Updated April 23, 1998
CRS Report for Congress
Received through the CRS Web
Cloning: Where Do We Go From Here?
Specialist in Life Sciences
Science Policy Research Division
News in February 1997 that scientists in Scotland had succeeded in cloning an adult
sheep ignited a worldwide debate. Of concern are the ethical and social implications of
the potential application of cloning to produce human beings. The announcement
marked the first time that researchers were able to produce an exact genetic replica of
an animal adult. Scientists identify a number of potential medical and agricultural
applications for this technique. Within hours of the February 24 news, President Clinton
asked his National Bioethics Advisory Commission (NBAC) to initiate a complete review
of the ethical and social issues related to cloning and report back within 90 days. On
March 4, 1997, the President sent a memorandum to the heads of all executive
departments and agencies making it “absolutely clear that no federal funds will be used
for human cloning.” He also urged the private sector to adopt a voluntary ban on the
cloning of humans until the NBAC completed its evaluation.
Bills were introduced in the 1st session that would ban federally supported human
cloning research (S. 368 and H.R. 922), or human cloning altogether, H.R. 923 . One,
H.R. 922, was reported to the House (amended), H.Rept. 105-239, but received no floor
action. Hearings on cloning were held in both chambers. The NBAC presented its
report in June, recommending — among other things — that federal legislation be
enacted to prohibit anyone from attempting to create a child through cloning. The
President sent up to Congress legislation (the “Cloning and Prohibition Act of 1997”)
reflecting the NBAC recommendations; however, it was not introduced in the first
session. News reports on January 7, 1998, disclosed that a Chicago scientist, Dr.
Richard Seed, intended to clone a human being and that he already had 8 volunteers who
were willing to be cloned. Since then, 6 more cloning prohibition bills have been
introduced: S. 1574, H.R. 3133, S. 1599, S. 1601, S.1602, and S.1611. On February
11, 1998, efforts to call up S.1601 for consideration in the Senate failed (by a vote of
On February 24, 1997, scientists at the Roslin Institute in Edinburgh, Scotland,
announced that they had cloned an adult mammal for the first time. The researchers used
Congressional Research Service ˜ The Library of Congress
the nucleus of a mammary gland cell from an adult sheep and a sheep egg that had its
nucleus removed. The two were fused using electrical pulses; the pulses also prompted
the egg to start dividing and form an embryo. The embryo was then transferred to the
uterus of a surrogate sheep, where, one embryo implanted and grew to term resulting in
the birth of a live lamb, Dolly.1 Analyses of the genetic material confirmed that Dolly was
derived from the adult lamb’s mammary cell. Before cloning the adult sheep, scientists
believed that an early embryo was required as the source of the genetic material for cloning
and that a clone could not be derived from a cell of an adult animal.
The cloning method used to produce Dolly, known as somatic cell nuclear transfer
cloning, could have a number of significant medical and agriculture applications.
Examples include the creation of improved breeds of livestock, development of animals
that can produce drugs for use by or whose organs can be used in, humans. In the sheep
cloning experiment, the number of embryo implants that resulted in live births was very
low. A total of 277 fused eggs were implanted, but only one lamb was born. However,
researchers believe that further research will improve the efficiency of the technique. It
does not yet appear possible to clone humans. Nevertheless, a major concern of many
people, including some who support the cloning of animals, is that this technique could in
the future be developed to a point that would make it possible to clone humans.
In response to concerns about the potential application of cloning to produce humans,
actions were taken by the Administration and Congress. President Clinton, on February
24, 1997, asked the NBAC2 to thoroughly review the ethical and legal issues associated
with the use of cloning technology. The Commission reported its findings and
recommendations to the President on June 9, 1997. It recommended that federal
legislation be enacted to prohibit the use of cloning to create a child in both the public and
private sector. The NBAC found it morally unacceptable at this time to attempt to clone
humans because current scientific data indicate that the method is not safe. The “Cloning
and Prohibition Act” which the President sent to Congress for “immediate consideration
and prompt enactment” was not introduced in the first session of 105th Congress.
However, several bills which would ban cloning were introduced.
