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University of Edinburgh researchers grew human eggs in a laboratory for the first time. The scientific breakthrough could lead to new fertility treatments such as new ways of preserving the fertility of children before they undergo cancer treatment, BBC reported.
The study, published last week in the Molecular Human Reproduction journal, said that the eggs were developed from an early stage in ovarian tissue to a mature stage ready for fertilization. The researchers collected tissue samples from the ovaries of 10 women who were going to have elective caesarian sections, KFOR reported.
They isolated from the follicles of the ovarian tissue fragments around 48 early-stage eggs. These were cultured in a lab of which nine reached the final stage of development. What the scientists achieved was a progression from human eggs grown only from a relatively late stage of development.
But David Albertini, the director of the Division of Laboratories at the Center for Human Reproduction in New York, said that the eggs appeared to have several abnormalities. He said that if the eggs are examined, they can tell there were a lot of things wrong with it. However, because the researchers would know what is wrong with the eggs, it can allow the scientists to return to the lab and refine the technology.
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He expressed hope that in the future, some of the abnormalities would disappear in the quality of eggs grown. Nevertheless, despite the limitations, it is still a technological breakthrough for scientists interested in understanding how the ovary works and its impact on a woman’s fertility. Albertini said it is a research triumph that opens new doors for them to understand how a human egg develops.
To grow the eggs, it required controlling carefully the laboratory conditions, including oxygen levels, hormones, proteins that stimulate growth, and the medium in which the eggs are cultured. But since the eggs have not been fertilized, it is unknown how viable they are.
No need to re-implant the tissue
The new study made available a way for eggs to be extracted, grown, and used. But there is no need to re-implant the tissue which means there would be no contaminating cancer cells. After the egg is grown in the lab to maturity, scientists hope that it would be implanted back in as an embryo, Stuart Lavery, a consultant gynecologist at Hammerstein Hospital, said.
Prior to the new research, young girls with cancer can preserve their fertility by having their ovarian tissue taken before treatment and frozen to be implanted later. However, the approach has drawbacks because, in the case of re-implanted tissue, the big risk and the big worry was that surgeons can put the cancer cells back, Evelyn Telfer, a professor at the University of Edinburgh, said, The Guardian reported.
Only nine eggs out of 48 reached full maturity. Telfer said that while it is very exciting to obtain proof of principle that it is possible to reach this stage in human tissue, it has to be tempered by the whole lot of work needed to have better culture conditions and to test the quality of the oocytes.
Tightly controlled process
Egg development is a very tightly controlled process and is timed in the human body. During the teenage years, some eggs will mature, while for some, it will take 20 years. During the development, the egg needs to lose half of its genetic material, or else there would be too much DNA when the egg is fertilized by a sperm.
Normally, the excess DNA is cast off into a polar body, a miniature cell. However, in the study, the polar bodies were abnormally large. Although it is a concern, Telfer said it likely can be addressed by improving the technology.
Lavery pointed out that although the lab-grown eggs are small in number and required optimization, the preliminary work still offers hope for patients.
Because of difference in laws, it would be legal to fertilize one of the lab-grown eggs in the UK to create an embryo for research purposes. However, the Edinburgh team lacks a license to perform the experiment. The researchers are still discussing if they will apply to the embryo authority for a license or collaborate with a center that has one.
But it will take many years before the study leads to new fertility preservation treatments. The authors noted that the eggs grown in the lab developed faster than they would in the body. The unusually large polar body might also suggest abnormal development.
Albertini estimated that it would be between 5 and 10 years away from seeing the technology applied clinically. He said that the team has a lot of work to do in terms of improving the efficiency of the procedure and in improving the quality of the eggs that come out.
Nevertheless, Professor Helen Picton, an expert in reproduction and early development from the University of Leeds, said that the latest breakthrough is valuable. But she added that significant further research is needed to confirm that the eggs are healthy and functioning as they should.
[researchpaper 리서치페이퍼=Vittorio Hernandez 기자]