Thursday, October 11, 2007

Stem cells

There are two kinds of stem cells, adult stem cells and embryonic stem cells. Adult stem cells have proven to be very effective in treating certain ailments. Embryonic stem cells have proven to be very effective mostly at causing cancer. Adult cells taken from the umbilical cord bear resemblance to both kinds, but are really adult cells.

The characteristics that distinguish adult stem cells from embryonic stem cells is that adult stem cells are created by particular parts of the body and have the ability to (divide and) change only into the kinds of cells needed in those parts, while embryonic stem cells are able to change into cells for any part of the body.

All current successful stem cell therapies (actual cures and treatments of disease) are from adult stem cells.

Adult cells are obtainable from bone marrow and from umbilical cord blood.

Currently, embryonic stem cells can only be obtained in two ways: through growing them from an existing batch of embryonic stem cells, or by destroying a blastocyst, an embryo in the first week of pregnancy.

Researchers have found a way to create mouse embryonic cells from mouse adult skin cells. Mouse cells and human cells have different chemistry, however, and so they're still working on it. If it proves successful in humans, this technique could provide a ethics-clean source of embryonic cells. It could also serve as a cover for researchers who, hypothetically, obtain their cells from blastocysts, or on the gray market.

Some people think embryonic stem cell research would eventually lead to all kinds of cures and therapies. Other people counter that such funding would encourage people to have abortions, and they consider abortion to be manslaughter. Both of those positions are reasonable.

While the number of abortions in the US annually, on the order of a million, already dwarfs the need for embryonic stem cells, and the best time to harvest stem cells is in the first week of pregnancy, women with unwanted pregnancies (typically discovered at 2-6 weeks) would be offered and cling to the notion that their abortion would further science. While embryonic stem cells are present in older fetuses, a blastocyst is the preferred source.

And there is, in fact, a ready supply of blastocysts, coming from the practice of in-vitro fertilization (IVF), the making of "test-tube babies". Eggs are retrieved, fertilized, and begin to divide. The resulting blastocysts are inspected before being reimplanted. Those which fail inspection are considered "not viable", and are discarded. In some cases, there are more viable blastocysts than can be implanted. Those which appear viable but are not chosen to be implanted may be frozen, or discarded. It is this tiny number of blastocysts which could be used for research, if we allow them to be used for this purpose.

And if these are allowed to be used for research, it is a certainty that in every case of IVF, more eggs than are needed will be harvested, and as many as possible will be retained for research -- whether the parents know it or not.

There is a probability, however remote, that embryonic stem cell research could yield cures to many diseases. It could extend the life of those living. But the creation of every new line results with certainty in one human death. Until someone can show that the likelihood of curing enough disease and preventing enough sickness is greater than the likelihood of causing additional human death, I think the moratorium on Federal funding of harvesting new embryonic stem cells should stay in place.


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1 comment:

Anonymous said...

Nice article, Loren. Also glad to see you have a little "free time" to write. Enjoy it.

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