Creating stem cell lines without destroying embryos

The recent announcements that a commercial company has been able to create stem cell lines without destroying embryos has hit most of the news programs and other outlets--with the expected feedback.

The technique involves the removal of a single cell from an 8-cell embryo (outside the human body) and culturing this cell to produce stem cells. The arguments against "destroying embryos" presumably do not apply because the embryo is not harmed in the process. You may remember that harvesting cells from a more-developed blastocyst--after the embryo has developed into a hollow ball with an inner cell mass--does destroy the embryo.

So, why 8 cells?

  • The previous cell division--which doubles the number of cells in the embryo--was made by a 4-cell embryo. One cell of an embryo at this stage could become a fetus--with perhaps 3 other babies created from the other 3 cells, giving the parents quadruplets.
  • Cell division is so rapid in the newly fertilized egg that "catching" an embryo at the 8-cell stage requires careful attention. Presumably, some of the embryos could be any number of cells prior to formation of the blastula. This is why the news reports tend to say "8-to-10-cell stage". Also, the cells do not necessarily divide simultaneously.
  • There are many reports that cells at early stages of division may not be genetically identical. Rapid cell divisions in the embryo may sometimes produce cells with very slightly different DNA content.
  • In pre-implantation genetic diagnosis, cells have been successfully removed from embryos of 8 cells or more without harming the embryo. This one is a bit tricky to prove, though, since more than one embryo so examined is usually introduced into the uterus for development into a fetus. If only one of 2-4 embryos develop into a fetus, there's no way of knowing why the others did not so develop.
  • Smoke and mirrors--there appears to be less public concern about an embryo with one cell removed than there is about a blastula with its germ cells removed. Good publicity for a commercial company and eventually great profits from newly-created cell lines.

Here are some considerations you might not have thought of--whatever your opinion about embryonic stem cells and their creation:

  • What will happen to the rest of the embryo? If it will be discarded, or used for potentially creating additional stem cell lines, this technique is no different from any technique that destroys an embryo.
  • Is the technique useful only for people planning in vitro fertilization and pre-implantation genetic diagnosis? If so, would two cells have to be removed--one for the genetic diagnosis and one for the stem stem line? Will removing two cells damage the embryo?
  • Will there be a market for embryos created solely for generating stem cell lines?
  • How will stem cell lines be created for diseases such as Alzheimers or other adult-onset conditions generally occurring when a person is no longer fertile?
  • If the embryo is yours, do you get the rights to any money made from the stem cell line(s) developed from that embryo?
  • If the method is so successful, how come only 2 cell lines could be created from 81 embryos?

Want to add some comments of your own? Please do.

Marie Godfrey, PhD

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