Egg Cells Grown From Stem Cells Produce Healthy Offspring In Mice

Credit: Wellcome Images

In a fantastic achievement, mouse egg cells produced from stem cells outside of the body have been shown to be fertile and able to produce healthy offspring

A team of scientists from Kyoto University has been developing ways to form egg and sperm cell types from stem cells for over a decade;  successfully producing fertile mouse eggs in 2012 from embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). While they had great success in the laboratory, the culmination of the research was to implant these eggs into mice - determining whether they were truly viable. 

What did the procedure involve?

Using both ESCs and iPSCs the researchers created egg precursor cells. They then implanted these within a group of cells sourced from fetal mouse ovaries. After a month of cell culturing they were able to produce over 50 mature egg cells.

Poor efficiency

While this was an immense achievement, a large number of mature egg cells displayed chromosomal abnormalities and only 75% appeared normal under the microscope. When they fertilised the eggs with sperm cells to form over 300 embryos they discovered that only 11% were viable - in contrast to the 62% success rate when using extracted adult egg cells. 

“If a similar strategy proves successful in human pluripotent stem cells, then the options for reproductive biology, but also genetic modification of the germ line, are profound” 

Future prospects

Due to the error rate the technique is a considerable way off being used in humans, but it does provide a novel route for studying germ cell development. It may be a possible option in the future when it comes to fertility treatment, but due to the large number of cells with genomic abnormalities the method is currently too risky for human adoption and might lead to serious diseases or disabilities. The study builds on other research proving that these cell types can be grown in the laboratory however, which is extremely encouraging news. 

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