Improvement of embryonic development and production of offspring by transferring meiosis-II chromosomes of senescent mouse oocytes into cytoplasts of young mouse oocytes

Purpose  The effects of reciprocal transplantation of meiosis-II chromosomes between senescent and young mouse oocytes were evaluated based on pre- and post-implantation development ability of resultant embryos. Methods  Karyoplasts including meiosis-II chromosomes of oocytes from senescent Rockefeller mouse/Ms-Rb(6, 15) females (10 to 12 months, age-related infertile mice) were transferred into cytoplasts of oocytes from young F₁ females (3 to 5 months). Reconstructed oocytes were fertilized in vitro, and then the resultant embryos were cultured in vitro and transferred to recipient mice. Results  The reconstructed oocytes that consisted of aged-karyoplasts and young-cytoplasts showed significantly improved embryonic development (from 23.2% to 30.0%) and development to term (from 6.3% to 27.1%, P < 0.05) as compared with the oocytes reconstructed from young-karyoplasts and aged-cytoplasts. Conclusions  The present study showed successful rejuvenation for age-related infertility using transplantation of meiosis-II chromosomes in animal experimental models. Capsule Transplantation of meiosis-II chromosomes of senescent mouse oocytes into cytoplasts of young mouse oocytes improves subsequent embryonic and fetal development until birth.