Developmental kinetics of pig embryos by parthenogenetic activation or by handmade cloning

Division Behaviors and Their Effects on Preimplantation Development of Pig Embryos

Quality of preimplantation embryos could affect development efficiency after embryo transfer. However, assessment of preimplantation embryos was unsatisfied especially in pig embryos to date. Therefore, the present study was design to investigate available and applicable parameters which indicating development potential and quality of porcine preimplantation embryos produced by handmade cloning (HMC), parthenogenetic activation without zona pellucida (PAZF) and with zona pellucida (PAZI). Results firstly detected a common division behavior that formation of uneven division with two unequal size blastomeres (UD 2-cell), especially in HMC embryos, the proportion of UD 2-cell was significantly higher than that of equal size blastomeres (ED 2-cell) with 72.56 ± 4.56 vs. 24.57 ± 1.92. Formation of UD 2-cell might due to spindle migrates along the long axis in 1-cell stage, and the cleavage furrow not formed in the center of cytoplasm. In the two sister blastomeres of UD 2-cell, unevenly distribution of organelles (mitochondria and lipid droplet) was observed with lower proportion in the smaller one (p<0.05). Althoug no difference of blastocyst rate was observed between UD and ED 2-cell embryos, the cell number per blastocyst from UD 2-cell embryos was lower than that from ED 2-cell embryos (44.15 ± 2.05 vs. 51.55 ± 1.83). Besides, because of nonsynchronized division of each blastomeres, another common behavior that three cleavage routes were observed in all of HMC/PAZF/PAZI embryos that T1 (2-cell → 3-cell → 4-cell → ≥ 5-cell → morula → blastocyst), T2 (2-cell → 3-cell → 4-cell → morula → blastocyst), and T3 (2-cell → 3-cell / 4-cell → morula → blastocyst). Therefore, in pig in vitro produced embryos, division behaviors of uneven volume of cytoplasm and nonsynchronized cell cycles were observed at the early embryonic developmental stage, which might be another potential factor to evaluate embryonic development.

Systematic in vitro and in vivo characterization of Leukemia-inhibiting factor- and Fibroblast growth factor-derived porcine induced pluripotent stem cells

Derivation and stable maintenance of porcine induced pluripotent stem cells (piPSCs) is challenging. We herein systematically analyzed two piPSC lines, derived by lentiviral transduction and cultured under either leukemia inhibitory factor (LIF) or fibroblast growth factor (FGF) conditions, to shed more light on the underlying biological mechanisms of porcine pluripotency. LIF‐derived piPSCs were more successful than their FGF‐derived counterparts in the generation of in vitro chimeras and in teratoma formation. When LIF piPSCs chimeras were transferred into surrogate sows and allowed to develop, only their prescence within the embryonic membranes could be detected. Whole‐transcriptome analysis of the piPSCs and porcine neonatal fibroblasts showed that they clustered together, but apart from the two pluripotent cell populations of early porcine embryos, indicating incomplete reprogramming. Indeed, bioinformatic analysis of the pluripotency‐related gene network of the LIF‐ versus FGF‐derived piPSCs revealed that ZFP42 (REX1) expression was absent in both piPSC‐like cells, whereas it was expressed in the porcine inner cell mass at Day 7/8. A second striking difference was the expression of ATOH1 in piPSC‐like cells, which was absent in the inner cell mass. Moreover, our gene expression analyses plus correlation analyses of known pluripotency genes identified unique relationships between pluripotency genes in the inner cell mass, which are to some extent, in the piPSC‐like cells. This deficiency in downstream gene activation and divergent gene expression may be underlie the inability to derive germ line‐transmitting piPSCs, and provides unique insight into which genes are necessary to achieve fully reprogrammed piPSCs. 84: 229–245, 2017. © 2016 Wiley Periodicals, Inc.

Evaluation of porcine stem cell competence for somatic cell nuclear transfer and production of cloned animals

Porcine somatic cell nuclear transfer (SCNT) has been used extensively to create genetically modified pigs, but the efficiency of the methodology is still low. It has been hypothesized that pluripotent or multipotent stem cells might result in increased SCNT efficacy as these cells are closer than somatic cells to the epigenetic state found in the blastomeres and therefore need less reprogramming. Our group has worked with porcine SCNT during the last 20 years and here we describe our experience with SCNT of 3 different stem cell lines. The porcine stem cells used were: Induced pluripotent stem cells (iPSCs) created by lentiviral doxycycline-dependent reprogramming and cultered with a GSK3β- and MEK-inhibitor (2i) and leukemia inhibitor factor (LIF) (2i LIF DOX-iPSCs), iPSCs created by a plasmid-based reprogramming and cultured with 2i and fibroblast growth factor (FGF) (2i FGF Pl-iPSCs) and embryonic germ cells (EGCs), which have earlier been characterized as being multipotent. The SCNT efficiencies of these stem cell lines were compared with that of the two fibroblast cell lines from which the iPSC lines were derived. The blastocyst rates for the 2i LIF DOX-iPSCs were 14.7%, for the 2i FGF Pl-iPSC 10.1%, and for the EGCs 34.5% compared with the fibroblast lines yielding 36.7% and 25.2%. The fibroblast- and EGC-derived embryos were used for embryo transfer and produced live offspring at similar low rates of efficiency (3.2 and 4.0%, respectively) and with several instances of malformations. In conclusion, potentially pluripotent porcine stem cells resulted in lower rates of embryonic development upon SCNT than multipotent stem cells and differentiated somatic cells.