OPINION OF THE NATIONAL BIOETHICS COMMITTEE ON THE
THERAPEUTIC USE OF STEM CELLS
27 October 2000
Introduction and definitions
1. Research on stem cells and their possible
therapeutic applications did not begin yesterday. However, in
recent times interest in them has increased, among other things
as a result of the consulting committee set up on the topic by
the British government, of the guidelines published by the US
Health Ministry and of the resolution of the European Parliament.
On several occasions, the National Bioethics Committee has
expressed its opinion on problems related to human genetics in
specific documents: Identity and status of the human embryo on 21
June 1996, Cloning on 17 October 1997, Declaration on the
possibility of patenting cells of human embryonic origin of 25
February 2000 and Opinion on the project for a European protocol
on the protection of the human embryo and foetus of 31 March
2000. Furthermore, within the National Bioethics Committee a
working group was set up several months ago which has collected a
large body of documentation and discussed the problem in detail
in its various aspects. The following document is the collective
expression of this work: it aims to make a timely contribution to
the discussion of the scientific, ethical and political questions
that the use of stem cells for therapeutic purposes raises for
society and government. For the reader's convenience, several
preliminary definitions are given, also for the purpose of
correcting the ambiguities and distortions introduced into the
debate by the association between the expression "stem cells" and
the term "cloning", which refers to one of the techniques by
which it is possible to produce them.
2. The expression "stem cell" is used to refer to a
cell capable, in the course of the continuous process of its
successive duplications, of differentiating until it becomes a
"mature" cell of a specific tissue or generates other stem cells.
It had been known for some time that certain bone marrow cells
act as "progenitors", that is, as cells capable of
differentiating into blood cells which are thus continuously
replaced. As late as 1998 it was observed that stem cells
extracted from a human embryo may be isolated, cultured in the
laboratory and induced not only to differentiate into a single
specific type of cell (such blood, muscle, or heart, etc.) but to
differentiate into any type of cell whenever the culture
conditions are suitable. Stem cells can multiply indefinitely,
giving rise to both lines of new stem cells and to specialized
"daughter" cells. This property could in future allow completely
new forms of cell or tissue therapy to be performed, and allow
the creation of both undifferentiated and differentiated cells
and tissues. The therapy applied to a diseased or damaged cell or
tissue could actually consist of transplanting new cells or
tissues, which are added to the diseased or damaged ones and
ultimately replace them. In recent research on mice, for example,
it was found that embryonic stem cells injected into the heart of
an adult mouse were incorporated perfectly into the heart muscle
of the adult animal, that is, they differentiated into heart
muscle cells and became perfectly synchronized with the beat of
the host heart.
3. The capacity of the stem cells to differentiate into
specific tissues changes according to the origin of the cells and
to the development stage of the organism from which they have
been extracted. "Multipotent" cells, socalled because of their
capacity to multiply and remain in the culture but without the
capacity to be renewed an unlimited number of times, have been
identified in foetuses as well as in the adult human being,
although in limited numbers.
4. By day 4-5 after zygote formation (fertilization) an
embryo consists of identical cells (2 in number after about 30
hours, 4 after about 40 hours, 12-16 after about three days,
etc.) that are called "totipotent" insofar as they are not
specialized and thus have the property of differentiating into
all the cell lines required to form the embryo, including those
that will produce the placenta and the surrounding membranes. By
day four or five after fertilization (morula stage), the embryo
still consists of identical embryonic cells, although these cells
can no longer form an embryo. From day five to day six after
fertilization (blastocyst stage, some hundred or more cells) a
spherical cavity is formed in the morula from the external cell
mass of which the cells that will ultimately make up the placenta
begin to differentiate, together with the membranes surrounding
the embryo, while from the internal cell mass (20-30 cells) the
cells that will form the actual embryo itself start to
differentiate. The latter cells, isolated from the cell mass of
the internal cavity are "pluripotent" stem cells, in the sense
that they have the potential to differentiate into any type of
adult animal cell but not the property specific to totipotent
cells of producing an embryo. Indeed if these cells were
transferred into a uterus, they would not have the capacity to
become implanted and develop because the development of the
embryo cannot take place unless they are synchronized with that
of the placenta from which the embryo draws its nourishment.
Lastly, "germ" cells are defined as those pluripotent stem cells
that have been isolated from the progenitor reproductive cells,
those that will subsequently develop spermatozoa and egg
cells.
