Arguments for Embryonic stem cell research

Proponents of embryonic stem cell research state these reasons:

1) The utilitarianism argument

Embryonic stem cells have the capacity to grow indefinitely in a laboratory environment and can differentiate into almost all types of bodily tissue. This makes embryonic stem cells an attractive prospect for cellular therapies to treat a wide range of diseases.

The social, economic and personal costs of the diseases that embryonic stem cells have the potential to treat are far greater than the costs associated with the destruction of embryos.

2) The human potential and humanity argument

This argument often goes hand-in-hand with the utilitarian argument, and can be presented in several forms:

Embryos, while of value, are not equivalent to human life while they are still incapable of existing outside the womb (i.e. they only have the potential for life).

Approximately 18% of zygotes do not implant after conception. Thus far more embryos are lost due to chance than are proposed to be used for embryonic stem cell research or treatments.

Blastocysts are a cluster of human cells that have not differentiated into distinct organ tissue; making cells of the inner cell mass no more "human" than a skin cell .

Some parties contend that embryos are not humans, believing that the life of Homo sapiens only begins when the heartbeat develops, which is during the 5th week of pregnancy, or when the brain begins developing activity, which has been detected at 54 days after conception.

3) The consequentialism argument

This can be seen as a more extreme view of the utilitarianism argument.

4) The efficiency argument

If an embryo is going to be destroyed anyway, isn't it more efficient to make practical use of it?

In vitro fertilization (IVF) generates large numbers of unused embryos (e.g. 70,000 in Australia alone). Many of these thousands of IVF embryos are slated for destruction. Using them for scientific research utilizes a resource that would otherwise be wasted.

While the destruction of human embryos is required to establish a stem cell line, no new embryos have to be destroyed to work with existing stem cell lines. It would be wasteful not to continue to make use of these cell lines as a resource.

Abortions are legal in many countries and jurisdictions. A logical argument follows that if these embryos are being destroyed anyway, why not use them for stem cell research or treatments?

5) Arguments for the superiority of embryonic stem cells

Embryonic stem cells can be considered far more useful therapeutically than adult stem cells

This is usually presented as a counter-argument to using adult stem cells as an alternative that doesn't involve embryonic destruction.

• Embryonic stem cells make up a significant proportion of a developing embryo, while adult stem cells exist as minor populations within a mature individual (e.g. in every 10,000 cells of the bone marrow, only 10 will be usable stem cells). Thus, embryonic stem cells are likely to be easier to isolate and grow ex vivo than adult stem cells.
• Embryonic stem cells divide more rapidly than adult stem cells, potentially making it easier to generate large numbers of cells for therapeutic means. In contrast, adult stem cell might not divide fast enough to offer immediate treatment.
  
• Embryonic stem cells have greater plasticity, allowing them to treat a wider range of diseases.
• Adult stem cells from the patient's own body might not be effective in treatment of genetic disorders. Allogeneic embryonic stem cell transplantation (i.e. from a healthy donor) may be more practical in these cases than gene therapy of a patient's own cell.
• DNA abnormalities found in adult stem cells that are caused by toxins and sunlight may make them poorly suited for treatment.
• Embryonic stem cells have been shown to be effective in treating heart damage in mice

6) Beginning of life

Before the primitive streak is formed when the embryo attaches to the uterus at approximately 14 days after fertilization, a single fertilized egg can split in two to form identical twins.

Also, rarely, two separately fertilized eggs can, instead of resulting in fraternal twins, fuse together and develop into a single human individual (a tetragametic chimera).

Therefore before the primitive streak is formed, an individual human life does not exist at fertilization, as it can go on to split into two separate individuals. Therefore, an individual human life begins when the primitive streak is formed — beyond which the cell group cannot split to make twins — and not before.

Therefore the blastocysts destroyed for embryonic stem cells do not have human life, and it is ethical to use them.

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