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07/05/2018

Labs are growing human embryos for longer than ever before

That’s only a slight paraphrase of a news feature article this week in Nature.  The clearly-written article is devoid of scientific jargon, with helpful illustrations, open-access online, and readily accessible to the non-specialist.  Check it out.

Key points include:

  • Scientists who do not find it ethically unacceptable to create and destroy human embryos solely for research purposes continue to follow the so-called “14-day rule,” by which such experimentation is limited to the first 14 days after fertilization. At that point, the human nervous system starts to form and the time for twinning is past.
  • The 14-day rule is law in some nations, but until now has not been a practical issue because scientists have been unable to grow human embryos that long in the laboratory.
  • That technical limit has been sufficiently overcome that embryos are now surviving for almost 14 days. Scientists have not directly challenged the 14-day rule yet, but might, and would like to revisit it.
  • Experiments on human embryos in that time have included editing of critical genes to see what happens (sometimes they stop growing), and making hybrids of animal embryos with human cells whose purpose is to “organize” embryonic development rather than remain part of the developing individual.
  • Embryo-like structures, referred to as “embryoids” in the article, and sounding similar to “SHEEFs” (“synthetic human entities with embryo-like features”) are also being created. These entities don’t necessarily develop nervous systems in the same way as a natural embryo, prompting questions of just how much they are like natural embryos, whether the 14-day rule applies, and whether they raise other ethical concerns.

The last paragraph of the article, reproduced here with emphases added, is striking and more than a little ironic in light of arguments that embryos are “just a clump of cells”:

As the results of this research accumulate, the technical advances are inspiring a mixture of fascination and unease among scientists. Both are valuable reactions, says [Josephine] Johnston [bioethicist from the Hastings Center]. “That feeling of wonder and awe reminds us that this is the earliest version of human beings and that’s why so many people have moral misgivings,” she says. “It reminds us that this is not just a couple of cells in a dish.”

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