5. In research on stem cells, the term cloning is often
used ambiguously. In the first instance it is necessary to make a
distinction between cloning by cell division and cloning by
nuclear transplant. The former consists in producing several
embryos by separating the cells during the early stages of
division. It has been carried out successfully on human embryos
for the purpose of increasing the effectiveness of in vitro
fertilization methods and in pre-implantation diagnosis. The
latter, associated with the highly-publicized generation of the
sheep Dolly, is performed by removing the nucleus from an egg
cell ("enucleated oocyte") and replacing it ("nuclear
transplant") with the nucleus of a somatic cell from a patient
("somatic nuclear transplant"). If it were to prove possible to
apply this technique to human beings, all the pluripotent stem
cells cultured from the embryo formed by transferring the nucleus
of a cell of any kind (for example, a blood cell) of a patient
affected by any disease (for example, of the cardiac muscle),
would be genetically identical to those of the patient
him/herself and, if injected into the cardiac muscle, would
probably not give rise to any rejection reaction. The production
of these stem cells by means of this technique requires the
formation of an embryo, the development of which is arrested at
the blastocyst stage and from which the stem cells are isolated
for the purpose of growing them indefinitely in vitro. It thus
does not consist of the complete development of a embryo from
which spare tissues or organs would be taken. If this technique
were used in a treatment programme, the aim would be to
accumulate an adequate source of cell supplies for the patient.
It is still not understood how the material contained in the
enucleated egg cell succeeds in reprogramming the activity of the
transplanted adult nucleus, although it has been suggested that
it may be possible to create pluripotent cell lines directly from
the patients' transplanted cells, thus avoiding the step of the
formation of an embryo by means of an actual auto-transplant:
however, this option is not available at the present time. The
somatic nuclear transplant defined above is also known as
"therapeutic cloning", an ambiguous term as it suggests the
duplication of completely formed individuals from which tissues
or even spare organs are taken. They are instead actually stem
cells deriving from the embryo that, when grown in the
laboratory, can be induced to differentiate into cells and
ultimately into tissues of therapeutic interest.
6. The sheep Dolly is genetically identical to the
adult sheep whose mammary gland was extracted, and the nucleus of
which was transplanted into the enucleated egg cell from which
the animal was subsequently born. In this case we are dealing
with cloning of an entire organism, not just of a cell, and the
term "reproductive cloning" is used to distinguish this complete
development process from the previous one, which is partial and
not aimed at the reproduction of a human or animal organism
which, after insertion in a host uterus, can develop until birth
and ultimately evolve into an adult organism. Reproductive
cloning applied to man is explicitly prohibited by art. 1 of the
Additional Protocol to the Convention on Human Rights and
Biomedicine of the Council of Europe. Reference is often made to
the latter by the National Bioethics Committee, which shares the
same views on prohibition and so reproductive cloning will not be
taken into consideration in the present document.
How stem cells are isolated
7. Stem cells may be obtained from tissues of different
origin and, at the present state of our knowledge, may be
distinguished by the greater or lesser facility with which they
can be isolated, multiplied and grown in the laboratory and by
the variety and types of mature tissue cells that they may be
induced to produce. Hitherto stem cells have been isolated in the
tissues of adult individuals, foetuses, umbilical cord blood,
embryos in the early stages of development and, for the time
being, only as a potential possibility, as a conceivable
"reprogramming" of the adult cells which are thus already
differentiated and specialized into the desired cell type.
8. It has so far been possible to isolate and grow in
the laboratory stem cells derived from the cells of adult
individuals for the following tissue types: bone marrow, blood,
endothelium, nervous system, muscle. Table I shows the results of
the most recent results, from which it may be seen that, so far,
no stem cells have been found in other adult individual tissues.
The use of stem cells derived from the above-mentioned tissues is
subject to two main constraints: the difficulty of isolating
them, expanding them and maintaining them in an undifferentiated
state in the laboratory (a difficulty that for the time being it
seems possible to solve only in the case of bone marrow) and,
once they have been isolated, the difficulty of inducing them to
specialize over a wide range of tissues that are different from
the one from which they were isolated. So far in man only bone
marrow stem cells have successfully been induced to differentiate
into other types of cells (see Table I). In rat, one research
group has succeeded in getting nervous system stem cells to
differentiate into blood cells . The potential offered by this
research, which is of vital interest as it would allow
genetically compatible cell transplants, will certainly be
developed over the long term. This explains why research into
embryonic stem cells, which are much easier to isolate, expand,
maintain and differentiate, is considered by many researchers as
a necessary preliminary to the identification of the potential of
stem cells derived from adult individual tissues, i.e. that which
will most likely be used for therapeutic applications.
