Genetic Engineering - Cloning, DNA, Stem Cells Pros and Cons
Molecular genetics

The future technology

Arguments Against Embryonic Stem Cell Research

1) Embryos are lives

An embryo is actually a human; it should be valued as highly as a human life.

The reasoning can be summed up by the fact that, once an egg is fertilized, unless inhibited, it will develop into a fully-developed adult. This opinion is often related to religious doctrines which assert that conception marks the beginning of human life or the presence of a soul.

Based upon this reasoning, the subsequent argument against embryonic stem cell research is that human life is inherently valuable and should not be voluntarily destroyed. It has been argued that "the line at which an embryo becomes a human life remains as arbitrary as ever".

Viability is another standard under which embryos and fetuses have been regarded as human lives. In the United States, the 1973 Supreme Court case of Roe v. Wade concluded that viability determined the permissibility of abortions performed for reasons other than the protection of the woman's health, defining viability as the point at which a fetus is "potentially able to live outside the mother's womb, albeit with artificial aid."

The point of viability was 24 to 28 weeks when the case was decided and has since moved to about 22 weeks due to advancement in medical technology.

If further technological advances allow a sperm and egg to be combined and fully developed completely outside of the womb, an embryo will be viable as soon as it is conceived, and under the viability standard, life will begin at conception.

2) Exploring alternatives

Embryonic stem cells should be abandoned in favor of alternatives, such as those involving adult stem cells.

This argument is used by opponents of embryonic destruction as well as researchers specializing in adult stem cell research. It is often claimed by pro-life supporters that the use of adult stem cells from sources such as umbilical cord blood has consistently produced more promising results than the use of embryonic stem cells.

Furthermore, adult stem cell research may be able to make greater advances if less money and resources were channeled into embryonic stem cell research. Adult stem cells have already produced therapies, while embryonic stem cells have not.

Moreover, there have been many advances in adult stem cell research, including a recent study where pluripotent adult stem cells were manufactured from differentiated fibroblast by the addition of specific transcription factors.

Newly created stem cells were developed into an embryo and were integrated into newborn mouse tissues, analogous to the properties of embryonic stem cells. This argument remains hotly debated on both sides.

Those critical of embryonic stem cell research point to a current lack of practical treatments, while supporters argue that advances will come with more time and that breakthroughs cannot be predicted.

3) Scientific flaws in embryonic stem cell research

The use of embryonic stem cell in therapies may be fundamentally flawed. For instance, one study suggests that autologous embryonic stem cells generated for therapeutic cloning may still suffer from immune rejection.

The researchers note that: "Our results raise the provocative possibility that even genetically matched cells derived by therapeutic cloning may still face barriers to effective transplantation for some disorders." In other words, therapeutic cloning may not always produce matched tissues.

In contrast, there are reports of adult stem cells being successfully reintegrated into an autogenic animal. Another concern with embryonic stem cell treatments is a tendency of stem cells from embryos to create tumors.

4) Overstatement of research potential

Scientists have long promised spectacular results from embryonic stem cell research, and this has not yet occurred. Conspicuously, such criticism has even come from researchers themselves.

For example, in November 2004, Princeton University president and geneticist Shirley Tilghman said, "Some of the public pronouncements in the field of stem-cell research come close to overpromising at best and delusional fantasizing at worst."

Similarly, fertility expert and former president of the British Association for the Advancement of Science, Lord Winston has warned of a public backlash against stem cell research if it fails to deliver on some of the "hype" surrounding potential treatments.

Stem cells without embryonic destruction

Notably, a fundamental impediment to the widespread acceptance of embryonic stem cell research is the destruction of the embryo. Consequently, some stem cell researchers are working to develop techniques of isolating stem cells that are as potent as embryonic stem cells, but do not require the destruction of a human embryo.

Some believe that human somatic cells can be coaxed to "de-differentiate" and revert to an embryonic state. Researchers at Harvard University, led by Kevin Eggan, have attempted to transfer the nucleus of a somatic cell into an existing embryonic stem cell, thus creating a new stem cell line.

Another study published in August 2006 also indicates that differentiated cells can be reprogrammed to an embryonic-like state by introducing four specific factors.

Researchers at Advanced Cell Technology, led by Robert Lanza, reported the successful derivation of a stem cell line using a process similar to preimplantation genetic diagnosis, in which a single blastomere is extracted from a blastocyst.

It should be noted that this process has not yet demonstrated the ability of donor blastocysts to survive to term as well after blastomere harvesting. Nevertheless, the Lanza technique may in future allow for the creation of stem cells without embryonic destruction.

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