Embryonic stem cells generated by nuclear transfer of human somatic nuclei into rabbit oocytes

To solve the problem of immune incompatibility, nuclear transplantation has been envisaged as a means to produce cells or tissues for human autologous transplantation. Here we have derived embryonic stem cells by the transfer of human somatic nuclei into rabbit oocytes. The number of blastocysts that developed from the fused nuclear transfer was comparable among nuclear donors at ages of 5, 42, 52 and 60 years, and nuclear transfer (NT) embryonic stem cells (ntES cells) were subsequently derived from each of the four age groups. These results suggest that human somatic nuclei can form ntES cells independent of the age of the donor. The derived ntES cells are human based on karyotype, isogenicity, in situ hybridization, PCR and immunocytochemistry with probes that distinguish between the various species. The ntES cells maintain the capability of sustained growth in an undifferentiated state, and form embryoid bodies, which, on further induction, give rise to cell types such as neuron and muscle, as well as mixed cell populations that express markers representative of all three germ layers. Thus, ntES cells derived from human somatic cells by NT to rabbit eggs retain phenotypes similar to those of conventional human ES cells, including the ability to undergo multilineage cellular differentiation.

Establishment of customized mouse stem cell lines by sequential nuclear transfer

Therapeutic cloning, whereby embryonic stem cells （ESCs） are derived from nuclear transfer （NT） embryos, may play a major role in the new era of regenerative medicine. In this study we established forty nuclear transfer-ESC （NTESC） lines that were derived from NT embryos of different donor cell types or passages. We found that NT-ESCs were capable of forming embryoid bodies. In addition, NT-ESCs expressed pluripotency stem cell markers in vitro and could differentiate into embryonic tissues in vivo. NT embryos from early passage RI donor cells were able to form full term developed pups, whereas those from late passage RI ES donor cells lost the potential for reprogramming that is essential for live birth. We subsequently established sequential NT-RI-ESC lines that were developed from NT blastocyst of late passage R 1 ESC donors. However, these NT-R I-ESC lines, when used as nuclear transfer donors at their early passages, failed to result in live pups. This indicates that the therapeutic cloning process using sequential NT-ESCs may not rescue the developmental deficiencies that resided in previous donor generations.

Experimental cloning of embryos through human-rabbit inter-species nuclear transfer

Therapeutic cloning,which is based on human somatic cell nuclear transfer,is one of our major research objectives.Though inter-species nuclear transfer has been introduced to construct human somatic cell cloned embryos,the effects of type,passage,and preparation method of donor cells on embryo development remain unclear.In our experiment,cloned embryos were reconstructed with different passage and preparation methods of ossocartilaginous cell,skin fibroblast,and cumulus cells.The cumulus cell embryos showed significantly higher development rates than the other two(P<0.05).The development rate of embryos reconstruct-ed with skin fibroblasts of different passage number and somatic cells of different chilling durations showed no significant difference.Also,fluorescence in situ hybridization(FISH)was conducted to detect nuclear derivation of the embryos.The result showed that the nuclei of the inter-species cloned embryo cells came from human.We conclude that(1)cloned embryos can be constructed through human-rabbit interspecies nuclear transfer;(2)different kinds of somatic cells result in different efficiency of nuclear transfer,while in vitro passage of the donor does not influence embryo development;(3)refrigeration is a convenient and efficient donor cell preparation method.Finally,it is feasible to detect DNA genotype through FISH.