Legislation was introduced in the Senate on February 27, 1997, and House on March
5, 1997, that would prohibit the use of federal funds for human cloning research (S. 368
and H.R. 922), or, human cloning altogether (H.R. 923). H.R. 922, the Human Cloning
Research Prohibition Act, would prohibit the use of federal funds for any cloning research,
including the use of human somatic cell nuclear transfer technology to produce an embryo.
The bill would allow federal funds to be used to support research involving somatic cell
nuclear transfer or other cloning techniques to clone molecules, DNA cells other than
human embryo cells, or tissue. The use of somatic cell nuclear techniques to create
nonhuman animals would be permitted. H.R. 922 was reported to the House from the
Committee on Science (amended) on August 1, 1997 (H.Rept. 105-239, Part I).
Wilmut, I. et.al. Viable Offspring Derived From Fetal and Adult Mammalian Cells. Nature,
v.385, February 27, 1997, pp. 810-813.
NBAC was established by Presidential Executive Order 12975 on October 3, 1995, to
provide guidance to federal agencies on the ethical conduct of current and future human biological
and behavioral research.
A number of cloning prohibition bills have been introduced in the second session.
S. 1574 (Campbell), the “Human Cloning Prohibition Act,” introduced on January 27,
1998, would prohibit the cloning of a human being or research for the purpose of cloning
a human being or otherwise creating a human embryo. H.R. 3133 (Stearns), the “Human
Cloning Research Prohibition Act,” introduced on January 28, 1998, would prohibit
federal funding of research that includes the use of human somatic cell nuclear transfer
technology to produce an oocyte that is undergoing cell division toward development of
a fetus. S. 1599 (Bond) and S. 1601 (Lott), the “Human Cloning Prohibition Act of
1998,” introduced on February 3, 1998, would prohibit the use of, and the importation of,
an embryo produced through human somatic cell nuclear transfer technology. S.
1602/S.1611 (Feinstein), the “Prohibition on Cloning of Human Beings Act of 1998,”
introduced on February 3, 1998 and February 4, 1998, respectively, would prohibit the
implantation or attempt to implant the product of somatic cell nuclear transfer into a
What Is Cloning? Cloning is defined as making genetically identical copies of a single
cell or organism.3 Before cloning the adult sheep, researchers had created animal clones
only from early embryos, or embryo-derived cells. Cloning of animals has been done using
one of three techniques: blastomere separation, blastocyst division and twinning, or nuclear
transplantation. For each technique, an embryo is produced by in vitro fertilization (IVF),
where an egg is fertilized with sperm in a laboratory dish. Once fertilized, the embryo is
allowed to divide into a 2- to 8-cell stage and then is cloned by one of the three
In Blastomere Separation,5 the outer coating, or zona pellucida, is removed from
around a 2- to 8-cell embryo, then placed in a special solution that causes the cells, called
blastomeres, to separate. Each cell can then be cultured individually, because at this stage
of embryo development, each cell is totipotent, that is, it is undifferentiated and can
develop into an organism. After dividing a few times, each blastomere may develop into
a smaller-than-normal embryo that can be transferred to the uterus.
In Blastocyst Division, also called induced twinning, an embryo, at the blastocyst
stage, a more advanced stage of development than the blastomere, is mechanically split
into two. The two parts can be transferred to the uterus. If both halves develop, then, at
most, one blastocyst gives rise to identical twins.
In Nuclear Transplantation, a nucleus is transferred from each blastomere of a 4to 8-cell or later-stage embryo into the cytoplasm (cell contents other than nucleus) of an
egg from which the genetic material has been removed (enucleated egg). To do this, the
blastomere is placed beside an enucleated egg and their membranes are fused together
National Institutes of Health. Report of the Human Embryo Research Panel, vol. 1,
September 1994, p. D-4.
Today, in treating infertile couples, once an embryo is created by IVF, it is allowed to divide
into a 32-cell stage embryo and can then be transferred to the patient’s uterus. If the procedure is
successful, the embryo implants and results in the birth of a baby.
