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Comment by Dr Patrick Dixon on stem cell research and science of ageing, health care, life expectancy, medical advances, pensions, retirement, lifestyles.
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Comment by Dr Patrick Dixon on Scottish
Council on Human Bio-ethics Stem Cell Research Briefing Paper below:
stem cell research continues to make rapid progress, particularly
using adult stem cells from skin or bone marrow. In animal studies
these adult stem cells have been treated in the laboratory and re-injected
into animals that have been given artificial strokes or heart attacks.
The adult stem cells automatically identify damaged tissue and produce
almost perfect repairs.
( See also latest: Growing new tissue and organs - stem cell research
Bone marrow and other tissues could repair your brain, spinal cord and heart and cure diabetes or old-age blindness. Adult stem cells promise investor returns while embryonic stem cells and therapeutic cloning raise major ethical, legal, and image problems.)
This should not suprise us: all adult stem cells of course contain
all the genetic code needed to produce an entire clone of the adult
and so are well able in theory to produce whatever tissues or organs
are needed.
In practice the position of a cell in the embryo determines which
genes get shut down, as the fetus develops and cells become more
and more specialised. It was thought that once these cells had been
"determined" in the womb, they could no longer act as
flexibly as embryo stem cells from which they were originally derived.
But we now know this is incorrect. It is just a question of creating
the right chemical bath.
The lazy way to do that (cheating) is to place the adult cell nucleus
inside a human egg and let the contents of the egg (hardly understood)
do it all for you. The result is a human clone
with all the associated ethical problems whether you destroy it
or let it be born.
The clever way to do it is to create exactly the right chemcial
bath needed, in a test tube, and to bath adult cells in it, so they
are tricked into thinking they must behave once more as embryo cells.
As I say, the progress here has been breathtaking.
Of course there are no ethical objections whatever to using adult
stem cells to create new tissues, unlike the tacky process of taking
an adult cell, fusing it with an unfertilised egg, creating a cloned
embryo, taking cells from it and throwing the rest away.
In human cloning an adult nucleus is placed into an egg and in
that "natural" chemical bath all the genes are activated
to produce an entire human being. Embryo stem cell researchers have
been taking stem cells at the pre-implantation stage from human
embryos because they believed that it was not possible to reactivate
genes in adult cells.
So watch this space: embryo stem cells will I believe look increasingly
last century and ethically suspect as a means of treating disease,
compared to the remarkable potential of using the sick person's
own cells.
Bioethics paper by Kevin J. Dillon is below:
Summary of the
Main Points
Introduction
Definition, Source
and Application of Stem Cells
Criteria for the
successful use of stem cells in medical research.
Stem cells: update
and analysis of the most current research
Conclusion
Summary of the Main Points
The object of this Paper is to provide
an independent assessment of the Donaldson Committee's Recommendations
in light of the most recent advances in stem cell research.
Stem cells should be defined by their
ability to renew themselves and diversify into other cell types.
There are several readily accessible
sources of stem cells. Strict criteria apply to the use of these
sources in medical research.
Stem cells have wide potential application
in medicine. "Adult" stem cells have already been
used in the world's first recorded case of successful gene therapy
"surgery".
The views expressed by the Donaldson
Committee's on the limitations of "adult" stem cells
are now defunct.
Unlike "embryonic" stem cells,
"adult" stem cells have already been used extensively
in the successful treatment of a range of degenerative diseases
and conditions and have outstanding development potential.
The objections to the use of "adult"
stem cells advanced by the National Institutes of Health in
the U.S. have been overcome, according to the most up-to-date
research.
8. "Adult" stem cells have now surpassed
all other sources of stem cells in terms of widespread clinical
application, safety, availability and potential.
