Somatic cells could be directly reprogrammed into stem state by ectopic expression of transcription factors, which share similar features of embryonic stem cells (ESC). Induced pluripotent stem cells (iPSC) possess promising application in producing genetically modified animals, whereas the generation of porcine offspring from iPSC is still difficult and controversial, and new materials are needed. In this study, we report the generation of iPSC from porcine adipose-derived stem cells (pADSC) using drug-inducible expression of defined human factors (Oct4, Sox2, Klf4, and c-Myc) and ‘2i’ plus leukemia inhibitory factor (LIF) culture system. pADSC were isolated from subcutaneous adipose tissue of a 28-day-old Danish Landrace, and subsequently characterised by high proliferation rate at low passages, long period passaging without significant replication senescence, mesenchymal stem cell-specific surface markers expression, including CD29 (0.995 ± 0.0577), CD44 (0.999 ± 0.0333), and CD90 (0.994 ± 0.0333), together with successful adipogenic and osteogenic differentiation ability in vitro. The reprogramming of iPSC from pADSC was evidently more efficient than the process from adult fibroblasts (P < 0.01), both of which were carried out under feeder-independent and serum-free conditions, and this may be due to the higher demethylation level of genomic DNA in pADSC. Two lines of porcine iPSC with naïve-like state were finally obtained through feeder-independent and serum-free conditions. The successful reprogramming of iPSC was demonstrated by short cell cycle interval, alkaline phosphatase (AP) staining positive, expression of stemness-related proteins including OCT-4, SOX2, NANOG, SSEA3, and SSEA4. Full reprogramming of iPSC was evaluated by the significant up-regulation of LIN28, ESRRB, UTF1, and DPPA5. Naïve-like state of porcine iPSC was further confirmed by the striking resemblance to naïve mESC, single-cell dissociation, LIF-dependency, up-regulation of STELLA and ERAS, and little translation of TRA-1-60 and TRA-1-81. In addition, porcine naïve-like iPSC possessed normal karyotypes, and could differentiate into cell types of all three germ layers in vitro and in vivo. Furthermore, in vivo studies to determine the capacity of these cells to integrate into the inner cell mass of blastocysts are still being undertaken for validation. Together, our study provided an efficient method to derive porcine naïve-like iPSC from pADSC, which may be useful for the production of living offspring.
Y. Zhang and C. Wei contributed equally to this work. Y.-H. Zhang is the corresponding author. This work was supported by the National Natural Science Foundation Program 31272442.
Defined, serum-free conditions for in vitro culture of primary human T-ALL blasts
