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. Author manuscript; available in PMC: 2018 Jan 1.
Published in final edited form as: Biotechnol Adv. 2016 Dec 20;35(1):77–94. doi: 10.1016/j.biotechadv.2016.12.002

Table 1.

Examples of methods to reprogram somatic cells into induced pluripotent stem cells.

Method Notes on Method Advantages and
Disadvantages		 Reference
Viral Integration

  • Gammaretroviral vectors for introducing transcription factors (Oct4, Sox2, Klf4, and c-Myc):

    • -

      11–25 days of reprogramming

    • -

      reprogramming efficiency of 0.001–0.01% (efficiency can be improved with mouse receptor for retroviruses)

  • Lentiviral vectors for introducing transcription factors (Oct4, Sox2, Klf4, and c-Myc) combined with 2A peptide and internal ribosome entry site:

    • -

      16 days of reprogramming

    • -

      15% reprogrammed iPSCs

    • -

      reprogramming efficiency of 0.5%

  • Low efficiency with gammaretroviral vectors

  • Higher efficiency with lentiviral vectors

  • Safety concern with viral integration

  • Potentially tumorigenic

 (Romli et al., 2013,
Sommer et al., 2009,
Takahashi, Tanabe, 2007,
Takahashi and Yamanaka, 2006)
Non-integrating
viral vector

  • Adenoviral system introducing Sox2, Klf4, and c-Myc to adherent Oct4 cells in presence of doxycycline:

    • -

      required 24 to 30 days of culturing infected cells

    • -

      yielded reprogramming efficiency of 0.0001% to 0.1%

  • Extremely low efficiency

  • No viral integration necessary

  • Potentially tumorigenic

 (Stadtfeld et al., 2008)
Recombinant reprogramming
protein

  • Cell-penetrating protein fused with reprogramming factors (Oct4, Sox2, Klf4, and c-Myc) and 9 arginines delivered to cells:

    • -

      reprogramming process took 8 weeks

    • -

      reprogramming efficiency of 0.001%

  • Inclusion body proteins from E. coli fused with 11 arginines and reprogramming factors (Oct4, Sox2, Klf4, and c-Myc):

    • -

      30–35 days of reprogramming

    • -

      valproic acid can significantly improve reprogramming efficiency

  • Low efficiency

  • Repeated protein treatment required

 (Kim et al., 2009,
Zhou, Wu, 2009)

  • Single transfer of embryonic stem cell-derived proteins:

    • -

      28 days of reprogramming

  • Only require a single transfer of protein extract

  • Ethical issues

 (Cho et al., 2010)
Small Molecules

  • Chemicals can be used to replace core reprogramming factors or increase reprogramming efficiency:

    • -

      VPA histone deacetylase inhibitor increase reprogramming efficiency 100 fold with Oct4, Sox2, Klf4, and c-Myc

    • -

      AZA DNA methyltransferase inhibitor increase reprogramming efficiency with Oct4, Sox2, Klf4, and c-Myc 4 to 10 folds

    • -

      BIX-01294 G9a histone methyltransferase inhibitor can replace Sox2 and increase reprogramming efficiency 5 times more than Oct4 and Klf4

  • Avoids genomic integrations of exogenous sequence

  • Enhance reprogramming efficiency

  • Chemicals might promote genetic aberrations

 (Feng et al., 2009,
Huangfu et al., 2008,
Ma et al., 2013b,
Mikkelsen et al., 2008)