Nuclear and cytoskeletal dynamics during oocyte maturation and development of somatic cell cloned pig embryos injected with membrane disintegrated donor cells

Genetic polymorphisms, growth performance, hematological parameters, serum enzymes, and reproductive characteristics in phenotypically normal Landrace boars produced by somatic cell nuclear transfer

Understanding the performances of cloned pigs and their offspring is critical to evaluate the practical applications of somatic cell nuclear transfer. In this study, genetic polymorphism, growth performance, hematological parameters, and reproduction characteristics of cloned Landrace boars were compared with those of controls. In addition, the growth performance of clone offspring was also evaluated. A total of 479 reconstructed embryos were transferred to five recipient pigs and resulted in the delivery of 14 piglets (overall cloning of 2.9%) from two litters. Analyses of microsatellite markers and polymorphisms of the specific genes confirmed that the 14 clones were genetically identical to the nuclear donor and maintained the desirable genotypes. Growth performance of five healthy, phenotypically normal cloned boars from one litter and eight of their male offspring did not differ from age, breed, and management-matched controls. Although some significant differences were observed between cloned and control boars in hematological and serum enzymes, most of these parameters were within the normal range. Cloned boars had less (P < 0.05) normal sperm in the ejaculated boars than in control boars (71.4% vs. 77.9%, respectively), but sperm production (ejaculate volume, sperm concentration, and total sperm) did not differ between these groups. In addition, use of frozen-thawed semen from cloned boars for insemination produced results that seemed comparable to a control. In conclusion, the present study reported that somatic cell nuclear transfer is effective in reproducing preferred genetic traits and has potential applications to conserve elite bloodlines in a routine pig breeding program.

Ascorbic acid improves the developmental competence of porcine oocytes after parthenogenetic activation and somatic cell nuclear transplantation

In this study, a dose-response assessment was performed to understand the relation between supplementation of media with L-ascorbic acid or vitamin C and porcine oocyte maturation and the in vitro development of parthenotes (PA) and handmade cloned (HMC) embryos. Various concentrations (0, 25, 50 and 100 µg/ml) of vitamin C supplemented in in vitro maturation (IVM) and culture (IVC) media were tested. None of these vitamin C additions affected nuclear maturation of oocytes, yet supplementation at 50 µg/ml led to significantly increased intracellular glutathione (GSH) levels and reduced reactive oxygen species (ROS). When cultured in IVM- and/or IVC-supplemented media, the group supplemented with 50 µg/ml of vitamin C showed improved cleavage rates, blastocyst rates and total cell numbers per blastocyst (P<0.05) compared with other groups (control, 25 µg/ml and 100 µg/ml). In contrast, supplementation with 50 µg/ml vitamin C decreased (P<0.05) the apoptosis index as compared with the groups supplemented with 100 µg/ml. In addition, even with a lower blastocyst rate to start with (37.6 vs. 50.3%, P<0.05), supplementation of HMC embryos with vitamin C ameliorated their blastocyst quality to the extent of PA embryos as indicated by their total cell numbers (61.2 vs. 59.1). Taken together, an optimized concentration of vitamin C supplementation in the medium not only improves blastocyst rates and total cell numbers but also reduces apoptotic indices, whereas overdosages compromise various aspects of the development of parthenotes and cloned porcine embryos.

Sonic Hedgehog improves in vitro development of porcine parthenotes and handmade cloned embryos

This study investigated the expression of Sonic Hedgehog (Shh) signaling pathway and its effect on porcine parthenogenetic (PA) embryo development. The Shh receptor Patched (Ptc1) and co-receptor Smoothened (Smo) were expressed at various stages of PA porcine embryos, at both mRNA and protein levels. Furthermore, the transcriptional activator Gli1 mRNA was first present in the 2-cell stage embryos, and was readily detected at the 4-cell stage and beyond. Culture medium supplemented with 0.5 μg/mL Shh optimized blastocyst rates (58.6 vs. 41.1%; P < 0.05) and the total number of cells per blastocyst (56.4 vs. 45.6 cells; P < 0.05); however, this response was prevented by simultaneous addition of 1 mM cyclopamine (an Shh inhibitor). Moreover, blastocysts that developed in medium containing 0.5 μg/mL Shh had lower apoptotic indices and reduced DNA damage (evaluated by TUNEL and comet assays, respectively). Based on Western-blot analysis, expression of phosphorylated Akt protein in Shh-treated blastocysts was higher than that of the control group (1.22- vs. 0.66-fold, P < 0.05), and less total PARP-1/2 protein was accumulated (0.7-fold, P < 0.05) in treated blastocysts compared to untreated controls. Furthermore, supplementation of Shh (1 μg/mL) also supported development of handmade cloned embryos (50.3 vs. 26.8%; P < 0.05) with reduced apoptotic rates (2.8 vs. 6.3%; P < 0.05). We inferred that the Shh signaling pathway existed in porcine PA embryos and we concluded that Shh supplementation improved the quality and developmental competence of early PA embryos, at least in part, by increasing cell proliferation and reducing apoptosis of the developing embryos.

Transient in vitro epigenetic reprogramming of skin fibroblasts into multipotent cells

Multipotent stem cells have the potential to establish a new field of promising regenerative medicine to treat tissue damage, genetic disorders, and degenerative diseases. However, limited resource of stem cells has turned to be an evitable obstacle in clinical applications. We utilized a simple in vitro epigenetic reprogramming approach to convert skin fibroblasts into multipotent cells. After transient reprogramming, stem cell markers, including Oct4 and Nanog, became activated in the treated cells. The reprogrammed cells were multipotent as demonstrated by their ability to differentiate into a variety of cells and to form teratomas. Genomic imprinting of insulin-like growth factor II (Igf2) and H19 was not affected by this short period of cell reprogramming. This study may provide an alternative strategy to efficiently generate patient-specific stem cells for basic and clinical research, solving major hurdles of virally-induced pluripotent stem (iPS) cells that entail the potential risks of mutation, gene instability, and malignancy.

Sonic hedgehog promotes porcine oocyte maturation and early embryo development

In the present study, we investigated the effects of the Sonic hedgehog (Shh) protein on porcine oocyte maturation and early embryo development. Immunohistochemistry showed activation of Shh signalling in cumulus–oocyte complexes (COCs), as reflected by Patched (Ptc), Smoothened (Smo) and Gli1 expression in oocytes, cumulus cells and granulosa cells, particularly those of small follicles (<2 mm in diameter). Western blot analysis showed Smo expression in COCs and in denuded oocytes derived from small and medium (3–7 mm)-sized follicles. Small follicles contained the highest concentration of Shh in follicular fluid compared with medium-sized and large (>7 mm in diameter) follicles. Supplementation with Shh (0.5 or 1 μg mL–1) enhanced oocyte maturation compared with the control group (92.4% and 90.4% v. 81.9%, respectively; P < 0.05). This effect was reversed by the simultaneous addition of cyclopamine (1–2 μm), an Shh inhibitor. Similar to intact COCs, denuded COCs showed enhanced maturation following Shh supplementation. Furthermore, cyclin B1 content, extracellular signal-regulated kinase 1/2 phosphorylation, intracellular calcium release, blastocyst rate and total cell numbers were greater (P < 0.05) in oocytes matured in the presence of 0.5 and 1 μg mL–1 Shh compared with control oocytes. The findings of the present study provide the first evidence that the Shh signalling pathway is active, or at least partially activated, in the porcine ovary and is likely to promote oocyte cytoplasmic and nuclear maturation, as well as subsequent in vitro development, although the underlying mechanisms remain to be elucidated.