Introduction
Following the publication of stem cell research: Medical Progress
with Responsibility, the long-awaited Report of the Chief Medical
Officer's Expert Advisory Group on Therapeutic Cloning (August 2000),
a fierce debate has ensued over the Government's decision to "accept
the Report's recommendations in full."1
Focusing on the first Recommendation made by the Advisory Group
(otherwise known as the Donaldson Committee) that:
"Research using human embryos (whether created by in vitro
fertilisation or cell nuclear replacement) to increase understanding
about human disease and disorders and their cell based treatments
should be permitted, subject to the controls in the Human Fertilisation
and Embryology Act 1990."2,
serious ethical objections have been raised to the proposal to deliberately
create and clone human embryos for the purpose of stem cell extraction,
particularly in view of what opponents claim is a clearly defined
and ethical alternative in adult stem cells.
However, the Donaldson Committee's Report clearly states that the
ethical objections to the cloning of human embryos for this purpose
are "outweighed by the potential benefits" of using embryonic
stem cells to advance research into the treatment of degenerative
diseases.
Submitted to the Department of Health as long ago as January 2000,
the Report's recommendations are based on the most up-to-date scientific
evidence available to the Donaldson Committee between January and
December 1999, no less than nine months ago. And such is the pace
of advances in the field of stem cell research, many experts, including
scientists and medical doctors, have since challenged the basis
for the Report's findings.
The object of this Briefing Paper, therefore, is to provide independent
and informed analysis of the most up-to-date, cutting-edge stem cell research, in order to better inform those Members of the United
Kingdom Parliament who intend to vote on whether to accept the Recommendations
made by the Donaldson Committee.
This Paper is further intended as a resource for policy makers,
members of the legal and medical professions and other interested
parties who wish to keep abreast of the latest developments in the
field of stem cell research. All information contained within this
document has been obtained from sources freely available within
the public domain.
1. Definition, Source and Application
of Stem Cells.
1.1 What are Stem Cells?
The Chief Medical Officer's Advisory Group defined stem cells as
"unspecialised cells which have not yet differentiated into any
specific type of tissue."3 This
definition is consistent with the one applied by the National Institutes
of Health, the body appointed by President Clinton to consider the
value of research using Human Pluripotent Stem Cells (HPSCs).
However, the limitations of this definition were made clear by David
A. Prentice, Professor of Medical and Molecular Genetics at Indiana
State University, in his testimony before the American Congress
in February 2000. Dr Prentice defined stem cells as:
"...cells that can proliferate with almost unlimited potential,
maintaining a pool of growing and dividing cells, with the added
ability that some of the daughter cells can differentiate into specific
cell types."4
This definition accords greater significance to the unique capacity
of stem cells to constantly renew themselves, whilst maintaining
an ability to adapt to the specific cell types needed by the human
body. It is these unique properties that distinguish stem cells
from other cell-types in terms of clinical application and that
are central to the debate over the use of embryonic versus adult
stem cells.
1.2 Sources of Stem Cells.
The human body is a stem cell "gold mine", providing an almost unlimited
source of stem cells. However, the problem lies not in locating
these cells, but in isolating them from their source.
With this in mind, scientists have isolated several key "ready-made"
sources of stem cells, often referred to as "reservoirs". The following
sources fall within this category:
Blastocysts - embryos after six days of growth.
Early embryos created by human cloning.
Fetal Tissue.
Adult or child tissue.
Adult or child cells that can be grown into stem cells.
To date, only stem cells taken from adults or children (known generically
as "adult stem cells") have been used extensively and effectively
in the treatment of degenerative diseases.
1.3 Application of Stem Cells in Clinical
Medicine.
There are over 4,000 registered diseases specifically linked to
genetic abnormalities, as well as a host of others which are thought
to have a genetic component. Yet, although stem cells are unlikely
to provide fast-track miracle cures for these conditions - and are
even less likely to lead to a cure for all known human disease,
as certain commentators have speculated - they are unique in their
potential application to a large number of these diseases. As tiny
factories that have an ability to "re-stock" themselves when required
and develop a wide range of specialisms, stem cells meet the technical
specifications for use in gene therapy..