9. Stem cells can be isolated also from human foetal
tissue derived from the reproductive cells of foetuses resulting
from spontaneous abortions or voluntary interruption of
pregnancy, or else from the blood of the umbilical cord removed
at birth. At present it is not known what potential they have for
differentiation into different tissues. For example, stem cells
from umbilical cord blood currently have the potential to develop
certain tissues (bone marrow and blood) but not others, which
indicates that the differentiation of these cells into tissues
different from those in which they were isolated still has a
limited outcome, although mesenchymal progenitor cells have
recently been identified in umbilical cord blood . In Italy
research in this area is fairly well advanced, although the
determination of the degree of multipotentiality of stem cells
obtained by this procedure still requires much verification
before they can be considered as an alternative to embryonic cell
use.
10. The source of pluripotent stem cells that are easy
to isolate and culture in vitro in the laboratory is currently
the embryo at day five or six after fertilization (at the
blastocyst stage). The empirical demonstration of the truth of
this claim is obtained by examining the results of numerous
experiments carried out animals, in the first place the mouse ,
but also in guinea pigs, chickens, pigs, primates, etc. In late
1998 a group of US researchers published a preliminary report
describing the cultivation of human stem cells derived from 14
blastocysts successfully developed from 36 embryos donated by
women who had undergone medically assisted procreation . This
result was confirmed by other researchers who succeeded in
isolating and then in maintaining in culture human stem cells
derived from four blastocysts, which were then induced to
differentiate into progenitor cells of many different types of
tissue. However, only in mouse has it so far been possible to
transplant these progenitor cells into host mouse tissues and to
induce them to differentiate and be integrated. For example,
hemopoietic stem cells from mouse bone marrow were transplanted
into rats affected by the human equivalent of type I hereditary
tyrosinemia, a fatal metabolic disease, the target of which is
mainly liver hepatocytes: the transplanted stem cells induced
regeneration of the liver cells of the diseased mice and thus
repaired their genetic defect.
11. The nuclear transplant technique described in
section 5 above and tested in sheep, cattle, goats, pigs and mice
has shown that it is possible to generate embryos without using
spermatozoa. In the case of certain animals (the sheep Dolly, for
example), the process was carried out before birth. If however,
in the case of man, the process is halted after five or six days
(at the blastocyst stage), the stem cells derived from the
blastocysts not only behave like the stem cells derived from an
embryo generated by the union of sperm and egg, but could also
afford the substantial advantage of being genetically identical
to the cells of the person from which the nucleus was extracted,
thus avoiding all problems of rejection of the cell transplant in
the case in which the nucleus donor is a patient and the cell
transplant is aimed at repairing damage to diseased tissue in him
(auto-transplant). It should be noted however that animals born
as a result of the nuclear transplant technique are not exactly
identical to the animals whose cell nucleus was used to generate
them. Indeed they inherit the mitochondrial DNA contained in the
cytoplasm of the enucleated cell egg and the effects of this
mitochondrial inheritance on the immunological compatibility
between donor cell and receiving egg cell are still unknown.
Another problem that renders nuclear transplantation a
therapeutic option of difficult clinical generalization is the
finite number of human egg cells available, which cannot be
increased at will. However, somatic nuclear transplant may be
said to represent a very promising research avenue (although by
no means yet of treatment) regarding the possibility of
"reprogramming" adult human cells (see following section), which
is the most ambitious cell transplantation treatment project.
12. There is no doubt that the long-term aim of
research on stem cells for therapeutic purposes is to
"reprogramme" a mature cell of an adult individual in such a way
as to convert it back to its undifferentiated state and then to
induce it to differentiate into a specific type of cell different
from the type to which it belonged prior to "reprogramming". Once
it is understood how the human egg cell, after removal of its
nucleus, is capable of controlling the conversion of a
differentiated cell into a stem cell not only will it no longer
be necessary to form an embryo but also nuclear transplantation
will probably not be accompanied by the problem of tissue
incompatibility and subsequent rejection of the tissues
introduced into the individual hosting the transplant. This
long-term objective nevertheless means that experiments must be
performed on embryonic stem cells, the only ones that are
available today at a pluripotent stage. Obviously this
experimentation must be performed in animals in the initial
stages.
