Cloned blastocysts produced by nuclear transfer from somatic cells in cynomolgus monkeys (Macaca fascicularis)

In nonhuman primates (NHPs), there have so far been few reports about nuclear transfer (NT), especially using adult somatic cells. The objective of this study was to determine the developmental competence of NT embryos derived from various somatic cells embryonic stem (ES), amniotic epithelial, cumulus, or fetal fibroblast cells] and the nuclear transfer method, such as electro fusion or piezo microinjection, activation with chemical reagent [ionomycine/6-dimethylaminopurine (DMAP), calcium ionophore A23187/DMAP, or cycloheximide (CHX)] and reprogramming time (1, 2, or 4 h; in this study, the duration from injection or fusion to activation was defined as the reprogramming time). Our results showed that a 1-h reprogramming and activation with ionomycin/DMAP are suitable for NT in monkeys. Developing cleaved embryos up to the six-cell stage was similar among all experiments. However, beyond the eight-cell stage, developmental rates were higher in NT embryos reconstructed with fetal fibroblast cells and amniotic epithelial cells, and we were able to produce NT blastocysts from these cells. Interestingly, electro fusion is sufficient for amniotic epithelial cells and piezo microinjection is better suited for fetal fibroblast cells to produce NT blastocysts, thus suggesting that the best method for somatic cell NT may be different between cell types.