ABSTRACT
OBJECTIVE: Human embryonic stem (hES) cells can be differentiated into pancreatic endoderm structures in vitro. The study was performed to determine whether induced pluripotent stem (iPS) cells can be differentiated into similar structures with comparable efficiency. METHODS: We compared the ability of hES cells and iPS cells derived from human epidermal keratinocytes to progressively differentiate into pancreatic endoderm. Human foreskin keratinocytes were reprogrammed to pluripotency by transduction with retroviruses encoding Oct4, Sox2, and Klf4. The resulting keratinocyte-derived iPS (KiPS) cell lines and a hES cell line were subjected to a modified pancreatic endoderm differentiation protocol. Cells and embryoid-body structures derived from both hES and KiPS cells were compared at different stages of development for expression of stem cell and differentiation markers, including Sox2, Oct4, Mixl1, Brachyury, Gsc, FoxA2, Sox17, Hnf4α, Hnf1ß, Nkx2.2, Nkx6.1, Hex, Isl1, Pdx1, and Slc2A, via Taqman real-time PCR, flow-cytometry, and/or immunocytochemistry. RESULTS: hES cells and KiPS cells expressed similar levels of the stem cell factors Sox2 and Oct4. Upon differentiation, both cell types underwent remarkably similar changes in gene expression. They acquired the definitive endoderm markers Sox17 and FoxA2. Most Sox17+ and FoxA2+ cells co-expressed Hnf4α and Hnf1ß, found in the primitive gut tube, a pancreas precursor. Most FoxA2+ cells were also Pdx1+, and many expressed Nkx2.2, Nkx6.1, and Isl1. CONCLUSIONS: Keratinocyte-derived iPS cells can be differentiated into pancreatic endoderm, and the efficiency of this process is comparable to that seen for hES cells. Thus keratinocytes have the potential to serve as a source of patient-specific pancreatic endoderm for transplantation.
Subject(s)
Cell Differentiation , Embryonic Stem Cells/cytology , Endoderm/cytology , Epidermal Cells , Pancreas/embryology , Cell Line , Cells, Cultured , Embryonic Stem Cells/metabolism , Endoderm/metabolism , Epidermis/embryology , Epidermis/metabolism , Gene Expression Regulation, Developmental , Homeobox Protein Nkx-2.2 , Homeodomain Proteins , Humans , Induced Pluripotent Stem Cells/cytology , Induced Pluripotent Stem Cells/metabolism , Keratinocytes/cytology , Keratinocytes/metabolism , Kruppel-Like Factor 4 , Nuclear Proteins , Pancreas/cytology , Pancreas/metabolism , Transcription Factors/genetics , Transcription Factors/metabolismABSTRACT
Induced pluripotent stem cells (iPSC) provide an invaluable resource for regenerative medicine as they allow the generation of patient-specific progenitors with potential value for cell therapy. However, in many instances, an off-the-shelf approach is desirable, such as for cell therapy of acute conditions or when the patient's somatic cells are altered as a consequence of a chronic disease or aging. Cord blood (CB) stem cells appear ideally suited for this purpose as they are young cells expected to carry minimal somatic mutations and possess the immunological immaturity of newborn cells; additionally, several hundred thousand immunotyped CB units are readily available through a worldwide network of CB banks. Here we present a detailed protocol for the derivation of CB stem cells and how they can be reprogrammed to pluripotency by retroviral transduction with only two factors (OCT4 and SOX2) in 2 weeks and without the need for additional chemical compounds.