Possible therapeutic uses of stem cells and nuclear
transplants
13. Tissues and organs damaged by traumas or disease can
recover spontaneously. In some cases, however, treatment consists
of repair or even of replacement. For example, the transplanting
of bone marrow cells has been used with varying degrees of
success in the treatment of certain forms of leukaemia and
certain genetic diseases. The biological mechanisms underlying
their repair would be able to act much more effectively if an
adequate supply of undamaged cells was available to colonize the
organ or the damaged tissue in such as way as to speed up the
repair action and the normal physiological mechanisms. This is
the direction currently being followed by research into the
therapeutic use of stem cell lines: the laboratory reconstruction
of entire organs, such as kidneys or the heart, with their
lymphatic and blood vessel systems and their complex tissue
architecture or even their parts is still considered too remote a
goal for therapeutic applications realistically to be expected in
the short term. Available scientific evidence points rather to
the possibility that laboratory culture of cells capable of
repairing the damage suffered by certain organs may become
possible quite rapidly. The following table lists the diseases
that could represent a possible target for the specialized cells
generated by inducing the differentiation of stem cells.
| Cell type |
Disease |
| Nervous system cells |
Cerebral infarctus, Parkinson's,
Alzheimer's, Spinal cord damage, Multiple sclerosis |
| Heart muscle cells |
Infarctus of the myocardium |
| Insulin-synthetizing cells |
Diabetes |
| Cartilage cells |
Osteoarthritis |
| Blood cells |
Cancer, immunodeficiencies, diseases
of the hemopoietic system, leukaemia |
| Liver cells |
Hepatis, cirrhosis |
| Epithelial cells |
Burns, wounds |
|
Skeletal muscle cells
|
Muscular dystrophy |
| Bone cells |
Traumas, osteoporosis |
One of the socially more significant applications of this
innovative therapeutic technology could well prove to be the
treatment of diabetes, a multifactorial disease of genetic origin
that affects about 3% of the Italian population . In this way it
would be possible to inject patients with stem cells instead of
the current practice of injecting large quantities of pure
insulin; with the same end in view, stem cell lines induced to
produce human insulin on a permanent basis could conceivably be
prepared in the laboratory.
14. The nuclear transplant technique could be used for
purposes other than the production of stem cells, for instance,
for the correction of genetic defects during the early stages of
embryonic development or to treat diseases caused by alteration
of the mitochondrial DNA. Furthermore, progress in our knowledge
of human cell differentiation would allow animal experimentation
to be progressively reduced. These arguments nevertheless lie
beyond the scope of the present document and will be further
investigated by the Committee.
Technical problems and risks
15. The use of stem cells to produce tissues for
treatment purposes raises a number of technical issues,
including: how "normal" is the resulting tissue in terms of rate
of ageing, effects of harmful mutations, contamination of
different tissues, immunological tolerance; b) if the stem cells
produced by nuclear transplant from adult tissues give rise to as
broad a range of differentiated tissues as that derived from the
stem cells of an embryo produced by the fusion of sperm and egg
cell; c) if it is possible to general the number of cells
required for treatment purposes; d) to what extent and in what
dosage is the incorporation of health tissue derived from stem
cells effective in repairing damaged tissue. Obviously research
will be able to provide answers to these fundamental questions
only after a large quantity of experimental work has been done
initially using animal models, as is customary in all
experimentation performed for therapeutic purposes.
16. It may be anticipated that the two greatest risks
involved in the use of stem cells are: immunological rejection of
the nuclear transplant (mentioned above), which is common to all
transplants and with respect to which the simplest theoretical
solution would be to derive stem cells from the patients
themselves, a process that could be defined as cellular
auto-transplantation; and the risk of tumour formation due to the
transplantation of incompletely or anomalously developed stem
cells. Also in the latter case only experimentation, in the first
instance on animal models, will allow us to understand the
probable behaviour of laboratory-cultivated cells after
transplantation into an organism, their capacity to perform
normal functions, to integrate with existing cells, and the
factors that may induce them to develop tumours.
