Two papers reported the generation of human blastocysts by culturing non-embryonic cells under specific conditions to transform them into blastocyst-like structures, called blastoids. In one study scientists treated stem cells derived from an established stem cell line with specific growth factors to generate the blastoids. In the second study, scientists used adult skin cells to reprogram them into blastoids.
In the same issue, Nature reported that scientists have developed an artificial womb that allows the development of early mouse embryos into a fetus that contained fully formed organs. In this study, scientists at Weizmann Institute of Science implanted mouse blastocysts into their artificial placenta that contained special media and gases to study organ development, unconstrained by the need to image these structures inside a uterus. These mouse embryos were healthy until day 11 before dying, maintaining viable gestation for about halfway through the animals' normal 20-day gestation. I believe, it's only a matter of time when this technology will be further developed to generate healthy newborn pups.
Society needs to consider the potential health benefits emerging from these studies to decide whether the benefits trump ethical principles and guidelines. We need to consider the definition of humanhood, and the idea of generating a human being in the absence of a woman's body.
Generating and developing a human from fertilisation to 'birth' (especially in the absence of the sperm and egg) challenges our definition of what it means to be a human being. We believe a human being gestated in an artificial womb is still human and deserves human dignity. Humanhood, should not be restricted only to an organism born from a human but should include the generation of an organism that looks human and is composed of the essential genetic code of homo sapiens.
However, the cultural ethical challenges arising from this technology can be daunting. How will people feel if women don't need to become pregnant in order to produce children? Many women feel biologically and psychologically connected to the fetus they are gestating. Moreover, the absence of human pregnancy may impact epigenetic processes and change the mother-child bonding. One could argue, however, that pregnancy may not be a critical process for human development and bonding, since normal human development occurs post-gestationally, in many families that have adopted children. In addition, the burden of medical responsibility for maintaining these embryos in an artificial placenta would fall on our overloaded hospital system. Should health insurance fund this technology?
In addition, it is important that regulators, politicians, physicians, scientists, religious scholars, and concerned citizens reflect on the nature of the internationally accepted '14-day rule,' which limits the growth of artificially generated human embryos for more than 14 days, when normally the primitive streak appears in the embryo, which is a band of cells that forms and is regarded as a precursor of the neural tube and nervous system. Both Nature reports were mindful of this 14-day rule and did not maintain these artificially generated embryos past 14 days.
The use of stem cell lines or adult cells, rather than sperm and eggs, avoids one important ethical issue associated with early human embryological research – the destruction of a traditional human embryo. Normally, premature embryos that gestate in utero less than 25 weeks face serious, if not fatal, consequences. The Nature ectogenesis article coupled with a previous report on how to better maintain premature sheep fetuses in an artificial womb may help us learn how to maintain the health and development of premature human fetuses. However, a profound ethical issue arises if scientists combine the two technologies (ie, generating human blastocyts from skin cells or stem cell lines and the artificial placenta). Attempting to gestate an embryo in vitro, from start to finish, sets the stage for a revolution in human gestation.
Because of the complex nature of ethical ectogenesis, it would be appropriate for the US National Academy of Science to organise a committee to examine these ethical issues, decide whether there should be limits on scientific ectogenesis research, and propose policies to guide decision-making. Perhaps, at this time research should focus only on the use of ectogenesis in treating premature fetuses and restrict the development of creating a completely viable artificial placenta. In an era of rapidly advancing science, our experts at the National Academy of Science should be proactive in providing research guidelines regarding ectogenesis.