LCMS Convention Workbook St. Louis, Missouri — 2007, Page 384

Transcription machine transcription, uncorrected

⤓ Download .txt · copy text

384 THEOLOGICAL DOCUMENTS—COMMISSION ON THEOLOGY AND CHURCH RELATIONS

7, Astem cell isa cell from the embryo, fetus, or adult that has, un-
der certain conditions, the ability to reproduce itself for long pe-
riods or, in the case of adult stem cells, throughout the life of the
organism. Stem cells are able to give rise to specialized cells that
make up the tissues and organs of the body. This definition and
the following definitions are drawn from information on stem
cells provided by the National Institutes of Health of the United
States Government.”

Adult stem cells (also called somatic stem cells): Research be-
gan in the 1960s, and scientists have reported that “adult stem cells
occur in many tissues and that they enter normal differentiation
pathways to form the specialized cell types of the tissue in which
they reside. Adult stem cells may also exhibit the ability to form
specialized cell types of other tissues, which is known as transdif-
ferentiation or plasticity.”

Embryonic stem cells: Research on mouse embryos began more
than twenty years ago. In late 1998 the first successful isolation and
culture of human embryonic stem cells occurred at the University
of Wisconsin-Madison.

The embryos used in these studies were created for infertility purposes
through in vitro fertilization procedures and when they were no longer
needed for that purpose, they were donated for research with the in-
formed consent of the donor. . . . In the 3 to 5 day old embryo, called a
blastocyst, a small group of about 30 cells called the inner cell mass
gives rise to the hundreds of highly specialized cells needed to make up
an adult organism. In the developing fetus, stem cells in developing tis-
sues give rise to the multiple specialized cell types that make up the heart,
lung, skin, and other tissues. In some adult tissues, such as bone mar-
row, muscle, and brain, discrete populations of adult stem cells gener-
ate replacements for cells that are lost through normal wear and tear,
injury, or disease.”’

8. Stem cells derived from a blastocyst are said to be pluripotent:
[T]he fertilized egg is said to be totipotent—from the Latin torus, mean-
ing entire—because it has the potential to generate all the cells and tis-
sues that make up an embryo and that support its development in utero.
The fertilized egg divides and differentiates until it produces a mature

- organism. Adult mammais, including humans, consist of more than 200

kinds of cells. These include nerve cells (neurons), muscle cells (my-
ocytes), skin (epithelial) cells, blood cells (erythrocytes, monocytes,
lymphocytes, etc.), bone cells (osteocytes), and cartilage cells (chon-
drocytes). Other cells, which are essential for embryonic development
but are not incorporated into the body of the embryo, include the ex-
traembryonic tissues, placenta, and umbilical cord. All of these cells are
generated from a single, totipotent cell—the zygote, or fertilized egg....
Most scientists use the term pluripotent to describe stem cells that can
give rise to cells derived from all three embryonic germ layers—meso-
derm, endoderm, and ectoderm. These three germ layers are the embry-
onic source of all cells of the body. 78
Pluripotent human embryonic stem cells are derived from the
inner cell mass of a four- or five-day-old blastocyst. “Adult stem
cells are generally limited to differentiating into different cell
types of their tissue of origin. However, some evidence suggests
that adult stem cell plasticity may exist, increasing the number
of cell types a given adult stem cell can become.” ?°

9. Cloning techniques can be used to produce an embryo” without
the need for bringing sperm and egg together. Cloning for bio-
medical research, so-called “therapeutic” cloning, is the practice
of using cloning not to bring about another live-bom human be-
ing (reproductive cloning) but to provide an embryo that could be
used as a source of stem cells and for other research. The techni-
cal term for this cloning technique is “Somatic Cell Nuclear Trans-

fer” (SCNT). Many of the proposed therapeutic benefits of SCNT

are closely connected to stem cell research. Others suggest that

SCNT could be used to separate the nucleus from the egg of a pre-

implantation life threatened by diseased mitochondria, thus per-

mitting this life to develop disease-free in a donor egg.

2007 Convention Workbook

10. When stem cells are derived from an embryo, the embryo is de-
stroyed. People disagree about the significance of discarding
or destroying embryos, including the totipotent cells produced
by SCNT.

11. Many scientists argue that embryonic stem cells offer great
promise for medical research. Research on embryonic stem
cells may help scientists better understand how undifferenti-
ated stem cells become differentiated. Serious medical condi-
tions like cancer and various birth defects are due to abnormal
cell division and differentiation. Improved understanding,
therefore, may help with future therapies. Scientists also hope
to learn how to use stem cells to generate cells and tissues that
could be used for cell-based therapies.

Stem cells, directed to differentiate into specific cell types, offer the
possibility of a renewable source of replacement cells and tissues to
treat diseases including Parkinson’s and Alzheimer’s diseases, spinal
cord injury, stroke, burns, heart disease, diabetes, osteoarthritis, and
rheumatoid arthritis.*!

However, “a significant hurdle to this use and most uses of stem cells
is that scientists do not yet fully understand the signals that turn spe-
cific genes on and off to influence the differentiation of the stem cell.”
Stem cells may also be used to help in the testing of new drugs to de-
termine risks and benefits to human health.

A survey of contemporary science does not, of course, take us very
deeply into the moral questions and problems raised by the possibili-
ties opened to us by scientific research. In the next part of the report
we will be discussing the moral significance of pre-implantation hu-
man life in the very earliest stages. In connection with this discussion,
the following terms and descriptions may prove helpful:

Stages of development: An ovum, after fertilization, is called a
zygote. This becomes, in turn, a morula, blastocyst, embryo
and fetus. After birth, the fetus is a newborn.

Day 1 — Zygote: A recently fertilized ovum (first cell division).
Day 2 — 2-4 cell stage.

Days 3-4 — Morula: A very early stage of pre-natal mammalian
development. This stage starts when the zygote has developed
into a mass of 8-16 cells. This is typically 4 days after
fertilization, and about 10 days before it becomes implanted in
the wall of the womb. Some IVF techniques transfer the
embryo into the woman’s reproductive system at this stage.

Days 5-7 — Blastocyst: A stage of pre-natal mammalian
development that (in humans) extends from the morula stage (a
shapeless mass of cells about 4 days after fertilization), to a
bilaminar (two layer) embryo stage, 30-150 cells (1 week after
fertilization). Some IVF techniques transfer the embryo at this
stage, and this is the stage at which stem cells can be obtained.

Embryo: A stage of pre-natal mammalian development that (in
humans) extends from 2 to 8 weeks after fertilization. It is
termed a “bilaminar” or two-layer embryo during its second
week and becomes a trilaminar (three-layer) embryo during its
third week. At 9 weeks it is called a fetus. The word “embryo”
is also used generally to speak of all the early stages of
development.

Fetus: A stage of pre-natal mammalian development that (in
humans) extends from 9 weeks after fertilization until birth.

Pre-embryo: A term popularized by many writers, almost all of
whom are not scientists. It refers to a zygote, morula (8 cells),
blastocyst, or embryo before it develops a “primitive streak.”

Primitive streak: A marking which appears on a blastocyst about
14 days after fertilization, at about the time that it is implanted
in the wall of the uterus. Division into identical twins is very
rare after this point. (See below on “Twinning.”) The streak
will eventually develop into the spinal column.