Production of viable pigs from fetal somatic stem cells

Fetal somatic stem cells (FSSCs) are a novel type of somatic stem cells that have recently been discovered in primary fibroblast cultures from pigs and other species. The goal of the present study was to produce viable piglets from FSSCs. NT complexes were prepared from both FSSCs and porcine fetal fibroblasts (pFF) to permit comparison of these two donor cell types. FSSCs from isolated attached colonies were compared with pFF in their ability to form blastocysts upon use in NT. Fusion and cleavage rates were similar between the two groups, while blastocyst rates were significantly higher when using pFF as donor cells. FSSCs of three different size categories derived from dissociation of spheroids yielded similar results. The use of FSSCs of 15-20 mu m in size yielded similar cleavage and blastocyst rates as fetal fibroblasts. In the final experiment NT complexes produced from FSSCs were transferred to foster mothers. After transfer to prepubertal gilts, three of seven recipients established pregnancies and delivered seven piglets, of which three piglets were viable and showed normal development. Results for the first time demonstrate that FSSCs are able to produce cloned embryos, and that pregnancies can be established and viable piglets can be produced.