The information describing the 3 cloning techniques was obtained from The NIH Report of
the Human Embryo Research Panel, September 1994.
artificially for example, with electrical pulses. The nucleus from the blastomere enters the
egg cytoplasm and directs development of the embryo.
The Scottish scientists used a variant of the nuclear transplantation technique, where
the nucleus that programmed the creation of Dolly was transferred from the adult sheep
mammary cell, not an embryo. Researchers had thought that when cells became
differentiated to do certain jobs in the body, they could not revert to the embryo stage.
For example, they thought that a cell that became a liver cell remained a liver, but that
belief was disproved by the Scottish scientists. They were able to reprogram the genes in
a mammary-gland cell to make it act like an undifferentiated embryo, which then
developed into a sheep.
Potential Uses of Cloning
Cloning conceivably could be used to produce large numbers of genetically identical
organisms. However, many scientists wish to use it as a research tool to understand how
genes in cells can be switched off and on. Each cell in the body (with a few exceptions)
has the same genes. One embryo cell becomes mammary tissue and another liver when
certain genes are switched on and others switched off. The technique used by the Scottish
scientists turned off the genes for mammary function and turned on those that function at
the embryo stage. But scientists do not know how the technique worked. When more is
known, the hope is that this knowledge can be used for other research, such as growing
new skin for burn victims, culturing bone marrow that could be used to treat cancer
patients, and manipulating genes to cure sickle cell anemia.
The first public report of cloning human embryos occurred in 1993.6 However, those
embryos were never transferred into the uterus. Using IVF embryos which were
determined to be unsuitable to be transferred to the uterus, researchers at an IVF clinic at
George Washington University (GWU), supported with private funds, cloned the early
human embryos with the blastomere separation method. Seventeen 2- to 8-cell embryos,
which had been fertilized in vitro were separated into individual blastomeres and placed
in a special solution so that they could divide again. A total of 48 new embryos were
produced, although, most of them did not develop to the stage where they could be
implanted into the uterus (32-cell stage).
One potential application of cloning human embryos may be to treat infertility.
Infertility affects more than 2.8 million U.S. couples. About one-half of those couples
eventually conceive with some form of treatment, such as IVF. There have been more
than 16,000 IVF births worldwide since 1978 when the first IVF birth, of Louise Brown,
occurred in England. However, the overall live-birth rate for IVF is low. Research
indicates that if more than one embryo is transferred to the uterus per treatment cycle, the
chance that at least one will implant and lead to a live birth increases. However, some
patients (for example, older reproductive-age and so-called “poor responder” patients)
undergoing IVF have a limited number of embryos for transfer and implantation.
Researchers have suggested that those patients could benefit from having their embryos
Kolberg, R. Human Embryo Cloning Reported. Sci.,v. 262, Oct. 29, 1993, p. 652-653.
cloned. However, it is unclear that embryo cloning would help in these cases because the
quality of the embryos from such patients also tends to be diminished.7
An application of blastomere separation that is being done in the private sector and
is known as preimplantation diagnosis may be improved with cloning research. This
technique has been used experimentally to diagnose an early embryo for diseases like cystic
fibrosis, Duchenne muscular dystrophy, and Tay-Sachs. In the procedure, one or two cells
can be removed from an IVF embryo at the 8- to 16-cell stage for biopsy, without
affecting subsequent development of the embryo. The genetic material retrieved for biopsy
is analyzed for the presence or absence of a specific genetic defect. Unaffected embryos
can then be transferred to a woman’s uterus for implantation on the same day as the
biopsy. Since 1992 when this experimental technique was first used, more than 30 healthy
children have been born worldwide as a result of preimplantation diagnosis.
Ethical and Social Issues
The possibility of cloning human beings raises profound moral and ethical questions.
No scientific rationale has yet been identified for cloning an existing human. NIH Director
Harold Varmus stated at a February 26, 1997 hearing held by the House Appropriations
Subcommittee on Labor, HHS, and Education that he personally agrees with the public’s
opinion that cloning human beings is “repugnant.” A major concern is that cloning would
seriously affect society’s perception of what it means to be a human being. There are also
unanswered questions about a cloned individual’s personal identity, uniqueness, and
individuality. Many worry that cloning would lead to diminished respect for humans in
general, and for cloned individuals, in particular, since the cloned person could simply be
replaced with another clone. Others point out, that does not occur today with identical
twins, who are naturally produced clones.
