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.

Background: Pluripotent stem cells (PSCs) including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) offer the immense therapeutic potential in stem cell-based therapy of degenerative disorders. However, clinical trials of human ESCs cause heavy ethical concerns. With the derivation of iPSCs established by reprogramming from adult somatic cells through the transgenic expression of transcription factors, this problems would be able to overcome. In the present study, we tried to differentiate porcine iPSCs (piPSCs) into endothelial cells (ECs) for stem cell-based therapy of vascular diseases. Methods: piPSCs (OSKMNL) were induced to differentiation into ECs in four differentiation media (APEL-2, APEL-2 + 50 ng/mL of VEGF, EBM-2, EBM-2 + 50 ng/ mL of VEGF) on cultured plates coated with matrigel® (1:40 dilution with DMEM/F-12 medium) for 8 days. Differentiation efficiency of these cells were exanimated using qRT-PCR, Immunocytochemistry, Western blotting and FACS. Results: As results, expressions of pluripotency-associated markers (OCT-3/4, SOX2 and NANOG) were higher observed in all porcine differentiated cells derived from piPSCs (OSKMNL) cultured in four differentiation media than piPSCs as the control, whereas endothelial-associated marker (CD-31) in the differentiated cells was not expressed. Conclusions: It can be seen that piPSCs (OSKMNL) were not suitable to differentiate into ECs in the four differentiation media unlike porcine epiblast stem cells (pEpiSCs). Therefore, it would be required to establish a suitable PSCs for differentiating into ECs for the treatment of cardiovascular diseases.

The use of pigs in neuroscience has increased over the past years because the pigs are closely related to humans in terms of anatomy and physiology. Especially, the blood-brain barrier (BBB) maintains the homeostatic microenvironment in the central nervous system (CNS) and they can provide a valuable tool for studying the neurobiology. However, only a few putative blood-brain barrier (BBB) models have been generated by co-culture of porcine primary cells. The fundamental problem is that they lose some of their phenotypes when maintained in vitro for long-term culture. To establish improved in vitro porcine BBB models, we differentiated novel brain microvascular endothelial cells (BMECs) from porcine induced pluripotent stem cells (iPSCs) using a modified human-based protocol. Briefly, the dissociated single cells from iPSCs were seeded in Geltrex. For differentiation, cells were maintained for 3 days of expansion and then switched to unconditioned medium (UM) lacking bFGF for 6-7 days. Then, we subcultured cells onto collagen/fibronectin coated plates and changed BMEC medium for 2-3 weeks. About two weeks later, we observed a cluster of round cells surrounded by spindle shaped adherent cells termed as colony-forming units (CFU) of putative BMECs. Over time, the cluster of cells disappears and remained adherent spindle-shaped cells showed properties of endothelial cells. Although further studies will be needed, this study would be a great comparative analysis of the porcine and human in vitro BBB model.

Little is known to date about neural development of pig and directed differentiation of porcine pluripotent stem cells (PSCs) to neuronal cells remains elusive. To determine whether soluble factors from glioblastoma multiforme (GBM) promoted the neural differentiation from porcine induced PSCs (iPSCs), cells were treated cultured media of GBM cells. First of all, we isolated and established primary GBM cell line (WHO grade IV). The cellular morphology of GBM cancer cell line are dendritic-like with positive expression in NESTIN, SOX2, VIMENTIN and GFAP using immunofluorescence analysis. G-banded karyotype from primary GBM cell line revealed severe numerical chromosomal aberrations. GBM-cultured medium (CM) treated iPSC-NPCs survive well in vitro when supplemented with a combination of growth factors, including EGF and bFGF. The GBM-CM treated differentiated cells showed an increased mRNA expression level of astrocyte marker, GFAP and the dopaminergic neuron marker, tyrosine hydroxylase (TH). However, there was no significant difference in mRNA expression level of oligodendrocyte marker, MBP. The protocol developed in the present study for large animal models might provide an exciting tool to bridge the present gaps in neuroscience studies between rodents and humans.

RNA Sendai virus (SeV) vector system has no risk of being integrated into the host genome. Sendai virus (SeV) vectors expressing pluripotent factors have been used to produce integration-free induced pluripotent stem cells (iPSCs) with high efficiency from various cell types in human and mouse. In this study, we generated iPSCs from pig ear fibroblast cells using the SeV vector expressing 4 human factors (POU5F1, SOX2, C-MYC, and KLF4). Colonies were emerged at Day 14 of transduction and expressed the classical pluripotency markers (POU5F1, NANOG, and SOX2) and surface marker (SSEA1). Furthermore, they showed a domed shape and could passage over 40 times under 2i (CHIR99021 and PD0325901)-LIF and MEF feeder culture condition having in vitro differentiation ability into 3 germ layers. Next, we examined the ability of six feeder free culture conditions to maintain piPSCs in a pluripotent state. piPSCs were plated on Matrigel coated dishes in different media: 1. CM: control media (LIF culture media); 2. CM-F: CM+100 ng Fetuin-A; 3. CM-N: CM+100 ng Nanog-TAT; 4. CM-2i: CM+3 uM CHIR99021+1 uM PD0325901; 5. CM-2iN: CM-2i+100 ng Nanog-TAT; 6. CM-2iN+100 ng Fetuin-A. However, piPSC could not maintain the typical self-renewal morphology on feeder free conditions regardless of culture media tested here. Further, expression of pluripotency-related genes (Oct4, Nanog and Klf4) of piPSCs cultured on feeder free conditions could not be compared with that of iPSCs cultured on MEF feeder plate. Our results suggest that integration free pluripotent stem cell from pigs could be generated by SeV vector system and maintained their pluripotency under 2i-LIF and MEF feeder culture condition, but further optimization of culture conditions may be required.

