One of the big aims in stem cell research has been to take DNA from adult into an egg cell to create a clone. Ever since the cloning of Dolly the sheep in 1996, researchers have been trying to recreate this experiment with other animals as well as humans. The results have been mixed over the years but in October a lab in the US published some results showing an extraction of reproducing stem cell from embryos, after injecting adult cells into egg cells (Noggle, S. et al. Nature 478, 70-75 (2011)).
Recently after the creation of induced pluripotent stem (iPS) cells in 2006 it has been questioned whether it is still necessary to work on conventional stem cells. The advantage of this approach is that it does not need egg cells and avoids most ethical issues associated with embryonic stem cells.
In conventional cloning techniques, the single set of chromosomes are removed from the egg cell, inject the two sets of chromosomes from the adult cells and try to get the introduced DNA to drive the egg towards embryonic development. These new cells normally are not like stem cells because they do not self replicate after a few divisions.
The current experiments were run on “… 270 eggs from 16 donors, isolating the three key events of conventional cloning techniques to see which was causing the problem. The culprit turned out to be removing the egg’s DNA.
Miodrag Stojkovic, a cloning expert at the University of Kragujevac in Serbia, echoes these concerns. “These are abnormal cells and therefore are a very limited tool to understand early human development,” …”
The problem with the current results are that the embryos are not true clones, because the DNA of the stem-cell line does not match that of the original adult cell but addresses some of the problem in this, still very open area of research.
The scientific community will pursue research in this exciting area which could potentially yield huge benefits.