Scientists Grow Human Embryo Model Without Sperm Or Egg

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A group of scientists in Israel have grown “complete” models of human embryos without the aid of sperm or eggs, according to a paper published Wednesday.

The Weizmann Institute team presented their findings to the journal, Nature. They mimicked the development of a human embryo using stem cells which were reprogrammed, giving them the potential to become any type of tissue in the body, the BBC reported. The resulting embryo took on the appearance of a “textbook” 14-day human embryo, even releasing the same hormones that trigger positive results in pregnancy tests, the outlet stated. (RELATED: Scientists Are Bioengineering Pig Livers To Meet Human Transplant Demands)

To create the embryo, scientists reportedly took the reprogrammed stem cells and subjected them to chemicals which were used to encourage them into becoming four types of cells found in the earliest stages of human life. Epiblast cells, which become fetus; trophoblast cells, which become the placenta; hypoblast cells, which become the supportive yolk sac; and extraembryonic mesoderm cells. Each of these cells were then mixed in a precise ratio. Scientists then stepped back to observe the results, BBC News reported.

Scientists observed approximately 1% of the mixture began to spontaneously assemble themselves into the structure of a human embryo.

“I give great credit to the cells — you have to bring the right mix and have the right environment and it just takes off,” Jacob Hanna from the Weizmann Institute of Science told BBC News. “That’s an amazing phenomenon.”

Though not identical, researchers hope to learn more about the earliest stages of human development and unknown causes of miscarriage, The Guardian reported.

Dr Peter Rugg-Gunn, a researcher of embryonic development at the Babraham Institute near Cambridge, called the Weizmann Institute’s work “impressive” and “significant.” However, he pointed out the lab-generated embryo would not be able to develop if transferred to the womb, “because it bypasses the stage needed to attach to the womb lining,” The Guardian reported.

Furthermore, the trophoblast, the cells which eventually become the placenta, were not properly organized, Rugg-Gunn stated.

Questions as to whether the lab-created embryo could exist and develop beyond 14-days are yet unanswered, since many countries only allow embryo research up to that time. In the United Kingdom (UK), however, embryo models are legally distinct from embryos, though ethical questions will undoubtedly arise.

“Some will welcome this — but others won’t like it,” Robin Lovell Badge, a researcher of embryo development at the Francis Crick Institute, told BBC News.

The Weizmann team stressed that to attempt pregnancy with the lab-generated cells would be unethical, illegal and actually impossible. They agree with Rugg-Gunn’s assessment that the lab-development goes beyond the point an embryo could successfully implant into the lining of the womb, the BBC reported.