Researchers at Vrije Universiteit Brussel have derived human embryonic stem cells (hESC) earlier in the development stage of a blastomere (when it only has four cells), so the whole embryo is not destroyed.

Previously, scientists were able to derive hESC lines at the 8-cell stage, but that method had variable success rates and required the cells to be cultured with established hESCs. The new method doesn’t require a co-culture.

The development could make stem cell research easier to conduct by not raising as many ethical concerns. It could also change pre-implantation genetic diagnosis (PGD), by enabling the biopsy of one cell from a 4-cell stage embryo. This would let the remaining three cells grow into a blastocyst (five-day embryo) that could be implanted into the uterus and develop into a healthy baby. Currently GPD is performed at the 8-cell stage.

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