L'Ombre de l'Olivier

The Shadow of the Olive Tree

being the maunderings of an Englishman on the Côte d'Azur

11 April 2007 Blog Home : April 2007 : Permalink

Stem Cell Errors

Recently I wrote about how stem cell research is one of the areas that people don't grok properly. A good example of this is the coverage of the diabetes results today. The BBC and the Times both mae misleading statements. The BBC explains:

Stem cells are immature cells which can become different types of adult tissue.

and the Times similarly says:

Stem cells are immature, unprogrammed cells that have the ability to grow into different kinds of tissue and can be sourced from people of all ages.

The Times article then goes on to make what Tim W perceives as a gratuitous swipe at President Bush by bringing up the embryonic stem cell issue. I agree with Tim that if you are going to mention Bush's ban on federal stem cell funding it helps if you get the details right. i.e. mention that the ban is merely on the federal funding of research. However Tim does get a bit confused here:

It might also be worth noting a further fact. The phrase "most versatile" is as yet unproven. There are as yet no treatments at all that stem from (sorry) embryonic stem cells, but there are as above, some very interesting ones from adult lines. We might yet find out that adult line sare indeed more versatile, especially when we consider the subject of rejection.

No one has yet identified any adult stem cell that can create all cell types. This is precisely what both Auntie and the Wapping Liar get wrong or at least make it so that a casuak reader will misunderstand. Adult stem cells can only produce a handful of cell types, in almost all cases just one cell type, so if you harvest pancreatic stem cells (say) then you won't be able to grow bone marrow or heart muscle from them. On the other hand embryonic stem cells can actually make any sort of cell so that in theory an embryonic stem cell could be used to make any part of the body from brain to toenail. This fact (the abaility of embryonic stem cells to make anything but adult ones to only make limited sorts of cells) has been demonstrated all over the place in scientitic literature and was one of the reasons why the ability to clone entire organisms by inserting their DNA into a denuclearized embryo was such a surprise. In fact IIRC part of the problem with adult stem cells is that we haven't yet identified stem cells for every cell type. Another problem is that some stem cells are hard to get at. E.g. the brain stem cells appear to live in the middle of the brain so getting access to them without harming the rest of the brain is a non-trivial exercise.

Now there is another problem which the science writers don't mention: namely that outside of the embryo, where all cells are stem cells, no one has developed a way to identify stem cells from their non-stem neighbours other than by observing that they can split and produce new cells apparently infinitely.

The result of these facts is that if it were possible (from both a tehnical and ethical POV) to obtain embyonic cells which could be given the nucleus of an adult cell and then grown to make arbitrary adult cells rather than an entire embryo this would seem to be a better course of action than hunting around for the right sort of adult stem cell. However no one has yet got beyond some very basic levels of research when it comes to embryonic stem cells so no one knows how feasible this is let alone whether it has unfortunate side effects. We do know that clones that are born seem to exhibit abnormalities but no one knows whether this is due to the way they are created (there are tens if not hundreds of failed attempts for every viable clone produced as it is anyway) or something inherent to the adult DNA that they have received.

On the other hand despite some recent successes in isolating adult stem cells and creating and implanting tissue from them we don't know whether these techniques are any good either. They may work but we simply haven't done enough tests to know if the inserted cells do end up helping the body or not and if they do for how long this period lasts. Neither this diabetes treatment nor the heart stem cell stuff from last week is ready to graduate from the laboratory trial yet.

In fact we have a lot of research to do on the whole stem cell process and all sorts of stem cells which is why I think that President Bush's funding ban was counterproductive. We simply don't know enough to know what works and what doesn't.

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I despise l'Escroc and Vile Pin