Science moves fast; last year a scientific article from Shoukhrat Mitalipov’s lab (1) claimed that they had succeeded in cloning a human up to the stage of embryo and produced stem cells from it. I was sceptical back then and commented “Other labs still have to reproduce Mitalipov’s experiments…”. So far this year at least 3 labs (2,3) have reproduced Mitalipov’s work: they have introduced the nuclei of adult cells into oocytes, produced embryos and generated embryonic stem cells from those embryos. This has been –in many ways- a big scientific breakthrough. Now a wider debate should take place to determine whether there is any need to continue producing more embryonic stem cells lines by this method.
Embryonic stem cells (ESCs) can be propagated almost indefinitely in culture and have the potential to differentiate into any one of the more than 200 cell types in the adult body. These properties make them an ideal tool for research and regenerative medicine. There are currently hundreds of embryonic stem cell lines that were generated from normal embryos. Extensive comparisons between normal ESCs and ESCs produced by cloning may be required to establish their equivalence. The exact number of cells produced by cloning that will be required for doing this is open to question.
In 2006 -before human cloning was achieved- a method was developed for generating embryonic-like stem cells directly from adult cells, without the need of using embryos (4). These cells are called iPSCs. We can produce iPSCs routinely now, through chemical or genetic manipulation of adult cells. Scientists have found that iPSCs are not exactly equivalent to ESCs. iPSCs show different marks that allow for their separation from true ESCs (5). But scientists have also shown (in several animal models) that iPSCs are capable of generating any organ in the body, including the sexual organs . Hence, iPSCs can do pretty much everything ESCs do, regardless of “marks”. Too much emphasis on classifications by marks and fingerprints can be misleading if, at the end of the day, iPSCs act like ESCs.
For the moment, the weakest point of iPSCs is that they are generated mainly by genetic manipulation. This makes their approval for clinical use burdensome; there might be “off-target” effects rendering the cells prone to becoming cancerous. Cloned ESCs do not require genetic manipulation. On the other hand, cloned ESCs may also carry abnormalities, and their genetic material is not 100% identical to the DNA of the individual that was cloned -The mitochondrial DNA belongs to the oocyte’s donor.
There are many ethical problems regarding both human cloning and generation of embryos for medical or experimental purposes. Some countries, like Germany, have pre-emptively banned the creation –by any means- of embryos for research; in the UK there is no such a ban but funding for this type of research needs to be approved by an ethics committee (the Human Fertilisation and Embryology Authority or HFEA). In the US, after the 2009 repeal of regulations imposed during Bush’s administration, there seems not to be a clear framework regarding the creation of embryos (6). The existence of moral issues does not mean that the procedure should be banned outright. Many things that are morally questionable -like wars- are some times necessary. In the case of human cloning and embryo generation -as with war- there needs to be public consensus and general certainty that what we are doing has the right objectives and clear, achievable goals.Follow @arielpoliandri