yu et al, 2007].…”

Rapid and efficient reprogramming of human fetal and adult blood CD34+ cells into mesenchymal stem cells with a single factor

“…+ cells We have previously reported the efficient generation of iPSCs from human CB-CD34 + cells with a single vector that expresses OCT4 and SOX2 (Lenti SFFV-OCT4-2A-SOX2) [25]. When the two factors were expressed by two individual lentiviral vectors (Lenti SFFV-OCT4 and Lenti SFFV-SOX2), we observed that ~80% of the colonies morphologically resemble mesenchymal cells.…”

“…To further investigate the safety of these cells, we injected 1-2 × 10 6 iMSCs systemically or subcutaneously into 20 immunodeficient mice. Unlike iPSCs [25], iMSCs did not form tumors during 3 months of follow-up. In comparison, injection of iMSCs that were generated with OCT4 and MYC led to tumor formation at 1 month after systemic or subcutaneous inoculation (data not shown).…”

Stem cell manipulation, gene therapy and the risk of cancer stem cell emergence

“…Dopaminergic-like neural cells are obtained by exposing iPSCs to the extrinsic control of microenvironment stromal cell-derived inducing activity (113). Blood and neural immature cells have a predisposition for reprogramming and do so in a more efficient manner, probably due to their epigenetic memory (114)(115)(116). The difference between iPSCs and ESCs initially appears to be very slight (Figure 4), especially when considering molecular factors involved in their regulation (99).…”