MicroRNAs are ~22nt small noncoding RNAs that control gene expression at the posttranscriptional level through translational inhibition and destabilization of their target mRNAs. Micro RNAs are phylogenetically conserved and have been shown to be instrumental in a wide variety of key biological processes including cell cycle regulation, apoptosis, control of metabolic pathways, imprinting and differentiation. The expression of miRNAs is often regulated in tissue specific and developmental stage‐specific manners. More than 500 miRNAs have been reported in diverse eukaryotic organism so far. One of the biological functions of miRNAs seems to be the regulation of self‐renewal versus differentiation in stem cells. Recent efforts have focused on defining the miRNA expression profile in undifferentiated ESCs as compared to their differentiated progeny. Among the so‐called ES‐specific miRNAs, the 302‐367 cluster stands out due to its intracellular abundance and high cell type specificity. Levels of miRNA 302‐367 correlate with Oct4 transcripts in ESCs and early embryonic development, indicating an important role in ESC homeostasis and maintenance of pluripotency. Several months ago, a paper showed that expression of the miRNA 302‐367 cluster can directly reprogram mouse and human somatic cell to an iPS cell in absence of any of the four factors (Oct4, Sox2, c‐Myc, Klf4) efficiently. To apply this efficient method to porcine, we made an inducible vector system including miRNA 302‐367 cluster originated from porcine embryonic fibroblasts and could make porcine ips by the miRNA 302‐367 cluster.

Several studies have been conducted with the aim of establishing embryonic stem cell lines from porcine embryos. However, most researchers to date have found it difficult to maintain an ES-like state in derived cell lines, with the cells showing a strong tendency to differentiate into an epithelial or EpiSC-like state. We have also been able to derive cell lines of an EpiSC-like state and a differentiated non-ES-like state from porcine embryos of various origins, including invitro fertilized(IVF), in vivo derived, IVF aggregated and parthenogenetic embryos. In addition, we have generated induced pluripotent stem cells(piPSCs) via plasmid transfection of reprogramming factors (Oct4, Sox2, Klf4 and c-Myc) into porcine fibroblast cells. X chromosome inactivation (XCI) have recently been addressed as a hallmark to determine whether pluripotent cell is naïve or primed state. In this study, we could confirm the X chromosome inactivation status in female cell lines as well as marker expression, pluripotency and of our Epi- SC-like pESC lines along with our piPSC line. All of our cell lines showed AP activity and expressions of the genes Oct4, Sox2, Nanog, Rex, TDGF1, bFGF, FGFR1, FGFR2, Nodal and Activin-A involved in pluripotency and signaling pathways, XCI in female cell lines, in vitro differentiation potential and a normal karyotype, thus displaying similarities to epiblast stem cells or hES cells. Therefore, it may be inferred that, as a non-permissive species, the porcine species undergoes reprogramming into a primed state during the establishment of pluripotent stem cell lines.

Unlike mouse results, cloning efficiency of nuclear transfer from porcine induced pluripotent stem cells (piPSCs) is very low. The present study was performed to investigate the effect of cell cycle inhibitors on the cell cycle synchronization of piPSCs. piPSCs were generated using combination of six human transcriptional factors under stem cell culture condition. To examine the efficiency of cell cycle synchronization, piPSCs were cultured on a matrigel coated plate with stem cell media and they were treated with staurosporine (STA, 20 nM), daidzein (DAI, 100 μM), roscovitine (ROSC, 10 μM), or olomoucine (OLO, 200 μM) for 12 h. Flow Cytometry (FACs) data showed that piPSCs in control were in G1 (37.5±0.2%), S (34.0±0.6%) and G2/M (28.5±0.4%). The proportion of cells at G1 in DAI group was significantly higher than that in control, while STA, ROSC and OLO treatments could not block the cell cycle of piPSCs. Both of viability and apoptosis were affected by STA and ROSC treatment, but there were no significantly differences between control and DAI groups. Real-Time qPCR and FACs results revealed that DAI treatment did not affect the expression of pluripotent gene, Oct4. In case of OLO, it did not affect both of viability and apoptosis, but Oct4 expression was significantly decreased. Our results suggest that DAI could be used for synchronizing piPSCs at G1 stage and has any deleterious effect on survival and pluripotency sustaining of piPSCs.