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Myth turned material: Human-monkey chimeric embryos

In Greek Mythology, a chimera is a hybrid monster of a lion, serpent and goat. Less menacingly, a genetic chimera is an organism or embryo that contains two distinct sets of DNA, most likely from a combination of different fertilized zygotes. 

Genetic chimeras are distinctly different from hybrids (which contain genetically identical cells resulting from the cross of two different species) and genetic mosaics (which contain genetically different cells from a single zygote). Interestingly, a paper published in April of this year saw the successful creation of human-primate chimera embryos. Mammal chimeras have been created in lab settings for many years now, but this novel primate chimera was allowed through recent technological developments. For the first time, a primate embryo could be kept alive outside of the body for a much longer period. 

Six days after the creation of primate embryos, each was injected with 25 human cells from an induced pluripotent cell line. Of the original 132 chimera embryos created, survival rapidly declined, and only three remained by day 19. Despite this, the count of human cells in each embryo remained high throughout the course of the experiment, which has left many hopeful for future experiments. 

Someday, many hope that these cells could be used to experimentally model human development and disease while avoiding the ethical constraints of human research. However, there are still ethical concerns regarding the creation of human/non-human primate chimeras. 

Despite caveats, the chimera system could represent a breakthrough for the field of human development and infectious disease. With Covid-19 still a pressing global issue, many may be more perceptive to the use of human chimera cells to model disease as a prevention method for future outbreaks as well as for the experimental testing of vaccinations. 

Obviously, there is still a long way to go to ensure that chimera embryos can remain viable for a long enough period to allow for experimental use. Do you think this is a feasible option for future research in human developmental biology? 



Sources 

Cell Press. (2021, April 15). Scientists generate human-monkey chimeric embryos. ScienceDaily. Retrieved April 18, 2021 from www.sciencedaily.com/releases/2021/04/210415142904.htm

Chimera. (n.d.). Retrieved April 19, 2021, from https://www.britannica.com/science/chimera-genetics

Tan et al. Chimeric contribution of human extended pluripotent stem cells to monkey embryos ex vivo. Cell, 2021 DOI: 10.1016/j.cell.2021.03.020


Comments

  1. miredelkindApril 23, 2021 at 12:56 PM

    I wonder about the ethics of this scientific feat. Growing a single organ is one thing-- although I'm not sure if that's possible-- but seeing an entire individual for use as an organ farm seems questionable. Ethically, chimps already are so human like that I wonder if someone could actually. bring themselves to let these individuals fully develop. Although I think this is a really interesting topic, I don't think society would allow this to come to fruition.

    ReplyDelete
  2. Josiah JohnsonApril 25, 2021 at 6:38 PM

    I agree with @miredelkind that it is highly unlikely that any of these individuals would be allowed to fully develop if that even becomes scientifically possible. The question still remains then of how much development is ethically acceptable (probably not far, given that even at the embryo stage this is already an ethically gray area). We already use human cell lines, so I think there is a possibility this could become acceptable in those early stages.

    I am also curious as to what the research implications for human development would be. I see the point in creating such hybrids to more closely model human systems, which would be huge for disease research, but in terms of development having such a hybrid could muddle things greatly. Could a hybrid accurately model human development, or would it dictate an altered developmental scheme to accommodate both halves? The interaction between the two cell lines creates a novel mini-ecosystem with unknown implications. It is a very interesting line of research and obviously still in its infancy, so I will be curious as to how this reaches fruition (provided it is not a Planet of the Apes scenario).

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