Ethical problems
17. The use of human stem cells raises important
ethical issues that essentially concern the origin of the cells
and the way in which they are derived. The fact that these cells
are currently isolated from human embryos at the blastocyst stage
(about day 5 or 6) or from tissues obtained from spontaneous
abortions or from voluntary interruptions of pregnancy implies
that the ethical problems should be treated very carefully prior
to any scientific discussion of the therapeutic potential or
research in this sector. Considering the matter in the light of
the origin of the stem cells, it would be preferable to divide
the arguments according to whether these cells derive: from
embryos created ad hoc for the purposes of scientific research;
from tissues of foetuses obtained from spontaneous abortions or
from voluntary interruptions of pregnancy; from tissues obtained
by means of somatic nuclear transplant; from embryos not used in
medically assisted fertilization.
18. The illegitimacy of creating an embryo in vivo or
in vitro for the sole purpose of research is a principle on which
a strong consensus exists at both the national and the European
level. More specifically, the Council of Europe has explicitly
banned it in art. 18, paragraph 2 of the Convention of Human
Rights and Biomedicine. Also the National Bioethics Committee has
expressed an opinion in this sense and reiterates this position
on the previously stated grounds. What remains to be debated are
the various ethical issues raised by the other procedures for
obtaining stem cells.
19. Although there is no specific legislation in Italy
regulating the use of foetal cells, tissues and organs, it is
quite easy to derive norms in this field from international
conventions and other laws or regulations. Ethically speaking,
the use of tissues from aborted foetuses has already been taken
into consideration by the National Bioethics Committee in one of
its previous documents and deemed legitimate in principle
whenever warranted by exclusive study, research or treatment
purposes. Conversely, the National Bioethics Committee is of the
opinion that the decision to interrupt pregnancy must be
conditioned by the expectation of possible economic and
therapeutic benefits deriving from the use of cells, tissues or
organs from the foetus. Likewise, the marketability and
patentability of the latter must be excluded. The National
Bioethics Committee deems that the use for therapeutic purposes
of stem cells deriving from foetal tissues must be subject to the
informed consent of the aborting woman, that it must consist of a
free, gratuitous and unconditioned act of disposition and that
the physicians performing the abortion must be different from
those performing removal of the organs.
20. It is considered that the possibility of deriving
pluripotent stem cells from the somatic cells of a patient with a
damaged tissue or organ would not raise any particular ethical
problem, except for those commonly related to human
experimentation, which include the need for adequate preliminary
testing on animal models. If such stem cells were found to have
the potential to differentiate into the damaged tissue and to
integrate with it, they would be able to begin or accelerate the
repair process. It would represent an actual autologous cell or
tissue transplant, or auto-transplant, that would have the
fundamental advantage from the therapeutic standpoint of not
causing any rejection reactions. The problem consists in the fact
that, at the present state of research, human stem cells in
optimal conditions of pluripotency, stability (when cultivated in
the laboratory) and of indefinite growth, can be obtained only
from embryos in the early stages of development.
21. Under what conditions and with what limitations is
it possible to allow the formation of embryos specifically
intended to be a source of material to prepare pluripotent cell
lines for treatment purposes? In this connection, several
different positions are represented on the National Bioethics
Committee. Several members identify the formation of the zygote
as the beginning of an individual human being that must be
guaranteed the same protection as a person. Other members of the
National Bioethics Committee consider that the status of person
is acquired at a later stage, and that the degree of protection
due to the embryo must be offset by an at least equivalent
concern for the treatment of the sick person. This concern,
together with that for the progress of scientific knowledge,
would, after rigorous investigation and scrutiny, justify the
creation of embryos for therapeutic purposes. As stated earlier,
art. 18, paragraph 2 of the Convention on Human Rights and
Biomedicine, awaiting ratification by the Italian parliament, is
significant in this connection. Lastly, some members consider as
compatible with their ethical values only the use of embryonic
cells for therapeutic purposes, but not their creation. These
different positions are represented within the Committee, which
acknowledges their respective ethical legitimacy.
