An optimized protocol of a human-to-cattle interspecies somatic cell nuclear transfer.

Human somatic cells were transferred into cattle enucleated oocytes, and a prospective, randomized study was designed to optimize donor cell preparation, fusion medium, and culture method. As a result, improved development of interspecies embryos was achieved by employing serum-starved cord fibroblasts, with Ca(2+)/Mg(2+)-free fusion medium and a serum-free medium being used for bovine embryos.