Two separate teams have successfully isolated a new type of rodent stem cell that closely resembles human embryonic stem cell (hES). The Oxford and Cambridge University studies, both published in the journal Nature, show that this new stem cell type could help shed light on hES cell biology.
Roger Pederson, who headed the Cambridge research team, described the new stem cells - taken from the 'epiblast', the inner cell layer, of one-week-old rodent embryos - as the 'missing link' between mice and human ES cells. Previous efforts with three-day-old embryos failed to find ES cells that were similar to hES cells. The one-week-old epiblast cells are more mature than most harvested ES cells and might provide a closer glimpse of that crucial developmental cusp when cells begin to differentiate into fixed cell types.
If the strong molecular correlation is accurate then rodent cells could substitute human ES cells for many research purposes. Such an 'ethical alternative' could help some ES cell research to proceed free from the moral controversy surrounding human embryo destruction.
Ronald McKay, who headed the Oxford team, emphasised that epiblast cells offer unprecedented study opportunities through genetically inducing diseases. Until recently no viable technologies existed to avoid embryo destruction incurred during hES cell derivation and no known species could substitute for studies of human function and development. Epiblast cells provide a realistic alternative, but the impact and extent of species variation is largely unknown.
The same day, Pope Benedict XVI announced that the Roman Catholic Church staunchly opposes human ES cell research because embryo destruction violates life's human dignity. But critics of alternative sources to viable human embryos say these approaches are premature and complicate the debate. For example, last week Lifeline Cell Technology successfully triggered embryo development through stimulation of unfertilised eggs. However, the resulting cloned hES cells risk inferiority due to their parthenogenetic origin, and therapies derived from them could only ever be used to treat women. And as with therapeutic cloning, embryo destruction still occurs, although these cloned 'embryos' cannot legally and scientifically develop.
Researchers are studying how embryonic cells are 'programmed' to later produce only specific cell types such as heart cells versus liver cells. If scientists could solve the mystery of cell programming, then they could manipulate stem cells to create replacements for damaged cells, tissues and organs.
Sources and References
Pope Benedict supports adult stem cell research
Missing link stem cells may speed race for cures
Scientists: Stem cells created from eggs