22. However, there is a de facto situation with which
the Committee cannot come to terms, namely the existence in Italy
of embryos not used for implantation and cryoconserved in the
various centres in which medically assisted fertilization is
carried out. The substantial lack of control over these centres
means that the number of these socalled "supernumerary" embryos
cannot be assessed, although by extrapolating the data from other
countries and from personal knowledge, it is believed to be very
high. This is not the proper place to discuss the reasons for
these large numbers, or even to express the obvious desire that
they should decrease or disappear, but rather to show how these
embryos, owing to the fact that they were not implanted within a
period of time compatible with an acceptable biological risk, are
today doomed to be destroyed. The likelihood of some of them
being donated by married couples to other couples in any case
currently involves only a small number of cases. Part of the
Committee believe that removal and laboratory culture of stem
cells taken from an embryo that cannot be implanted does not
signify lack of respect for it, but if anything may be considered
a contribution by the donor couple to research into possible
treatment of diseases that are hard to treat and often incurable
which stems from an act of solidarity. The same part of the
National Bioethics Committee are aware that any use for research
purposes of cells derived from supernumerary embryos must be
measured against the constitutional principles which include the
protection of the life of the conceived being, the right to
health and the freedom of scientific research. They in any case
call for a regulatory mechanism coordinated with the more general
and now urgent regulation of medically assisted fertilization
techniques, without prejudice to the fact that it should in any
case consist of regulations based on transitory criteria. Another
part of the Committee expressed the opinion that the respect due
to human beings prevents the instrumental use of embryos leading
to their destruction which - at the time of thawing for the
purpose of removing pluripotent stem cells - must necessarily be
still alive in order to be used as a source of stem cells. This
direct and intentional destruction of "supernumerary" embryos,
even though performed for research or therapeutic purposes, is in
contrast with the duty to respect human life from the time of
conception on. The supporters of this opinion also criticize the
practice of freezing and storing human embryos in the socalled
embryo banks as this could encourage also other instrumental uses
of them.
23. The National Bioethics Committee has not neglected
reflection on the ethical significance that in research on stem
cells is acquired not only by the embryo's ontological status,
not only the health that it is hoped to restore to sick persons
by applying this research, but also the autonomy of women in
deciding to donate their egg cells to make somatic
transplantation possible (socalled "therapeutic cloning") and the
freedom of women and couples to decide on the fate of non
implanted embryos. For that part of the Committee who consider it
acceptable to remove and culture in the laboratory the stem cells
of an embryo that cannot be implanted, two factors thus become
particularly important: the quality of the information available
to the woman and the couple concerning the use of their donation,
which may involve research in the field of medically assisted
procreation or else therapeutic purposes; and the imperative need
for consent to the donation, in full respect of privacy and of
the principles governing the treatment of sensitive data, as is
in any case provided for by the laws of those European countries
that have legislated on the issue of research performed on the
embryo.
24. Several members of the Committee have expressed the
opinion that, for the time being, the right conditions do not
exist to commence experimentation on human beings and that a lot
more information must be gathered in the field of animal
experimentation.
Conclusions and recommendations
The National Bioethics
Committee:
25. deems that the possibility of cultivating in the
laboratory stem cells having the capacity to reproduce
indefinitely and to specialize in the formation of any tissue of
the human body represents a line of research of particular
interest as regards therapeutic applications. The use of these
cells to repair damaged tissues and, in future, also damaged
organs, by means of cell transplantation opens up new prospects
of treatment for a wide range of frequently occurring human
diseases that are today difficult to treat and often
incurable.
26. expresses the hope that such a line of research
will pursue the optimal objective of succeeding in
"reprogramming" mature cells, that is, of deriving stem cells
capable of differentiating into the desired tissues directly from
the already differentiated cells of the patient whose tissue it
is intended to regenerate. This would represent a cellular
auto-transplant that had the substantial advantage of tissue
compatibility and would thus presumably be used for important
therapeutic applications.
27. is fully aware that the pluripotent stem cells with
the greatest potential for differentiating into the widest range
of tissues (in animal models and in observed cases also in man)
are the stem cells derived from the embryo at the blastocyst
stage even when they are derived from the somatic nuclear
transplant process. The alternative attempts to derive stem cells
from umbilical cord blood or from other tissues that are capable
of expanding and differentiating into cells of tissues other than
the original ones are still at the early experimental stage.
