1. Research Techniques Made Simple: Induced Pluripotent Stem Cells in Dermatological Research Jason Dinella 1-3, Maranke I. Koster 1-3, and Peter J. Koch 1-4 1. Department of Dermatology, 2. Charles C. Gates Center for Regenerative Medicine and Stem Cell Biology, 3. Graduate Program in Cell Biology, Stem Cells and Development, 4. Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado, USA

2. Induced Pluripotent Stem Cells (iPSCs) iPSCs are pluripotent cells generated from somatic cells through the forced expression of reprogramming factors controlling self-renewal and pluripotency. iPSCs can be generated from patient biopsies. iPSCs can be differentiated into any cell type of the body.

3. iPSC Technology Can be used to study basic cell biology and mechanisms driving cellular differentiation. Presents the ideal alternative approach to using embryonic stem cells (ESCs) in disease modeling and therapeutic applications. Allows researchers to sidestep ethical and immunological limitations associated with the generation and use of ESCs.

4. Human iPSC Generation Somatic cells Cellular Reprogramming Putative iPSCs (arrow) Clonal Expansion/ Characterization iPSCs 2-3 weeks3-4 weeks Characterization a b c d SSEA-3 TRA 1-60 NANOG

5. Keratinocyte Differentiation TP63 KRT14 LOR KRT14DSC3 KRT14

6. Methods of Inducing Pluripotency Reprogramming MethodIntegrative?EfficiencyReferences RetrovirusYesModerateTakahashi et al., 2006 AdenovirusNoLowStadtfeld et al., 2008 LentivirusYesModerate-HighSommer et al., 2009 Transposible elementYesLowWoltjen et al., 2009 Episomal vectorsNoLowYu et al., 2009 ProteinNoLowZhou et al., 2009 Sendai virusNoHighFusaki et al., 2009 mRNA/miRNANoModerate-HighWarren et al., 2010 Small moleculesNoModerateHou et al., 2013 Stimulus-triggeredNoHighObokata et al., 2014

7. Summary and Future Directions Please insert Figure 4 (being redrawn) of Dinella et al., 2014 here

8. Advantages and Limitations of iPSCs iPSCs can be generated from skin biopsies. iPSCs can be cultured indefinitely in vitro, providing a renewable source of cells. iPSCs can be differentiated into any cell type of the body. Cells differentiated from iPSCs can be used for disease modeling and drug screening. Disease-causing mutations can be corrected in iPSCs iPSC-derived cells, such as keratinocytes, can be used in cell therapy. Generation of iPSCs involves the use of adult cells, bypassing ethical concerns associated with using ESCs. iPSCs can acquire genetic mutations during reprogramming or during in vitro culture. Undifferentiated iPSCs, if transferred to a patient, could form tumors (teratomas). More stringent protocols must be developed and standardized for the generation, maintenance, characterization, and differentiation of iPSCs before they can be considered a viable option for clinical use.