Indeed, in many pioneering research projects, completed since the
turn of the Millennium, scientists have demonstrated that stem cells
can be used to replenish or rejuvenate damaged cells within the
immune system of the human body and that damaged stem cells can
miraculously repair themselves and their neighbours.
For example, in what is regarded as the first documented case of
successful gene-therapy "surgery", scientists at the Necker Hospital
for Sick Children in Paris succeeded in treating two infants diagnosed
with Severe Combined Immunodeficiency Disease (SCID), a life-threatening
degenerative disease caused by defects on the male (X) chromosome.5
The team extracted "adult" stem cells from the children's bone marrow,
manipulated the cells in the laboratory to replace the damaged gene
with a functioning gene, then re-injected the cells back into the
bone marrow. The repaired cells then "replenished" the immune system
("re-stocked" it with healthy cells) and the children have since
gone on to make a full recovery.
2. Criteria for the Successful Use of
Stem Cells in Medical Research
The Donaldson Committee established a very strict set of criteria
governing the application of stem cells in research to develop treatments
for degenerative diseases. Attempting to strike a balance between
the availability and potential of stem cells (from all sources)
against the likelihood of their successful application in such research,
the Committee specified that:
"The successful application of stem cell research
would depend upon:
whether stem cells can be successfully isolated and grown in the
laboratory;
whether stem cells grown in the laboratory can be influenced to
turn into specific cell types;
whether stem cells that have formed particular cell types could
be used to treat patients whose tissue was diseased or damaged through
injury;
whether tissue grown in this way would develop normally or whether
there might be risks to the patient."
Based on above criteria, the Committee reached the conclusion that
so-called "transitional research" is "warranted across the whole
range of possible sources of stem cells in the first instance, including
embryos...", but with the proviso that the use of embryos be "...necessary
for the purposes of the research..."
However, whether indeed this research is "warranted across
the whole range" of sources, including human embryos, is called
into question by the extensive research on the medical application
of adult stem cells that has been published since the submission
of the Donaldson Committee's Report In January 2000.
3. Stem Cells: Analysis of the Most Up-To-Date
Research
The Recommendations made by the Donaldson Committee can only be
judged according to the yardstick of the most recent advances in
stem cell research.
3.1 Research Contradicting the Donaldson
Committee's Findings
A comparative analysis of the Donaldson Committee's findings against
the most up-to-date research (available in the public domain) on
the clinical application of stem cells, reveals a significant number
of anomalies. The Committee's Report makes misleading, and in some
cases totally incorrect, statements about the limited potential
of adult stem cells as an ethical alternative to human embryonic
stem cells.6 At this point,
it is important to remember that the remit of the Donaldson Committee
included the assessment of "...any alternative approaches that might
be pursued to achieve the same benefits."7
Consider the assertion made in Section 5 of
the Report:
"Theoretically, stem cells derived from early embryos have the greatest
potential to develop into most types of tissue.[..] Stem cells can
be extracted from some adult tissues but their potential to develop
into other kinds of tissue is also likely to be limited."8
Again, this statement mirrors a claim made more recently by the
Institutes of Health in the United States in its Guidelines for
Research Using Human Pluripotent Stem Cells. However, research
published in the August editions of the Journal of Neuroscience
Research and the American Journal Science, revealed that
adult stem cells can now be grown into liver or nerve tissue and
that human adult stem cells are of "generalised potential". It is
therefore a fact that, akin to embryonic stem cells, adult stem
cells are now considered by the majority of research scientists
to be "pluripotent" (of almost unlimited potential).
Initially published in the April 2000 edition of the Journal Science,
the account of this ground-breaking research came three months after
the submission of the Donaldson Committee's Report to the Government.
And without prior hindsight, the Report concluded that "(t)his is
basic research which if permitted would precede, probably by many
years, any possible application to treatment...", and further that:
"Most scientists consulted felt that the science was still several
years away from being able to deliver many of the technical building
blocks needed to make significant progress in achieving healthcare
benefits."
