Akiko Yabuuchi from George Daley’s lab at Children’s Hospital of Boston reported on using somatic cell nuclear transfer to reprogram human nuclei (Daley’s in fact) in bovine egg cells at the Society for the Study of Reproduction meeting in Kona, today. Interspecies nuclear transfer is highly controversial, so it wasn’t exactly surprising that one of Yabuuchi’s first slides mentioned that the project has approval from the Institutional Review Boards and Embryonic Stem Cell Research Oversight committees at Brigham and Women’s and Children’s Hospital where the work was carried out. The efficiency wasn’t very high, but the hybrid embryos were able to undergo cleavage and correct segregation of the human chromosomes. Several made it to the 16-cell stage, but none survived past that. The goal was not implantation or pregnancy, of course, but to monitor development in these hybrid embryos and see if they could potentially lead to embryonic stem cell lines. The project includes tests to see whether extract from human embryonic cells will provide some of the necessary materials to allow normal nuclear reprogramming in the foreign egg environment. Yabuuchi in her acknowledgement said Daley was a great boss for, among other things, providing the skin cells they were using as nuclei donors.
This wasn’t the first instance of interspecies cloning I heard about today. So-Gun Hong from Seol National University was performing interspecies somatic cell nuclear transfer with dog nuclei and bovine egg cells. It’s preliminary work, with little success so far. The interspecies nuclear transfer experiments are ancillary to a project to simply create a transgenic dog expressing GFP using somatic cell nuclear transfer into dog egg cells, but these eggs are notoriously hard to come by. No luck in getting a live birth yet, according to So-Gun.
In one of the stranger incidences of hybrid cloning talked about today, Sandra Lencka-Ostrowaska from the Institute of Genetics and Animal Breeding of the Polish Academy of Sciences in Jastrzebiec, Poland presented her work using mouse eggs to try and reprogram the nuclei of Clethrionomys glareolus, the bank vole. The reason? Generating interspecies hybrids may provide ways to study species specific nuclear reprogramming. The technical challenges in nuclear reprogramming using egg cells remain despite the tremendous advances of Shinya Yamanaka and others with so-called induced pluripotent stem cells. The work continues and it will be interesting to see what happens next.