28. deems it to be ethically legitimate to derive stem
cells from the cells of spontaneously aborted foetuses or those
produced by voluntary interruption of pregnancy provided suitable
steps are taken to exclude both causal relations between abortion
and stem cell derivation and any collaboration among
corresponding operators and marketability. Some members of the
Committee have nevertheless expressed reservations concerning the
possibility of distinguishing de facto collaboration among those
performing the abortion and the team using the foetuses derived
from the voluntary interruption of pregnancy even when suitable
formal procedures are adopted to distinguish the relationship of
causality between abortion and stem cell derivation.
29. points out that several of its members acknowledge
and agree with the ban on creating human embryos for the sole
purpose of using them for scientific research, as provided for in
art. 18, paragraph 2, of the Convention on Human Rights and
Biomedicine. A thorough evaluation of the experimental results of
somatic nuclear transplantation suggests, according to other
members of the Committee, that this new line of research could
produce therapeutic results of great significance and for the
time being without any alternative such as to suggest evaluating
the ethical aspects of future applications on a case by case
basis.
30. reiterates the illegitimacy of using the somatic
nuclear transplant technique for reproductive purposes
("reproductive cloning").
31. points out that part of the Committee consider it
ethically legitimate to derive stem cells for therapeutic
purposes from embryos that it is no longer possible to implant,
again on condition that they are wittingly donated by the women
or the couples concerned. They nevertheless recommend performing
investigations and rigorous verifications on a case by case basis
concerning the suitability for implantation, the consent to
donate and the therapeutic purpose of the experimentation. These
should be carried out by applying ad hoc indicators of a
reasonable degree of impossibility of implantation, as well as
the relative guidelines, ensuring that a preventive evaluation is
made by the ethical committees. Other members are in any case
against using supernumerary embryos even when cryopreserved and
not required for transfer to the uterus, as they consider such
practices to entail the direct and deliberate suppression of the
embryos and thus an instrumental use of human beings and an
offence to their dignity.
32. expresses the hope that a topic of such importance
for biological and medical research and so significant as regards
the possible treatment of diseases of great social impact and
today difficult to treat will be the object of accurate
information and wide debate. This should be the case not only
within the scientific community but also in civil society, so
that the latter can be made aware of and responsibly address the
problems of a chapter of medicine that, while certainly new, it
is hoped will also be effective, and to which the name of
"regenerative medicine" has been given.
| adult |
tissue/original cells |
tissue/final cells |
Authors |
Year |
|
from
cadaver |
progenitor cells
of hippocampus neurons |
neurons |
Eriksson P.S. et
al., Nature Medicine 1998, 4:1313-1317 |
1998 |
|
mesenchymal
cells of bone marrow |
adipocytes,
chondrocytes, osteocytes |
Pittinger M.F.
et al., Science 1999, 284: 143-147 |
1999 |
|
umbilical
cord |
progenitor
hemopoietic cells |
erythrocytes,
granulocytes, megakaryocytes, monocytes |
Fasouliotis
S.J., Schenker J.G., Obstetrics & Gynecology 2000, 90:
13-25 |
2000 |
|
bone
marrow |
cells expressing
neural proteins (neuron-like and glial cells) |
Sanchez-Ramos J
et al., Exp. Neur. 2000, 164: 247-256 |
2000 |
|
neuron
progenitor pool |
progenitor cells
of hippocampus neurons |
neurons |
Neeta Singh Roy
et al., Nature Medicine 2000, 6: 271-277 |
2000 |
|
olfactory
bulb |
neurons,
astrocytes, oligodendrocytes |
Pagano S.F. et
al., Stem Cells 2000, 18: 295-300 |
2000 |
|
healthy adult
volunteers |
stromal cells of
bone marrow (mesenchymal derivation) |
(non
mesenchymal) neuronal cells |
Woodbury D. et
al., Journal of Neuroscience Research 2000, 61:
364-370 |
2000 |
|
stem cells from
bone marrow |
hepatocytes |
Alison M.R. et
al., Nature 2000, 406: 257 |
2000 |
|
tissues from
autopsies and biopsies |
stem cells from
bone marrow |
hepatocytes and
cholangiocytes |
Theise N.D. et
al., Hepatology 2000, 32: 11-16 |
2000 |
|
case report and
review |
progenitor cells
from umbilical cord |
"hemopoietic and
immunological reconstitution" in acute leukaemia
patient |
Elhasid R. et
al., Leukemia 2000, 14: 931-934 |
2000 |
