Melanocytes derived from transgene-free human induced pluripotent stem cells.
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ABSTRACT:
SUBMITTER: Jones JC
PROVIDER: S-EPMC3714355 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Induced pluripotent stem cells (iPSCs) are a potent cell source for neurogenesis. Previously we have generated iPSCs from human dental stem cells carrying transgene vectors. These exogenous transgenes may affect iPSC behaviors and limit their clinical applications. The purpose of this study was to establish transgene-free iPSCs (TF-iPSCs) reprogrammed from human stem cells of apical papilla (SCAP) and determine their neurogenic potential.A single lentiviral 'stem cell cassette' flanked by the loxP site (hSTEMCCA-loxP), encoding four human reprogramming factors, OCT4, SOX2, KLF4, and c-MYC, was used to reprogram human SCAP into iPSCs. Generated iPSCs were transfected with plasmid pHAGE2-EF1?-Cre-IRES-PuroR and selected with puromycin for the TF-iPSC subclones. PCR was performed to confirm the excision of hSTEMCCA. TF-iPSC clones did not resist to puromycin treatment indicating no pHAGE2-EF1?-Cre-IRES-PuroR integration into the genome. In vitro and in vivo analyses of their pluripotency were performed. Embryoid body-mediated neural differentiation was undertaken to verify their neurogenic potential.TF-SCAP iPSCs were generated via a hSTEMCCA-loxP/Cre system. PCR of genomic DNA confirmed transgene excision and puromycin treatment verified the lack of pHAGE2-EF1?-Cre-IRES-PuroR integration. Transplantation of the TF-iPSCs into immunodeficient mice gave rise to teratomas containing tissues representing the three germ layers -- ectoderm (neural rosettes), mesoderm (cartilage and bone tissues) and endoderm (glandular epithelial tissues). Embryonic stem cell-associated markers TRA-1-60, TRA-2-49 and OCT4 remained positive after transgene excision. After neurogenic differentiation, cells showed neural-like morphology expressing neural markers nestin, ?III-tubulin, NFM, NSE, NeuN, GRM1, NR1 and CNPase.TF-SCAP iPSCs reprogrammed from SCAP can be generated and they may be a good cell source for neurogenesis.
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Project description:Induced pluripotent stem (iPS) cells hold great promise for regenerative medicine. To overcome potential problems associated with transgene insertions, efforts have been directed over the past several years to generate transgene-free iPS cells by using non-viral-vector approaches. To date, however, cells generated through such procedures have had problems producing reproductively competent animals, suggesting that their quality needed further improvement. Here we report the use of optimized assemblies of reprogramming factors and selection markers incorporated into single plasmids as nonintegrating episomes to generate germ-line-competent iPS cells. In particular, the pMaster12 episome can produce transgene-free iPS cells that, when grown in 2i medium, recapitulate good mouse ES cells, in terms of their competency for generating germ-line chimeras.
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Project description:We describe a platform to derive, culture, and differentiate genomically stable, transgene-free human induced pluripotent stem cells (iPSCs) on a fully synthetic polymer substrate made of a grafted zwitterionic hydrogel: poly2-(methacryloyloxy)ethyl dimethyl-(3-sulfopropyl) ammonium hydroxide (PMEDSAH). Three independent transgene-free iPSC lines derived in these conditions demonstrated continuous self-renewal, genomic stability, and pluripotency in vitro and in vivo after up to 9 months of continuous in vitro culture on PMEDSAH-grafted plates. Together, these data demonstrate the strength this alternative platform offers to generate and maintain human iPSCs for regenerative medicine.
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Project description:Epidermal melanocytes have an important role in protecting skin from UV rays, and are implicated in a variety of skin diseases. Here, we developed an efficient method for differentiating induced pluripotent stem cells (iPSCs) into melanocytes. We first generated iPSCs from adult mouse tail-tip fibroblasts (TTFs) using retroviral vectors or virus-free piggyBac transposon vectors carrying murine Sox2, Oct3/4, c-Myc, and Klf4. The TTF-derived iPSC clones exhibited similar morphology and growth properties as mouse embryonic stem (ES) cells. The iPSCs expressed ES cell markers, displayed characteristic epigenetic changes, and formed teratomas with all three germ layers. The iPSCs were used to generate embryonic bodies and were then successfully differentiated into melanocytes by treatment with growth factors. The iPSC-derived melanocytes expressed characteristic melanocyte markers and produced melanin pigment. Electron microscopy showed that the melanocytes contained mature melanosomes. We manipulated the conditions used to differentiate iPSCs to melanocytes and discovered that Wnt3a is not required for mouse melanocyte differentiation. This report shows that melanocytes can be readily generated from iPSCs, providing a powerful resource for the in vitro study of melanocyte developmental biology and diseases. By inducing iPSCs without viruses, the possibility of integration mutagenesis is alleviated, and these iPSCs are more compatible for cell replacement therapies.
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Project description:Although a variety of reprogramming strategies have been reported to create transgene-free induced pluripotent stem (iPS) cells from differentiated cell sources, a fundamental question still remains: Can we generate safe iPS cells that have the full spectrum of features of corresponding embryonic stem (ES) cells? Studies in transgene-free mouse iPS cells have indicated a positive answer to this question. However, the reality is that no other species have a derived transgene-free iPS cell line that can truly mimic ES cell quality. Specifically, critical data for chimera formation and germline transmission are generally lacking. To date, the rat is the only species, other than the mouse, that has commonly recognized authentic ES cells that can be used for direct comparison with measure features of iPS cells. To help find the underlying reasons of the current inability to derive germline-competent ES/iPS cells in nonrodent animals, we first used optimized culture conditions to isolate and establish rat ES cell lines and demonstrated they are fully competent for chimeric formation and germline transmission. We then used episomal vectors bearing eight reprogramming genes to improve rat iPS (riPS) cell generation from Sprague-Dawley rat embryonic fibroblasts. The obtained transgene-free riPS cells exhibit the typical characteristics of pluripotent stem cells; moreover, they are amenable to subsequent genetic modification by homologous recombination. Although they can contribute significantly to chimeric formation, no germline transmission has been achieved. Although this partial success in achieving competency is encouraging, it suggests that more efforts are still needed to derive ground-state riPS cells. Stem Cells Translational Medicine 2017;6:340-351.
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