Increased Pre-Implantation Development of Cloned Wuzhishan Miniature Pig Embryos Treated With Scriptaid and Valproic Acid

The aim of the present study was to examine the effects of scriptaid (SCR), a histone deacetylase inhibitor (HDACi), on the in vitro and in vivo development of Wuzhishan miniature pig somatic cell nuclear transfer (SCNT) embryos. Experiment 1 compared the in vitro developmental competence of nuclear transfer embryos treated with various concentrations of SCR for 24 h. Embryos treated with 250 nM SCR showed a significantly increased rate of blastocyst formation compared with controls or embryos treated with 50 nM or 500 nM SCR (20.00% vs. 12.16%, 8.89%, and 11.86%, respectively). Experiment 2 examined the in vitro developmental competence of nuclear transfer embryos treated with 250 nM SCR for different time periods following chemical activation. Embryos treated for 24 h showed higher rates of blastocyst formation than controls or embryos treated for 12 h or 48 h (22.22% vs. 11.54%, 10.00%, and 18.52%, respectively). Experiment 3 directly compared the effects of SCR and VPA treatment and examined the additive effect of SCR and VPA on nuclear transfer embryos following chemical activation. Embryos treated with 250 nM SCR or 2 mM VPA for 24 h showed a significantly increased rate of blastocyst formation compared with controls (19.85% and 18.32 vs. 9.23%, respectively), but not increased with a combination of 250 nM SCR and 2 mM VPA for 24 h (18.90% vs. 19.85%, 18.32%). In experiment 4, nuclear transfer embryos treated with 250 nM SCR for 24 h and non-treated controls were transferred to surrogate mothers, resulting in the birth of healthy cloned pups from the controls but no births in the SCR-treated group. These results suggest that SCR treatment increases the rate of blastocyst formation in somatic cell nuclear transfer embryos and affects their subsequent growth. Also, co-treatment with VPA and SCR did not improve the blastocyst formation rate.