RepSox Increases Porcine Cloning Efficiency by Improving Pluripotency of Donor Nuclei

Accumulating evidence suggests that a low pluripotency of donor nuclei might lead to abnormal development of cloned embryos and underlie the inefficiency of mammalian somatic cell nuclear transfer (SCNT). To improve the pluripotency of SCNT embryo, RepSox, a defined small-molecule compound that functions in inhibiting the transforming growth factor β signaling pathway, was used to treat nuclear-transferred porcine oocytes after activation. We found that the developmental ability of porcine SCNT embryos (defined as the blastocyst rate) was significantly increased (13.5% vs. 21.8%) when 25 μm RepSox was added to the porcine embryo culturing system for 14-16 hours after activation. Of note, RepSox treatment significantly increased the transcriptional expression of the pluripotency gene NANOG at the four- and eight-cell stages. Furthermore, according to the TUNEL (TdT-mediated dUTP nick end labeling) staining and expression levels of the apoptosis-regulated gene Caspase 3 and proapoptotic gene Bax, the percentage of apoptotic cells in blastocyst cells was not affected after RepSox treatment. These results indicated that treatment with RepSox enhanced the developmental competence of porcine SCNT embryos through improvements in nuclear pluripotency.