This statement was already out-of-date on the day of the Report's
publication. The above evidence makes it clear that adult stem cells
are already being used extensively to save or enhance the lives
of a significant number of people, whereas embryonic stem cells
have yet to really "scratch the surface" in terms of clinical
application.
3.2 Significant "Healthcare Benefits"
Unique to Adult Stem Cells
Over the past year, adult stem cells have been used either exclusively
or in combination with other treatments to achieve significant "healthcare
benefits" for sufferers of the following conditions:
Brain Tumours
Ovarian Cancer
Solid Tumours
Multiple Myeloma
Breast Cancer
Non-Hodgkin's Lymphoma
Multiple Sclerosis
Systemic Lupus
Rheumatoid Arthritis
Anaemia
Stroke
Blindness
Immuno-deficiency.
Furthermore, the future application of adult stem cells to treatment
therapies, where clinical trials have already indicated significant
potential benefit, include:
Parkinsons
Alzheimers
Nerve Damage
Organ Transplantation/Growth
Blood Production
Muscle Regeneration
Diabetes/Pancreatic Disorders
Heart Valve Replacement.
Following on from the specific example given in Section 1.39,
documentary evidence of the above cases of successful treatment
using adult stem cells can be found in a host of Journals published
by and large within the past year. To give three additional examples:
1. The March 2000 Edition of the Journal Blood reported the
successful treatment of Breast Cancer using a combination of chemotherapy
and adult stem cell transplantation.10
2. The October 1999 Edition of the Journal of Clinical Oncology
reported on "Long-Term Survivors" of "Advanced Neuroblastoma" who
had remained disease-free for 66 months. The scientists behind their
treatment reached the conclusion that:
"The requisites for survival in such patients seem to be intensive
induction chemotherapy, effective surgery, irradiation, and the
use of (adult) SCT (Stem cell Transplantation).11
3. The July 1999 Edition of the Journal of Clinical Oncology
reported on a clinical trial on patients with solid tumours using
chemotherapy supported by adult stem cell transplantation. 96% of
patients responded to the treatment and the use of adult stem cells
was found to be both "safe" and "feasible".12
It should be noted that, of these three Papers, two were published
several months prior to the submission of the Donaldson Committee's
Report to the Government. Taken in conjunction with the extensive
research documenting other successes in the clinical application
of adult stem cells, there emerges a clear inconsistency between
the position adopted by the Committee and the most recent advances
in stem cell research. Adult stem cells, derived from the human
body of both adults and children, have clearly "stolen" a considerable
"march" on other sources of stem cells in terms of low-risk clinical
application.
3.2 Further Research Confirming the Feasibility
of Adult Stem Cells
The Report of the National Institutes of Health (NIH), the body
charged with advising the United States Government on research using
HPSC, also failed systematically to represent the considerable body
of research supporting the use of adult stem cells.
However, the NIH went a step further than the Donaldson Committee
in outlining several very specific reasons why it believed that
"adult stem cells may have more limited potential than embryonic
stem cells."13
Firstly, the NIH claimed that "stem cells in adults are present
in only minute quantities" and are "...difficult to isolate and
purify..."
This contradicts findings published in the March 2000 Edition of
the Proceedings of the National Academy of Sciences, which highlighted
that adult stem cells can now be grown "billion-fold" in the laboratory.
Even the NIH itself recently conceded that stem cells can be produced
to provide a "virtually limitless supply".14
Secondly, the NIH asserted the opinion that invasive surgery would
be required (removal of "a portion of the brain") in order to obtain
a source of neural stem cells to treat diseases such as Parkinsons
and Alzheimers.
However, this is also an outdated claim, given that the June 2000
Edition of the Journal Nature confirmed that neural stem cells
can be regrown inside the brain without the need for open surgery.15
Research published more recently in the Journal of Neuroscience
Research (August 2000) has added further weight to this case
confirming that bone marrow cells can now be grown into neural stem
cells (brain cells), thereby eliminating the need for invasive surgery.16
Thirdly and finally, the NIH claimed that "stem cells for all cell
and tissue types have not yet been found in the adult human."
