Background: Porcine pluripotent stem cells (pPSCs) would provide enormous potential for agriculture and biomedicine. However, authentic pPSCs have not established yet because standards for pPSCs-specific markers and culture conditions are not clear. Therefore, the present study reports comparative pluripotency characteristics in porcine induced pluripotent stem cells (piPSCs) derived from different viral transduction and reprogramming factors [Lenti-iPSCs (OSKM), Lenti-iPSCs (OSKMNL) and Sev-iPSCs (OSKM)]. Methods: Porcine fibroblasts were induced into Lenti-iPSCs (OSKM) and Lenti-iPSCs (OSKMNL) by using Lentiviral vector and Sev-iPSCs (OSKM) by using Sendaiviral vector. Expressions of endogenous or exogenous pluripotency-associated genes, surface marker and in vitro differentiation in between Lenti-piPSCs (OSKM), Lenti-iPSCs (OSKMNL) and Sev-piPSCs (OSKM) were compared. Results: Colonial morphology of Lenti-iPSCs (OSKMNL) closely resembles the naïve mouse embryonic stem cells colony for culture, whereas Sev-iPSCs (OSKM) colony is similar to the primed hESCs. Also, the activity of AP shows a distinct different in piPSCs (AP-positive (+) Lenti-iPSCs (OSKMNL) and Sev-iPSCs (OSKM), but AP-negative (-) LentiiPSCs (OSKM)). mRNAs expression of several marker genes (OCT-3/4, NANOG and SOX2) for pluripotency was increased in Lenti-iPSCs (OSKMNL) and Sev-iPSCs (OSKM), but Sev-iPSCs (OSKM). Interestingly, SSEA-1 of surface markers was expressed only in Sev-iPSCs (OSKM), whereas SSEA-4, Tra-1-60 and Tra-1-81 were positively expressed in Lenti-iPSCs (OSKMNL). Exogenous reprogramming factors continuously expressed in Lenti-iPSCs (OSKMNL) for passage 20, whereas Sev-iPSCs (OSKM) did not express any exogenous transcription factors. Finally, only Lenti-iPSCs (OSKMNL) express the three germ layers and primordial germ cells markers in aggregated EBs. Conclusions: These results indicate that the viral transduction system of reprograming factors into porcine differentiated cells display different pluripotency characteristics in piPSCs.

INTRODUCTION
MATERIALS AND METHODS
    Culture of porcine fibroblasts
    Induction of porcine induced pluripotent stem cells
    Determining reprogramming efficiency with alkalinephosphatase
    Immunocytochemistry
    RT-PCR and quantitative real-time PCR
    Cell cycle, population doubling time and karyotypinganalysis
    In vitro differentiation
    Statistical analysis
RESULTS
    Induction efficiency of porcine fibroblasts into porcineinduced pluripotent stem cells by using Lentiviralvector
    Induction efficiency of porcine fibroblasts into porcineinduced pluripotent stem cells by using Sendaivirusvector
    Comparative expression of endogenous pluripotencyassociatedgenes in between Lenti-piPSCs and SevpiPSCs
    Comparative expression of exogenous reprograminggenes in between Lenti-piPSCs and Sev-piPSCs
    Comparative expression of pluripotency and surfacemarkers in Lenti-piPSCs and Sev-piPSCs
    Cell cycle phase and population doubling time inLenti-piPSCs and Sev-piPSCs
    In vitro differentiation of Lenti-piPSCs and SevpiPSCs
DISCUSSION
CONCLUSION
REFERENCES

• Sang-Ki Baek(Department of Animal Bioscience, College of Agriculture & Life Sciences, Gyeongsang National University, Jinju 52828, Korea)
• In-Won Lee(Department of Animal Bioscience, College of Agriculture & Life Sciences, Gyeongsang National University, Jinju 52828, Korea, Division of Applied Life Science, Gyeongsang National University, Jinju 52828, Korea)
• Yeon-Ji Lee(Department of Animal Bioscience, College of Agriculture & Life Sciences, Gyeongsang National University, Jinju 52828, Korea, Division of Applied Life Science, Gyeongsang National University, Jinju 52828, Korea)
• Bo-Gyeong Seo(Division of Life Science, College of Natural Sciences, Gyeongsang National University, Jinju 52828, Korea, Division of Applied Life Science, Gyeongsang National University, Jinju 52828, Korea)
• Jung-Woo Choi(College of Animal Life Science, Kangwon National University, Chuncheon 24341, Korea)
• Tae-Suk Kim(Department of Animal Bioscience, College of Agriculture & Life Sciences, Gyeongsang National University, Jinju 52828, Korea)
• Cheol Hwangbo(Division of Applied Life Science, Gyeongsang National University, Jinju 52828, Korea)
• Joon-Hee Lee(Department of Animal Bioscience, College of Agriculture & Life Sciences, Gyeongsang National University, Jinju 52828, Korea, Institute of Agriculture & Life Science, College of Agriculture & Life Sciences, Gyeongsang National University, Jinju 52828, Korea) Corresponding author