Friday, December 16, 2005

More controversy on embryonic stem cell research

Embryonic stem cell research might now be more potentially viable for the UK Stem Cell Bank, which learned that samples from 150 random human embryos, far fewer than previously thought, might be able to generate materials beneficial for two thirds of the population. Embryonic stem cells can mature into various types of tissue that can potentially be used to replace “diseased or damaged tissue in conditions such as diabetes and neurodegenerative disorders.” A University of Cambridge team studying such potentialities has explained that the tissues generated from a mere ten samples of specific genetic makeup could theoretically support a UK bank. Researcher Professor Roger Pederson points out that a selective process as described would require “additional regulatory review.”

Displeased opponents say "false hope" is being raised among "desperate patients". Disregarding such criticisms, many scientists welcome stem cell research from spare IVF embryos as offering the possibility of a more cost-effective and practical alternative to therapeutic cloning. The scientific team calculated that cells from 150 random embryos would be enough to provide the best possible match for 13% of recipients, a favourable level of match for 65%, and some use for as many as 85%. Surprisingly, just 10 types of specifically selected genetic material would be enough to provide a favourable level of match for 78% of recipients.

At present the UK bank contains stem cells suitable only for research. Professor Pedersen told the BBC News website that “this research tells us is that the number of lines needed to achieve a significant clinical value is in the practical realm.” Professor Pederson also said that researchers were already working from spare IVF embryos. Dr Glyn Stacey, director of the UK Stem Cell Bank, acknowledged the importance of recent findings, but admitted researchers were still “a long way away in terms of establishing the basic cell culture methods” and do not know “whether all stem cell lines will give the full range of tissues." The charity Life argues that research had shown adult stem cells preferable to embryonic stem cells fro the purposes of treating disease. Spokesman Matthew O'Gorman said: "The UK stem cell debate is obscured by hype which only serves to raise false hope among desperate patients. “Embryonic stem cell research involves destructive experiments on tiny human beings, which is why it has been outlawed in the majority of countries worldwide.” Read more:


4 comments:

Sue Trinidad said...

Given the past week's revelations about the the South Koreans' research in this area, however, we should all be quite a bit more skeptical of promises of cures for human disease any time soon. If somatic stem cell nuclear transfer has in fact *not* worked in humans, this field is nowhere near as far along as had been reported/believed. . . doesn't mean it can't, or won't, happen--but from a policy standpoint, a realistic understanding of what might be possible, and when, is important information.

Kevin T. Keith said...

Recall that stem cell research and stem-cell-based therapies are completely separate questions, scientifically, morally, and, one hopes, policy-wise, from cloning or any other source of stem cells.

The only reason SCNT, or cloning, plays a role in the search for stem-cell-based therapies is that it provides a source of the stem cells that are needed. And the reason that source was seen as attractive is that it does not require the destruction of embryos created for potential reproductive purposes, as IVF-based embryonic stem cell research does. Of course, SCNT-derived embryos are different only in the mechanism of their creation from IVF embryos, so - despite attempts to distinguish "therapeutic clones" from "reproductive clones" - many of the same objections to destructive research on embryos raised to IVF-derived stem cells were also raised to SCNT-derived stem cells. But, again, the point to SCNT as an adjunct to stem-cell research was that it was intended to provide a less-objectionable source of the stem cells, not that it contributed in any way to the technical efficacy of using stem cells for therapy.

The Korean debacle underscores the technical difficulties of performing SCNT to obtain viable embryos - but it has no direct impact on actual stem cell research, or the potential use of stem cells in therapy. Geron, Inc. is planning human trials of stem-cell-based spinal neuron regeneration for the middle of this coming year (amid some controversy over whether they should test the procedure in primates first). Therapeutic trials using stem cells in animal models have already been conducted for neocortical diseases, blood diseases, heart disease, several muscular wasting diseases, and others - human trials would be the obvious next step. This work is in no way implicated by the apparent problems with the Korean cloning attempt.

Given that human stem cells were first cultured only in 1998, tremendous progress has been made toward their therapeutic application. The issue of SCNT as a means of generating blastulas for stem-cell harvesting is a side issue, one that arose only as an (unsuccessful) attempt to placate ideological opponents of any work with embryos - but it has nothing to do with that research itself. Stem cell therapy progress continues apace.

Sue Trinidad said...

Kevin, a question--since it seems like you know something about the science end of this. I understand that SCNT is about where to *get* stem cells, etc.

But I also thought that the reason SCNT was seen as attractive was that it would enable the creation of stem cells that would be compatible (because genetically identical) to the cell donor--which would theoretically reduce the risk of rejection. Am I off base here?

Kevin T. Keith said...

That's also true. That's a very good point - and you're right, I overstated the case in my comment above.

However, there are approaches to the immunocompatibility issue using non-autologous embryonic stem cells, not just self-donated adult stem cells. An interesting abstract is here:
http://www.nature.com/nri/journal/v2/n11/abs/nri934_fs.html;jsessionid=95164C47F024B0E2E3ABE6F0CA01868B

What I meant to emphasize is that there are embryonic stem cell trials in the pipeline that do not depend on SCNT, and it is unfortunate if the Korean mess is seen to cast a shadow over stem cell research generally, when really it involves only a method of producing stem cells.

But I spoke wrongly when I said that was its only purpose or benefit. Thanks for the correction.