How early human embryos can be mimicked by stem cells

A Creative Method for Researching Human Development :

The creation of synthetic human embryos that resemble the real ones at 14 days after fertilisation by an Israeli research team is an amazing accomplishment. They accomplished this without the use of sperm, eggs, or wombs by solely using stem cells.

Such models have never been created before, and they provide a unique opportunity to study and comprehend the intricate processes that occur during the earliest phases of human development. Due to ethical and legal restrictions, genuine human embryos cannot be used for study in most of these techniques.

After presenting their findings at the annual meeting of the International Society for Stem Cell Research (ISSCR) in Boston in June, the researchers, lead by Prof. Jacob Hanna of the Weizmann Institute of Science, published their findings in the journal Nature on Wednesday.

How did they succeed?

The researchers used two different kinds of stem cells: trophoblast stem cells (TSCs), which give rise to the placenta, and embryonic stem cells (ESCs), which can develop into any type of cell in the body. They combined these cells and cultivated them in a unique medium that replicated the womb's environment.

The cells grouped into a spherical structure that mimicked a blastocyst, the hollow ball of cells that forms following fertilisation, after a few days. Both the trophectoderm, the placenta's outer layer of cells, and the inner cell mass (ICM), which later turns into the embryo, are found in the blastocyst.

The blastocyst-like structures were then put into a different medium that might allow continued development by the researchers. They noticed that the ICM cells developed into the ectoderm, mesoderm, and endoderm, three germ layers. These are the fundamental layers from which the body's organs and tissues develop.

The human chorionic gonadotropin (hCG), which is used to identify pregnancy, is one among the hormones that the TSCs have continued to secrete and multiply. In fact, a pregnancy test in the lab produced a positive result when using the synthetic models.

The artificial models progressed until they resembled a human embryo at day fourteen, when gastrulation takes place. The germ layers rearrange themselves at this point, forming the primitive stripe that denotes the start of the body axis. Gastrulation is also seen as the moment at which a person's identity is established and at which twinning is no longer possible.

What Consequences Follow?

The artificial models have some drawbacks and are not exact replicas of actual human embryos. For instance, they lack the yolk sac, which gives the embryo nutrition and blood cells. Additionally, they lack a healthy amniotic cavity, which guards and cushions the embryo. Furthermore, they are not likely to continue to grow after 14 days since they lack some essential signals and structures.

However, because they accurately depict some of the key characteristics and dynamics of early embryogenesis, synthetic models are still very helpful for research on human development. Additionally, they might support study into numerous facets of reproductive health, including organ regeneration, miscarriage, infertility, and birth abnormalities.

According to Prof. Hanna, the goal of his team was not to build an embryo from scratch but rather to develop a tool that may advance scientific understanding and be advantageous to society. He claimed to be aware of the moral and legal ramifications of his work and to have adhered to the rules and procedures already in place for embryo research.

He added that he welcomed any comments and recommendations from other professionals and stakeholders and expressed the hope that his effort will lead to greater discussion and debate on the subject. He stated that he was willing to work with other scientists if they were interested in utilising his synthetic models in their own study.

Using skin cells to build a model of a human embryo

The team's leader said that they used both stem cells that were produced in the lab and those that were taken from adult subjects' skin. They forced these cells to revert to a stage when they could differentiate into several cell types.

Then, they were altered to create something that resembled an embryo. It was a technique to demonstrate how an embryo functions, not a genuine or artificial embryo—a term that some people disliked.

According to him, the cells started to alter, move correctly, and take the proper shape approximately 1 out of every 100 times. Up to 14 days, which is how long a human embryo grows, could be spent doing this.

The next goal, according to him, was to extend its shelf life to 21 days and increase its efficiency to 50%.

Contrasting human embryo models with other models :

It was similar to six other studies that produced models of human embryos this year, including one from Magdalena Ernicka-Goetz's group at the University of Cambridge, according to her.

None of these models, according to her, accurately reflected how people develop, but they all aided in understanding how humans develop through experimentation.

Considering the moral dilemmas :

Hanna and others noted that the discovery also caused some individuals to wonder what may occur if someone attempted to alter the course of human embryonic development. He clarified, though, that it was similar to understanding how atoms function, and that you shouldn't cease all research in this field just because someone might wish to set off a large explosion.

He emphasised the significance of being open and honest with others and not keeping anything from them.

Content Source Courtesy :

https://www.google.com/amp/s/www.indiatoday.in/amp/science/story/scientists-create-human-embryo-in-lab-without-eggs-sperm-2432267-2023-09-07

https://www.bbc.com/news/health-66715669.amp

https://www.reuters.com/science/israeli-scientists-create-model-human-embryo-without-eggs-or-sperm-2023-09-07/

1. medindia.net

2. in.ign.com

3. phys.org

4. wis-wander.weizmann.ac.il

5. vce.usc.edu

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