Stem cell research

I would like to make a couple of scientific comments in relation to Mr Paul Vincenti's comments on "The problems with stem cell research" (The Sunday Times, October 15).

I agree with Mr Vincenti's stand about wholeheartedly disagreeing with the use of embryos - spare or otherwise - in the development of treatments for others. I am saddened (as I am sure are many others) to see the rapid agreement and tabling of a bill to entrench the position of the Ombudsman in the Constitution while a bill on the protection of the unborn child is always talked about but never tabled, despite the alleged wide bipartisan support.

While disagreeing with the chairman of Alternattiva Demokratika on this issue, one can at least see that his opinions are genuine. Whether the same can be said of the members of both major parties who regularly pay lip service to this issue without doing the required deed, remains to be seen.

I make these points because it is important to argue from a point of scientific correctness, otherwise an argument of this kind can appear to be a biased statement based on incomplete or incorrect information which unfortunately weakens the pro-life position, something I would not like to see.

Adult stem cells are not naturally totipotent, as Mr Vincenti suggests. Totipotency means the capability to re-create all the diverse tissues of the embryo including those of the placenta. It is only the first ball of eight cells which have this capability. Even within the very early embryo at a later stage, this natural ability is lost. The cells of the early embryo or blastocyst which are used regularly to make embryonic stem cells are called pluripotent, meaning that they can naturally re-capitulate all the cell types of the embryo without the placenta. Other adult stem cells, some of which can be induced to make many different types of tissues, such as the mesenchymal stem cells of cord blood, are called multipotent. The extent of multipotency differs with different types of adult stem cells but none are clearly totipotent. In fact the capability of trans-differentiation of adult stem cells is being challenged in some major clinical trials at present, though this is clearly still in debate and there is plenty of evidence to show that trans-differentiation does occur, although possibly not as frequently and easily as previously suggested.

Despite this, treatments with adult stem cells still provide some benefits, although the mechanism is unclear but may be due to factors they release which promote healing of the patient's tissue rather than replacement of that tissue. Mr Vincenti accurately points out that presently there are a lot of ongoing studies with adult stem cells but virtually none (at least in ethically regulated Western countries) with embryonic stem cells. This is quite true and it is likely to remain that way for the next 10 years or so.

This statement was made by one of the chairs of a stem cell session at the recent meeting I attended in Rotterdam organised by the European Chapter of the International Tissue Engineering and Regenerative Medicine Society (TERMIS). The reasons he gives are quite accurate too. The main problem with embryonic stem cells is that ensuring they have completely differentiated to the tissue one wants to implant is presently very difficult, and implanting even a small proportion of undifferentiated embryonic stem cells carries with it a real possibility of tumorigenesis. So the likelihood of embryonic stem cells finding their way into the clinic are slight.

I would personally be much happier to see these twin developments happen locally in the near future: Constitutional protection of the unborn child from conception - as many people, scientists and lay people alike wish - and development of public stem cell banking facilities, particularly using umbilical cord blood, as I have proposed myself in the past and which a number of colleagues are interested in re-proposing (a clear investment in the future health of the nation).