Abstract
Faulty reprogramming of the donor somatic nucleus to a totipotent embryonic state by the recipient oocyte is a major obstacle for cloning success. Accordingly, treatment of cloned embryos with epigenetic modifiers, such as histone deacetylase inhibitors (HDACi), enhances cloning efficiency. The purpose of our study was to further explore the potential effect of valproic acid (VPA), used in previous studies, and to investigate the effect of psammaplin A (PsA), a novel HDACi, on the development and quality of cloned mouse embryos. To this aim, cloned embryos were treated with 5, 10, and 20 μM PsA or 2 and 4 mM VPA for 8-9 h (before and during activation) or 16 h or 24 h (during and after activation), and their in vitro developmental potential and blastocyst quality were evaluated. Treatments with 10 μM PsA and 2 mM VPA for 16 h were selected as the most optimal, showing higher blastocyst rates and quality. These treatments had no significant effects on the expression of Nanog, Oct4, and Cdx2 or on global histone and DNA methylation levels at the blastocyst stage, but both increased global levels of histone acetylation at early developmental stages. This was correlated with a two-fold (for VPA) and four-fold (for PsA) increase in full-term development, and a 11.5-fold increase when PsA was combined with the use of latrunculin A instead of cytochalasin B. In conclusion, PsA improves mouse cloning efficiency to a higher extent than VPA.