This statement may have been true when the Report was published.
However, neither can this be said of embryonic stem cells (the preferred
option according to the NIH). Furthermore, the March Editions of
Nature Medicine and the British Medical Journal (BMJ) reported
that vital adult stem cell types, such as heart and pancreas stem
cells, have been identified in animal experimentation, the traditional
precursor to clinical use in humans. Further studies have also shown
that stem cells can be grown into other types of cells, bone marrow
cells to neural cells, for example. Again, the most current evidence
contradicts the findings of the NIH.
4. Conclusion
The recommendations made in the Reports of the Donaldson Committee
in the U.K. and the NIH in the United States respectively, on the
utility of using human embryos as a source of stem cells, and further
on the limitations of adult stem cells, are now completely out-dated.
Based on the most recent and ground-breaking medical research using
stem cells, it has become clear that "adult" stem cells
have outstanding advantages in terms of immediate clinical application,
safety and feasibility over all other sources of stem cells
and that the objections to the use of "adult" stem cells
have now been overcome. Objective analysis of the most up-to-date
stem cell research has revealed the following key points:
1. Adult stem cells are already being used extensively and successfully
in clinical medicine.
2. Stem cells taken from human embryos have significant problems
of rejection and have limited medical application.
3. Extensive documentary evidence exists to prove that adult stem
cells now meet all of the criteria set down by both the Donaldson
Committee and the NIH in the U.S.
1 Government Response
to the Recommendations Made in the Chief Medical Officer's Expert
Group Report: "stem cell research: Medical Progress with Responsibility",
Department of Health, Crown Copyright, August 2000.
2stem cell research:
Medical Progress with Responsibility, Department of Health,
Crown Copyright, August 2000.
3 Stem Cell Research:
Medical Progress with Responsibility, Department of Health,
Crown Copyright, August 2000.
4 Congressional
Testimony of David A. Prentice, Ph.D., http://www.stemcellresearch.org/prentice.
htm, February 7, 2000.
5 "Gene Therapy
of Severe Combined Immunodeficiency (SCID)-X1 Disease", Science
288, 669-672, April 28 2000.
6 N.B. It is these
claims that form the backbone of the case in support of the cloning
of human embryos for their stem cells.
7stem cell research:
Medical Progress with Responsibility, Department of Health,
Crown Copyright, August 2000.
8stem cell research:
Medical Progress with Responsibility, Department of Health,
Crown Copyright, August 2000.
9 The successful
treatment of Severe Combined Immuno-deficiency Disease (SCID).using
adult stem cells.
10 "Autologous
transplantation of ex vivo expanded bone marrow cells grown from
small aliqouts after high-dose chemotherapy for breast cancer.",
Blood, Vol.95 No.6, 2169-2174, March 15 2000.
11 "Long-term
survivors of Advanced Neuroblastoma with MYCN amplification: a report
of 19 patients surviving disease-free for more than 66 months",
Journal of Clinical Oncology, Vol. 17 Issue 10, 3216-3220, October
1999.
12 "Phase
1 trial of multiple cycles of high-dose chemotherapy supported by
autologous peripheral-blood stem cells.", Journal of Clinical
Oncology, Vol. 17 Issue 7, 2198, July 1999.
13 Guidelines
for Research Using Human Pluripotent Stem Cells, National Institutes
of Health, United States Government, August 2000.
14 Proceedings
of the National Academy of Sciences, 97, 3213-3218, 28 March
2000.
15 "Induction
of Neurogenesis in the neocortex of mice", Nature 405,
951-955, 22 June 2000.
16 "Adult
rat and human bone marrow stromal cells differentiate into neurons",
Journal of Neuroscience Research, Issue 61, 364-370, August
2000.