In addition to possible problems related to individuality, identity, and human values,
cloning human embryos raises difficult questions about the rights of parents to control
their own embryos, other issues in reproductive rights, and privacy. Some observers
believe that it would be ethical to clone human embryos to help infertile couples conceive
in an IVF setting. For example, some believe that the technique, if perfected, could be
used by parents to grow one embryo to term and store (by freezing) the others indefinitely.
Later, one of these spare embryos could be thawed, transferred, implanted, and grown to
term, where it would become an identical, but younger, twin of the first sibling. Many are
concerned, however, that the production of a human clone of an existing embryo would
be counter to human values as civilization has defined them. Some parents might want to
store embryo clones as a backup in case their child died, or so that if their child needed an
organ or tissue transplant, such as bone marrow, the mother could give birth to the child’s
identical twin. Others argue that the use of clones as potential sources of tissue or organs
would be unethical. The National Advisory Board on Ethics in Reproduction (NABER)
has recommended that legislation be enacted to ban the commercial use of human
Jones, H.W. et.al. On Attempts at Cloning in the Human. Fertility and Sterility vol. 61,
March 1994, pp. 423-426.
National Advisory Board on Ethics in Reproduction. Report on Human Cloning through
Currently no regulations exist in the United States that would prohibit cloning
research like that done in Scotland, in which cells from an adult animal were used to make
the sheep clone. However, restrictions have been in place since January 1996 that prohibit
the Department of Health and Human Services (DHHS) from using federal funds to
support cloning research involving human embryos9 (see CRS Report 95-910). President
Clinton’s March 4 directive to all executive departments and agencies extends this ban to
all federally supported research, but does not apply to research done in the private sector.
An NIH-appointed Human Embryo Research Panel in 1994 developed guidelines and
recommendations on human embryo research. It determined that cloning by blastomere
separation or blastocyst splitting without transfer to the uterus warranted additional review
before the Panel could recommend whether the research should be federally funded.
However, the Panel concluded that federal funding for cloning by these two techniques
followed by transfer to the uterus should be unacceptable into the foreseeable future.
NIH’s review in this area was halted with the 1996 DHHS appropriations ban and a similar
ban applies to FY1998 funds (see CRS Report 95-910 for more information on the human
embryo research ban).
In the United States, human IVF has been developed and advanced in the private
sector. Currently, more than 300 IVF clinics are located throughout the United States and
operate with no federal money and little federal oversight. A law enacted in 1992, P.L.
102-493, mandates that all assisted reproductive technology programs comply with
certification and pregnancy-success-rates reporting-requirements. The Centers for Disease
Control and Prevention of the DHHS is responsible for implementing the Fertility Clinic
Success Rate and Certification Act of 1992. CDC released its first set of reports that rate
the success of more than 280 fertility clinics in the United States.10 Guidelines have been
developed by the industry but compliance is voluntary.
The American Society for Reproductive Medicine, which represents most of the IVF
clinics, published a set of ethical considerations for assisted reproductive technologies in
1994 for its members. Included was a recommendation that human blastomere research
be performed to determine which, if any, clinical indications may justify the practical use
of this technology. Guidelines on human cloning through blastomere separation were
developed by NABER in 1994. The group opposed certain applications of cloning,
including that done only to produce identical twins separated by years.
Embryo Splitting: An Amber Light.Kennedy Institute of Ethics Journal, Vol. 4, September 1994,
The National Institutes of Health (NIH), the agency that might support human embryo
research was prohibited from using FY1996 appropriated funds to support human embryo research
including that involving cloning with the January 26, 1996 enactment of P.L.104-99. This
restriction also applied to NIH FY1997 appropriations, P.L.104-208 and applies to NIH FY1998
1995 Assisted Reproductive Technology Success Rates. National Summary and Fertility
Clinic Reports, Volumes I, II, III, Centers for Disease Control and Prevention, American Society
for Reproductive Medicine, and Resolve, December 1997.