In what represents a major breakthrough in infertility treatment, reproductive biologist Evelyn Telfer and colleagues at the University of Edinburgh have finally completed the development of a human egg outside the human body for the first time, it was announced in January. The development represents the first step it what may be a major victory for both infertile couples and women who have suffered illnesses such as cancer in prepubescence, looking to have children.
Telfer and her team took samples from the ovaries of 10 women undergoing elective caesarean procedures. This tissue bears clusters of cells known as primordial follicles which surround the precursors of eggs. Telfer isolated 87 of these samples and allowed them to develop in a nutrient sub straight. After this Telfer removed immature eggs and placed them on a membrane alongside various growth-supportive proteins. Nine of these selected eggs were able to divide into 23-chromosome forms necessary for fertilisation.
Initial stages of this process have been achieved before. Telfer and her team succeeded in the first stage of this process in 2008, nourishing follicles to a semi-developed state. This was followed in 2015, by a team in Northwestern University in Chicago, creating matured eggs from follicles. But this is the first time anyone has successfully put these stages together. The process has also been successfully replicated in mouse eggs previously.
Erring on the side of caution
Whilst this is a fantastic development, it is necessary to point out that this research is still in its very early stages. The team are yet to test if the eggs, which matured over 22 days rather than the usual five months are normal in every respect, most importantly, can they actually be successfully fertilised?
It’s also vital to note that only 9 of the 87 samples actually successfully matured, a low success rate in a low-sample size which suggests that we should err on the side of caution when considering this research.
Mitinori Saitou, a stem cell biologist at Kyoto University in Japan whose team developed methods to create mouse egg cells from embryonic or reprogrammed stem cells told Science that he had serious reservations about the research. He noted that the paper doesn’t include any genetic analysis of the final eggs that confirms they are healthy. Saitou also points out that the shortened maturation process in the lab can’t possibly mirror development that naturally takes place over months. And the details of the final chromosome-halving division give him pause. Normally, a smaller cell called a polar body pinches off from the egg. In Telfer’s experiments, the polar bodies were abnormally large, suggesting that the egg hasn’t matured properly. “The final products they got are clearly abnormal,” he says. “Even if what they report is true, there are a lot of things that should be improved.”
Telfer has pointed out that this hasted maturity process is a result of the absence of inhibitory signals from the body, and that it does not necessarily point to invalid eggs, or results.
Looking to the future
Whilst there are clearly reservations that should be held when considering this research, Telfer points out that her team is working on improving the process and also hopes, that with approval from the United Kingdom’s Human Fertilisation and Embryology Authority, her team may begin trying to fertilize the lab-matured eggs to create human embryos. Any such embryos would just be studied during their early development for now—there are no plans yet to try to create a pregnancy with them.
Telfer isn’t the only researcher positive about the results of this study. Kyle Orwig, a stem cell biologist at the Magee-Womens Research Institute at the University of Pittsburgh in Pennsylvania who was not involved in the new work, told Science [The research is] extraordinarily important,” adding “It has real potential for application. We already have the patients.”
Clearly, this is just the beginning of a new paradigm of pregnancy and reproduction. offering a new hope to millions of women.
It’s difficult not to be positive about that.