Stem cell research is advancing, and has made it possible to create synthetic embryos without a sperm or an egg. Researchers recently used stem cells to create synthetic embryos, without a sperm or an egg, The Guardian reported. The model embryos resemble natural embryos in the earliest stages of human development.
According to a Guardian report, the embryos could help scientists understand the impact of genetic disorders and the biological reasons behind recurrent miscarriages.
But the entities grown in the laboratory fall outside current legislation in the United Kingdom and most other countries, because of which the research raises serious ethical and legal issues, the report said.
Stem cells are cells that can regenerate or develop into many different types of specialised cells in the body, such as muscle cells, blood cells and brain cells, serve as a repair system for the body, and can divide and renew themselves over a long time.
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Which cells does the embryo have?
Cells which eventually form the placenta, yolk sac and the embryo itself were present in the artificial structure. However, it is devoid of a beating heart or the beginnings of a brain.
According to the report, Professor Magdalena Żernicka-Goetz from the University of Cambridge and California Institute of Technology described the research on Wednesday at the annual meeting of the International Society for Stem Cell Research in Boston.
Quoting Żernicka-Goetz, the report said human embryo-like models can be created by the reprogramming of embryonic stem cells.
The report stated that there is no near-term possibility of the synthetic embryos being used clinically, and it would be illegal to implant them into a patient's womb. The report also said it is not yet clear whether the structures will be able to mature beyond the earliest stages of development.
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The motivation behind this research
Scientists were motivated to conduct this research to understand the "black box" period of development. The black box period of human development occurs about 16 or 17 days after fertilisation, and more than a week after the free-floating embryo has anchored itself to the lining of the womb. Since scientists are only allowed to cultivate embryos in the laboratory up to a legal limit of 14 days, the researchers decided to conduct this study to observe what happens during the black box period.
Quoting Robin Lovell-Badge, the head of stem cell biology and developmental genetics at the Francis Crick Institute in London, the report said the idea is that if one really models normal human embryonic development using stem cells, they can gain an "awful" lot of information about how human development begins, and what can go wrong, without having to use early embryos for research.
Earlier, a team led by Żernicka-Goetz and a rival group at the Weizmann Institute in Israel showed that mice stem cells could be encouraged to self-assemble into early embryo-like structures with an intestinal tract, a beating heart and the beginnings of a brain.
What is gastrulation?
In the new research, each model structure has been grown from a single embryonic stem cell. The model structures have reached the beginning of a developmental milestone called gastrulation, an early developmental process in which an embryo transforms from a one-dimensional layer of epithelial cells, the blastula, and reorganises into a multi-layered and multidimensional structure called the gastrula. According to the US National Institutes of Health, a mammalian gastrula is a three-tissue-layered organism that consists of the ectoderm, mesoderm and endoderm. The gastrula sets up the basic axes of the body.
A beating heart, intestinal tract of the beginnings of the brain are not present in a gastrula.
The model, however, shows the presence of primordial cells called amnion and germ cells, which are the precursor cells of egg and sperm.
It is not known whether the structures could theoretically grow into a living creature. For instance, while the synthetic embryos created from mouse cells appeared almost identical to natural embryos, they did not develop into live animals when implanted into the wombs of female mice.