Parthenogenetic babies from IVM eggs and tetraploid complementation

Abstract

OBJECTIVE: Produce offspring from parthegenotes to demonstrate their pluripotency, and test whether activated eggs can contribute to all tissues, and therefore provide a valuable source of cells for regenerative medicine. Women facing cancer therapy or combat could benefit from pluripotent cells for regenerative medicine. Parthenogenetic embryonic stem (pES) cells produced from activated eggs avoid ethical constraints, but their digyneic origin raises concerns about abnormal imprinting, including hypomorphic placenta and limited contributions to some fetal tissues. In vitro maturation (IVM) disrupts imprinting, so paradoxically may help erase digyneic imprinting of parthenogenetic embryos. Also, stem cells undergo extensive epigenetic reprogramming, and tetraploid complementation can furnish a placenta to support development and differentiation of pES cells to pups. DESIGN: Laboratory-based mouse study. MATERIALS AND METHODS: IVM-produced B6C3F1 mouse eggs were activated with strontium, cultured to blastocyts, pES cells produced and characterized, injected into KM tetraploid embryos, transferred to ICR surrogates, and the contribution of pES cells to tissues in resulting pups studied. PCR analysis of DNA microsatellites and allele heterozygosity determined the pups' origin. RESULTS: pES cells were Oct 4, SSEA-1, AP, TERT, Nanog postive, karyotypically normal and produced teratomas in nude mice. We produced for the first time term pups from parthenogenesis by using IVM eggs and tetraploid complementation. Microsatellite and heterozygoisity analyses confirmed the pES cell origin of all pups. CONCLUSIONS: Epigenetic reprogramming from IVM and passage through the stem cell state overcome digyneic imprinting, and tetraploid complementation furnishes placentas to produce term pups from pES cells. This does not justify fatherless reproduction, but does suggest that pES cells may provide a valuable and ethically justifiable source of private pluripotent cells.