Synthetic human embryo models: A new frontier in science with ethical implications

By Ricardo Diaz Milian.

The world has recently seen a significant breakthrough, as researchers announced the creation of the first synthetic human embryos derived from stem cells without using sperm or eggs. The details are lacking since the work has yet to be published in a peer-reviewed journal.  However, this development clearly raises both interesting prospects and complex ethical questions that have not been explored and that we must tackle as a society. To date, there is no ethical or legal framework for the development of synthetic human embryos.

The innovation, led by Prof. Magdalena Zernicka-Goetz and her team at the University of Cambridge and the California Institute of Technology, involves reprogramming embryonic stem cells to form embryo-like structures. These synthetic embryos include cells that typically form the placenta, yolk sac, and embryo. However, they lack key organs, such as a brain or a beating heart, and importantly, they are not the product of human reproduction.

One potential advantage of this type of research is the possibility to bring about revolutionary developments in organ transplantation. If this work progresses, it could potentially provide a limitless supply of organ transplants, reducing or even eliminating the current reliance on human donors, and potentially eliminating the need for immunosupressant therapy.  This could dramatically improve the lives of thousands of patients with organ failure who are waiting for a transplant.

However, we must be cautious. The creation of synthetic human embryos from stem cells without using sperm or eggs raises substantial ethical questions. Currently, there is an urgent need to establish a legal and ethical framework for this rapidly emerging field. Frankly, this news has caught most of the medical ethical community off guard. While the technology is progressing at a rapid pace, regulations and guidelines are struggling to keep up.

An international effort is crucial in the establishment of such frameworks. Otherwise, researchers may take advantage of the lack of regulation by moving their operations to countries with fewer restrictions, leading to a ‘race to the bottom’.  The collaborative, international development of a robust ethical and legal structure is the only way to ensure the responsible progress of this type of research.

At the same time, we must contemplate the future implications of this research. The generation of synthetic human embryos, while opening a potential gateway to breakthroughs in human development studies, organ transplantation, human tissue production for medical research, and infertility treatments, could also potentially pave the way towards a world with synthetic humans. One of the significant drawbacks of this scenario is the potential loss of genetic diversity. When working with synthetic embryos, researchers might inadvertently select for or against certain traits that initially appear advantageous, such as eliminating genes that cause disease. This process, however, could unintentionally erode the human genetic diversity typically preserved by natural reproduction. As a result, researchers may unknowingly select desirable traits or deselect undesirable ones, independent of natural selection.

This scenario poses a considerable risk as less genetically diverse populations could theoretically be more susceptible to unpredictable environmental changes. This type of selection also borders on eugenics, one of the most ethically controversial philosophies of the last century. The creation of synthetic human embryos differs from gene editing in embryos in that the latter involves targeted manipulation of specific genes, while the former focuses on building an embryo “from scratch” using stem cells. Both processes could lead to the development of less genetically diverse humans, potentially increasing susceptibility to future environmental changes.

As we stand at the precipice of this new era in science and medicine, the research from Zernicka-Goetz’s team, yet to be fully appraised by the wider scientific community, undeniably offers exciting prospects. It promises to improve our understanding of early human development and could potentially revolutionize organ transplantation. However, the creation of synthetic human embryos is not only a testament to human ingenuity and the relentless pursuit of knowledge but also a reminder of the responsibility we bear as stewards of this technology. The potential benefits of this groundbreaking research should not overshadow the importance of conducting it within a robust ethical framework.

Author: Ricardo Diaz Milian

Affiliations: Mayo Clinic, Jacksonville, Florida

Competing interests: None declared.

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