A team of scientists have successfully created authentic models of a human embryo using stem cells, and successfully grown them outside of a womb until key embryonic features such as a yolk sac, and the precurser to a placenta appeared.
The researchers hope that their work will shed light on a relatively poorly understood early stage of human development, during which diseases and birth defects are known to develop. It had previously been challenging to gain a greater understanding of this formative period, owing to the practical and ethical issues surrounding the study of human embryos.
“The drama is in the first month, the remaining eight months of pregnancy are mainly lots of growth,” said professor Jacob Hanna of the Weizmann Institute of Science in Isreal, who led the international team behind the research. “But that first month is still largely a black box. Our stem cell–derived human embryo model offers an ethical and accessible way of peering into this box. It closely mimics the development of a real human embryo, particularly the emergence of its exquisitely fine architecture.”
Previous attempts to create such a model lacked a number of important cell-types present in early-stage embryos developing in the womb under normal conditions. The new study, which is published in the Journal Nature, built on earlier research that saw scientists create accurate models of mouse embryos, without the need to use a fertilised egg for a basis.
As part of the new research, scientists took a collection of flexible stem cells called pluripotent stem cells –
some of which were partially collected from human skin – and reverted them to an earlier form, known as ‘naive stem cells’. These early biological building blocks have the ability to transform themselves into an even greater variety of specialized cells as they mature.
The researchers then split the stem cells into three sets. One of these groups was left in its naive state, while the other two were subjected to chemical stimuli designed to switch on specific genes that would encourage them to transform into tissues needed to sustain the model embryo.
After this the three sets were combined. “It’s critical to mix in the right kinds of cells at the beginning, which can only be derived from naïve stem cells that have no developmental restrictions,” explained Hanna. “Once you do that, the embryo-like model itself says, ‘Go!’.”
One percent of the clumps that formed among the cells were able to successfully merge into embryo-like structures, which then grew for a further eight days. At this stage, the model embryos contained roughly 2,500 cells, and had reached a level of maturity the equivalent to a 14 day old human embryo that had grown in the womb.
“Our complete embryo models will help researchers address the most basic questions about what determines its proper growth.”
The team found that the structural compartments, and key features such as the yolk sac, and placenta precursor matched well with previous observations of their real world counterparts, though the location of some cell-types was not exactly right. It was also discovered that secretions from the models returned a positive response when subjected to a pregnancy test, which suggests that they are following similar biological processes to human embryos.
“An embryo is not static. It must have the right cells in the right organization, and it must be able to progress — it’s about being and becoming,” said Hanna. “Our complete embryo models will help researchers address the most basic questions about what determines its proper growth.”
However, when speaking to IGN study co-author professor Vincent Pasque of the Katholieke Universiteit Leuven in Belgium was keen to emphasise that the models created by the team are by no means actual human embryos.
“The goal of this research is absolutely not to create embryos or even less to create people, but to conduct basic research to better understand, because if we understand better, we may be help to design new advances in medicine,” explained professor Pasque. “In the future we will be able to gain more knowledge about early human embryo development. And knowledge is the foundation of applications.”
It is hoped that the research could one day help identify how human embryos form in a healthy way, and conversly, how this phase of early development can go awry, leading to complications in later life.
Image Credit: Weizmann Institute of Science
Anthony is a freelance contributor covering science and video gaming news for IGN. He has over eight years experience of covering breaking developments in multiple scientific fields and absolutely no time for your shenanigans. Follow him on Twitter @BeardConGamer
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The researchers hope that their work will shed light on a relatively poorly understood early stage of human development, during which diseases and birth defects are known to develop. It had previously been challenging to gain a greater understanding of this formative period, owing to the practical and ethical issues surrounding the study of human embryos.
“The drama is in the first month, the remaining eight months of pregnancy are mainly lots of growth,” said professor Jacob Hanna of the Weizmann Institute of Science in Isreal, who led the international team behind the research. “But that first month is still largely a black box. Our stem cell–derived human embryo model offers an ethical and accessible way of peering into this box. It closely mimics the development of a real human embryo, particularly the emergence of its exquisitely fine architecture.”
Our fun journey continues - latest lab preprint is now out in @Nature
Check out in great detail how we derive Complete and Structured human day 14 post-implantation embryo models (SEMs) solely from unmodified HENSM naïve ESCs@Beroldak @EmilieWildschu1 @vlad_bndk @noashefi… pic.twitter.com/BP3wduxL1H
— Jacob (يعقوب) Hanna (@jacob_hanna) September 6, 2023
Previous attempts to create such a model lacked a number of important cell-types present in early-stage embryos developing in the womb under normal conditions. The new study, which is published in the Journal Nature, built on earlier research that saw scientists create accurate models of mouse embryos, without the need to use a fertilised egg for a basis.
As part of the new research, scientists took a collection of flexible stem cells called pluripotent stem cells –
some of which were partially collected from human skin – and reverted them to an earlier form, known as ‘naive stem cells’. These early biological building blocks have the ability to transform themselves into an even greater variety of specialized cells as they mature.
The researchers then split the stem cells into three sets. One of these groups was left in its naive state, while the other two were subjected to chemical stimuli designed to switch on specific genes that would encourage them to transform into tissues needed to sustain the model embryo.
After this the three sets were combined. “It’s critical to mix in the right kinds of cells at the beginning, which can only be derived from naïve stem cells that have no developmental restrictions,” explained Hanna. “Once you do that, the embryo-like model itself says, ‘Go!’.”
One percent of the clumps that formed among the cells were able to successfully merge into embryo-like structures, which then grew for a further eight days. At this stage, the model embryos contained roughly 2,500 cells, and had reached a level of maturity the equivalent to a 14 day old human embryo that had grown in the womb.
“Our complete embryo models will help researchers address the most basic questions about what determines its proper growth.”
The team found that the structural compartments, and key features such as the yolk sac, and placenta precursor matched well with previous observations of their real world counterparts, though the location of some cell-types was not exactly right. It was also discovered that secretions from the models returned a positive response when subjected to a pregnancy test, which suggests that they are following similar biological processes to human embryos.
“An embryo is not static. It must have the right cells in the right organization, and it must be able to progress — it’s about being and becoming,” said Hanna. “Our complete embryo models will help researchers address the most basic questions about what determines its proper growth.”
However, when speaking to IGN study co-author professor Vincent Pasque of the Katholieke Universiteit Leuven in Belgium was keen to emphasise that the models created by the team are by no means actual human embryos.
“The goal of this research is absolutely not to create embryos or even less to create people, but to conduct basic research to better understand, because if we understand better, we may be help to design new advances in medicine,” explained professor Pasque. “In the future we will be able to gain more knowledge about early human embryo development. And knowledge is the foundation of applications.”
It is hoped that the research could one day help identify how human embryos form in a healthy way, and conversly, how this phase of early development can go awry, leading to complications in later life.
Image Credit: Weizmann Institute of Science
Anthony is a freelance contributor covering science and video gaming news for IGN. He has over eight years experience of covering breaking developments in multiple scientific fields and absolutely no time for your shenanigans. Follow him on Twitter @BeardConGamer
Continue reading...